Socio-ecological costs of Amazon nut and timber production at community household forests in the Bolivian Amazon

PubMed Central

Mohren, Frits; Ascarrunz, Nataly; Dressler, Wolfram; Peña-Claros, Marielos

2017-01-01

The Bolivian Amazon holds a complex configuration of people and forested landscapes in which communities hold secure tenure rights over a rich ecosystem offering a range of livelihood income opportunities. A large share of this income is derived from Amazon nut (Bertholletia excelsa). Many communities also have long-standing experience with community timber management plans. However, livelihood needs and desires for better living conditions may continue to place these resources under considerable stress as income needs and opportunities intensify and diversify. We aim to identify the socioeconomic and biophysical factors determining the income from forests, husbandry, off-farm and two keystone forest products (i.e., Amazon nut and timber) in the Bolivian Amazon region. We used structural equation modelling tools to account for the complex inter-relationships between socioeconomic and biophysical factors in predicting each source of income. The potential exists to increase incomes from existing livelihood activities in ways that reduce dependency upon forest resources. For example, changes in off-farm income sources can act to increase or decrease forest incomes. Market accessibility, social, financial, and natural and physical assets determined the amount of income community households could derive from Amazon nut and timber. Factors related to community households’ local ecological knowledge, such as the number of non-timber forest products harvested and the number of management practices applied to enhance Amazon nut production, defined the amount of income these households could derive from Amazon nut and timber, respectively. The (inter) relationships found among socioeconomic and biophysical factors over income shed light on ways to improve forest-dependent livelihoods in the Bolivian Amazon. We believe that our analysis could be applicable to other contexts throughout the tropics as well. PMID:28235090

Amazon rain-forest fires.

PubMed

Sanford, R L; Saldarriaga, J; Clark, K E; Uhl, C; Herrera, R

1985-01-04

Charcoal is common in the soils of mature rain forests within 75 kilometers of San Carlos de Rio Negro in the north central Amazon Basin. Carbon-14 dates of soil charcoal from this region indicate that numerous fires have occurred since the mid-Holocene epoch. Charcoal is most common in tierra firme forest Oxisols and Ultisols and less common in caatinga and igapo forest soils. Climatic changes or human activities, or both, have caused rain-forest fires.

Road building, land use and climate change: prospects for environmental governance in the Amazon.

PubMed

Perz, Stephen; Brilhante, Silvia; Brown, Foster; Caldas, Marcellus; Ikeda, Santos; Mendoza, Elsa; Overdevest, Christine; Reis, Vera; Reyes, Juan Fernando; Rojas, Daniel; Schmink, Marianne; Souza, Carlos; Walker, Robert

2008-05-27

Some coupled land-climate models predict a dieback of Amazon forest during the twenty-first century due to climate change, but human land use in the region has already reduced the forest cover. The causation behind land use is complex, and includes economic, institutional, political and demographic factors. Pre-eminent among these factors is road building, which facilitates human access to natural resources that beget forest fragmentation. While official government road projects have received considerable attention, unofficial road building by interest groups is expanding more rapidly, especially where official roads are being paved, yielding highly fragmented forest mosaics. Effective governance of natural resources in the Amazon requires a combination of state oversight and community participation in a 'hybrid' model of governance. The MAP Initiative in the southwestern Amazon provides an example of an innovative hybrid approach to environmental governance. It embodies a polycentric structure that includes government agencies, NGOs, universities and communities in a planning process that links scientific data to public deliberations in order to mitigate the effects of new infrastructure and climate change.

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

PubMed Central

Longo, Marcos; Baccini, Alessandro; Phillips, Oliver L.; Lewis, Simon L.; Alvarez-Dávila, Esteban; Segalin de Andrade, Ana Cristina; Brienen, Roel J. W.; Erwin, Terry L.; Feldpausch, Ted R.; Monteagudo Mendoza, Abel Lorenzo; Nuñez Vargas, Percy; Prieto, Adriana; Silva-Espejo, Javier Eduardo; Malhi, Yadvinder; Moorcroft, Paul R.

2016-01-01

Amazon forests, which store ∼50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale die-back of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size- and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem’s resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest’s response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions. PMID:26711984

Abrupt Increases in Amazonian Tree Mortality Due to Drought-Fire Interactions

NASA Technical Reports Server (NTRS)

Brando, Paulo Monteiro; Balch, Jennifer K.; Nepstad, Daniel C.; Morton, Douglas C.; Putz, Francis E.; Coe, Michael T.; Silverio, Divino; Macedo, Marcia N.; Davidson, Eric A.; Nobrega, Caroline C.;

Abrupt increases in Amazonian tree mortality due to drought-fire interactions.

PubMed

Brando, Paulo Monteiro; Balch, Jennifer K; Nepstad, Daniel C; Morton, Douglas C; Putz, Francis E; Coe, Michael T; Silvério, Divino; Macedo, Marcia N; Davidson, Eric A; Nóbrega, Caroline C; Alencar, Ane; Soares-Filho, Britaldo S

2014-04-29

Interactions between climate and land-use change may drive widespread degradation of Amazonian forests. High-intensity fires associated with extreme weather events could accelerate this degradation by abruptly increasing tree mortality, but this process remains poorly understood. Here we present, to our knowledge, the first field-based evidence of a tipping point in Amazon forests due to altered fire regimes. Based on results of a large-scale, long-term experiment with annual and triennial burn regimes (B1yr and B3yr, respectively) in the Amazon, we found abrupt increases in fire-induced tree mortality (226 and 462%) during a severe drought event, when fuel loads and air temperatures were substantially higher and relative humidity was lower than long-term averages. This threshold mortality response had a cascading effect, causing sharp declines in canopy cover (23 and 31%) and aboveground live biomass (12 and 30%) and favoring widespread invasion by flammable grasses across the forest edge area (80 and 63%), where fires were most intense (e.g., 220 and 820 kW ⋅ m(-1)). During the droughts of 2007 and 2010, regional forest fires burned 12 and 5% of southeastern Amazon forests, respectively, compared with <1% in nondrought years. These results show that a few extreme drought events, coupled with forest fragmentation and anthropogenic ignition sources, are already causing widespread fire-induced tree mortality and forest degradation across southeastern Amazon forests. Future projections of vegetation responses to climate change across drier portions of the Amazon require more than simulation of global climate forcing alone and must also include interactions of extreme weather events, fire, and land-use change.

Abrupt increases in Amazonian tree mortality due to drought–fire interactions

PubMed Central

Brando, Paulo Monteiro; Balch, Jennifer K.; Nepstad, Daniel C.; Morton, Douglas C.; Putz, Francis E.; Coe, Michael T.; Silvério, Divino; Macedo, Marcia N.; Davidson, Eric A.; Nóbrega, Caroline C.; Alencar, Ane; Soares-Filho, Britaldo S.

2014-01-01

Interactions between climate and land-use change may drive widespread degradation of Amazonian forests. High-intensity fires associated with extreme weather events could accelerate this degradation by abruptly increasing tree mortality, but this process remains poorly understood. Here we present, to our knowledge, the first field-based evidence of a tipping point in Amazon forests due to altered fire regimes. Based on results of a large-scale, long-term experiment with annual and triennial burn regimes (B1yr and B3yr, respectively) in the Amazon, we found abrupt increases in fire-induced tree mortality (226 and 462%) during a severe drought event, when fuel loads and air temperatures were substantially higher and relative humidity was lower than long-term averages. This threshold mortality response had a cascading effect, causing sharp declines in canopy cover (23 and 31%) and aboveground live biomass (12 and 30%) and favoring widespread invasion by flammable grasses across the forest edge area (80 and 63%), where fires were most intense (e.g., 220 and 820 kW⋅m−1). During the droughts of 2007 and 2010, regional forest fires burned 12 and 5% of southeastern Amazon forests, respectively, compared with <1% in nondrought years. These results show that a few extreme drought events, coupled with forest fragmentation and anthropogenic ignition sources, are already causing widespread fire-induced tree mortality and forest degradation across southeastern Amazon forests. Future projections of vegetation responses to climate change across drier portions of the Amazon require more than simulation of global climate forcing alone and must also include interactions of extreme weather events, fire, and land-use change. PMID:24733937

Ecosystem heterogeneity and diversity mitigate Amazon forest resilience to frequent extreme droughts.

PubMed

Longo, Marcos; Knox, Ryan G; Levine, Naomi M; Alves, Luciana F; Bonal, Damien; Camargo, Plinio B; Fitzjarrald, David R; Hayek, Matthew N; Restrepo-Coupe, Natalia; Saleska, Scott R; da Silva, Rodrigo; Stark, Scott C; Tapajós, Raphael P; Wiedemann, Kenia T; Zhang, Ke; Wofsy, Steven C; Moorcroft, Paul R

2018-05-22

The impact of increases in drought frequency on the Amazon forest's composition, structure and functioning remain uncertain. We used a process- and individual-based ecosystem model (ED2) to quantify the forest's vulnerability to increased drought recurrence. We generated meteorologically realistic, drier-than-observed rainfall scenarios for two Amazon forest sites, Paracou (wetter) and Tapajós (drier), to evaluate the impacts of more frequent droughts on forest biomass, structure and composition. The wet site was insensitive to the tested scenarios, whereas at the dry site biomass declined when average rainfall reduction exceeded 15%, due to high mortality of large-sized evergreen trees. Biomass losses persisted when year-long drought recurrence was shorter than 2-7 yr, depending upon soil texture and leaf phenology. From the site-level scenario results, we developed regionally applicable metrics to quantify the Amazon forest's climatological proximity to rainfall regimes likely to cause biomass loss > 20% in 50 yr according to ED2 predictions. Nearly 25% (1.8 million km 2 ) of the Amazon forests could experience frequent droughts and biomass loss if mean annual rainfall or interannual variability changed by 2σ. At least 10% of the high-emission climate projections (CMIP5/RCP8.5 models) predict critically dry regimes over 25% of the Amazon forest area by 2100. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Changes in the Carbon Cycle of Amazon Ecosystems During the 2010 Drought

NASA Technical Reports Server (NTRS)

Potter, Christophera; Klooster, Steven; Hiatt, Cyrus; Genovese, Vanessa; Castilla-Rubino, Juan Carlos

2011-01-01

Satellite remote sensing was combined with the NASA-CASA carbon cycle simulation model to evaluate the impact of the 2010 drought (July through September) throughout tropical South America. Results indicated that net primary production (NPP) in Amazon forest areas declined by an average of 7% in 2010 compared to 2008. This represented a loss of vegetation CO2 uptake and potential Amazon rainforest growth of nearly 0.5 Pg C in 2010. The largest overall decline in ecosystem carbon gains by land cover type was predicted for closed broadleaf forest areas of the Amazon River basin, including a large fraction of regularly flooded forest areas. Model results support the hypothesis that soil and dead wood carbon decomposition fluxes of CO2 to the atmosphere were elevated during the drought period of 2010 in periodically flooded forest areas, compared to forests outside the main river floodplains.

Exploring uncertainty of Amazon dieback in a perturbed parameter Earth system ensemble.

PubMed

Boulton, Chris A; Booth, Ben B B; Good, Peter

2017-12-01

The future of the Amazon rainforest is unknown due to uncertainties in projected climate change and the response of the forest to this change (forest resiliency). Here, we explore the effect of some uncertainties in climate and land surface processes on the future of the forest, using a perturbed physics ensemble of HadCM3C. This is the first time Amazon forest changes are presented using an ensemble exploring both land vegetation processes and physical climate feedbacks in a fully coupled modelling framework. Under three different emissions scenarios, we measure the change in the forest coverage by the end of the 21st century (the transient response) and make a novel adaptation to a previously used method known as "dry-season resilience" to predict the long-term committed response of the forest, should the state of the climate remain constant past 2100. Our analysis of this ensemble suggests that there will be a high chance of greater forest loss on longer timescales than is realized by 2100, especially for mid-range and low emissions scenarios. In both the transient and predicted committed responses, there is an increasing uncertainty in the outcome of the forest as the strength of the emissions scenarios increases. It is important to note however, that very few of the simulations produce future forest loss of the magnitude previously shown under the standard model configuration. We find that low optimum temperatures for photosynthesis and a high minimum leaf area index needed for the forest to compete for space appear to be precursors for dieback. We then decompose the uncertainty into that associated with future climate change and that associated with forest resiliency, finding that it is important to reduce the uncertainty in both of these if we are to better determine the Amazon's outcome. © 2017 John Wiley & Sons Ltd.

The Amazon forest-rainfall feedback: the roles of transpiration and interception

NASA Astrophysics Data System (ADS)

Dekker, Stefan; Staal, Arie; Tuinenburg, Obbe

2017-04-01

In the Amazon, deep-rooted trees increase local transpiration and high tree cover increase local interception evaporation. These increased local evapotranspiration fluxes to the atmosphere have both positive effects on forests down-wind, as they stimulate rainfall. Although important for the functioning of the Amazon, we have an inadequate assessment on the strength and the timing of these forest-rainfall feedbacks. In this study we (i) estimate local forest transpiration and local interception evaporation, (ii) simulate the trajectories of these moisture flows through the atmosphere and (iii) quantify their contributions to the forest-rainfall feedback for the whole Amazon basin. To determine the atmospheric moisture flows in tropical South America we use a Lagrangian moisture tracking algorithm on 0.25° (c. 25 km) resolution with eight atmospheric layers on a monthly basis for the period 2003-2015. With our approach we account for multiple re-evaporation cycles of this moisture. We also calculate for each month the potential effects of forest loss on evapotranspiration. Combined, these calculations allow us to simulate the effects of land-cover changes on rainfall in downwind areas and estimate the effect on the forest. We found large regional and temporal differences in the importance how forest contribute to rainfall. The transpiration-rainfall feedback is highly important during the dry season. Between September-November, when large parts of the Amazon are at the end of the dry season, more than 50% of the rainfall is caused by the forests upstream. This means that droughts in the Amazon are alleviated by the forest. Furthermore, we found that much moisture cycles several times during its trajectory over the Amazon. After one evapotranspiration-rainfall cycle, more than 40% of the moisture is re-evaporated again. The interception-evaporation feedback is less important during droughts. Finally from our analysis, we show that the forest-rainfall feedback is essential for the resilience of the south-western and northern parts of the Amazon forest. Without the forest-rainfall feedbacks, these forest wouldn't exist.

Response of free-living nitrogen-fixing microorganisms to land use change in the Amazon rainforest.

PubMed

Mirza, Babur S; Potisap, Chotima; Nüsslein, Klaus; Bohannan, Brendan J M; Rodrigues, Jorge L M

2014-01-01

The Amazon rainforest, the largest equatorial forest in the world, is being cleared for pasture and agricultural use at alarming rates. Tropical deforestation is known to cause alterations in microbial communities at taxonomic and phylogenetic levels, but it is unclear whether microbial functional groups are altered. We asked whether free-living nitrogen-fixing microorganisms (diazotrophs) respond to deforestation in the Amazon rainforest, using analysis of the marker gene nifH. Clone libraries were generated from soil samples collected from a primary forest, a 5-year-old pasture originally converted from primary forest, and a secondary forest established after pasture abandonment. Although diazotroph richness did not significantly change among the three plots, diazotroph community composition was altered with forest-to-pasture conversion, and phylogenetic similarity was higher among pasture communities than among those in forests. There was also 10-fold increase in nifH gene abundance following conversion from primary forest to pasture. Three environmental factors were associated with the observed changes: soil acidity, total N concentration, and C/N ratio. Our results suggest a partial restoration to initial levels of abundance and community structure of diazotrophs following pasture abandonment, with primary and secondary forests sharing similar communities. We postulate that the response of diazotrophs to land use change is a direct consequence of changes in plant communities, particularly the higher N demand of pasture plant communities for supporting aboveground plant growth.

Simulating fire regimes in the Amazon in response to climate change and deforestation.

PubMed

Silvestrini, Rafaella Almeida; Soares-Filho, Britaldo Silveira; Nepstad, Daniel; Coe, Michael; Rodrigues, Hermann; Assunção, Renato

2011-07-01

Fires in tropical forests release globally significant amounts of carbon to the atmosphere and may increase in importance as a result of climate change. Despite the striking impacts of fire on tropical ecosystems, the paucity of robust spatial models of forest fire still hampers our ability to simulate tropical forest fire regimes today and in the future. Here we present a probabilistic model of human-induced fire occurrence for the Amazon that integrates the effects of a series of anthropogenic factors with climatic conditions described by vapor pressure deficit. The model was calibrated using NOAA-12 night satellite hot pixels for 2003 and validated for the years 2002, 2004, and 2005. Assessment of the fire risk map yielded fitness values > 85% for all months from 2002 to 2005. Simulated fires exhibited high overlap with NOAA-12 hot pixels regarding both spatial and temporal distributions, showing a spatial fit of 50% within a radius of 11 km and a maximum yearly frequency deviation of 15%. We applied this model to simulate fire regimes in the Amazon until 2050 using IPCC's A2 scenario climate data from the Hadley Centre model and a business-as-usual (BAU) scenario of deforestation and road expansion from SimAmazonia. Results show that the combination of these scenarios may double forest fire occurrence outside protected areas (PAs) in years of extreme drought, expanding the risk of fire even to the northwestern Amazon by midcentury. In particular, forest fires may increase substantially across southern and southwestern Amazon, especially along the highways slated for paving and in agricultural zones. Committed emissions from Amazon forest fires and deforestation under a scenario of global warming and uncurbed deforestation may amount to 21 +/- 4 Pg of carbon by 2050. BAU deforestation may increase fires occurrence outside PAs by 19% over the next four decades, while climate change alone may account for a 12% increase. In turn, the combination of climate change and deforestation would boost fire occurrence outside PAs by half during this period. Our modeling results, therefore, confirm the synergy between the two Ds of REDD (Reducing Emissions from Deforestation and Forest Degradation in Developing Countries).

Lidar observed seasonal variation of vertical canopy structure in the Amazon evergreen forests

NASA Astrophysics Data System (ADS)

Tang, H.; Dubayah, R.

2017-12-01

Both light and water are important environmental factors governing tree growth. Responses of tropical forests to their changes are complicated and can vary substantially across different spatial and temporal scales. Of particular interest is the dry-season greening-up of Amazon forests, a phenomenon undergoing considerable debates whether it is real or a "light illusion" caused by artifacts of passive optical remote sensing techniques. Here we analyze seasonal dynamic patterns of vertical canopy structure in the Amazon forests using lidar observations from NASA's Ice, Cloud, and and land Elevation Satellite (ICESat). We found that the net greening of canopy layer coincides with the wet-to-dry transition period, and its net browning occurs mostly at the late dry season. The understory also shows a seasonal cycle, but with an opposite variation to canopy and minimal correlation to seasonal variations in rainfall or radiation. Our results further suggest a potential interaction between canopy layers in the light regime that can optimize the growth of Amazon forests during the dry season. This light regime variability that exists in both spatial and temporal domains can better reveal the dry-season greening-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.

Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm

PubMed Central

Nobre, Carlos A.; Sampaio, Gilvan; Borma, Laura S.; Castilla-Rubio, Juan Carlos; Silva, José S.; Cardoso, Manoel

2016-01-01

For half a century, the process of economic integration of the Amazon has been based on intensive use of renewable and nonrenewable natural resources, which has brought significant basin-wide environmental alterations. The rural development in the Amazonia pushed the agricultural frontier swiftly, resulting in widespread land-cover change, but agriculture in the Amazon has been of low productivity and unsustainable. The loss of biodiversity and continued deforestation will lead to high risks of irreversible change of its tropical forests. It has been established by modeling studies that the Amazon may have two “tipping points,” namely, temperature increase of 4 °C or deforestation exceeding 40% of the forest area. If transgressed, large-scale “savannization” of mostly southern and eastern Amazon may take place. The region has warmed about 1 °C over the last 60 y, and total deforestation is reaching 20% of the forested area. The recent significant reductions in deforestation—80% reduction in the Brazilian Amazon in the last decade—opens up opportunities for a novel sustainable development paradigm for the future of the Amazon. We argue for a new development paradigm—away from only attempting to reconcile maximizing conservation versus intensification of traditional agriculture and expansion of hydropower capacity—in which we research, develop, and scale a high-tech innovation approach that sees the Amazon as a global public good of biological assets that can enable the creation of innovative high-value products, services, and platforms through combining advanced digital, biological, and material technologies of the Fourth Industrial Revolution in progress. PMID:27638214

Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm.

PubMed

Nobre, Carlos A; Sampaio, Gilvan; Borma, Laura S; Castilla-Rubio, Juan Carlos; Silva, José S; Cardoso, Manoel

2016-09-27

For half a century, the process of economic integration of the Amazon has been based on intensive use of renewable and nonrenewable natural resources, which has brought significant basin-wide environmental alterations. The rural development in the Amazonia pushed the agricultural frontier swiftly, resulting in widespread land-cover change, but agriculture in the Amazon has been of low productivity and unsustainable. The loss of biodiversity and continued deforestation will lead to high risks of irreversible change of its tropical forests. It has been established by modeling studies that the Amazon may have two "tipping points," namely, temperature increase of 4 °C or deforestation exceeding 40% of the forest area. If transgressed, large-scale "savannization" of mostly southern and eastern Amazon may take place. The region has warmed about 1 °C over the last 60 y, and total deforestation is reaching 20% of the forested area. The recent significant reductions in deforestation-80% reduction in the Brazilian Amazon in the last decade-opens up opportunities for a novel sustainable development paradigm for the future of the Amazon. We argue for a new development paradigm-away from only attempting to reconcile maximizing conservation versus intensification of traditional agriculture and expansion of hydropower capacity-in which we research, develop, and scale a high-tech innovation approach that sees the Amazon as a global public good of biological assets that can enable the creation of innovative high-value products, services, and platforms through combining advanced digital, biological, and material technologies of the Fourth Industrial Revolution in progress.

Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm

NASA Astrophysics Data System (ADS)

Nobre, Carlos A.; Sampaio, Gilvan; Borma, Laura S.; Castilla-Rubio, Juan Carlos; Silva, José S.; Cardoso, Manoel

2016-09-01

For half a century, the process of economic integration of the Amazon has been based on intensive use of renewable and nonrenewable natural resources, which has brought significant basin-wide environmental alterations. The rural development in the Amazonia pushed the agricultural frontier swiftly, resulting in widespread land-cover change, but agriculture in the Amazon has been of low productivity and unsustainable. The loss of biodiversity and continued deforestation will lead to high risks of irreversible change of its tropical forests. It has been established by modeling studies that the Amazon may have two “tipping points,” namely, temperature increase of 4 °C or deforestation exceeding 40% of the forest area. If transgressed, large-scale “savannization” of mostly southern and eastern Amazon may take place. The region has warmed about 1 °C over the last 60 y, and total deforestation is reaching 20% of the forested area. The recent significant reductions in deforestation—80% reduction in the Brazilian Amazon in the last decade—opens up opportunities for a novel sustainable development paradigm for the future of the Amazon. We argue for a new development paradigm—away from only attempting to reconcile maximizing conservation versus intensification of traditional agriculture and expansion of hydropower capacity—in which we research, develop, and scale a high-tech innovation approach that sees the Amazon as a global public good of biological assets that can enable the creation of innovative high-value products, services, and platforms through combining advanced digital, biological, and material technologies of the Fourth Industrial Revolution in progress.

Amazon Forests Response to Droughts: A Perspective from the MAIAC Product

NASA Technical Reports Server (NTRS)

Bi, Jian; Myneni, Ranga; Lyapustin, Alexei; Wang, Yujie; Park, Taejin; Chi, Chen; Yan, Kai; Knyazikhin, Yuri

2016-01-01

Amazon forests experienced two severe droughts at the beginning of the 21st century: one in 2005 and the other in 2010. How Amazon forests responded to these droughts is critical for the future of the Earth's climate system. It is only possible to assess Amazon forests' response to the droughts in large areal extent through satellite remote sensing. Here, we used the Multi-Angle Implementation of Atmospheric Correction (MAIAC) Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation index (VI) data to assess Amazon forests' response to droughts, and compared the results with those from the standard (Collection 5 and Collection 6) MODIS VI data. Overall, the MAIAC data reveal more realistic Amazon forests inter-annual greenness dynamics than the standard MODIS data. Our results from the MAIAC data suggest that: (1) the droughts decreased the greenness (i.e., photosynthetic activity) of Amazon forests; (2) the Amazon wet season precipitation reduction induced by El Niño events could also lead to reduced photosynthetic activity of Amazon forests; and (3) in the subsequent year after the water stresses, the greenness of Amazon forests recovered from the preceding decreases. However, as previous research shows droughts cause Amazon forests to reduce investment in tissue maintenance and defense, it is not clear whether the photosynthesis of Amazon forests will continue to recover after future water stresses, because of the accumulated damages caused by the droughts.

Family Planning and Deforestation: Evidence from the Ecuadorian Amazon.

PubMed

Sellers, Samuel

2017-06-01

Despite an abundant body of literature exploring the relationship between population growth and forest cover change, comparatively little research has explored the forest cover impacts of family planning use, which is a key determinant of the rate of population growth in many developing country contexts. Using data from a farm-level panel survey in the Northern Ecuadorian Amazon, this paper addresses whether family planning use impacts forest cover change. Longitudinal model results show that after controlling for household life cycle and land use variables, family planning use did not have an independent effect on deforestation, reforestation, or net forest loss between 1990 and 2008. Forest cover change patterns appear indicative of farm life cycle effects. However, family planning use is associated with reduced subsequent fertility among households, suggesting that the relationship between population growth from births and forest cover change may be limited in this setting.

Family Planning and Deforestation: Evidence from the Ecuadorian Amazon

PubMed Central

Sellers, Samuel

2017-01-01

Despite an abundant body of literature exploring the relationship between population growth and forest cover change, comparatively little research has explored the forest cover impacts of family planning use, which is a key determinant of the rate of population growth in many developing country contexts. Using data from a farm-level panel survey in the Northern Ecuadorian Amazon, this paper addresses whether family planning use impacts forest cover change. Longitudinal model results show that after controlling for household life cycle and land use variables, family planning use did not have an independent effect on deforestation, reforestation, or net forest loss between 1990 and 2008. Forest cover change patterns appear indicative of farm life cycle effects. However, family planning use is associated with reduced subsequent fertility among households, suggesting that the relationship between population growth from births and forest cover change may be limited in this setting. PMID:29056808

AmazonFACE: Assessing the Effects of Increasing Atmospheric CO2 on the Resilience of the Amazon Forest through Integrative Model-Experiment Research

NASA Astrophysics Data System (ADS)

Lapola, D. M.

2015-12-01

The existence, magnitude and duration of a supposed "CO2 fertilization" effect in tropical forests remains largely undetermined, despite being suggested for nearly 20 years as a key knowledge gap for understanding the future resilience of Amazonian forests and its impact on the global carbon cycle. Reducing this uncertainty is critical for assessing the future of the Amazon region as well as its vulnerability to climate change. The AmazonFACE (Free-Air CO2 Enrichment) research program is an integrated model-experiment initiative of unprecedented scope in an old-growth Amazon forest near Manaus, Brazil - the first of its kind in tropical forest. The experimental treatment will simulate an atmospheric CO2 concentration [CO2] of the future in order to address the question: "How will rising atmospheric CO2 affect the resilience of the Amazon forest, the biodiversity it harbors, and the ecosystem services it provides, in light of projected climatic changes?" AmazonFACE is divided into three phases: (I) pre-experimental ecological characterization of the research site; (II) pilot experiment comprised of two 30-m diameter plots, with one treatment plot maintained at elevated [CO2] (ambient +200 ppmv), and the other control plot at ambient [CO2]; and (III) a fully-replicated long-term experiment comprised of four pairs of control/treatment FACE plots maintained for 10 years. A team of scientists from Brazil, USA, Australia and Europe will employ state-of-the-art methods to study the forest inside these plots in terms of carbon metabolism and cycling, water use, nutrient cycling, forest community composition, and interactions with environmental stressors. All project phases also encompass ecosystem-modeling activities in a way such that models provide hypothesis to be verified in the experiment, which in turn will feed models to ultimately produce more accurate projections of the environment. Resulting datasets and analyses will be a valuable resource for a broad community, especially ecosystem and climate modelers, and policy-makers.

The AmazonFACE research program: assessing the effects of increasing atmospheric CO2 on the ecology and resilience of the Amazon forest

NASA Astrophysics Data System (ADS)

Lapola, David; Quesada, Carlos; Norby, Richard; Araújo, Alessandro; Domingues, Tomas; Hartley, Iain; Kruijt, Bart; Lewin, Keith; Meir, Patrick; Ometto, Jean; Rammig, Anja

2016-04-01

The existence, magnitude and duration of a supposed "CO2 fertilization" effect in tropical forests remains largely undetermined, despite being suggested for nearly 20 years as a key knowledge gap for understanding the future resilience of Amazonian forests and its impact on the global carbon cycle. Reducing this uncertainty is critical for assessing the future of the Amazon region as well as its vulnerability to climate change. The AmazonFACE (Free-Air CO2 Enrichment) research program is an integrated model-experiment initiative of unprecedented scope in an old-growth Amazon forest near Manaus, Brazil - the first of its kind in tropical forest. The experimental treatment will simulate an atmospheric CO2 concentration [CO2] of the future in order to address the question: "How will rising atmospheric CO2 affect the resilience of the Amazon forest, the biodiversity it harbors, and the ecosystem services it provides, in light of projected climatic changes?" AmazonFACE is divided into three phases: (I) pre-experimental ecological characterization of the research site; (II) pilot experiment comprised of two 30-m diameter plots, with one treatment plot maintained at elevated [CO2] (ambient +200 ppmv), and the other control plot at ambient [CO2]; and (III) a fully-replicated long-term experiment comprised of four pairs of control/treatment FACE plots maintained for 10 years. A team of scientists from Brazil, USA, Australia and Europe will employ state-of-the-art methods to study the forest inside these plots in terms of carbon metabolism and cycling, water use, nutrient cycling, forest community composition, and interactions with environmental stressors. All project phases also encompass ecosystem-modeling activities in a way such that models provide hypothesis to be verified in the experiment, which in turn will feed models to ultimately produce more accurate projections of the environment. Resulting datasets and analyses will be a valuable resource for a broad community, especially ecosystem and climate modelers, and policy-makers.

Estimating Amazonian rainforest stability and the likelihood for large-scale forest dieback

NASA Astrophysics Data System (ADS)

Rammig, Anja; Thonicke, Kirsten; Jupp, Tim; Ostberg, Sebastian; Heinke, Jens; Lucht, Wolfgang; Cramer, Wolfgang; Cox, Peter

2010-05-01

Annually, tropical forests process approximately 18 Pg of carbon through respiration and photosynthesis - more than twice the rate of anthropogenic fossil fuel emissions. Current climate change may be transforming this carbon sink into a carbon source by changing forest structure and dynamics. Increasing temperatures and potentially decreasing precipitation and thus prolonged drought stress may lead to increasing physiological stress and reduced productivity for trees. Resulting decreases in evapotranspiration and therefore convective precipitation could further accelerate drought conditions and destabilize the tropical ecosystem as a whole and lead to an 'Amazon forest dieback'. The projected direction and intensity of climate change vary widely within the region and between different scenarios from climate models (GCMs). In the scope of a World Bank-funded study, we assessed the 24 General Circulation Models (GCMs) evaluated in the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4) with respect to their capability to reproduce present-day climate in the Amazon basin using a Bayesian approach. With this approach, greater weight is assigned to the models that simulate well the annual cycle of rainfall. We then use the resulting weightings to create probability density functions (PDFs) for future forest biomass changes as simulated by the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJmL) to estimate the risk of potential Amazon rainforest dieback. Our results show contrasting changes in forest biomass throughout five regions of northern South America: If photosynthetic capacity and water use efficiency is enhanced by CO2, biomass increases across all five regions. However, if CO2-fertilisation is assumed to be absent or less important, then substantial dieback occurs in some scenarios and thus, the risk of forest dieback is considerably higher. Particularly affected are regions in the central Amazon basin. The range of potential biomass change arising from the weighting of rainfall patterns is smaller than the uncertainty arising from CO2-fertilisation effects, which highlights the importance of reducing the uncertainties in the direct effects of CO2 on tropical ecosystems. Strong biomass changes also imply changes in forest structure and thus, forest stability. Our results display shifts in forest composition from closed rainforest to more open forest or even shrubland. Our probability-based risk analysis could be used to advise regional forest protection.

Response of Free-Living Nitrogen-Fixing Microorganisms to Land Use Change in the Amazon Rainforest

PubMed Central

Mirza, Babur S.; Potisap, Chotima; Nüsslein, Klaus; Bohannan, Brendan J. M.

2014-01-01

The Amazon rainforest, the largest equatorial forest in the world, is being cleared for pasture and agricultural use at alarming rates. Tropical deforestation is known to cause alterations in microbial communities at taxonomic and phylogenetic levels, but it is unclear whether microbial functional groups are altered. We asked whether free-living nitrogen-fixing microorganisms (diazotrophs) respond to deforestation in the Amazon rainforest, using analysis of the marker gene nifH. Clone libraries were generated from soil samples collected from a primary forest, a 5-year-old pasture originally converted from primary forest, and a secondary forest established after pasture abandonment. Although diazotroph richness did not significantly change among the three plots, diazotroph community composition was altered with forest-to-pasture conversion, and phylogenetic similarity was higher among pasture communities than among those in forests. There was also 10-fold increase in nifH gene abundance following conversion from primary forest to pasture. Three environmental factors were associated with the observed changes: soil acidity, total N concentration, and C/N ratio. Our results suggest a partial restoration to initial levels of abundance and community structure of diazotrophs following pasture abandonment, with primary and secondary forests sharing similar communities. We postulate that the response of diazotrophs to land use change is a direct consequence of changes in plant communities, particularly the higher N demand of pasture plant communities for supporting aboveground plant growth. PMID:24162570

Forest carbon emissions from cropland expansion in the Brazilian Cerrado biome

NASA Astrophysics Data System (ADS)

Noojipady, Praveen; Morton, C. Douglas; Macedo, N. Marcia; Victoria, C. Daniel; Huang, Chengquan; Gibbs, K. Holly; Edson Bolfe, L.

2017-02-01

Land use, land use change, and forestry accounted for two-thirds of Brazil’s greenhouse gas emissions profile in 2005. Amazon deforestation has declined by more than 80% over the past decade, yet Brazil’s forests extend beyond the Amazon biome. Rapid expansion of cropland in the neighboring Cerrado biome has the potential to undermine climate mitigation efforts if emissions from dry forest and woodland conversion negate some of the benefits of avoided Amazon deforestation. Here, we used satellite data on cropland expansion, forest cover, and vegetation carbon stocks to estimate annual gross forest carbon emissions from cropland expansion in the Cerrado biome. Nearly half of the Cerrado met Brazil’s definition of forest cover in 2000 (≥0.5 ha with ≥10% canopy cover). In areas of established crop production, conversion of both forest and non-forest Cerrado formations for cropland declined during 2003-2013. However, forest carbon emissions from cropland expansion increased over the past decade in Matopiba, a new frontier of agricultural production that includes portions of Maranhão, Tocantins, Piauí, and Bahia states. Gross carbon emissions from cropland expansion in the Cerrado averaged 16.28 Tg C yr-1 between 2003 and 2013, with forest-to-cropland conversion accounting for 29% of emissions. The fraction of forest carbon emissions from Matopiba was much higher; between 2010-2013, large-scale cropland conversion in Matopiba contributed 45% of total Cerrado forest carbon emissions. Carbon emissions from Cerrado-to-cropland transitions offset 5%-7% of the avoided emissions from reduced Amazon deforestation rates during 2011-2013. Comprehensive national estimates of forest carbon fluxes, including all biomes, are critical to detect cross-biome leakage within countries and achieve climate mitigation targets to reduce emissions from land use, land use change, and forestry.

Global warming and climate change in Amazonia: Climate-vegetation feedback and impacts on water resources

NASA Astrophysics Data System (ADS)

Marengo, José; Nobre, Carlos A.; Betts, Richard A.; Cox, Peter M.; Sampaio, Gilvan; Salazar, Luis

This chapter constitutes an updated review of long-term climate variability and change in the Amazon region, based on observational data spanning more than 50 years of records and on climate-change modeling studies. We start with the early experiments on Amazon deforestation in the late 1970s, and the evolution of these experiments to the latest studies on greenhouse gases emission scenarios and land use changes until the end of the twenty-first century. The "Amazon dieback" simulated by the HadCM3 model occurs after a "tipping point" of CO2 concentration and warming. Experiments on Amazon deforestation and change of climate suggest that once a critical deforestation threshold (or tipping point) of 40-50% forest loss is reached in eastern Amazonia, climate would change in a way which is dangerous for the remaining forest. This may favor a collapse of the tropical forest, with a substitution of the forest by savanna-type vegetation. The concept of "dangerous climate change," as a climate change, which induces positive feedback, which accelerate the change, is strongly linked to the occurrence of tipping points, and it can be explained as the presence of feedback between climate change and the carbon cycle, particularly involving a weakening of the current terrestrial carbon sink and a possible reversal from a sink (as in present climate) to a source by the year 2050. We must, therefore, currently consider the drying simulated by the Hadley Centre model(s) as having a finite probability under global warming, with a potentially enormous impact, but with some degree of uncertainty.

Efficiency of protected areas in Amazon and Atlantic Forest conservation: A spatio-temporal view

NASA Astrophysics Data System (ADS)

Sobral-Souza, Thadeu; Vancine, Maurício Humberto; Ribeiro, Milton Cezar; Lima-Ribeiro, Matheus S.

2018-02-01

The Amazon and Atlantic Forest are considered the world's most biodiverse biomes. Human and climate change impacts are the principal drivers of species loss in both biomes, more severely in the Atlantic Forest. In response to species loss, the main conservation action is the creation of protected areas (PAs). Current knowledge and research on the PA network's conservation efficiency is scarce, and existing studies have mainly considered a past temporal view. In this study, we tested the efficiency of the current PA network to maintain climatically stable areas (CSAs) across the Amazon and Atlantic Forest. To this, we used an ecological niche modeling approach to biome and paleoclimatic simulations. We propose three categories of conservation priority areas for both biomes, considering CSAs, PAs and intact forest remnants. The biomes vary in their respective PA networks' protection efficiency. Regarding protect CSAs, the Amazon PA network is four times more efficient than the Atlantic Forest PA network. New conservation efforts in these two forest biomes require different approaches. We discussed the conservation actions that should be taken in each biome to increase the efficiency of the PA network, considering both the creation and expansion of PAs as well as restoration programs.

Early recruitment responses to interactions between frequent fires, nutrients, and herbivory in the southern Amazon.

PubMed

Massad, Tara Joy; Balch, Jennifer K; Mews, Cândida Lahís; Porto, Pábio; Marimon Junior, Ben Hur; Quintino, Raimundo Mota; Brando, P M; Vieira, Simone A; Trumbore, Susan E

2015-07-01

Understanding tropical forest diversity is a long-standing challenge in ecology. With global change, it has become increasingly important to understand how anthropogenic and natural factors interact to determine diversity. Anthropogenic increases in fire frequency are among the global change variables affecting forest diversity and functioning, and seasonally dry forest of the southern Amazon is among the ecosystems most affected by such pressures. Studying how fire will impact forests in this region is therefore important for understanding ecosystem functioning and for designing effective conservation action. We report the results of an experiment in which we manipulated fire, nutrient availability, and herbivory. We measured the effects of these interacting factors on the regenerative capacity of the ecotone between humid Amazon forest and Brazilian savanna. Regeneration density, diversity, and community composition were severely altered by fire. Additions of P and N + P reduced losses of density and richness in the first year post-fire. Herbivory was most important just after germination. Diversity was positively correlated with herbivory in unburned forest, likely because fire reduced the number of reproductive individuals. This contrasts with earlier results from the same study system in which herbivory was related to increased diversity after fire. We documented a significant effect of fire frequency; diversity in triennially burned forest was more similar to that in unburned than in annually burned forest, and the community composition of triennially burned forest was intermediate between unburned and annually burned areas. Preventing frequent fires will therefore help reduce losses in diversity in the southern Amazon's matrix of human-altered landscapes.

A century of Amazon burning driven by Atlantic climate

NASA Astrophysics Data System (ADS)

Makou, M.; Thompson, L. G.; Davis, M. E.; Eglinton, T. I.

2011-12-01

Very little is known about annual burning trends in the Amazon Basin prior to remote sensing of fires beginning in the late 1970's. Fires reduce Amazon forest biomass and species richness, release pollutant aerosols, and impact the carbon cycle, compelling further investigation of fire-climate dynamics. We measured organic compounds derived from vegetation burning in ice core samples from the Quelccaya Ice Cap in Peru at better than annual resolution to reconstruct wet and dry season burning throughout the Twentieth Century. Variations in the abundance of methyl hexadecanoate, which is produced by thermal alteration of vascular plant alkanoic acids, were used as a proxy for past fire activity. Concentrations of this compound in Quelccaya ice varied strongly on seasonal, interannual, and decadal time scales over the last 100 years, with high-amplitude dry season variability and muted, decadal-scale changes in wet season fire activity. Decade-long periods of repeatedly enhanced burning occurred during the 1930's and 1960's when dry season precipitation was perpetually reduced, as evidenced by low stages of the Rio Negro. These decadal trends suggest that changes in dry season precipitation drive fire activity in the western Amazon and highlight the potential of Amazon forests to undergo repeated strong burning. Fires occurred during years when sea surface temperatures (SSTs) in the north tropical Atlantic were elevated and the north-south tropical Atlantic SST gradient was enhanced; this SST pattern likely displaced the intertropical convergence zone northward, driving subsidence and drought in the western and southern Amazon basin. Thus, our novel ice core record suggests that Amazon forest fire activity during the Twentieth Century was driven primarily by Atlantic climate processes, and future forest health will depend heavily on the evolution of tropical climate.

Current and future patterns of fire-induced forest degradation in Amazonia

NASA Astrophysics Data System (ADS)

De Faria, Bruno L.; Brando, Paulo M.; Macedo, Marcia N.; Panday, Prajjwal K.; Soares-Filho, Britaldo S.; Coe, Michael T.

2017-09-01

Amazon droughts directly increase forest flammability by reducing forest understory air and fuel moisture. Droughts also increase forest flammability indirectly by decreasing soil moisture, triggering leaf shedding, branch loss, and tree mortality—all of which contribute to increased fuel loads. These direct and indirect effects can cause widespread forest fires that reduce forest carbon stocks in the Amazon, with potentially important consequences for the global carbon cycle. These processes are expected to become more widespread, common, and intense as global climate changes, yet the mechanisms linking droughts, wildfires, and associated changes in carbon stocks remain poorly understood. Here, we expanded the capabilities of a dynamic forest carbon model to better represent (1) drought effects on carbon and fuel dynamics and (2) understory fire behavior and severity. We used the refined model to quantify changes in Pan-Amazon live carbon stocks as a function of the maximum climatological water deficit (MCWD) and fire intensity, under both historical and future climate conditions. We found that the 2005 and 2010 droughts increased potential fire intensity by 226 kW m-1 and 494 kW m-1, respectively. These increases were due primarily to increased understory dryness (109 kW m-1 in 2005; 124 kW m-1 in 2010) and altered forest structure (117 kW m-1 in 2005; 370 kW m-1 in 2010) effects. Combined, these historic droughts drove total simulated reductions in live carbon stocks of 0.016 (2005) and 0.027 (2010) PgC across the Amazon Basin. Projected increases in future fire intensity increased simulated carbon losses by up to 90% per unit area burned, compared with modern climate. Increased air temperature was the primary driver of changes in simulated future fire intensity, while reduced precipitation was secondary, particularly in the eastern portion of the Basin. Our results show that fire-drought interactions strongly affect live carbon stocks and that future climate change, combined with the synergistic effects of drought on forest flammability, may strongly influence the stability of tropical forests in the future.

Mapping and spatiotemporal characterization of degraded forests in the Brazilian Amazon through remote sensing

NASA Astrophysics Data System (ADS)

de Souza, Carlos Moreira, Jr.

Large forested areas have recently been impoverished by degradation caused by selective logging, forest fires and fragmentation in the Amazon region, causing partial change of the original forest structure and composition. As opposed to deforestation that has been monitored with Landsat images since the late 70's, degraded forests have not been monitored in the Amazon region. In this dissertation, remote sensing techniques for identifying and mapping unambiguously degraded forests with Landsat images are proposed. The test area was the region of Sinop, located in the state of Mato Grosso, Brazil. This region was selected because a gradient of degraded forest environments exist and a robust time-series of Landsat images and forest transect data were available. First, statistical analyses were applied to identify the best set of spectral information extracted from Landsat images to detect several types of degraded forest environments. Fraction images derived from Spectral Mixture Analysis (SMA) were the best type of information for that purpose. A new spectral index based on fraction images---Normalized Difference Fraction Index (NDFI)---was proposed to enhance the detection of canopy damaged areas in degraded forests. Second, a contextual classification algorithm was implemented to separate unambiguously forest degradation caused by anthropogenic activities from natural forest disturbances. These techniques were validated using forest transects and high resolution aerial videography images and proved to be highly accurate. Next, these techniques were applied to a time-series data set of Landsat images, encompassing 20 years, to evaluate the relationship between forest degradation and deforestation. The most important finding of the forest change detection analysis was that forest degradation and deforestation are independent events in the study area, making worse the current forest impacts in the Amazon region. Finally, the techniques developed and tested in the Sinop region were successfully applied to forty Landsat images covering other regions of the Brazilian Amazon. Standard fractions and NDFI images were computed for these other regions and both physically and spatially consistent results were obtained. An automated decision tree classification using genetic algorithm was implemented successfully to classify land cover types and sub-classes of degraded forests. The remote sensing techniques proposed in this dissertation are fully automated and have the potential to be used in tropical forest monitoring programs.

Forest loss maps from regional satellite monitoring systematically underestimate deforestation in two rapidly changing parts of the Amazon

NASA Astrophysics Data System (ADS)

Milodowski, D. T.; Mitchard, E. T. A.; Williams, M.

2017-09-01

Accurate, consistent reporting of changing forest area, stratified by forest type, is required for all countries under their commitments to the Paris Agreement (UNFCCC 2015 Adoption of the Paris Agreement (Paris: UNFCCC)). Such change reporting may directly impact on payments through comparisons to national Reference (Emissions) Levels under the Reducing Emissions from Deforestation and forest Degradation (REDD+) framework. The emergence of global, satellite-based forest monitoring systems, including Global Forest Watch (GFW) and FORMA, have great potential in aiding this endeavour. However, the accuracy of these systems has been questioned and their uncertainties are poorly constrained, both in terms of the spatial extent of forest loss and timing of change. Here, using annual time series of 5 m optical imagery at two sites in the Brazilian Amazon, we demonstrate that GFW more accurately detects forest loss than the coarser-resolution FORMA or Brazil’s national-level PRODES product, though all underestimate the rate of loss. We conclude GFW provides robust indicators of forest loss, at least for larger-scale forest change, but under-predicts losses driven by small-scale disturbances (< 2 ha), even though these are much larger than its minimum mapping unit (0.09 ha).

Forest loss maps from regional satellite monitoring systematically underestimate deforestation in two rapidly changing parts of the Amazon

NASA Astrophysics Data System (ADS)

Milodowski, D. T.; Mitchard, E. T. A.; Williams, M.

2016-09-01

Accurate, consistent reporting of changing forest area, stratified by forest type, is required for all countries under their commitments to the Paris Agreement (UNFCCC 2015 Adoption of the Paris Agreement (Paris: UNFCCC)). Such change reporting may directly impact on payments through comparisons to national Reference (Emissions) Levels under the Reducing Emissions from Deforestation and forest Degradation (REDD+) framework. The emergence of global, satellite-based forest monitoring systems, including Global Forest Watch (GFW) and FORMA, have great potential in aiding this endeavour. However, the accuracy of these systems has been questioned and their uncertainties are poorly constrained, both in terms of the spatial extent of forest loss and timing of change. Here, using annual time series of 5 m optical imagery at two sites in the Brazilian Amazon, we demonstrate that GFW more accurately detects forest loss than the coarser-resolution FORMA or Brazil’s national-level PRODES product, though all underestimate the rate of loss. We conclude GFW provides robust indicators of forest loss, at least for larger-scale forest change, but under-predicts losses driven by small-scale disturbances (< 2 ha), even though these are much larger than its minimum mapping unit (0.09 ha).

The spatial extent of change in tropical forest ecosystem services in the Amazon delta

NASA Astrophysics Data System (ADS)

de Araujo Barbosa, C. C.; Atkinson, P.; Dearing, J.

2014-12-01

Deltas hold major economic potential due their strategic location, close to seas and inland waterways, thereby supporting intense economic activity. The increasing pace of human development activities in coastal deltas over the past five decades has also strained environmental resources and produced extensive economic and sociocultural impacts. The Amazon delta is located in the Amazon Basin, North Brazil, the largest river basin on Earth and also one of the least understood. A considerable segment of the population living in the Amazon delta is directly dependent on the local extraction of natural resources for their livelihood. Areas sparsely inhabited may be exploited with few negative consequences for the environment. However, increasing pressure on ecosystem services is amplified by large fluxes of immigrants from other parts of the country, especially from the semi-arid zone in Northeast Brazil to the lowland forests of the Amazon delta. Here we present partial results from a bigger research project. Therefore, the focus will be on presenting an overview of the current state, and the extent of changes on forest related ecosystem services in the Amazon delta over the last three decades. We aggregated a multitude of datasets, from a variety of sources, for example, from satellite imagery such as the Advanced Very High Resolution Radiometer (AVHRR), the Global Inventory Modelling and Mapping Studies (GIMMS), the Moderate Resolution Imaging Spectroradiometer (MODIS), and climate datasets at meteorological station level from the Brazilian National Institute of Meteorology (INMET) and social and economic statistics data from the Brazilian Institute of Geography and Statistics (IBGE) and from the Brazilian Institute of Applied Economic Research (IPEA). Through analysis of socioeconomic and satellite earth observation data we were able to produce and present spatially-explicit information with the current state and transition in forest cover and its impacts to forest ecosystem services providing units in the Amazon delta.

Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

NASA Astrophysics Data System (ADS)

Baker, P. A.; Fritz, S. C.; Silva, C. G.; Rigsby, C. A.; Absy, M. L.; Almeida, R. P.; Caputo, M.; Chiessi, C. M.; Cruz, F. W.; Dick, C. W.; Feakins, S. J.; Figueiredo, J.; Freeman, K. H.; Hoorn, C.; Jaramillo, C.; Kern, A. K.; Latrubesse, E. M.; Ledru, M. P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W. E.; Ramos, M. I. F.; Ribas, C. C.; Trnadade, R.; West, A. J.; Wahnfried, I.; Willard, D. A.

2015-12-01

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

USGS Publications Warehouse

Baker, P.A.; Fritz, S.C.; Silva, C.G.; Rigsby, C.A.; Absy, M.L.; Almeida, R.P.; Caputo, Maria C.; Chiessi, C.M.; Cruz, F.W.; Dick, C.W.; Feakins, S.J.; Figueiredo, J.; Freeman, K.H.; Hoorn, C.; Jaramillo, C.A.; Kern, A.; Latrubesse, E.M.; Ledru, M.P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W.E.; Ramos, M.I.F.; Ribas, C.C.; Trinadade, R.; West, A.J.; Wahnfried, I.; Willard, Debra A.

2015-01-01

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Synergistic impacts of deforestation, climate change and fire on the future biomes distribution in Amazonia

NASA Astrophysics Data System (ADS)

Sampaio, G.; Cardoso, M. F.; Nobre, C. A.; Salazar, L. F.

2013-05-01

Several studies indicate future increase of environmental risks for the ecosystems in the Amazon region as a result of climate and land-use change, and their synergistic interactions. Modeling studies (e.g. Oyama and Nobre 2004, Salazar et al. 2007, Malhi et al. 2008) project rapid and irreversible replacement of forests by savannas with large-scale losses of biodiversity and livelihoods for people in the region. This process is referred to as the Amazon Dieback, where accelerated plant mortality due to environmental changes lead to forest collapse and savannas expansion after "tipping points" in climate and land surface changes are achieved. In this study we performed new analyses to quantify how deforestation, climate change and fire may combine to affect the distribution of major biomes in Amazonia. Changes in land use consider deforestation scenarios of 0%, 20%, 40%, and 50% (Sampaio et al., 2007), with and without fires (Cardoso et al., 2008), under the two greenhouse gases scenarios B1 and A2 and three "representative concentration pathways" (RCPs): 2.6, 4.5 and 8.5, for years 2015-2034 and 2040-2059 ("2025" and "2050" time-slices), from IPCC AR4 and CMIP5. The results show that the area affected in scenarios A2 and RCP 8.5 is larger than in the climate scenario B1 and RCP 2.6, and in both cases the effect is progressively higher in time. Most important changes occur in the East and South of the Amazon, with replacement of tropical forest by seasonal forest and savanna. The effect of fire in this region is important in all scenarios. The Northwest Amazon presents the smallest changes in the area of tropical forest, indicating that even for substantial land-use modifications and global climate change, the resulting atmospheric conditions would still support tropical forest in the region. In summary, we conclude that the synergistic combination of deforestation, climate change resulting from global warming, and the potential for higher fire occurrence may lead to important impacts that add considerably to the vulnerability of tropical forest ecosystems in the study region. REFERENCES Cardoso, M. F. ; Nobre, C. A. ; Sampaio, G. ; Hirota, M. ; Valeriano, D. ; Câmara, G. Long-term potential for tropical-forest degradation due to deforestation and fires in the Brazilian Amazon. Biologia (Bratislava), v. 64, p. 433-437, 2009. Malhi Y, et al. (2008) Climate change, deforestation, and the fate of the Amazon. Science 319:169-172. Oyama, M.D. and C.A. Nobre (2004), A simple potencial vegetation model for coupling with the Simple Biosphere Model (SIB). Revista Brasileira de Meteorologia, v. 19, n. 2, p. 203-216, 2004. Salazar, L. F., C. A. Nobre, and M. D. Oyama (2007), Climate change consequences on the biome distribution in tropical South America, Geophys. Res. Lett., 34, L09708, doi:10.1029/2007GL029695 Sampaio, G., C. A. Nobre, M. H. Costa, P. Satyamurty, B. S. Soares-Filho and, M. Cardoso (2007), Regional climate change over eastern Amazonia caused by pasture and soybean cropland expansion. Geophys. Res. Lett., 34, L17709, doi:10.1029/2007GL030612.

Vulnerability of Amazon forests to storm-driven tree mortality

NASA Astrophysics Data System (ADS)

Negrón-Juárez, Robinson I.; Holm, Jennifer A.; Magnabosco Marra, Daniel; Rifai, Sami W.; Riley, William J.; Chambers, Jeffrey Q.; Koven, Charles D.; Knox, Ryan G.; McGroddy, Megan E.; Di Vittorio, Alan V.; Urquiza-Muñoz, Jose; Tello-Espinoza, Rodil; Alegria Muñoz, Waldemar; Ribeiro, Gabriel H. P. M.; Higuchi, Niro

2018-05-01

Tree mortality is a key driver of forest community composition and carbon dynamics. Strong winds associated with severe convective storms are dominant natural drivers of tree mortality in the Amazon. Why forests vary with respect to their vulnerability to wind events and how the predicted increase in storm events might affect forest ecosystems within the Amazon are not well understood. We found that windthrows are common in the Amazon region extending from northwest (Peru, Colombia, Venezuela, and west Brazil) to central Brazil, with the highest occurrence of windthrows in the northwest Amazon. More frequent winds, produced by more frequent severe convective systems, in combination with well-known processes that limit the anchoring of trees in the soil, help to explain the higher vulnerability of the northwest Amazon forests to winds. Projected increases in the frequency and intensity of convective storms in the Amazon have the potential to increase wind-related tree mortality. A forest demographic model calibrated for the northwestern and the central Amazon showed that northwestern forests are more resilient to increased wind-related tree mortality than forests in the central Amazon. Our study emphasizes the importance of including wind-related tree mortality in model simulations for reliable predictions of the future of tropical forests and their effects on the Earth’ system.

Quantifying long-term changes in carbon stocks and forest structure from Amazon forest degradation

NASA Astrophysics Data System (ADS)

Rappaport, Danielle I.; Morton, Douglas C.; Longo, Marcos; Keller, Michael; Dubayah, Ralph; Nara dos-Santos, Maiza

2018-06-01

Despite sustained declines in Amazon deforestation, forest degradation from logging and fire continues to threaten carbon stocks, habitat, and biodiversity in frontier forests along the Amazon arc of deforestation. Limited data on the magnitude of carbon losses and rates of carbon recovery following forest degradation have hindered carbon accounting efforts and contributed to incomplete national reporting to reduce emissions from deforestation and forest degradation (REDD+). We combined annual time series of Landsat imagery and high-density airborne lidar data to characterize the variability, magnitude, and persistence of Amazon forest degradation impacts on aboveground carbon density (ACD) and canopy structure. On average, degraded forests contained 45.1% of the carbon stocks in intact forests, and differences persisted even after 15 years of regrowth. In comparison to logging, understory fires resulted in the largest and longest-lasting differences in ACD. Heterogeneity in burned forest structure varied by fire severity and frequency. Forests with a history of one, two, and three or more fires retained only 54.4%, 25.2%, and 7.6% of intact ACD, respectively, when measured after a year of regrowth. Unlike the additive impact of successive fires, selective logging before burning did not explain additional variability in modeled ACD loss and recovery of burned forests. Airborne lidar also provides quantitative measures of habitat structure that can aid the estimation of co-benefits of avoided degradation. Notably, forest carbon stocks recovered faster than attributes of canopy structure that are critical for biodiversity in tropical forests, including the abundance of tall trees. We provide the first comprehensive look-up table of emissions factors for specific degradation pathways at standard reporting intervals in the Amazon. Estimated carbon loss and recovery trajectories provide an important foundation for assessing the long-term contributions from forest degradation to regional carbon cycling and advance our understanding of the current state of frontier forests.

Is the Amazon Rainforest Drying Out?

NASA Astrophysics Data System (ADS)

Saatchi, S.; Xu, L.; Bloom, A. A.; Konings, A. G.; Yang, Y.; Aragão, L. E.; Fu, R.; Worden, J. R.; Schimel, D.

2017-12-01

Hotter droughts are the emerging characteristics of recent climate conditions, causing increased aridity over many land areas, broad-scale die-off, and pervasive mortality in forest ecosystems globally. Using a suite of eco-hydrological measurements from satellite observations combined with ecosystem data assimilation model, we show the Amazon forests, under recent changes in climate, have been consistently losing water in vegetation from increased leaf temperature. These long-term changes have caused a decline in evapotranspiration with consequences of changing the seasonality of precipitation by increasing the dry season length and delaying the wet season arrival. Three severe droughts (2005, 2010, 2015), occurring on the background of this long-term warming have an unprecedented legacy resulting in longer delays in recharging of water storage and recovery of forests after drought induced disturbances (4-5 years after each drought). The paper discusses the evidences of eco-hydrological changes pointing to the drying of forests of Amazonia.

Deforestation effects on Amazon forest resilience

NASA Astrophysics Data System (ADS)

Zemp, D. C.; Schleussner, C.-F.; Barbosa, H. M. J.; Rammig, A.

2017-06-01

Through vegetation-atmosphere feedbacks, rainfall reductions as a result of Amazon deforestation could reduce the resilience on the remaining forest to perturbations and potentially lead to large-scale Amazon forest loss. We track observation-based water fluxes from sources (evapotranspiration) to sinks (rainfall) to assess the effect of deforestation on continental rainfall. By studying 21st century deforestation scenarios, we show that deforestation can reduce dry season rainfall by up to 20% far from the deforested area, namely, over the western Amazon basin and the La Plata basin. As a consequence, forest resilience is systematically eroded in the southwestern region covering a quarter of the current Amazon forest. Our findings suggest that the climatological effects of deforestation can lead to permanent forest loss in this region. We identify hot spot regions where forest loss should be avoided to maintain the ecological integrity of the Amazon forest.

GLCF: Data & Products

Science.gov Websites

Imagery Products Derived from Satellite Imagery Landsat Forest Change Products Amazon Basin Central Africa Paraguay Coastal Marsh Health Index Forest Cover Change Impervious Surface Cover Landsat Mosaics Landsat Guides * Data Policies * Restricted Access Quick Links * EROS Data Center * Global Change Master

Deforestation and climate feedbacks threaten the ecological integrity of south–southeastern Amazonia

PubMed Central

Coe, Michael T.; Marthews, Toby R.; Costa, Marcos Heil; Galbraith, David R.; Greenglass, Nora L.; Imbuzeiro, Hewlley M. A.; Levine, Naomi M.; Malhi, Yadvinder; Moorcroft, Paul R.; Muza, Michel Nobre; Powell, Thomas L.; Saleska, Scott R.; Solorzano, Luis A.; Wang, Jingfeng

2013-01-01

A mosaic of protected areas, including indigenous lands, sustainable-use production forests and reserves and strictly protected forests is the cornerstone of conservation in the Amazon, with almost 50 per cent of the region now protected. However, recent research indicates that isolation from direct deforestation or degradation may not be sufficient to maintain the ecological integrity of Amazon forests over the next several decades. Large-scale changes in fire and drought regimes occurring as a result of deforestation and greenhouse gas increases may result in forest degradation, regardless of protected status. How severe or widespread these feedbacks will be is uncertain, but the arc of deforestation in south–southeastern Amazonia appears to be particularly vulnerable owing to high current deforestation rates and ecological sensitivity to climate change. Maintaining forest ecosystem integrity may require significant strengthening of forest conservation on private property, which can in part be accomplished by leveraging existing policy mechanisms. PMID:23610166

Deforestation and climate feedbacks threaten the ecological integrity of south-southeastern Amazonia.

PubMed

Coe, Michael T; Marthews, Toby R; Costa, Marcos Heil; Galbraith, David R; Greenglass, Nora L; Imbuzeiro, Hewlley M A; Levine, Naomi M; Malhi, Yadvinder; Moorcroft, Paul R; Muza, Michel Nobre; Powell, Thomas L; Saleska, Scott R; Solorzano, Luis A; Wang, Jingfeng

2013-06-05

A mosaic of protected areas, including indigenous lands, sustainable-use production forests and reserves and strictly protected forests is the cornerstone of conservation in the Amazon, with almost 50 per cent of the region now protected. However, recent research indicates that isolation from direct deforestation or degradation may not be sufficient to maintain the ecological integrity of Amazon forests over the next several decades. Large-scale changes in fire and drought regimes occurring as a result of deforestation and greenhouse gas increases may result in forest degradation, regardless of protected status. How severe or widespread these feedbacks will be is uncertain, but the arc of deforestation in south-southeastern Amazonia appears to be particularly vulnerable owing to high current deforestation rates and ecological sensitivity to climate change. Maintaining forest ecosystem integrity may require significant strengthening of forest conservation on private property, which can in part be accomplished by leveraging existing policy mechanisms.

Differential Response of Acidobacteria Subgroups to Forest-to-Pasture Conversion and Their Biogeographic Patterns in the Western Brazilian Amazon

PubMed Central

Navarrete, Acacio A.; Venturini, Andressa M.; Meyer, Kyle M.; Klein, Ann M.; Tiedje, James M.; Bohannan, Brendan J. M.; Nüsslein, Klaus; Tsai, Siu M.; Rodrigues, Jorge L. M.

2015-01-01

Members of the phylum Acidobacteria are among the most abundant soil bacteria on Earth, but little is known about their response to environmental changes. We asked how the relative abundance and biogeographic patterning of this phylum and its subgroups responded to forest-to-pasture conversion in soils of the western Brazilian Amazon. Pyrosequencing of 16S rRNA genes was employed to assess the abundance and composition of the Acidobacteria community across 54 soil samples taken using a spatially nested sampling scheme at the landscape level. Numerically, Acidobacteria represented 20% of the total bacterial community in forest soils and 11% in pasture soils. Overall, 15 different Acidobacteria subgroups of the current 26 subgroups were detected, with Acidobacteria subgroups 1, 3, 5, and 6 accounting together for 87% of the total Acidobacteria community in forest soils and 75% in pasture soils. Concomitant with changes in soil chemistry after forest-to-pasture conversion—particularly an increase in properties linked to soil acidity and nutrient availability—we observed an increase in the relative abundances of Acidobacteria subgroups 4, 10, 17, and 18, and a decrease in the relative abundances of other Acidobacteria subgroups in pasture relative to forest soils. The composition of the total Acidobacteria community as well as the most abundant Acidobacteria subgroups (1, 3, 5, and 6) was significantly more similar in composition across space in pasture soils than in forest soils. These results suggest that preponderant responses of Acidobacteria subgroups, especially subgroups 1, 3, 4, 5, and 6, to forest-to-pasture conversion effects in soils could be used to define management-indicators of agricultural practices in the Amazon Basin. These acidobacterial responses are at least in part through alterations on acidity- and nutrient-related properties of the Amazon soils. PMID:26733981

Seasonal changes in leaf area of Amazon forests from leaf flushing and abscission

NASA Astrophysics Data System (ADS)

Samanta, Arindam; Knyazikhin, Yuri; Xu, Liang; Dickinson, Robert E.; Fu, Rong; Costa, Marcos H.; Saatchi, Sassan S.; Nemani, Ramakrishna R.; Myneni, Ranga B.

2012-03-01

A large increase in near-infrared (NIR) reflectance of Amazon forests during the light-rich dry season and a corresponding decrease during the light-poor wet season has been observed in satellite measurements. This increase has been variously interpreted as seasonal change in leaf area resulting from net leaf flushing in the dry season or net leaf abscission in the wet season, enhanced photosynthetic activity during the dry season from flushing new leaves and as change in leaf scattering and absorption properties between younger and older leaves covered with epiphylls. Reconciling these divergent views using theory and observations is the goal of this article. The observed changes in NIR reflectance of Amazon forests could be due to similar, but small, changes in NIR leaf albedo (reflectance plus transmittance) resulting from the exchange of older leaves for newer ones, but with the total leaf area unchanged. However, this argument ignores accumulating evidence from ground-based reports of higher leaf area in the dry season than the wet season, seasonal changes in litterfall and does not satisfactorily explain why NIR reflectance of these forests decreases in the wet season. More plausibly, the increase in NIR reflectance during the dry season and the decrease during the wet season would result from changes in both leaf area and leaf optical properties. Such change would be consistent with known phenological behavior of tropical forests, ground-based reports of seasonal changes in leaf area, litterfall, leaf optical properties and fluxes of evapotranspiration, and thus, would reconcile the various seemingly divergent views.

Forest Canopy Heights in Amazon River Basin Forests as Estimated with the Geoscience Laser Altimeter System (GLAS)

Treesearch

E. H. Helmer; M. A. Lefsky

2006-01-01

Land-use change, mainly forest burning, harvest, or clearing for agriculture, may compose 15 to 40 percent of annual human-caused emissions of carbon (C) to the atmosphere. Spatially extensive data on forest C pools can validate and parameterize atmospheric and ecosystem models of those fluxes and quantify fluxes from forest change. Excellent evidence exists that light...

Spatially and seasonally asymmetric responses of Amazon forests to El Niño

NASA Astrophysics Data System (ADS)

Mao, J.; Yan, B.; Dickinson, R. E.; Shi, X.; Ricciuto, D. M.; Norby, R. J.; Dai, Y.; Zhang, X.; McDowell, N.; Wu, J.

2017-12-01

El Niño Southern Oscillation (ENSO) events impose strong inter-annual signals on local climate changes and terrestrial ecosystem dynamics in many regions on the Earth especially tropical forests in the Amazon basin. However, much is still unknown regarding the vulnerability of tropical forests to ENSO effects, especially in a spatially-explicit context. Here, using satellite and ground observations with reanalysis data of climate variables, we analyzed the spatial and temporal patterns of plant growth in response to the warm phase of ENSO (i.e., El Niño), which resulted in precipitation anomaly (or drought) over a large area across the Amazon. We found that the influence of El Niño events on vegetation growth varied spatially and seasonally. During each season (dry or wet), the forests were divided into two sub-regions that were either controlled by precipitation or radiation. The boundaries between the two sub-regions were determined, which were distributed from northwest to southeast in the dry season and from northeast to southwest in the wet season. This result improves our understanding of the water and energy availability co-modulating the vegetation growth in Amazonia and the magnitude and direction of Amazon forests responding to drought.

Effects of seasonality and land-use change on carbon and water fluxes across the Amazon basin: synthesizing results from satellite-based remote sensing, towers, and models

NASA Astrophysics Data System (ADS)

Saleska, S.; Goncalves, L. G.; Baker, I.; Costa, M.; Poulter, B.; Christoffersen, B.; Da Rocha, H. R.; Didan, K.; Huete, A.; Imbuziero, H.; Kruijt, B.; Manzi, A.; von Randow, C.; Restrepo-Coupe, N.; Silva, R.; Tota, J.; Denning, S.; Gulden, L.; Rosero, E.; Zeng, X.

2008-12-01

Amazon forests play an important and complex role in the global carbon cycle, and important advances have been made in understanding Amazon processes in recent years. However, reconciling modeled mechanisms of carbon cycling with observations across scales remains a challenge. To better address this challenge, we initiated a Model intercomparison Project for the 'Large-Scale Biosphere Atmosphere Experiment in Amazonia' (LBA-MIP) to integrate modeling and observational studies for improved understanding of Amazon basin carbon cycling. Here, we report on the initial results of this project, which used the network of meteorological and climate data (sunlight, radiation, precipitation) from Amazon tower sites in forest and converted lands to drive a suite of 20 ecosystem models that simulate energy, water and CO2 fluxes. We compared model mechanisms to each other and to the relevant flux observations from those towers, as well as from satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS). Remote sensing and flux tower observations tend to show higher primary forest photosynthetic activity in the dry season than in the wet season in central Amazon, a broad pattern that is now captured in many models, but for different reasons. A reversal from the primary forest pattern was observed in areas converted to pasture, agriculture, or secondary forests, likely a consequence of the elimination of deep root access to deep soil waters which often persist through the dry season. Testing the models with observed fluxes under different land use patterns, and across different spatial scales with remote sensing, is enabling us to distinguish correct vs. incorrect model mechanisms and improve understanding of Amazon processes.

Forest-rainfall cascades buffer against drought across the Amazon

NASA Astrophysics Data System (ADS)

Staal, Arie; Tuinenburg, Obbe A.; Bosmans, Joyce H. C.; Holmgren, Milena; van Nes, Egbert H.; Scheffer, Marten; Zemp, Delphine Clara; Dekker, Stefan C.

2018-06-01

Tree transpiration in the Amazon may enhance rainfall for downwind forests. Until now it has been unclear how this cascading effect plays out across the basin. Here, we calculate local forest transpiration and the subsequent trajectories of transpired water through the atmosphere in high spatial and temporal detail. We estimate that one-third of Amazon rainfall originates within its own basin, of which two-thirds has been transpired. Forests in the southern half of the basin contribute most to the stability of other forests in this way, whereas forests in the south-western Amazon are particularly dependent on transpired-water subsidies. These forest-rainfall cascades buffer the effects of drought and reveal a mechanism by which deforestation can compromise the resilience of the Amazon forest system in the face of future climatic extremes.

Neogene origins and implied warmth tolerance of Amazon tree species

PubMed Central

Dick, Christopher W; Lewis, Simon L; Maslin, Mark; Bermingham, Eldredge

2013-01-01

Tropical rain forest has been a persistent feature in South America for at least 55 million years. The future of the contemporary Amazon forest is uncertain, however, as the region is entering conditions with no past analogue, combining rapidly increasing air temperatures, high atmospheric carbon dioxide concentrations, possible extreme droughts, and extensive removal and modification by humans. Given the long-term Cenozoic cooling trend, it is unknown whether Amazon forests can tolerate air temperature increases, with suggestions that lowland forests lack warm-adapted taxa, leading to inevitable species losses. In response to this uncertainty, we posit a simple hypothesis: the older the age of a species prior to the Pleistocene, the warmer the climate it has previously survived, with Pliocene (2.6–5 Ma) and late-Miocene (8–10 Ma) air temperature across Amazonia being similar to 2100 temperature projections under low and high carbon emission scenarios, respectively. Using comparative phylogeographic analyses, we show that 9 of 12 widespread Amazon tree species have Pliocene or earlier lineages (>2.6 Ma), with seven dating from the Miocene (>5.6 Ma) and three >8 Ma. The remarkably old age of these species suggest that Amazon forests passed through warmth similar to 2100 levels and that, in the absence of other major environmental changes, near-term high temperature-induced mass species extinction is unlikely. PMID:23404439

Landscape fragmentation, severe drought, and the new Amazon forest fire regime.

PubMed

Alencar, Ane A; Brando, Paulo M; Asner, Gregory P; Putz, Francis E

2015-09-01

Changes in weather and land use are transforming the spatial and temporal characteristics of fire regimes in Amazonia, with important effects on the functioning of dense (i.e., closed-canopy), open-canopy, and transitional forests across the Basin. To quantify, document, and describe the characteristics and recent changes in forest fire regimes, we sampled 6 million ha of these three representative forests of the eastern and southern edges of the Amazon using 24 years (1983-2007) of satellite-derived annual forest fire scar maps and 16 years of monthly hot pixel information (1992-2007). Our results reveal that changes in forest fire regime properties differentially affected these three forest types in terms of area burned and fire scar size, frequency, and seasonality. During the study period, forest fires burned 15% (0.3 million ha), 44% (1 million ha), and 46% (0.6 million ha) of dense, open, and transitional forests, respectively. Total forest area burned and fire scar size tended to increase over time (even in years of average rainfall in open canopy and transitional forests). In dense forests, most of the temporal variability in fire regime properties was linked to El Nino Southern Oscillation (ENSO)-related droughts. Compared with dense forests, transitional and open forests experienced fires twice as frequently, with at least 20% of these forests' areas burning two or more times during the 24-year study period. Open and transitional forests also experienced higher deforestation rates than dense forests. During drier years, the end of the dry season was delayed by about a month, which resulted in larger burn scars and increases in overall area burned later in the season. These observations suggest that climate-mediated forest flammability is enhanced by landscape fragmentation caused by deforestation, as observed for open and transitional forests in the Eastern portion of the Amazon Basin.

Seasonal Changes in Leaf Area of Amazon Forests from Leaf Flushing and Abscission

NASA Astrophysics Data System (ADS)

Samanta, A.; Knyazikhin, Y.; Xu, L.; Dickinson, R.; Fu, R.; Costa, M. H.; Ganguly, S.; Saatchi, S. S.; Nemani, R. R.; Myneni, R.

2011-12-01

A large increase in near-infrared (NIR) reflectance of Amazon forests during the light-rich dry season and a corresponding decrease during the light-poor wet season has been observed in satellite measurements. This has been variously interpreted as seasonal changes in leaf area resulting from net leaf flushing in the dry season and net leaf abscission in the wet season, enhanced photosynthetic activity during the dry season from flushing new leaves and as change in leaf scattering and absorption properties between younger and older leaves covered with epiphylls. Reconciling these divergent views using theory and observations is the goal of this article. The observed changes in NIR reflectance of Amazon forests could be due to similar, but small, changes in NIR leaf albedo (reflectance plus transmittance) only, from exchanging older leaves with newer ones, with total leaf area unchanged. However, this argument ignores accumulating evidence from ground-based studies of higher leaf area in the dry season relative to the wet season, seasonal changes in litterfall and does not satisfactorily explain why NIR reflectance of these forests decreases in the wet season. A more convincing explanation for the observed increase in NIR reflectance during the dry season and decrease during the wet season is one that invokes changes in both leaf area and leaf optical properties. Such an argument is consistent with known phonological behavior of tropical forests, ground-based reports of seasonal changes in leaf area, litterfall, leaf optical properties and fluxes of evapotranspiration, and thus, reconciles the various seemingly divergent views.

Are Brazil’s Deforesters Avoiding Detection?

PubMed Central

Richards, Peter; Arima, Eugenio; VanWey, Leah; Cohn, Avery; Bhattarai, Nishan

2017-01-01

Rates of deforestation reported by Brazil’s official deforestation monitoring system have declined dramatically in the Brazilian Amazon. Much of Brazil’s success in its fight against deforestation has been credited to a series of policy changes put into place between 2004 and 2008. In this research, we posit that one of these policies, the decision to use the country’s official system for monitoring forest loss in the Amazon as a policing tool, has incentivized landowners to deforest in ways and places that evade Brazil’s official monitoring and enforcement system. As a consequence, we a) show or b) provide several pieces of suggestive evidence that recent successes in protecting monitored forests in the Brazilian Amazon may be doing less to protect the region’s forests than previously assumed. PMID:29270225

Forecasting Fire Season Severity in South America Using Sea Surface Temperature Anomalies

NASA Technical Reports Server (NTRS)

Chen, Yang; Randerson, James T.; Morton, Douglas C.; DeFries, Ruth S.; Collatz, G. James; Kasibhatla, Prasad S.; Giglio, Louis; Jin, Yufang; Marlier, Miriam E.

2011-01-01

Fires in South America cause forest degradation and contribute to carbon emissions associated with land use change. We investigated the relationship between year-to-year changes in fire activity in South America and sea surface temperatures. We found that the Oceanic Ni o Index was correlated with interannual fire activity in the eastern Amazon, whereas the Atlantic Multidecadal Oscillation index was more closely linked with fires in the southern and southwestern Amazon. Combining these two climate indices, we developed an empirical model to forecast regional fire season severity with lead times of 3 to 5 months. Our approach may contribute to the development of an early warning system for anticipating the vulnerability of Amazon forests to fires, thus enabling more effective management with benefits for climate and air quality.

The importance of forest structure for carbon fluxes of the Amazon rainforest

NASA Astrophysics Data System (ADS)

Rödig, Edna; Cuntz, Matthias; Rammig, Anja; Fischer, Rico; Taubert, Franziska; Huth, Andreas

2018-05-01

Precise descriptions of forest productivity, biomass, and structure are essential for understanding ecosystem responses to climatic and anthropogenic changes. However, relations between these components are complex, in particular for tropical forests. We developed an approach to simulate carbon dynamics in the Amazon rainforest including around 410 billion individual trees within 7.8 million km2. We integrated canopy height observations from space-borne LIDAR in order to quantify spatial variations in forest state and structure reflecting small-scale to large-scale natural and anthropogenic disturbances. Under current conditions, we identified the Amazon rainforest as a carbon sink, gaining 0.56 GtC per year. This carbon sink is driven by an estimated mean gross primary productivity (GPP) of 25.1 tC ha‑1 a‑1, and a mean woody aboveground net primary productivity (wANPP) of 4.2 tC ha‑1 a‑1. We found that successional states play an important role for the relations between productivity and biomass. Forests in early to intermediate successional states are the most productive, and woody above-ground carbon use efficiencies are non-linear. Simulated values can be compared to observed carbon fluxes at various spatial resolutions (>40 m). Notably, we found that our GPP corresponds to the values derived from MODIS. For NPP, spatial differences can be observed due to the consideration of forest successional states in our approach. We conclude that forest structure has a substantial impact on productivity and biomass. It is an essential factor that should be taken into account when estimating current carbon budgets or analyzing climate change scenarios for the Amazon rainforest.

Monitoring Strategies for REDD+: Integrating Field, Airborne, and Satellite Observations of Amazon Forests

NASA Technical Reports Server (NTRS)

Morton, Douglas; Souza, Carlos, Jr.; Souza, Carlos, Jr.; Keller, Michael

2012-01-01

Large-scale tropical forest monitoring efforts in support of REDD+ (Reducing Emissions from Deforestation and forest Degradation plus enhancing forest carbon stocks) confront a range of challenges. REDD+ activities typically have short reporting time scales, diverse data needs, and low tolerance for uncertainties. Meeting these challenges will require innovative use of remote sensing data, including integrating data at different spatial and temporal resolutions. The global scientific community is engaged in developing, evaluating, and applying new methods for regional to global scale forest monitoring. Pilot REDD+ activities are underway across the tropics with support from a range of national and international groups, including SilvaCarbon, an interagency effort to coordinate US expertise on forest monitoring and resource management. Early actions on REDD+ have exposed some of the inherent tradeoffs that arise from the use of incomplete or inaccurate data to quantify forest area changes and related carbon emissions. Here, we summarize recent advances in forest monitoring to identify and target the main sources of uncertainty in estimates of forest area changes, aboveground carbon stocks, and Amazon forest carbon emissions.

Recovery of Methane Consumption by Secondary Forests in the Amazon River Basin

NASA Astrophysics Data System (ADS)

Webster, K. D.; Meredith, L. K.; Piccini, W.; Pedrinho, A.; Nüsslein, K.; Van Haren, J. L. M.; Camargo, P. B. D.; Mui, T. S.; Saleska, S. R.

2017-12-01

Methane (CH4) is a major greenhouse gas in Earth's atmosphere and its atmospheric global mole fraction has roughly doubled since the start of the industrial revolution. The tropics are thought to be a major CH4 emitter, with the Amazon River Basin estimated to contribute 7 % of the annual flux to the atmosphere. The Amazon has experienced extensive land use change during the past 30 years, but we lack an understanding of the qualitative and quantitative effects of land use change on CH4 flux from the Amazon and the associated reasons. To illuminate the factors controlling CH4 flux across land use gradients in the Amazon we measured the CH4 fluxes and will measure the associated stable isotopic composition from pastures, primary forests, and secondary forests, at Ariquemes (Western Amazon, more deforested), and Santarem (Eastern Amazon, less deforested), Brazil. The sites near Santarem were sampled in June of 2016 and the sites near Ariquemes were sampled in March and April of 2017, both at the end of the wet season. Little difference was observed between land use types in Santarem with each land use type slightly consuming atmospheric CH4. However, pasture fluxes at Ariquemes were higher (+520 μg-C m-2 hr-1) than in primary (0 μg-C m-2 hr-1) and secondary forests (-20 μg-C m-2 hr-1; p = 6*10-4). CH4 flux from individual Santarem sites was not correlated with environmental variables. CH4 flux from Airquemes was correlated with several parameters across all samples including soil temperature (p = 7*10-4), and soil humidity (p = 0.02). Despite the fact that pastures experienced higher soil temperatures than forest soils this appears to be a low predictor of CH4 flux from these environments as it was seen at both Santarem and Ariquemes. The analysis of the stable isotopic composition of CH4 from these chambers will aid in understanding the competing processes of microbial CH4 consumption and production in these soils and why pastures may become CH4 sources and secondary forests are able to regain the function as a CH4 sink in some instances. Support: NSF, FAPESP-Biota, CNPq, CAPES.

Detection of Green up Phenomenon in Amazon Forests Using Spaceborne Solar-induced Fluorescence

NASA Astrophysics Data System (ADS)

Chen, S.; Chen, X.; Chen, J.; Cao, X.

2016-12-01

The role of Amazon forests in the global carbon budget still remains uncertain. The critical issue is whether tropical forest productivity is more limited by sunlight or rainfall. Recent studies using satellite data have challenged the paradigm of light-limited net primary production in Amazon forests and enhanced forest growth during drought conditions because of the adding effects of variations in sun-sensor geometry. To reducing uncertainties in knowing the sensitivity of Amazon rainforests to dry season droughts, we evaluated a newly emerging satellite retrieval, solar-induced fluorescence (SIF) of chlorophyll for the seasonal green-up phenomenon, providing for the first time a direct measurement related to vegetation photosynthetic activity as well as unaffected by sun-sensor geometry. Moreover, NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) products (the enhanced vegetation index (EVI) and leaf area index (LAI)) and Landsat Operational Land Imager (OLI) data are also compared to evaluate this phenomenon. Here we show that the green up of Amazon forests in the study area around manas site did show in SIF of chlorophyll data in 2015 drought resulted from seasonal changes. The EVI has more apparent green up phenomenon than the NDVI data both in MODIS and OLI data, suggesting that the EVI can better reflect near-infrared (NIR) and LAI information of vegetation. The OLI data is less influenced by variations caused by bidirectional reflectance effect. In addition, SIF of chlorophyll data shows well correlation relationship with the EVI, LAI and NDVI, suggesting that the SIF of chlorophyll data present well quality to capture the characteristics of the phenology of vegetation.

Stability in a changing world - palm community dynamics in the hyperdiverse western Amazon over 17 years.

PubMed

Olivares, Ingrid; Svenning, Jens-Christian; van Bodegom, Peter M; Valencia, Renato; Balslev, Henrik

2017-03-01

Are the hyperdiverse local forests of the western Amazon undergoing changes linked to global and local drivers such as climate change, or successional dynamics? We analyzed local climatic records to assess potential climatic changes in Yasuní National Park, Ecuador, and compared two censuses (1995, 2012) of a palm community to assess changes in community structure and composition. Over 17 years, the structure and composition of this palm community remained remarkably stable. Soil humidity was significantly lower and canopy conditions were significantly more open in 2012 compared to 1995, but local climatic records showed that no significant changes in precipitation, temperature or river level have occurred during the last decade. Thus, we found no evidence of recent directional shifts in climate or the palm community in Yasuní. The absence of changes in local climate and plant community dynamics in Yasuní contrasts with recent findings from eastern Amazon, where environmental change is driving significant changes in ecosystem dynamics. Our findings suggest that until now, local forests in the northwest Amazon may have escaped pressure from climate change. The stability of this rich palm community embedded in the hyperdiverse Yasuní National Park underlines its uniqueness as a sanctuary for the protection of Amazonian diversity from global change impacts. © 2016 John Wiley & Sons Ltd.

Changing Amazon biomass and the role of atmospheric CO2 concentration, climate, and land use

NASA Astrophysics Data System (ADS)

Almeida Castanho, Andrea D.; Galbraith, David; Zhang, Ke; Coe, Michael T.; Costa, Marcos H.; Moorcroft, Paul

2016-01-01

The Amazon tropical evergreen forest is an important component of the global carbon budget. Its forest floristic composition, structure, and function are sensitive to changes in climate, atmospheric composition, and land use. In this study biomass and productivity simulated by three dynamic global vegetation models (Integrated Biosphere Simulator, Ecosystem Demography Biosphere Model, and Joint UK Land Environment Simulator) for the period 1970-2008 are compared with observations from forest plots (Rede Amazónica de Inventarios Forestales). The spatial variability in biomass and productivity simulated by the DGVMs is low in comparison to the field observations in part because of poor representation of the heterogeneity of vegetation traits within the models. We find that over the last four decades the CO2 fertilization effect dominates a long-term increase in simulated biomass in undisturbed Amazonian forests, while land use change in the south and southeastern Amazonia dominates a reduction in Amazon aboveground biomass, of similar magnitude to the CO2 biomass gain. Climate extremes exert a strong effect on the observed biomass on short time scales, but the models are incapable of reproducing the observed impacts of extreme drought on forest biomass. We find that future improvements in the accuracy of DGVM predictions will require improved representation of four key elements: (1) spatially variable plant traits, (2) soil and nutrients mediated processes, (3) extreme event mortality, and (4) sensitivity to climatic variability. Finally, continued long-term observations and ecosystem-scale experiments (e.g. Free-Air CO2 Enrichment experiments) are essential for a better understanding of the changing dynamics of tropical forests.

The Amazon Basin in transition

Treesearch

Eric A. Davidson; Alessandro C. de Araujo; Paulo Artaxo; Jennifer K. Balch; I. Foster Brown; Mercedes M.C. Bustamente; Michael T. Coe; Ruth S. DeFriess; Michael Keller; Marcos Longo; J. William Munger; Wilfrid Schroeder; Britaldo Soares-Filho; Carlos M. Souza, Jr.; Steven C. Wofsy

2012-01-01

Agricultural expansion and climate variability have become important agents of disturbance in the Amazon basin. Recent studies have demonstrated considerable resilience of Amazonian forests to moderate annual drought, but they also show that interactions between deforestation, fire and drought potentially lead to losses of carbon storage and changes in regional...

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses.

PubMed

Garcia, Elizabeth S; Swann, Abigail L S; Villegas, Juan C; Breshears, David D; Law, Darin J; Saleska, Scott R; Stark, Scott C

2016-01-01

Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates of deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia's GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. Our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change.

The economic value of the climate regulation ecosystem service provided by the Amazon rainforest

NASA Astrophysics Data System (ADS)

Heil Costa, Marcos; Pires, Gabrielle; Fontes, Vitor; Brumatti, Livia

2017-04-01

The rainy Amazon climate allowed important activities to develop in the region as large rainfed agricultural lands and hydropower plants. The Amazon rainforest is an important source of moisture to the regional atmosphere and helps regulate the local climate. The replacement of forest by agricultural lands decreases the flux of water vapor into the atmosphere and changes the precipitation patterns, which may severely affect such economic activities. Assign an economic value to this ecosystem service may emphasize the significance to preserve the Amazon rainforest. In this work, we provide a first approximation of the quantification of the climate regulation ecosystem service provided by the Amazon rainforest using the marginal production method. We use climate scenarios derived from Amazon deforestation scenarios as input to crop and runoff models to assess how land use change would affect agriculture and hydropower generation. The effects of forest removal on soybean production and on cattle beef production can both be as high as US 16 per year per ha deforested, and the effects on hydropower generation can be as high as US 8 per year per ha deforested. We consider this as a conservative estimate of a permanent service provided by the rainforest. Policy makers and other Amazon agriculture and energy businesses must be aware of these numbers, and consider them while planning their activities.

Variations in Amazon forest productivity correlated with foliar nutrients and modelled rates of photosynthetic carbon supply

PubMed Central

Mercado, Lina M.; Patiño, Sandra; Domingues, Tomas F.; Fyllas, Nikolaos M.; Weedon, Graham P.; Sitch, Stephen; Quesada, Carlos Alberto; Phillips, Oliver L.; Aragão, Luiz E. O. C.; Malhi, Yadvinder; Dolman, A. J.; Restrepo-Coupe, Natalia; Saleska, Scott R.; Baker, Timothy R.; Almeida, Samuel; Higuchi, Niro; Lloyd, Jon

2011-01-01

The rate of above-ground woody biomass production, WP, in some western Amazon forests exceeds those in the east by a factor of 2 or more. Underlying causes may include climate, soil nutrient limitations and species composition. In this modelling paper, we explore the implications of allowing key nutrients such as N and P to constrain the photosynthesis of Amazon forests, and also we examine the relationship between modelled rates of photosynthesis and the observed gradients in WP. We use a model with current understanding of the underpinning biochemical processes as affected by nutrient availability to assess: (i) the degree to which observed spatial variations in foliar [N] and [P] across Amazonia affect stand-level photosynthesis; and (ii) how these variations in forest photosynthetic carbon acquisition relate to the observed geographical patterns of stem growth across the Amazon Basin. We find nutrient availability to exert a strong effect on photosynthetic carbon gain across the Basin and to be a likely important contributor to the observed gradient in WP. Phosphorus emerges as more important than nitrogen in accounting for the observed variations in productivity. Implications of these findings are discussed in the context of future tropical forests under a changing climate. PMID:22006971

Modeling forest dynamics along climate gradients in Bolivia

NASA Astrophysics Data System (ADS)

Seiler, C.; Hutjes, R. W. A.; Kruijt, B.; Quispe, J.; Añez, S.; Arora, V. K.; Melton, J. R.; Hickler, T.; Kabat, P.

2014-05-01

Dynamic vegetation models have been used to assess the resilience of tropical forests to climate change, but the global application of these modeling experiments often misrepresents carbon dynamics at a regional level, limiting the validity of future projections. Here a dynamic vegetation model (Lund Potsdam Jena General Ecosystem Simulator) was adapted to simulate present-day potential vegetation as a baseline for climate change impact assessments in the evergreen and deciduous forests of Bolivia. Results were compared to biomass measurements (819 plots) and remote sensing data. Using regional parameter values for allometric relations, specific leaf area, wood density, and disturbance interval, a realistic transition from the evergreen Amazon to the deciduous dry forest was simulated. This transition coincided with threshold values for precipitation (1400 mm yr-1) and water deficit (i.e., potential evapotranspiration minus precipitation) (-830 mm yr-1), beyond which leaf abscission became a competitive advantage. Significant correlations were found between modeled and observed values of seasonal leaf abscission (R2 = 0.6, p <0.001) and vegetation carbon (R2 = 0.31, p <0.01). Modeled Gross Primary Productivity (GPP) and remotely sensed normalized difference vegetation index showed that dry forests were more sensitive to rainfall anomalies than wet forests. GPP was positively correlated to the El Niño-Southern Oscillation index in the Amazon and negatively correlated to consecutive dry days. Decreasing rainfall trends were simulated to reduce GPP in the Amazon. The current model setup provides a baseline for assessing the potential impacts of climate change in the transition zone from wet to dry tropical forests in Bolivia.

Amazon Forest Structure from IKONOS Satellite Data and the Automated Characterization of Forest Canopy Properties

Treesearch

Michael Palace; Michael Keller; Gregory P. Asner; Stephen Hagen; Bobby Braswell

2008-01-01

We developed an automated tree crown analysis algorithm using 1-m panchromatic IKONOS satellite images to examine forest canopy structure in the Brazilian Amazon. The algorithm was calibrated on the landscape level with tree geometry and forest stand data at the Fazenda Cauaxi (3.75◦ S, 48.37◦ W) in the eastern Amazon, and then compared with forest...

Amazon Deforestation Fires Increase Plant Productivity through Changes in Diffuse Radiation

NASA Astrophysics Data System (ADS)

Rap, A.; Reddington, C.; Spracklen, D. V.; Mercado, L.; Haywood, J. M.; Bonal, D.; Butt, N.; Phillips, O.

2013-12-01

Over the past few decades a large increase in carbon storage has been observed in undisturbed forests across Amazonia. The reason for such a sink is unclear, although many possible mechanisms have been suggested, including changes in temperature, carbon dioxide, precipitation, clouds, and solar radiation. In this work we focus on one such mechanism, namely the increase in plant photosynthesis due to changes in diffuse radiation caused by atmospheric aerosols from large-scale deforestation fires that now occur throughout the Amazon region. We estimate that this mechanism has increased dry season (August-September) net primary productivity (NPP) by up to 30% across wide regions of the Amazon. We conclude that aerosol from deforestation fires may be responsible for a substantial fraction of the Amazon carbon sink that has been observed. Our approach is based on the combined use of three models: (i) the Global Model of Aerosol Processes (GLOMAP), (ii) the Edwards-Slingo radiation model, and (iii) the UK Met Office JULES land-surface scheme, constrained against in-situ aerosol and radiation observation datasets from several Amazonian sites. A 10 year (1999-2008) GLOMAP simulation using GFED3 biomass burning emissions is first evaluated against aerosol observations, indicating that the model is able to capture the Amazon aerosol seasonality, with enhanced concentrations during the dry season driven by biomass burning. The radiation scheme is then shown to be in good agreement with total and diffuse radiation in-situ observations, the model being able to capture the high total and low diffuse radiation flux in the dry season, as well as the low total and high diffuse radiation flux in the wet season. We then use our modelling framework to quantify the contribution of deforestation fires to diffuse/direct radiation fraction and forest productivity. We calculate that deforestation fires increase dry season diffuse radiation by up to 60% or 30 Wm-2. Finally, we use the JULES model to show that this increase in diffuse radiation is responsible for a substantial growth in gross primary productivity (GPP), enhancing Amazon-wide dry-season GPP by 5% with local increases of up to 15%. Most of this GPP response results in an increase in NPP, estimated in the dry season at 10% across the Amazon with local increases as large as 30%. This substantial NPP enhancement spatially matches observed increases in forest biomass storage across the Amazon. We thus suggest that deforestation fires have an important impact on the Amazon carbon budget and attempt to estimate the fraction of the observed forest carbon sink that can be attributed to this mechanism. Change [%] in diffuse radiation due to deforestation

Assessment of Large Scale Land Cover Change Classifications and Drivers of Deforestation in Indonesia

NASA Astrophysics Data System (ADS)

Wijaya, A.; Sugardiman Budiharto, R. A.; Tosiani, A.; Murdiyarso, D.; Verchot, L. V.

2015-04-01

Indonesia possesses the third largest tropical forests coverage following Brazilian Amazon and Congo Basin regions. This country, however, suffered from the highest deforestation rate surpassing deforestation in the Brazilian Amazon in 2012. National capacity for forest change assessment and monitoring has been well-established in Indonesia and the availability of national forest inventory data could largely assist the country to report their forest carbon stocks and change over more than two decades. This work focuses for refining forest cover change mapping and deforestation estimate at national scale applying over 10,000 scenes of Landsat scenes, acquired in 1990, 1996, 2000, 2003, 2006, 2009, 2011 and 2012. Pre-processing of the data includes, geometric corrections and image mosaicking. The classification of mosaic Landsat data used multi-stage visual observation approaches, verified using ground observations and comparison with other published materials. There are 23 land cover classes identified from land cover data, presenting spatial information of forests, agriculture, plantations, non-vegetated lands and other land use categories. We estimated the magnitude of forest cover change and assessed drivers of forest cover change over time. Forest change trajectories analysis was also conducted to observe dynamics of forest cover across time. This study found that careful interpretations of satellite data can provide reliable information on forest cover and change. Deforestation trend in Indonesia was lower in 2000-2012 compared to 1990-2000 periods. We also found that over 50% of forests loss in 1990 remains unproductive in 2012. Major drivers of forest conversion in Indonesia range from shrubs/open land, subsistence agriculture, oil palm expansion, plantation forest and mining. The results were compared with other available datasets and we obtained that the MOF data yields reliable estimate of deforestation.

El Niño drought increased canopy turnover in Amazon forests.

PubMed

Leitold, Veronika; Morton, Douglas C; Longo, Marcos; Dos-Santos, Maiza Nara; Keller, Michael; Scaranello, Marcos

2018-03-25

Amazon droughts, including the 2015-2016 El Niño, may reduce forest net primary productivity and increase canopy tree mortality, thereby altering both the short- and the long-term net forest carbon balance. Given the broad extent of drought impacts, inventory plots or eddy flux towers may not capture regional variability in forest response to drought. We used multi-temporal airborne Lidar data and field measurements of coarse woody debris to estimate patterns of canopy turnover and associated carbon losses in intact and fragmented forests in the central Brazilian Amazon between 2013-2014 and 2014-2016. Average annualized canopy turnover rates increased by 65% during the drought period in both intact and fragmented forests. The average size and height of turnover events was similar for both time intervals, in contrast to expectations that the 2015-2016 El Niño drought would disproportionally affect large trees. Lidar-biomass relationships between canopy turnover and field measurements of coarse woody debris were modest (R 2  ≈ 0.3), given similar coarse woody debris production and Lidar-derived changes in canopy volume from single tree and multiple branch fall events. Our findings suggest that El Niño conditions accelerated canopy turnover in central Amazon forests, increasing coarse woody debris production by 62% to 1.22 Mg C ha -1  yr -1 in drought years . No claim to original US Government works New Phytologist © 2018 New Phytologist Trust.

A long-term perspective on deforestation rates in the Brazilian Amazon

NASA Astrophysics Data System (ADS)

Velasco Gomez, M. D.; Beuchle, R.; Shimabukuro, Y.; Grecchi, R.; Simonetti, D.; Eva, H. D.; Achard, F.

2015-04-01

Monitoring tropical forest cover is central to biodiversity preservation, terrestrial carbon stocks, essential ecosystem and climate functions, and ultimately, sustainable economic development. The Amazon forest is the Earth's largest rainforest, and despite intensive studies on current deforestation rates, relatively little is known as to how these compare to historic (pre 1985) deforestation rates. We quantified land cover change between 1975 and 2014 in the so-called Arc of Deforestation of the Brazilian Amazon, covering the southern stretch of the Amazon forest and part of the Cerrado biome. We applied a consistent method that made use of data from Landsat sensors: Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI). We acquired suitable images from the US Geological Survey (USGS) for five epochs: 1975, 1990, 2000, 2010, and 2014. We then performed land cover analysis for each epoch using a systematic sample of 156 sites, each one covering 10 km x 10 km, located at the confluence point of integer degree latitudes and longitudes. An object-based classification of the images was performed with five land cover classes: tree cover, tree cover mosaic, other wooded land, other land cover, and water. The automatic classification results were corrected by visual interpretation, and, when available, by comparison with higher resolution imagery. Our results show a decrease of forest cover of 24.2% in the last 40 years in the Brazilian Arc of Deforestation, with an average yearly net forest cover change rate of -0.71% for the 39 years considered.

Atmosphere-biosphere exchange of CO2 and O3 in the Central Amazon Forest

NASA Technical Reports Server (NTRS)

Fan, Song-Miao; Wofsy, Steven C.; Bakwin, Peter S.; Jacob, Daniel J.; Fitzjarrald, David R.

1990-01-01

An eddy correlation measurement of O3 deposition and CO2 exchange at a level 10 m above the canopy of the Amazon forest, conducted as part of the NASA/INPE ABLE2b mission during the wet season of 1987, is presented. It was found that the ecosystem exchange of CO2 undergoes a well-defined diurnal variation driven by the input of solar radiation. A curvilinear relationship was found between solar irradiance and uptake of CO2, with net CO2 uptake at a given solar irradiance equal to rates observed over forests in other climate zones. The carbon balance of the system appeared sensitive to cloud cover on the time scale of the experiment, suggesting that global carbon storage might be affected by changes in insolation associated with tropical climate fluctuations. The forest was found to be an efficient sink for O3 during the day, and evidence indicates that the Amazon forests could be a significant sink for global ozone during the nine-month wet period and that deforestation could dramatically alter O3 budgets.

Characterizing Temporal and Spatial Changes in Land Surface Temperature across the Amazon Basin using Thermal and Infrared Satellite Data

NASA Astrophysics Data System (ADS)

Cak, A. D.

2017-12-01

The Amazon Basin has faced innumerable pressures in recent years, including logging, mining and resource extraction, agricultural expansion, road building, and urbanization. These changes have drastically altered the landscape, transforming a predominantly forested environment into a mosaic of different types of land cover. The resulting fragmentation has caused dramatic and negative impacts on its structure and function, including on biodiversity and the transfer of water and energy to and from soil, vegetation, and the atmosphere (e.g., evapotranspiration). Because evapotranspiration from forested areas, which is affected by factors including temperature and water availability, plays a significant role in water dynamics in the Amazon Basin, measuring land surface temperature (LST) across the region can provide a dynamic assessment of hydrological, vegetation, and land use and land cover changes. It can also help to identify widespread urban development, which often has a higher LST signal relative to surrounding vegetation. Here, we discuss results from work to measure and identify drivers of change in LST across the entire Amazon Basin through analysis of past and current thermal and infrared satellite imagery. We leverage cloud computing resources in new ways to allow for more efficient analysis of imagery over the Amazon Basin across multiple years and multiple sensors. We also assess potential drivers of change in LST using spatial and multivariate statistical analyses with additional data sources of land cover, urban development, and demographics.

Distribution of Aboveground Live Biomass in the Amazon Basin

NASA Technical Reports Server (NTRS)

Saatchi, S. S.; Houghton, R. A.; DosSantos Alvala, R. C.; Soares, J. V.; Yu, Y.

2007-01-01

The amount and spatial distribution of forest biomass in the Amazon basin is a major source of uncertainty in estimating the flux of carbon released from land-cover and land-use change. Direct measurements of aboveground live biomass (AGLB) are limited to small areas of forest inventory plots and site-specific allometric equations that cannot be readily generalized for the entire basin. Furthermore, there is no spaceborne remote sensing instrument that can measure tropical forest biomass directly. To determine the spatial distribution of forest biomass of the Amazon basin, we report a method based on remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 plot measurements of forest biomass distributed over the basin. A decision tree approach was used to develop the spatial distribution of AGLB for seven distinct biomass classes of lowland old-growth forests with more than 80% accuracy. AGLB for other vegetation types, such as the woody and herbaceous savanna and secondary forests, was directly estimated with a regression based on satellite data. Results show that AGLB is highest in Central Amazonia and in regions to the east and north, including the Guyanas. Biomass is generally above 300Mgha(sup 1) here except in areas of intense logging or open floodplains. In Western Amazonia, from the lowlands of Peru, Ecuador, and Colombia to the Andean mountains, biomass ranges from 150 to 300Mgha(sup 1). Most transitional and seasonal forests at the southern and northwestern edges of the basin have biomass ranging from 100 to 200Mgha(sup 1). The AGLB distribution has a significant correlation with the length of the dry season. We estimate that the total carbon in forest biomass of the Amazon basin, including the dead and below ground biomass, is 86 PgC with +/- 20% uncertainty.

Neogene vegetation development in the Amazon Basin: evidence from marine well-2, Foz do Amazonas (Brazil)

NASA Astrophysics Data System (ADS)

Bogota-Angel, Raul; Chemale Junior, Farid; Davila, Roberto; Soares, Emilson; Pinto, Ricardo; Do Carmo, Dermeval; Hoorn, Carina

2014-05-01

Origen and development of the highly diverse Amazon tropical forest has mostly been inferred from continental sites. However, sediment records in the marine Foz do Amazonas Basin can provide important information to better understand the influence of the Andes uplift and climate change on its plant biomes evolution since the Neogene. Sediment analyses of samples from BP-Petrobras well 1 and 2, drilled in the Amazon Fan, allowed to infer the onset of the transcontinental Amazon river and the fan phase during the middle to late Miocene (c. 10.5 Ma). As part of the CLIMAMAZON research programme we performed pollen analysis on the 10.5 to 0.4 Ma time interval. 76 ditch cutting samples of the upper 4165 m sediments of well 2 permitted us to infer changes in floral composition in the Amazon Basin. The palynological spectra across this interval (nannofossil based age model) include pollen, fern spores, dinocysts and foram lignings. When possible pollen and fern spores were grouped in four vegetation types: estuarine, tropical, mountain forest and high mountain open treeless vegetation. Pollen is generally corroded and reflects the effects of sediment transportation while reworked material is also common. Good pollen producers such as Poaceae, Asteraceae and Cyperaceae are common and reflect indistinctive vegetation types particularly those associated to riverine systems. Rhizophora/Zonocostites spp. indicate "close-distance" mangrove development. Tropical forest biomes are represented by pollen that resemble Moraceae-Urticaceae, Melastomataceae-Combretaceae, Sapotaceae, Alchornea, Euphorbiaceae, Rubiaceae, Bignoniaceae, Mauritia and Arecaceae. Myrica, and particularly sporadic occurrences of fossil fern spores like Lophosoria, and Cyathea suggest the development of a moist Andean forest in areas above 1000 m. First indicators of high altitudes appear in the last part of late Miocene with taxa associated to current Valeriana and particularly Polylepis, a neotropical taxon currently growing along the Andean fluvial system on altitudes between c. 2000 up to c. 4800 m. Alnus is an important Andean forest taxa since Pliocene. In summary, the Neogene palynological record of the Amazon Fan strongly reflects and confirms the influence of the uplift of the Andes and its transcontinental character from late Miocene onwards.

High-resolution forest carbon stocks and emissions in the Amazon.

PubMed

Asner, Gregory P; Powell, George V N; Mascaro, Joseph; Knapp, David E; Clark, John K; Jacobson, James; Kennedy-Bowdoin, Ty; Balaji, Aravindh; Paez-Acosta, Guayana; Victoria, Eloy; Secada, Laura; Valqui, Michael; Hughes, R Flint

2010-09-21

Efforts to mitigate climate change through the Reduced Emissions from Deforestation and Degradation (REDD) depend on mapping and monitoring of tropical forest carbon stocks and emissions over large geographic areas. With a new integrated use of satellite imaging, airborne light detection and ranging, and field plots, we mapped aboveground carbon stocks and emissions at 0.1-ha resolution over 4.3 million ha of the Peruvian Amazon, an area twice that of all forests in Costa Rica, to reveal the determinants of forest carbon density and to demonstrate the feasibility of mapping carbon emissions for REDD. We discovered previously unknown variation in carbon storage at multiple scales based on geologic substrate and forest type. From 1999 to 2009, emissions from land use totaled 1.1% of the standing carbon throughout the region. Forest degradation, such as from selective logging, increased regional carbon emissions by 47% over deforestation alone, and secondary regrowth provided an 18% offset against total gross emissions. Very high-resolution monitoring reduces uncertainty in carbon emissions for REDD programs while uncovering fundamental environmental controls on forest carbon storage and their interactions with land-use change.

Land Use and Land Cover Change in Forest Frontiers: The Role of Household Life Cycles

NASA Technical Reports Server (NTRS)

Walker, Robert

2002-01-01

Tropical deforestation remains a critical issue given its present rate and a widespread consensus regarding its implications for the global carbon cycle and biodiversity. Nowhere is the problem more pronounced than in the Amazon basin, home to the world's largest intact, tropical forest. This article addresses land cover change processes at household level in the Amazon basin, and to this end adapts a concept of domestic life cycle to the current institutional environment of tropical frontiers. In particular, it poses a risk minimization model that integrates demography with market-based factors such as transportation costs and accessibility. In essence, the article merges the theory of Chayanov with the household economy framework, in which markets exist for inputs (including labor), outputs, and capital. The risk model is specified and estimated, using survey data for 261 small producers along the Transamazon Highway in the eastern sector of the Brazilian Amazon.

Predicting Fire Season Severity in South America Using Sea Surface Temperature Anomalies

NASA Technical Reports Server (NTRS)

Chen, Yang; Randerson, James T.; Morton, Douglas C.; Jin, Yufang; DeFries, Ruth S.; Collatz, George J.; Kasibhatla, Prasad S.; Giglio, Louis; Jin, Yufang; Marlier, Miriam

2011-01-01

Fires in South America cause forest degradation and contribute to carbon emissions associated with land use change. Here we investigated the relationship between year-to-year changes in satellite-derived estimates of fire activity in South America and sea surface temperature (SST) anomalies. We found that the Oceanic Ni o Index (ONI) was correlated with interannual fire activity in the eastern Amazon whereas the Atlantic Multidecadal Oscillation (AMO) index was more closely linked with fires in the southern and southwestern Amazon. Combining these two climate indices, we developed an empirical model that predicted regional annual fire season severity (FSS) with 3-5 month lead times. Our approach provides the foundation for an early warning system for forecasting the vulnerability of Amazon forests to fires, thus enabling more effective management with benefits for mitigation of greenhouse gas and air pollutant emissions.

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

PubMed Central

Garcia, Elizabeth S.; Swann, Abigail L. S.; Villegas, Juan C.; Breshears, David D.; Law, Darin J.; Saleska, Scott R.; Stark, Scott C.

2016-01-01

Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates of deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia’s GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. Our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change. PMID:27851740

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

DOE PAGES

Garcia, Elizabeth S.; Swann, Abigail L. S.; Villegas, Juan C.; ...

2016-11-16

Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates ofmore » deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia's GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. In conclusion, our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change.« less

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Elizabeth S.; Swann, Abigail L. S.; Villegas, Juan C.

Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates ofmore » deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia's GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. In conclusion, our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change.« less

Isotopes and soil physic analysis as a tool to meet answers related to soil-plant-atmosphere behavior of Amazon forest during droughts

NASA Astrophysics Data System (ADS)

Borma, L. D. S.; Oliveira, R. S.; Silva, R. D.; Chaparro Saaveedra, O. F.; Barros, F. V.; Bittencourt, P.

2015-12-01

Droughts and floods are part of the Amazon weather pattern, but in face of climate change, it has been expected an increase in their intensity and duration. Forests are important regulators of climate. However, it is still unknown how they respond to an increase in frequency and intensity of extreme droughts. Additionally, there are great uncertainties related with the forest behavior in an enriched CO2 environment. For the Amazon rainforest, some authors report forest growth in a drier climate, while others report forest mortality in these same conditions. The crucial factor in this process seem the linkage between atmospheric demand from water and its provision by soil moisture, intermediated by the plants. In theory, in regions where soil moisture is high, even in the absence of rainfall conditions, water exists in enough quantity to meet the atmospheric demand, and majority of plants behave as an evergreen forest. This is the case, for example, for some research sites of equatorial regions of the Amazon forest, which tend to increase evapotranspiration rates in dry season, when the atmospheric demand is higher. However, the extent to which soil moisture decreases, the plant is no longer able to meet the atmospheric demand, limiting evapotranspiration and possibly, entering in a dormant state. To understand the forest response to droughts, in terms of its potential to maintain or reduce evapotranspiration rates, it is necessary to know water dynamics in soil and soil layers where plants are able to extract water. It's a challenge, considering the great variability of soils and plants that forms the huge biodiversity of the Amazon forest. Here, we present an experiment design based on isotopic analyzes in a small watershed in Amazon basin. In order to understand the dynamics of the water used by the plant during the evaporation process, isotope analysis were carried out in soil water collected from shallow and deep groundwater, in the water collected on the bark of plants and rainfall water, intercepted or not by the canopy. These results were analyzed in conjunction with the soil properties, its moisture retention capacity and groundwater level variations. This study presents some insights about the capability of this methodology to answer questions related to the soil moisture sources and forest response to droughts.

Climate drivers of the Amazon forest greening.

PubMed

Wagner, Fabien Hubert; Hérault, Bruno; Rossi, Vivien; Hilker, Thomas; Maeda, Eduardo Eiji; Sanchez, Alber; Lyapustin, Alexei I; Galvão, Lênio Soares; Wang, Yujie; Aragão, Luiz E O C

2017-01-01

Our limited understanding of the climate controls on tropical forest seasonality is one of the biggest sources of uncertainty in modeling climate change impacts on terrestrial ecosystems. Combining leaf production, litterfall and climate observations from satellite and ground data in the Amazon forest, we show that seasonal variation in leaf production is largely triggered by climate signals, specifically, insolation increase (70.4% of the total area) and precipitation increase (29.6%). Increase of insolation drives leaf growth in the absence of water limitation. For these non-water-limited forests, the simultaneous leaf flush occurs in a sufficient proportion of the trees to be observed from space. While tropical cycles are generally defined in terms of dry or wet season, we show that for a large part of Amazonia the increase in insolation triggers the visible progress of leaf growth, just like during spring in temperate forests. The dependence of leaf growth initiation on climate seasonality may result in a higher sensitivity of these ecosystems to changes in climate than previously thought.

Conversion from forests to pastures in the Colombian Amazon leads to contrasting soil carbon dynamics depending on land management practices.

PubMed

Navarrete, Diego; Sitch, Stephen; Aragão, Luiz E O C; Pedroni, Lucio

2016-10-01

Strategies to mitigate climate change by reducing deforestation and forest degradation (e.g. REDD+) require country- or region-specific information on temporal changes in forest carbon (C) pools to develop accurate emission factors. The soil C pool is one of the most important C reservoirs, but is rarely included in national forest reference emission levels due to a lack of data. Here, we present the soil organic C (SOC) dynamics along 20 years of forest-to-pasture conversion in two subregions with different management practices during pasture establishment in the Colombian Amazon: high-grazing intensity (HG) and low-grazing intensity (LG) subregions. We determined the pattern of SOC change resulting from the conversion from forest (C3 plants) to pasture (C4 plants) by analysing total SOC stocks and the natural abundance of the stable isotopes (13) C along two 20-year chronosequences identified in each subregion. We also analysed soil N stocks and the natural abundance of (15) N during pasture establishment. In general, total SOC stocks at 30 cm depth in the forest were similar for both subregions, with an average of 47.1 ± 1.8 Mg C ha(-1) in HG and 48.7 ± 3.1 Mg C ha(-1) in LG. However, 20 years after forest-to-pasture conversion SOC in HG decreased by 20%, whereas in LG SOC increased by 41%. This net SOC decrease in HG was due to a larger reduction in C3-derived input and to a comparatively smaller increase in C4-derived C input. In LG both C3- and C4-derived C input increased along the chronosequence. N stocks were generally similar in both subregions and soil N stock changes during pasture establishment were correlated with SOC changes. These results emphasize the importance of management practices involving low-grazing intensity in cattle activities to preserve SOC stocks and to reduce C emissions after land-cover change from forest to pasture in the Colombian Amazon. © 2016 John Wiley & Sons Ltd.

Projected increases in the annual flood pulse of the western Amazon

NASA Astrophysics Data System (ADS)

Zulkafli, Zed; Buytaert, Wouter; Manz, Bastian; Veliz Rosas, Claudia; Willems, Patrick; Lavado-Casimiro, Waldo; Guyot, Jean-Loup; Santini, William

2016-04-01

The impact of a changing climate on the Amazon basin is a subject of intensive research due to its rich biodiversity and the significant role of rain forest in carbon cycling. Climate change has also direct hydrological impact, and there have been increasing efforts to understand such dynamics at continental and subregional scales such as the scale of the western Amazon. New projections from the Coupled Model Inter- comparison Project Phase 5 (CMIP5) ensemble indicate consistent climatic warming and increasing seasonality of precipitation in the Peruvian Amazon basin. Here we use a distributed land surface model to quantify the potential impact of this change in the climate on the hydrological regime of the river. Using extremes value analysis, historical and future projections of the annual minimum, mean, and maximum river flows are produced for a range of return periods between 1 and 100 years. We show that the RCP 4.5 and 8.5 scenarios of climate change project an increased severity of the wet season flood pulse (7.5% and 12% increases respectively for the 100- year return floods). These findings are in agreement with previously projected increases in high extremes under the Special Report on Emissions Scenarios (SRES) climate projections, and are important to highlight due to the potential consequences on reproductive processes of in-stream species, swamp forest ecology, and socio-economy in the floodplain, amid a growing literature that more strongly emphasises future droughts and their impact on the viability of the rain forest system over the greater Amazonia.

Deforestation, fire susceptibility, and potential tree responses to fire in the eastern Amazon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uhl, C.; Kauffman, J.B.

1990-04-01

In the state of Para, Brazil, in the eastern Amazon, the authors studied the potential for sustained fire events within four dominant vegetation cover types (undisturbed rain forest, selectively logged forest, second-growth forest, and open pasture), by measuring fuel availability, microclimate, and rates of fuel moisture loss. They also estimated the potential tree mortality that might result from a wide-scale Amazon forest fire by measuring the thermal properties of bark for all trees in a 5-ha stand of mature forest, followed by measurements of heat flux through bark during simulated fires. In pastures the average midday temperature was almost 10{degree}Cmore » greater and the average midday relative humidity was 30% lower than in primary forest. The most five-prone ecosystem was the open pasture followed by selectively logged forest, second growth forest, and undisturbed rain forest in which sustained combustion was not possible even after prolonged rainless periods. Even though the autogenic factors in primary forest of the eastern Amazon create a microclimate that virtually eliminates the probability of fire, they are currently a common event in disturbed areas of Amazonia. As many as 8 {times} 10{sup 6} ha burned in the Amazon Basin of Brazil in 1987 alone. In terms of current land-use patterns, altered microclimates, and fuel mass, there are also striking similarities between the eastern Amazon and East Kalimantan, Indonesia (the site of recent rain forest wildfires that burned 3.5 {times} 10{sup 6} ha).« less

Amazonian and neotropical plant communities on glacial time-scales: The failure of the aridity and refuge hypotheses

NASA Astrophysics Data System (ADS)

Colinvaux, P. A.; De Oliveira, P. E.; Bush, M. B.

2000-01-01

Plants respond to Pleistocene climatic change as species, not as associations or biomes. This has been demonstrated unequivocally by paleobotanical data for temperate latitudes. In the far richer vegetations of the tropics species populations also fluctuated independently in response to climatic forcing, from their longlasting glacial states to the patterns of brief interglacials like the present and back again. We use pollen data to reconstruct the vegetation of the Amazon basin in oxygen isotope stages 3 and 2 of the last glaciation in order to measure how the plant populations of the Amazon responded to the global warming at the onset of the Holocene. We find that plant communities of the neotropics vent copious pollen to lake sediments and that this pollen yields powerful signals for community composition. Three continuous sedimentary records reaching through oxygen isotope stage 2 are available from the Amazon lowlands, those from Carajas, Lake Pata and marine deposits off the mouth of the Amazon River. All three records yield pollen histories of remarkable constancy and stability. By comparing them with deposits of equal antiquity from the cerrado (savanna) of central Brazil, we show that most of the Amazon lowlands remained under forest throughout a glacial cycle. This forest was never fragmented by open vegetation as postulated by the refugia hypothesis. Instead the intact forest of glacial times included significant populations of plants that are now montane, suggesting that the global warming of the early Holocene resulted in the expulsion of heat intolerant plants from the lowland forest. Pollen data from the Amazonian flank of the Andes and from Pacific Panama provide evidence that populations of these heat intolerant plants survive the heat of interglacials in part by maintaining large populations at cooler montane altitudes. Our conclusion that the Amazon lowlands were forested in glacial times specifically refutes the hypothesis of Amazonian glacial aridity. Accordingly we examine the geomorphological evidence for glacial aridity and find it wanting. Of the three paleodune systems reported for tropical South America, that of NE Brazil was active in the Holocene as well as the Pleistocene. Parts of NE Brazil were actually moister than now in late-glacial times. Paleodunes in the Pantanal have never been seen on the ground, and those in the Orinoco Llanos are undated and may be of any age since the Tertiary. Arkosic sands in the Amazon fan deposits came from the Andean foothills or from down cutting by rivers and cannot be evidence of a former arid land surface. White sands of Amazonia formed as podzols, not by aeolian activity. Such Amazonian stone lines as have received critical scrutiny are concretionary pisolites in stratigraphic formations that are more than ten million years old. Although the Amazon was never arid, modeling cooler glacial tropics gives plausibility to a somewhat drier Amazon in glacial times, a concept given substance by pollen data for the movement of ecotones in Rondonia, by stream histories in the Bolivian Andes, and by evidence for lowered lake levels at Carajas and Lake Pata. But this reduced precipitation was never enough to fragment the forest in the Amazon lowlands themselves. Pleistocene mammals of the Napo river valley in Ecuador were able to live along the river system in a forested landscape. Our data suggest that the Amazon forests have been stable since the start of the Pleistocene, a fact that has contributed to the storage of vast diversity. The coming anthropogenic global warming and CO 2 enrichment will add to the global warming already endured by Amazon biota in the Holocene. We think it possible that the expulsion from the lowland forests of heat intolerant species is already complete and that the forest property of maintaining its own microhabitat will allow the high species richness to survive more global warming, provided large enough tracts of forest are preserved.

Long-term impacts of recurrent logging and fire in Amazon forests: a modeling study using the Ecosystem Demography Model (ED2)

NASA Astrophysics Data System (ADS)

Longo, M.; Keller, M.; Scaranello, M. A., Sr.; dos-Santos, M. N.; Xu, Y.; Huang, M.; Morton, D. C.

2017-12-01

Logging and understory fires are major drivers of tropical forest degradation, reducing carbon stocks and changing forest structure, composition, and dynamics. In contrast to deforested areas, sites that are disturbed by logging and fires retain some, albeit severely altered, forest structure and function. In this study we simulated selective logging using the Ecosystem Demography Model (ED-2) to investigate the impact of a broad range of logging techniques, harvest intensities, and recurrence cycles on the long-term dynamics of Amazon forests, including the magnitude and duration of changes in forest flammability following timber extraction. Model results were evaluated using eddy covariance towers at logged sites at the Tapajos National Forest in Brazil and data on long-term dynamics reported in the literature. ED-2 is able to reproduce both the fast (< 5yr) recovery of water, energy fluxes compared to flux tower, and the typical, field-observed, decadal time scales for biomass recovery when no additional logging occurs. Preliminary results using the original ED-2 fire model show that canopy cover loss of forests under high-intensity, conventional logging cause sufficient drying to support more intense fires. These results indicate that under intense degradation, forests may shift to novel disturbance regimes, severely reducing carbon stocks, and inducing long-term changes in forest structure and composition from recurrent fires.

Forest Understory Fire in the Brazilian Amazon in ENSO and Non-ENSO Years: Area Burned and Committed Carbon Emissions

NASA Technical Reports Server (NTRS)

Alencar, A.; Nepstad, D.; Ver-Diaz, M. Del. C.

2004-01-01

"Understory fires" that burn the floor of standing forests are one of the most important types of forest impoverishment in the Amazon, especially during the severe droughts of El Nino Southern Oscillation (ENSO) episodes. However, we are aware of no estimates of the areal extent of these fires for the Brazilian Amazon and, hence, of their contribution to Amazon carbon fluxes to the atmosphere. We calculated the area of forest understory fires for the Brazilian Amazon region during an El Nino (1998) and a non El Nino (1995) year based on forest fire scars mapped with satellite images for three locations in eastern and southern Amazon, where deforestation is concentrated. The three study sites represented a gradient of both forest types and dry season severity. The burning scar maps were used to determine how the percentage of forest that burned varied with distance from agricultural clearings. These spatial functions were then applied to similar forest/climate combinations outside of the study sites to derive an initial estimate for the Brazilian Amazon. Ninety-one percent of the forest area that burned in the study sites was within the first kilometer of a clearing for the non ENSO year and within the first four kilometers for the ENSO year. The area of forest burned by understory forest fire during the severe drought (ENSO) year (3.9 millions of hectares) was 13 times greater than the area burned during the average rainfall year (0.2 million hectares), and twice the area of annual deforestation rate. Dense forest was, proportionally, the forest area most affected by understory fires during the El Nino year, while understory fires were concentrated in transitional forests during the year of average rainfall. Our estimate of aboveground tree biomass killed by fire ranged from 0.06 Pg to 0.38 Pg during the ENSO and from 0,004 Pg to 0,024 Pg during the non ENSO.

Interactions among Amazon land use, forests and climate: prospects for a near-term forest tipping point.

PubMed

Nepstad, Daniel C; Stickler, Claudia M; Filho, Britaldo Soares-; Merry, Frank

2008-05-27

Some model experiments predict a large-scale substitution of Amazon forest by savannah-like vegetation by the end of the twenty-first century. Expanding global demands for biofuels and grains, positive feedbacks in the Amazon forest fire regime and drought may drive a faster process of forest degradation that could lead to a near-term forest dieback. Rising worldwide demands for biofuel and meat are creating powerful new incentives for agro-industrial expansion into Amazon forest regions. Forest fires, drought and logging increase susceptibility to further burning while deforestation and smoke can inhibit rainfall, exacerbating fire risk. If sea surface temperature anomalies (such as El Niño episodes) and associated Amazon droughts of the last decade continue into the future, approximately 55% of the forests of the Amazon will be cleared, logged, damaged by drought or burned over the next 20 years, emitting 15-26Pg of carbon to the atmosphere. Several important trends could prevent a near-term dieback. As fire-sensitive investments accumulate in the landscape, property holders use less fire and invest more in fire control. Commodity markets are demanding higher environmental performance from farmers and cattle ranchers. Protected areas have been established in the pathway of expanding agricultural frontiers. Finally, emerging carbon market incentives for reductions in deforestation could support these trends.

Changes in soil physical and chemical properties in long term improved natural and traditional agroforestry management systems of cacao genotypes in Peruvian Amazon

USDA-ARS?s Scientific Manuscript database

Traditional slash and burn agriculture practiced in the Peruvian Amazon region is leading to soil degradation and deforestation of native forest flora. The only way to stop such destructive processes is through the adoptation of sustainable alternatives such as growing crops in agroforestry systems....

Predicting Fire Susceptibility in the Forests of Amazonia

NASA Technical Reports Server (NTRS)

Nepstad, Daniel C.; Brown, I. Foster; Setzer, Alberto

2000-01-01

Although fire is the single greatest threat to the ecological integrity of Amazon forests, our ability to predict the occurrence of Amazon forest fires is rudimentary. Part of the difficulty encountered in making such predictions is the remarkable capacity of Amazon forests to tolerate drought by tapping moisture stored in deep soil. These forests can avoid drought-induced leaf shedding by withdrawing moisture to depths of 8 meters and more. Hence, the absorption of deep soil moisture allows these forests to maintain their leaf canopies following droughts of several months duration, thereby maintaining the deep shade and high relative humidity of the forest interior that prevents these ecosystems from burning. But the drought- and fire-avoidance that is conferred by this deep-rooting phenomenon is not unlimited. During successive years of drought, such as those provoked by El Nino episodes, deep soil moisture can be depleted, and drought-induced leaf shedding begins. The goal of this project was to incorporate this knowledge of Amazon forest fire ecology into a predictive model of forest flammability.

Daytime turbulent exchange between the Amazon forest and the atmosphere

NASA Technical Reports Server (NTRS)

Fitzjarrald, David R.; Moore, Kathleen E.; Cabral, Osvaldo M. R.; Scolar, Jose; Manzi, Antonio O.; Deabreusa, Leonardo D.

1989-01-01

Detailed observations of turbulence just above and below the crown of the Amazon rain forest during the wet season are presented. The forest canopy is shown to remove high frequency turbulent fluctuations while passing lower frequencies. Filter characteristics of turbulent transfer into the Amazon rain forest canopy are quantified. Simple empirical relations that relate observed turbulent heat fluxes to horizontal wind variance are presented. Changes in the amount of turbulent coupling between the forest and the boundary layer associated with deep convective clouds are presented both as statistical averages and as a series of case studies. These convective processes during the rainy season are shown to alter the diurnal course of turbulent fluxes. In wake of giant coastal systems, no significant heat or moisture fluxes occur for up to a day after the event. Radar data is used to demonstrate that even small raining clouds are capable of evacuating the canopy of substances normally trapped by persistent static stability near the forest floor. Recovery from these events can take more than an hour, even during mid-day. In spite of the ubiquitous presence of clouds and frequent rain during this season, the average horizontal wind speed spectrum is well described by dry CBL similarity hypotheses originally found to apply in flat terrain.

Daytime turbulent exchange between the Amazon forest and the atmosphere

NASA Technical Reports Server (NTRS)

Fitzjarrald, David R.; Moore, Kathleen E.; Cabral, Osvaldo M. R.; Scolar, Jose; Manzi, Antonio

1990-01-01

Detailed observations of turbulence just above and below the crown of the Amazon rain forest during the wet season are presented. The forest canopy is shown to remove high frequency turbulent fluctuations while passing lower frequencies. Filter characteristics of turbulent transfer into the Amazon rain forest canopy are quantified. Simple empirical relations that relate observed turbulent heat fluxes to horizontal wind variance are presented. Changes in the amount of turbulent coupling between the forest and the boundary layer associated with deep convective clouds are presented both as statistical averages and as a series of case studies. These convective processes during the rainy season are shown to alter the diurnal course of turbulent fluxes. In wake of giant coastal systems, no significant heat or moisture fluxes occur for up to a day after the event. Radar data is used to demonstrate that even small raining clouds are capable of evacuating the canopy of substances normally trapped by persistent static stability near the forest floor. Recovery from these events can take more than an hour, even during mid-day. In spite of the ubiquitous presence of clouds and frequent rain during this season, the average horizontal wind speed spectrum is well described by dry CBL similarity hypotheses originally found to apply in flat terrain.

Annual Carbon Emissions from Deforestation in the Amazon Basin between 2000 and 2010.

PubMed

Song, Xiao-Peng; Huang, Chengquan; Saatchi, Sassan S; Hansen, Matthew C; Townshend, John R

2015-01-01

Reducing emissions from deforestation and forest degradation (REDD+) is considered one of the most cost-effective strategies for mitigating climate change. However, historical deforestation and emission rates-critical inputs for setting reference emission levels for REDD+-are poorly understood. Here we use multi-source, time-series satellite data to quantify carbon emissions from deforestation in the Amazon basin on a year-to-year basis between 2000 and 2010. We first derive annual deforestation indicators by using the Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) product. MODIS indicators are calibrated by using a large sample of Landsat data to generate accurate deforestation rates, which are subsequently combined with a spatially explicit biomass dataset to calculate committed annual carbon emissions. Across the study area, the average deforestation and associated carbon emissions were estimated to be 1.59 ± 0.25 M ha•yr(-1) and 0.18 ± 0.07 Pg C•yr(-1) respectively, with substantially different trends and inter-annual variability in different regions. Deforestation in the Brazilian Amazon increased between 2001 and 2004 and declined substantially afterwards, whereas deforestation in the Bolivian Amazon, the Colombian Amazon, and the Peruvian Amazon increased over the study period. The average carbon density of lost forests after 2005 was 130 Mg C•ha(-1), ~11% lower than the average carbon density of remaining forests in year 2010 (144 Mg C•ha(-1)). Moreover, the average carbon density of cleared forests increased at a rate of 7 Mg C•ha(-1)•yr(-1) from 2005 to 2010, suggesting that deforestation has been progressively encroaching into high-biomass lands in the Amazon basin. Spatially explicit, annual deforestation and emission estimates like the ones derived in this study are useful for setting baselines for REDD+ and other emission mitigation programs, and for evaluating the performance of such efforts.

Annual Carbon Emissions from Deforestation in the Amazon Basin between 2000 and 2010

PubMed Central

Song, Xiao-Peng; Huang, Chengquan; Saatchi, Sassan S.; Hansen, Matthew C.; Townshend, John R.

2015-01-01

Reducing emissions from deforestation and forest degradation (REDD+) is considered one of the most cost-effective strategies for mitigating climate change. However, historical deforestation and emission rates―critical inputs for setting reference emission levels for REDD+―are poorly understood. Here we use multi-source, time-series satellite data to quantify carbon emissions from deforestation in the Amazon basin on a year-to-year basis between 2000 and 2010. We first derive annual deforestation indicators by using the Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) product. MODIS indicators are calibrated by using a large sample of Landsat data to generate accurate deforestation rates, which are subsequently combined with a spatially explicit biomass dataset to calculate committed annual carbon emissions. Across the study area, the average deforestation and associated carbon emissions were estimated to be 1.59 ± 0.25 M ha•yr−1 and 0.18 ± 0.07 Pg C•yr−1 respectively, with substantially different trends and inter-annual variability in different regions. Deforestation in the Brazilian Amazon increased between 2001 and 2004 and declined substantially afterwards, whereas deforestation in the Bolivian Amazon, the Colombian Amazon, and the Peruvian Amazon increased over the study period. The average carbon density of lost forests after 2005 was 130 Mg C•ha−1, ~11% lower than the average carbon density of remaining forests in year 2010 (144 Mg C•ha−1). Moreover, the average carbon density of cleared forests increased at a rate of 7 Mg C•ha−1•yr−1 from 2005 to 2010, suggesting that deforestation has been progressively encroaching into high-biomass lands in the Amazon basin. Spatially explicit, annual deforestation and emission estimates like the ones derived in this study are useful for setting baselines for REDD+ and other emission mitigation programs, and for evaluating the performance of such efforts. PMID:25951328

Changes in habitat use at rainforest edges through succession: A case study of understory birds in the Brazilian Amazon

Treesearch

Luke L. Powell; Gustavo Zurita; Jared D.  Wolfe; Erik I.  Johnson; Philip C  Stouffer

2015-01-01

Primary tropical rain forests are being rapidly perforated with new edges via roads, logging, and pastures, and vast areas of secondary forest accumulate following abandonment of agricultural lands. To determine how insectivorous Amazonian understory birds respond to edges between primary rain forest and three age classes of secondary forest, we radio-tracked two...

Scaling properties reveal regulation of river flows in the Amazon through a forest reservoir

NASA Astrophysics Data System (ADS)

Salazar, Juan Fernando; Villegas, Juan Camilo; María Rendón, Angela; Rodríguez, Estiven; Hoyos, Isabel; Mercado-Bettín, Daniel; Poveda, Germán

2018-03-01

Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we introduce a novel physical interpretation of the scaling properties of river flows and show that it leads to a parsimonious characterization of the flow regime of any river basin. This allows river basins to be classified as regulated or unregulated, and to identify a critical threshold between these states. We applied this framework to the Amazon river basin and found both states among its main tributaries. Then we introduce the forest reservoir hypothesis to describe the natural capacity of river basins to regulate river flows through land-atmosphere interactions (mainly precipitation recycling) that depend strongly on the presence of forests. A critical implication is that forest loss can force the Amazonian river basins from regulated to unregulated states. Our results provide theoretical and applied foundations for predicting hydrological impacts of global change, including the detection of early-warning signals for critical transitions in river basins.

Condition and fate of logged forests in the Brazilian Amazon.

PubMed

Asner, Gregory P; Broadbent, Eben N; Oliveira, Paulo J C; Keller, Michael; Knapp, David E; Silva, José N M

2006-08-22

The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest. Across 2,030,637 km2 of the Brazilian Amazon from 1999 to 2004, at least 76% of all harvest practices resulted in high levels of canopy damage sufficient to leave forests susceptible to drought and fire. We found that 16+/-1% of selectively logged areas were deforested within 1 year of logging, with a subsequent annual deforestation rate of 5.4% for 4 years after timber harvests. Nearly all logging occurred within 25 km of main roads, and within that area, the probability of deforestation for a logged forest was up to four times greater than for unlogged forests. In combination, our results show that logging in the Brazilian Amazon is dominated by highly damaging operations, often followed rapidly by deforestation decades before forests can recover sufficiently to produce timber for a second harvest. Under the management regimes in effect at the time of our study in the Brazilian Amazon, selective logging would not be sustained.

Condition and fate of logged forests in the Brazilian Amazon

PubMed Central

Asner, Gregory P.; Broadbent, Eben N.; Oliveira, Paulo J. C.; Keller, Michael; Knapp, David E.; Silva, José N. M.

2006-01-01

The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest. Across 2,030,637 km2 of the Brazilian Amazon from 1999 to 2004, at least 76% of all harvest practices resulted in high levels of canopy damage sufficient to leave forests susceptible to drought and fire. We found that 16 ± 1% of selectively logged areas were deforested within 1 year of logging, with a subsequent annual deforestation rate of 5.4% for 4 years after timber harvests. Nearly all logging occurred within 25 km of main roads, and within that area, the probability of deforestation for a logged forest was up to four times greater than for unlogged forests. In combination, our results show that logging in the Brazilian Amazon is dominated by highly damaging operations, often followed rapidly by deforestation decades before forests can recover sufficiently to produce timber for a second harvest. Under the management regimes in effect at the time of our study in the Brazilian Amazon, selective logging would not be sustained. PMID:16901980

Mapping Process to Pattern in the Landscape Change of the Amazonian Frontier

NASA Technical Reports Server (NTRS)

Walker, Robert

2003-01-01

Changes in land use and land cover are dynamic processes reflecting a sequence of decisions made by individual land managers. In developing economies, these decisions may be embedded in the evolution of individual households, as is often the case in indigenous areas and agricultural frontiers. One goal of the present article is to address the land use and land-cover decisions of colonist farmers in the Amazon Basin as a function, in part, of household characteristics. Another goal is to generalize the issue of tropical deforestation into a broader discussion on forest dynamics. The extent of secondary forest in tropical areas has been well documented in South America and Africa. Agricultural-plot abandonment often occurs in tandem with primary forest clearance and as part of the same decision-making calculus. Consequently, tropical deforestation and forest succession are not independent processes in the landscape. This article presents a framework that integrates them into a model of forest dynamics at household level, and in so doing provides an account of the spatial pattern of deforestation that has been observed in the Amazon's colonization frontiers.

The Fate of Amazonian Ecosystems over the Coming Century Arising from Changes in Climate, Atmospheric CO2 and Land-use

NASA Astrophysics Data System (ADS)

Moorcroft, P. R.; Zhang, K.; Castanho, A. D. D. A.; Galbraith, D.; Moghim, S.; Levine, N. M.; Bras, R. L.; Coe, M. T.; Costa, M. H.; Malhi, Y.; Longo, M.; Knox, R. G.; McKnight, S. L.; Wang, J.

2014-12-01

There is considerable interest and uncertainty regarding the expected fate of the Amazon over the coming century in face of the combined impacts of climate change, rising atmospheric CO2 levels, and on-going land transformation in the region. In this analysis, we explore the fate of Amazonian ecosystems under projected climate, CO2 and land-use change in the 21st century using three state-of-the-art terrestrial biosphere models (ED2, IBIS, and JULES) driven by three representative, bias-corrected GCM climate projections (PCM1, CCSM3, and HadCM3) under the SRES A2 scenario, coupled with two land-use change scenarios. We assess the relative roles of climate change, CO2 fertilization, land-use change, and fire in driving the projected changes in Amazonian biomass and forest extent. Our results indicate that the impacts of climate change depend strongly on the direction and severity of projected changes in precipitation regimes within the region: under the driest climate projection, climate change alone is predicted to reduce Amazonian forest cover by an average of 14%; however, the models predict that CO2 fertilization will enhance vegetation productivity and alleviate climate-induced increases in plant water stress, and as a result sustain high biomass forests, even under the driest climate scenario. Land-use change and changes in fire frequency are predicted cause additional aboveground live biomass loss and changes in forest extent. The relative impact of land-use and fire dynamics versus the impacts of climate and CO2 on the Amazon varies considerably, depending on both the climate and land-use scenarios used and on the terrestrial biosphere model, highlighting the importance of improved understanding of all four factors -- future climate, CO2 fertilization effects, fire and land-use -- to the fate of the Amazon over the coming century.

Dependence of hydropower energy generation on forests in the Amazon Basin at local and regional scales.

PubMed

Stickler, Claudia M; Coe, Michael T; Costa, Marcos H; Nepstad, Daniel C; McGrath, David G; Dias, Livia C P; Rodrigues, Hermann O; Soares-Filho, Britaldo S

2013-06-04

Tropical rainforest regions have large hydropower generation potential that figures prominently in many nations' energy growth strategies. Feasibility studies of hydropower plants typically ignore the effect of future deforestation or assume that deforestation will have a positive effect on river discharge and energy generation resulting from declines in evapotranspiration (ET) associated with forest conversion. Forest loss can also reduce river discharge, however, by inhibiting rainfall. We used land use, hydrological, and climate models to examine the local "direct" effects (through changes in ET within the watershed) and the potential regional "indirect" effects (through changes in rainfall) of deforestation on river discharge and energy generation potential for the Belo Monte energy complex, one of the world's largest hydropower plants that is currently under construction on the Xingu River in the eastern Amazon. In the absence of indirect effects of deforestation, simulated deforestation of 20% and 40% within the Xingu River basin increased discharge by 4-8% and 10-12%, with similar increases in energy generation. When indirect effects were considered, deforestation of the Amazon region inhibited rainfall within the Xingu Basin, counterbalancing declines in ET and decreasing discharge by 6-36%. Under business-as-usual projections of forest loss for 2050 (40%), simulated power generation declined to only 25% of maximum plant output and 60% of the industry's own projections. Like other energy sources, hydropower plants present large social and environmental costs. Their reliability as energy sources, however, must take into account their dependence on forests.

Satellite Observation of El Nino Effects on Amazon Forest Phenology and Productivity

NASA Technical Reports Server (NTRS)

Asner, Gregory P.; Townsend, Alan R.; Braswell, Bobby H.

2000-01-01

Climate variability may affect the functioning of Amazon moist tropical forests, and recent modeling analyses suggest that the carbon dynamics of the region vary interannually in response to precipitation and temperature anomalies. However, due to persistent orbital and atmospheric artifacts in the satellite record, remote sensing observations have not provided quantitative evidence that climate variation affects Amazon forest phenology or productivity, We developed a method to minimize and quantify non-biological artifacts in NOAA AVHRR satellite data, providing a record of estimated forest phenological variation from 1982-1993. The seasonal Normalized Difference Vegetation Index (NDVI) amplitude (a proxy for phenology) increased throughout much of the basin during El Nino periods when rainfall was anomalously low. Wetter La Nina episodes brought consistently smaller NDVI amplitudes. Using radiative transfer and terrestrial biogeochemical models driven by these satellite data, we estimate that canopy-energy absorption and net primary production of Amazon forests varied interannually by as much as 21% and 18%, respectively. These results provide large-scale observational evidence for interannual sensitivity to El Nino of plant phenology and carbon flux in Amazon forests.

Differentiation in the fertility of Inceptisols as related to land use in the upper Solimões river region, western Amazon.

PubMed

Moreira, Fatima Maria de Souza; Nóbrega, Rafaela Simão Abrahão; Jesus, Ederson da Conceição; Ferreira, Daniel Furtado; Pérez, Daniel Vidal

2009-12-20

The Upper Solimões river region, western Amazon, is the homeland of indigenous populations and contains small-scale agricultural systems that are important for biodiversity conservation. Although traditional slash-and-burn agriculture is being practiced over many years, deforestation there is relatively small compared to other Amazon regions. Pastures are restricted to the vicinity of cities and do not spread to the small communities along the river. Inceptisols are the main soil order (>90%) in the area and have unique attributes including high Al content and high cation exchange capacity (CEC) due to the enrichment of the clay fraction with 2:1 secondary aluminosilicates. Despite its importance, few studies have focussed on this soil order when considering land use effects on the fertility of Amazon soils. Thus, the objective of this study was to evaluate changes in soil fertility of representative land use systems (LUSs) in the Upper Solimões region, namely: primary rainforest, old secondary forest, young secondary forest, agroforestry, pasture and agriculture. LUSs were significantly differentiated by the chemical attributes of their topsoil (0-20 cm). Secondary forests presented soil chemical attributes more similar to primary rainforest areas, while pastures exhibited the highest dissimilarity from all the other LUSs. As a whole, soil chemical changes among Inceptisols dominated LUSs showed patterns that were distinct from those reported from other Amazon soils like Oxisols and Ultisols. This is probably related to the presence of high-activity clays enriched in exchangeable aluminum that heavily influenced the soil chemical reactions over the expected importance of organic matter found in most studies conducted over Oxisol and Ultisol.

Size and frequency of natural forest disturbances and the Amazon forest carbon balance

Treesearch

F.D.B. Espirito-Santo; M. Gloor; M. Keller; Y. Malhi; S. Saatchi; B. Nelson; R.C. Oliveira Junior; C. Pereira; J. Lloyd; S. Frolking; M. Palace; Y.E. Shimabukuro; V. Duarte; A. Monteagudo Mendoza; G. Lopez-Gonzalez; T.R. Baker; T.R. Feldpausch; R.J.W. Brienen; G.P. Asner; D.S. Boyd; O.L. Phillips

2014-01-01

Forest inventory studies in the Amazon indicate a large terrestrial carbon sink. However, field plots may fail to represent forest mortality processes at landscape-scales of tropical forests. Here we characterize the frequency distribution of disturbance events in natural forests from 0.01 ha to 2,651 ha size throughout Amazonia using a novel...

Higher absorbed solar radiation partly offset the negative effects of water stress on the photosynthesis of Amazon forests during the 2015 drought

NASA Astrophysics Data System (ADS)

Li, Xing; Xiao, Jingfeng; He, Binbin

2018-04-01

Amazon forests play an important role in the global carbon cycle and Earth’s climate. The vulnerability of Amazon forests to drought remains highly controversial. Here we examine the impacts of the 2015 drought on the photosynthesis of Amazon forests to understand how solar radiation and precipitation jointly control forest photosynthesis during the severe drought. We use a variety of gridded vegetation and climate datasets, including solar-induced chlorophyll fluorescence (SIF), photosynthetic active radiation (PAR), the fraction of absorbed PAR (APAR), leaf area index (LAI), precipitation, soil moisture, cloud cover, and vapor pressure deficit (VPD) in our analysis. Satellite-derived SIF observations provide a direct diagnosis of plant photosynthesis from space. The decomposition of SIF to SIF yield (SIFyield) and APAR (the product of PAR and fPAR) reveals the relative effects of precipitation and solar radiation on photosynthesis. We found that the drought significantly reduced SIFyield, the emitted SIF per photon absorbed. The higher APAR resulting from lower cloud cover and higher LAI partly offset the negative effects of water stress on the photosynthesis of Amazon forests, leading to a smaller reduction in SIF than in SIFyield and precipitation. We further found that SIFyield anomalies were more sensitive to precipitation and VPD anomalies in the southern regions of the Amazon than in the central and northern regions. Our findings shed light on the relative and combined effects of precipitation and solar radiation on photosynthesis, and can improve our understanding of the responses of Amazon forests to drought.

Changes of cloudiness over tropical land during the past few decades and its link to global climate change

NASA Astrophysics Data System (ADS)

Arias, P.; Fu, R.; Li, W.

2007-12-01

Tropical forests play a key role in determining the global carbon-climate feedback in the 21st century. Changes in rainforest growth and mortality rates, especially in the deep and least perturbed forest areas, have been consistently observed across global tropics in recent years. Understanding the underlying causes of these changes, especially their links to the global climate change, is especially important in determining the future of the tropical rainforests in the 21st century. Previous studies have mostly focus on the potential influences from elevated atmospheric CO2 and increasing surface temperature. Because the rainforests in wet tropical region is often light limited, we explore whether cloudiness have changed, if so, whether it is consistent with that expected from changes in forest growth rate. We will report our observational analysis examining the trends in annual average shortwave (SW) downwelling radiation, total cloud cover, and cumulus cover over the tropical land regions and to link them with trends in convective available potencial energy (CAPE). ISCCP data and radiosonde records available from the Department of Atmospheric Sciences of the University of Wyoming (http://www.weather.uwyo.edu/upperair/sounding.html) are used to study the trends. The period for the trend analysis is 1984-2004 for the ISCCP data and 1980-2006 for the radiosondes. The results for the Amazon rainforest region suggest a decreasing trend in total cloud and convective cloud covers, which results in an increase in downwelling SW radiation at the surface. These changes of total and convective clouds are consistent with a trend of decreasing CAPE and an elevated Level of Free Convection (LFC) height, as obtained from the radiosondes. All the above mentioned trends are statistically significant based on the Mann-Kendall test with 95% of confidence. These results consistently suggest the downward surface solar radiation has been increasing since 1984, result from a decrease of convective and total cloudiness over the Southern Amazon basin, due to an increase of LFC and atmospheric thermodynamic stability. Such an increase of surface SW radiation probably has contributed to the increasing in growth rate for the forests in the Amazon forests. Currently, the same analysis is being applied using radiosonde data from the Comprehensive Aerological Reference Data Set (CARDS) over the Amazon and Congo basins and the Southeast Asia. Our objective is to identify changes in cloudiness over tropical land and identify its underlying causes, especially the link to changes in surface temperature and humidity.

Soil microbiome responses to the short-term effects of Amazonian deforestation.

PubMed

Navarrete, Acacio A; Tsai, Siu M; Mendes, Lucas W; Faust, Karoline; de Hollander, Mattias; Cassman, Noriko A; Raes, Jeroen; van Veen, Johannes A; Kuramae, Eiko E

2015-05-01

Slash-and-burn clearing of forest typically results in increase in soil nutrient availability. However, the impact of these nutrients on the soil microbiome is not known. Using next generation sequencing of 16S rRNA gene and shotgun metagenomic DNA, we compared the structure and the potential functions of bacterial community in forest soils to deforested soils in the Amazon region and related the differences to soil chemical factors. Deforestation decreased soil organic matter content and factors linked to soil acidity and raised soil pH, base saturation and exchangeable bases. Concomitant to expected changes in soil chemical factors, we observed an increase in the alpha diversity of the bacterial microbiota and relative abundances of putative copiotrophic bacteria such as Actinomycetales and a decrease in the relative abundances of bacterial taxa such as Chlamydiae, Planctomycetes and Verrucomicrobia in the deforested soils. We did not observe an increase in genes related to microbial nutrient metabolism in deforested soils. However, we did observe changes in community functions such as increases in DNA repair, protein processing, modification, degradation and folding functions, and these functions might reflect adaptation to changes in soil characteristics due to forest clear-cutting and burning. In addition, there were changes in the composition of the bacterial groups associated with metabolism-related functions. Co-occurrence microbial network analysis identified distinct phylogenetic patterns for forest and deforested soils and suggested relationships between Planctomycetes and aluminium content, and Actinobacteria and nitrogen sources in Amazon soils. The results support taxonomic and functional adaptations in the soil bacterial community following deforestation. We hypothesize that these microbial adaptations may serve as a buffer to drastic changes in soil fertility after slash-and-burning deforestation in the Amazon region. © 2015 John Wiley & Sons Ltd.

Modelling conservation in the Amazon basin.

PubMed

Soares-Filho, Britaldo Silveira; Nepstad, Daniel Curtis; Curran, Lisa M; Cerqueira, Gustavo Coutinho; Garcia, Ricardo Alexandrino; Ramos, Claudia Azevedo; Voll, Eliane; McDonald, Alice; Lefebvre, Paul; Schlesinger, Peter

2006-03-23

Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we report that protected areas in the Amazon basin--the central feature of prevailing conservation approaches--are an important but insufficient component of this strategy, based on policy-sensitive simulations of future deforestation. By 2050, current trends in agricultural expansion will eliminate a total of 40% of Amazon forests, including at least two-thirds of the forest cover of six major watersheds and 12 ecoregions, releasing 32 +/- 8 Pg of carbon to the atmosphere. One-quarter of the 382 mammalian species examined will lose more than 40% of the forest within their Amazon ranges. Although an expanded and enforced network of protected areas could avoid as much as one-third of this projected forest loss, conservation on private lands is also essential. Expanding market pressures for sound land management and prevention of forest clearing on lands unsuitable for agriculture are critical ingredients of a strategy for comprehensive conservation.

The ambiguity of drought events, a bottleneck for Amazon forest drought response modelling

NASA Astrophysics Data System (ADS)

De Deurwaerder, Hannes; Verbeeck, Hans; Baker, Timothy; Christoffersen, Bradley; Ciais, Philippe; Galbraith, David; Guimberteau, Matthieu; Kruijt, Bart; Langerwisch, Fanny; Meir, Patrick; Rammig, Anja; Thonicke, Kirsten; Von Randow, Celso; Zhang, Ke

2016-04-01

Considering the important role of the Amazon forest in the global water and carbon cycle, the prognosis of altered hydrological patterns resulting from climate change provides strong incentive for apprehending the direct implications of drought on the vegetation of this ecosystem. Dynamic global vegetation models have the potential of providing a useful tool to study drought impacts on various spatial and temporal scales. This however assumes the models being able to properly represent drought impact mechanisms. But how well do the models succeed in meeting this assumption? Within this study meteorological driver data and model output data of 4 different DGVMs, i.e. ORCHIDEE, JULES, INLAND and LPGmL, are studied. Using the palmer drought severity index (PDSI) and the mean cumulative water deficit (MWD), temporal and spatial representation of drought events are studied in the driver data and are referenced to historical extreme drought events in the Amazon. Subsequently, within the resulting temporal and spatial frame, we studied the drought impact on the above ground biomass (AGB) and gross primary production (GPP) fluxes. Flux tower data, field inventory data and the JUNG data-driven GPP product for the Amazon region are used for validation. Our findings not only suggest that the current state of the studied DGVMs is inadequate in representing Amazon droughts in general, but also highlights strong inter-model differences in drought responses. Using scatterplot-studies and input-output correlations, we provide insight in the origin of these encountered inter-model differences. In addition, we present directives of model development and improvement in scope of Amazon forest drought response modelling.

Repeat-Pass Multi-Temporal Interferometric SAR Coherence Variations with Amazon Floodplain and Lake Habitats

NASA Astrophysics Data System (ADS)

Jung, H.; Alsdorf, D.

2006-12-01

Monitoring discharge in the main channels of rivers and upland tributaries as well as storage changes in floodplain lakes is necessary for understanding flooding hazards, methane production, sediment transport, and nutrient exchange. Interferometric processing of synthetic aperture radar (SAR) data may enable hydrologists to detect environmental and ecological changes in hydrological systems over space and time. An aim of our experiments is to characterize interferometric SAR coherence variations that occur in Amazon aquatic habitats. We analyze coherence variations in JERS-1 data at three central Amazon sites; Lake Balbina, the Cabaliana floodplain, and the confluence of the Purus and Amazon rivers. Because radar pulse interactions with inundated vegetation typically follow a double-bounce travel path which returns energy to the antenna, coherence will vary with vegetation type, physical baseline, and temporal baseline. Balbina's vegetation consists mostly of forest and inundated trunks of dead, leafless trees as opposed to Cabaliana and Amazon- Purus (dominated by flooded forests), thus it serves to isolate the vegetation signal. Coherence variations with baselines were determined from 253 interferograms at Balbina, 210 at Calbaliana, and 153 at Purus. The average temporal and perpendicular baselines (mean std.) are 574 394 days and 1708 1159 m at Balbina, 637 435 days and 1381 981 m at Cabaliana, and 587 425 days and 1430 964 m at Purus. Balbina has a stronger coherence than either Cabaliana or Amazon-Purus. With results of Mann-Whitney statistical tests, Balbina has a difference between terre-firme and flooded coherence values plotted with perpendicular baseline but Cabaliana and Amazon-Purus do not show this difference. Balbina has a linearly decreasing trend in coherence plotted with temporal baseline whereas Cabaliana and Amazon-Purus have a steep drop-off, non- linear change. A strong annual periodicity is evident on power spectrums of the coherence values for Cabaliana and Amazon-Purus, but not in Balbina and is likely an indicator of the annual Amazon flood wave. Each ecological habitat is delineated in the Balbina coherence values plotted with temporal baseline, but only during high water and time-periods less than 2 years is such delineation visible in the Cabaliana and Amazon-Purus regions. Taken together, these observations suggest terre-firme does not have a seasonal variation whereas flooded areas vary with the season.

Impact of a drier Early-Mid-Holocene climate upon Amazonian forests.

PubMed

Mayle, Francis E; Power, Mitchell J

2008-05-27

This paper uses a palaeoecological approach to examine the impact of drier climatic conditions of the Early-Mid-Holocene (ca 8000-4000 years ago) upon Amazonia's forests and their fire regimes. Palaeovegetation (pollen data) and palaeofire (charcoal) records are synthesized from 20 sites within the present tropical forest biome, and the underlying causes of any emergent patterns or changes are explored by reference to independent palaeoclimate data and present-day patterns of precipitation, forest cover and fire activity across Amazonia. During the Early-Mid-Holocene, Andean cloud forest taxa were replaced by lowland tree taxa as the cloud base rose while lowland ecotonal areas, which are presently covered by evergreen rainforest, were instead dominated by savannahs and/or semi-deciduous dry forests. Elsewhere in the Amazon Basin there is considerable spatial and temporal variation in patterns of vegetation disturbance and fire, which probably reflects the complex heterogeneous patterns in precipitation and seasonality across the basin, and the interactions between climate change, drought- and fire susceptibility of the forests, and Palaeo-Indian land use. Our analysis shows that the forest biome in most parts of Amazonia appears to have been remarkably resilient to climatic conditions significantly drier than those of today, despite widespread evidence of forest burning. Only in ecotonal areas is there evidence of biome replacement in the Holocene. From this palaeoecological perspective, we argue against the Amazon forest 'dieback' scenario simulated for the future.

Integration of Landsat TM and SPOT HRG Images for Vegetation Change Detection in the Brazilian Amazon

PubMed Central

Lu, Dengsheng; Batistella, Mateus; Moran, Emilio

2009-01-01

Traditional change detection approaches have been proven to be difficult in detecting vegetation changes in the moist tropical regions with multitemporal images. This paper explores the integration of Landsat Thematic Mapper (TM) and SPOT High Resolution Geometric (HRG) instrument data for vegetation change detection in the Brazilian Amazon. A principal component analysis was used to integrate TM and HRG panchromatic data. Vegetation change/non-change was detected with the image differencing approach based on the TM and HRG fused image and the corresponding TM image. A rule-based approach was used to classify the TM and HRG multispectral images into thematic maps with three coarse land-cover classes: forest, non-forest vegetation, and non-vegetation lands. A hybrid approach combining image differencing and post-classification comparison was used to detect vegetation change trajectories. This research indicates promising vegetation change techniques, especially for vegetation gain and loss, even if very limited reference data are available. PMID:19789721

Pre-Columbian urbanism, anthropogenic landscapes, and the future of the Amazon.

PubMed

Heckenberger, Michael J; Russell, J Christian; Fausto, Carlos; Toney, Joshua R; Schmidt, Morgan J; Pereira, Edithe; Franchetto, Bruna; Kuikuro, Afukaka

2008-08-29

The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters, representing small independent polities, within a regional peer polity. These patterns constitute a "galactic" form of prehistoric urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment systems relating to these societies has implications for conservation and sustainable development, notably to control ecological degradation and maintain regional biodiversity.

Hydrologic resilience and Amazon productivity.

PubMed

Ahlström, Anders; Canadell, Josep G; Schurgers, Guy; Wu, Minchao; Berry, Joseph A; Guan, Kaiyu; Jackson, Robert B

2017-08-30

The Amazon rainforest is disproportionately important for global carbon storage and biodiversity. The system couples the atmosphere and land, with moist forest that depends on convection to sustain gross primary productivity and growth. Earth system models that estimate future climate and vegetation show little agreement in Amazon simulations. Here we show that biases in internally generated climate, primarily precipitation, explain most of the uncertainty in Earth system model results; models, empirical data and theory converge when precipitation biases are accounted for. Gross primary productivity, above-ground biomass and tree cover align on a hydrological relationship with a breakpoint at ~2000 mm annual precipitation, where the system transitions between water and radiation limitation of evapotranspiration. The breakpoint appears to be fairly stable in the future, suggesting resilience of the Amazon to climate change. Changes in precipitation and land use are therefore more likely to govern biomass and vegetation structure in Amazonia.Earth system model simulations of future climate in the Amazon show little agreement. Here, the authors show that biases in internally generated climate explain most of this uncertainty and that the balance between water-saturated and water-limited evapotranspiration controls the Amazon resilience to climate change.

Land-use versus natural controls on soil fertility in the Subandean Amazon, Peru.

PubMed

Lindell, Lina; Aström, Mats; Oberg, Tomas

2010-01-15

Deforestation to amplify the agricultural frontier is a serious threat to the Amazon forest. Strategies to attain and maintain satisfactory soil fertility, which requires knowledge of spatial and temporal changes caused by land-use, are important for reaching sustainable development. This study highlights these issues by evaluating the relative effects of agricultural land-use and natural factors on chemical fertility of Inceptisols on redbed lithologies in the Subandean Amazon. Macro and micronutrients were determined in topsoil and subsoil in the vicinity of two villages at a total of 80 sites including pastures, coffee plantations, swidden fields, secondary forest and, as a reference, adjacent primary forest. Differences in soil fertility between the land cover classes were investigated by principal component analysis (PCA) and partial least squares regression (PLSR). Primary forest soil was found to be chemically similar to that of coffee plantations, pastures and secondary forests. There were no significant differences between soils of these land cover types in terms of plant nutrients (e.g. N, P, K, Ca, Mg, Mo, Mn, Zn, Cu and Co) or other fertility indicators (OM, pH, BS, EC, CECe and exchangeable acidity). The parent material (as indicated by texture and sample geographical origin) and the slope of the sampled sites were stronger controls on soil fertility than land cover type. Elevated concentrations of a few nutrients (NO(3) and K) were, however detected in soils of swidden fields. Despite being fertile (higher CECe, Ca and P) compared to Oxisols and Ultisols in the Amazon lowland, the Subandean soils frequently showed deficiencies in several nutrients (e.g. P, K, NO(3), Cu and Zn), and high levels of free Al at acidic sites. This paper concludes that deforestation and agricultural land-use has not introduced lasting chemical changes in the studied Subandean soils that are significant in comparison to the natural variability. Copyright 2009 Elsevier B.V. All rights reserved.

Condition and fate of logged forests in the Brazilian Amazon.

Treesearch

Gregory P. Asner; Eben N. Broadbent; Paulo J. C. Oliveira; Michael Keller; David E. Knapp; Jose N. M. Silva

2006-01-01

The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest....

Contrasting Patterns of Damage and Recovery in Logged Amazon Forests From Small Footprint LiDAR Data

NASA Technical Reports Server (NTRS)

Morton, D. C.; Keller, M.; Cook, B. D.; Hunter, Maria; Sales, Marcio; Spinelli, L.; Victoria, D.; Andersen, H.-E.; Saleska, S.

2012-01-01

Tropical forests ecosystems respond dynamically to climate variability and disturbances on time scales of minutes to millennia. To date, our knowledge of disturbance and recovery processes in tropical forests is derived almost exclusively from networks of forest inventory plots. These plots typically sample small areas (less than or equal to 1 ha) in conservation units that are protected from logging and fire. Amazon forests with frequent disturbances from human activity remain under-studied. Ongoing negotiations on REDD+ (Reducing Emissions from Deforestation and Forest Degradation plus enhancing forest carbon stocks) have placed additional emphasis on identifying degraded forests and quantifying changing carbon stocks in both degraded and intact tropical forests. We evaluated patterns of forest disturbance and recovery at four -1000 ha sites in the Brazilian Amazon using small footprint LiDAR data and coincident field measurements. Large area coverage with airborne LiDAR data in 2011-2012 included logged and unmanaged areas in Cotriguacu (Mato Grosso), Fiona do Jamari (Rondonia), and Floresta Estadual do Antimary (Acre), and unmanaged forest within Reserva Ducke (Amazonas). Logging infrastructure (skid trails, log decks, and roads) was identified using LiDAR returns from understory vegetation and validated based on field data. At each logged site, canopy gaps from logging activity and LiDAR metrics of canopy heights were used to quantify differences in forest structure between logged and unlogged areas. Contrasting patterns of harvesting operations and canopy damages at the three logged sites reflect different levels of pre-harvest planning (i.e., informal logging compared to state or national logging concessions), harvest intensity, and site conditions. Finally, we used multi-temporal LiDAR data from two sites, Reserva Ducke (2009, 2012) and Antimary (2010, 2011), to evaluate gap phase dynamics in unmanaged forest areas. The rates and patterns of canopy gap formation at these sites illustrate potential issues for separating logging damages from natural forest disturbances over longer time scales. Multi-temporal airborne LiDAR data and coincident field measurements provide complementary perspectives on disturbance and recovery processes in intact and degraded Amazon forests. Compared to forest inventory plots, the large size of each individual site permitted analyses of landscape-scale processes that would require extremely high investments to study using traditional forest inventory methods.

Feedbacks between land cover and climate changes in the Brazilian Amazon and Cerrado biomes

NASA Astrophysics Data System (ADS)

Coe, M. T.; Silverio, D. V.; Bustamante, M.; Macedo, M.; Shimbo, J.; Brando, P. M.

2016-12-01

An estimated 20% of Amazon forests and 45% of Cerrado savannas have been cleared to make way for the expansion of croplands and pasturelands in Brazil. Although deforestation rates have decreased or remained steady over the last decade, the cumulative area deforested continues to grow in both biomes. These land-use transitions are expected to influence regional climate by reducing evapotranspiration (ET), increasing land surface temperatures (LST), and ultimately reducing regional precipitation. Here we present results from spatial analyses to quantify the impact of land-use transitions on the regional climate of the Amazon-Cerrado agricultural frontier. The analyses combine satellite observations and model outputs from the MODIS dataset. Results from the southeastern Amazon indicate that transitions from forest to pasture or cropland decreased mean annual ET (by 24% and 32%, respectively) and increased LST (by 4.2°C and 6.4°C). Preliminary results from the Cerrado indicate that transitions from woody savannas to pasture or cropland also result in substantial reductions in mean annual ET (23% and 20%, respectively) and increases in LST (by 1.6°C in both cases). These results reinforce the need to better understand how land-use change at regional scales may alter climate by changing ecosystem properties (beyond carbon stocks and fluxes). It is important to evaluate these responses across different biomes, particularly in tropical regions under increasing deforestation pressure.

Climate change, deforestation, and the fate of the Amazon.

PubMed

Malhi, Yadvinder; Roberts, J Timmons; Betts, Richard A; Killeen, Timothy J; Li, Wenhong; Nobre, Carlos A

2008-01-11

The forest biome of Amazonia is one of Earth's greatest biological treasures and a major component of the Earth system. This century, it faces the dual threats of deforestation and stress from climate change. Here, we summarize some of the latest findings and thinking on these threats, explore the consequences for the forest ecosystem and its human residents, and outline options for the future of Amazonia. We also discuss the implications of new proposals to finance preservation of Amazonian forests.

Relationships Between Fire and Land Use Change in the Brazilian Amazon Based on Satellite Data

NASA Astrophysics Data System (ADS)

Fanin, T.; van der Werf, G.

2014-12-01

Fires are used as a tool in the process of deforestation. The relationship between fire and deforestation varies temporally and spatially according to the type of deforestation and climatic conditions. This study evaluates spatiotemporal variability between fire and deforestation over the 2002-2012 period in the Brazilian Legal Amazon (BLA). We based our study on four datasets: deforestation estimates from PRODES (Amazon Deforestation Monitoring Project) and forest cover loss from the Global Forest Change (GFC) project based on Landsat data, and burned area and land cover based on Moderate Resolution Imaging Spectroradiometer (MODIS) data. While GFC and PRODES supported similar findings on spatial and temporal dynamics, the Landsat-scale comparison also highlighted a number of differences. Both datasets show a decrease after 2004 in forest loss or deforestation extent mainly from decreasing clearing rates in evergreen broadleaf forest, mostly in the states of Mato Grosso and Rondonia. However, the drop is larger and more gradual in PRODES than in GFC, with the former having less than half the forest loss of the latter. GFC indicates anomalous high forest loss in the years 2007 and 2010 not seen in PRODES. Rescaling these forest dynamics datasets to 500-meter resolution, allowed for a comparison against the MODIS datasets. The burned area data indicates that the mismatch between PRODES and GFC is largely related to increased fire occurrence during these dry years, mainly in Para. In addition it indicates that the time interval between deforestation and fire differs according to land cover, which is important when estimating the atmospheric impact of forest loss. We found that evergreen broadleaf forests are burned shortly after deforestation due to slash and burn techniques, while croplands have longer intervals depending on the crop variety. As a final step, we used these insights to better quantify carbon emissions from this region.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jardine, Kolby

In conjunction with the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility GoAmazon campaign, the Terrestrial Ecosystem Science (TES)-funded Green Ocean Amazon (GoAmazon 2014/15) terrestrial ecosystem project (Geco) was designed to: • evaluate the strengths and weaknesses of leaf-level algorithms for biogenic volatile organic compounds (BVOCs) emissions in Amazon forests near Manaus, Brazil, and • conduct mechanistic field studies to characterize biochemical and physiological processes governing leaf- and landscape-scale tropical forest BVOC emissions, and the influence of environmental drivers that are expected to change with a warming climate. Through a close interaction between modeling and observationalmore » activities, including the training of MS and PhD graduate students, post-doctoral students, and technicians at the National Institute for Amazon Research (INPA), the study aimed at improving the representation of BVOC-mediated biosphere-atmosphere interactions and feedbacks under a warming climate. BVOCs can form cloud condensation nuclei (CCN) that influence precipitation dynamics and modify the quality of down welling radiation for photosynthesis. However, our ability to represent these coupled biosphere-atmosphere processes in Earth system models suffers from poor understanding of the functions, identities, quantities, and seasonal patterns of BVOC emissions from tropical forests as well as their biological and environmental controls. The Model of Emissions of Gases and Aerosols from Nature (MEGAN), the current BVOC sub-model of the Community Earth System Model (CESM), was evaluated to explore mechanistic controls over BVOC emissions. Based on that analysis, a combination of observations and experiments were studied in forests near Manaus, Brazil, to test existing parameterizations and algorithm structures in MEGAN. The model was actively modified as needed to improve tropical BVOC emission simulations on a regional scale.« less

The Impacts of Amazon Deforestation on Pacific Climate

NASA Astrophysics Data System (ADS)

Lindsey, Leah

Variability in eastern Pacific sea surface temperatures (SSTs) associated with the El Nino Southern Oscillation are known to affect Amazonian precipitation, but to what extent do changing Amazonian vegetation and rainfall impact eastern Pacific SST? The Amazon rainforest is threatened by many factors including climate change and clearing for agricultural reasons. Forest fires and dieback are more likely due to increased frequency and intensity of droughts in the region. It is possible that extensive Amazon deforestation can enhance El Nino conditions by weakening the Walker circulation. Correlations between annual rainfall rates over the Amazon and other atmospheric parameters (global precipitation, surface air temperature, low cloud amount, 500 hPa vertical velocity, surface winds, and 200 hPa winds) over the eastern Pacific indicate strong relationships among these fields. Maps of these correlations (teleconnection maps) reveal that when the Amazon is rainy SSTs in the central and eastern Pacific are cold, rainfall is suppressed over the central and eastern Pacific, low clouds are prominent over the eastern and southeastern Pacific, and subsidence over the central and eastern Pacific is enhanced. Precipitation in the Amazon is also consistent with a strong Walker circulation (La Nina conditions), manifest as strong correlations with the easterly surface and westerly 200 hPa zonal winds. Coupling between Amazon rainfall and these fields are seen in observations and model data. Correlations were calculated using data from observations, reanalysis data, two models under the Coupled Model Intercomparison Project/Atmospheric Model Intercomparison Project (CMIP5/AMIP), and an AMIP run with the model used in this study, the Community Earth System Model (CESM1.1.1). Although the correlations between Amazon precipitation and the aforementioned fields are strong, they do not show causality. In order to investigate the impact of tropical South American deforestation on the Pacific climate, numerical experiments were performed using the CESM. Amazon deforestation was studied in an idealized world where a single continent was covered in forest and then, in a separate simulation, covered in grassland. Four different sets of simulations were carried out: 1) the baseline idealized set-up with prescribed SST, 2) another with an Andes-like mountain range, 3) a simulation with a slab ocean model rather than prescribed SST, and 4) a simulation repeated with the standard Community Atmosphere Model (CAM4) replaced by the Superparameterized version (SP-CAM). The continent in these simulations was compared to the Amazon, and the ocean to the west of the continent was compared to the eastern Pacific. All of the simulations showed a strong warming of around 3-4°C over the continent going from forest to grassland. A notable decrease in precipitation over land of about 1-3 mm day-1 and increase to the west of the continent of about 1-2 mm day-1 was also observed in most of the simulations. The simulations with the slab ocean model showed enhanced precipitation changes with a corresponding decrease of 2-4 mm day-1 over land and increase of 3-5 mm day-1 west of the continent. Simulations that used the SP-CAM showed very small changes in precipitation, which was likely due to the decreased spin-up time allowed for these simulations. The decrease in the surface roughness and reduction in the evapotranspiration for the simulations with grassland contributed to these changes in surface temperature and precipitation. The conversion of forest to grassland in our experiments imply that deforestation can lead to weakening of the Walker circulation by weakening easterly surface winds and westerly upper tropospheric winds. These findings suggest that large-scale Amazon deforestation is capable of enhancing El Nino conditions.

Optimal use of land surface temperature data to detect changes in tropical forest cover

NASA Astrophysics Data System (ADS)

van Leeuwen, Thijs T.; Frank, Andrew J.; Jin, Yufang; Smyth, Padhraic; Goulden, Michael L.; van der Werf, Guido R.; Randerson, James T.

2011-06-01

Rapid and accurate assessment of global forest cover change is needed to focus conservation efforts and to better understand how deforestation is contributing to the buildup of atmospheric CO2. Here we examined different ways to use land surface temperature (LST) to detect changes in tropical forest cover. In our analysis we used monthly 0.05° × 0.05° Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of LST and Program for the Estimation of Deforestation in the Brazilian Amazon (PRODES) estimates of forest cover change. We also compared MODIS LST observations with an independent estimate of forest cover loss derived from MODIS and Landsat observations. Our study domain of approximately 10° × 10° included the Brazilian state of Mato Grosso. For optimal use of LST data to detect changes in tropical forest cover in our study area, we found that using data sampled during the end of the dry season (˜1-2 months after minimum monthly precipitation) had the greatest predictive skill. During this part of the year, precipitation was low, surface humidity was at a minimum, and the difference between day and night LST was the largest. We used this information to develop a simple temporal sampling algorithm appropriate for use in pantropical deforestation classifiers. Combined with the normalized difference vegetation index, a logistic regression model using day-night LST did moderately well at predicting forest cover change. Annual changes in day-night LST decreased during 2006-2009 relative to 2001-2005 in many regions within the Amazon, providing independent confirmation of lower deforestation levels during the latter part of this decade as reported by PRODES.

Connecting Amazonian, Cerrado, and Atlantic Forest histories: Paraphyly, old divergences, and modern population dynamics in tyrant-manakins (Neopelma/Tyranneutes, Aves: Pipridae).

PubMed

Capurucho, João Marcos Guimarães; Ashley, Mary V; Ribas, Camila C; Bates, John M

2018-06-11

Several biogeographic hypotheses have been proposed to explain connections between Amazonian and Atlantic forest biotas. These hypotheses are related to the timing of the connections and their geographic patterns. We performed a phylogeographic investigation of Tyrant-manakins (Aves: Pipridae, Neopelma/Tyranneutes) which include species inhabiting the Amazon and Atlantic forests, as well as gallery forests of the Cerrado. Using DNA sequence data, we determined phylogenetic relationships, temporal and geographic patterns of diversification, and recent intraspecific population genetic patterns, relative to the history of these biomes. We found Neopelma to be a paraphyletic genus, as N. chrysolophum is sister to Neopelma + Tyranneutes, with an estimated divergence of approximately 18 Myrs BP, within the oldest estimated divergence times of other Amazonian and Atlantic forest avian taxa. Subsequent divergences in the group occurred from Mid Miocene to Early Pliocene and involved mainly the Amazonian species, with an expansion into and subsequent speciation in the Cerrado gallery forests by N. pallescens. We found additional structure within N. chrysocephalum and N. sulphureiventer. Analysis of recent population dynamics in N. chrysocephalum, N. sulphureiventer, and N. pallescens revealed recent demographic fluctuations and restrictions to gene flow related to environmental changes since the last glacial cycle. No genetic structure was detected across the Amazon River in N. pallescens. The tyrant-manakins represent an old historical connection between the Amazon and Atlantic Forest. Copyright © 2018. Published by Elsevier Inc.

Amazon Forest maintenance as a source of environmental services.

PubMed

Fearnside, Philip M

2008-03-01

Amazonian forest produces environmental services such as maintenance of biodiversity, water cycling and carbon stocks. These services have a much greater value to human society than do the timber, beef and other products that are obtained by destroying the forest. Yet institutional mechanisms are still lacking to transform the value of the standing forest into the foundation of an economy based on maintaining rather than destroying this ecosystem. Forest management for commodities such as timber and non-timber forest products faces severe limitations and inherent contradictions unless income is supplemented based on environmental services. Amazon forest is threatened by deforestation, logging, forest fires and climate change. Measures to avoid deforestation include repression through command and control, creation of protected areas, and reformulation of infrastructure decisions and development policies. An economy primarily based on the value of environmental services is essential for long-term maintenance of the forest. Much progress has been made in the decades since I first proposed such a transition, but many issues also remain unresolved. These include theoretical issues regarding accounting procedures, improved quantification of the services and of the benefits of different policy options, and effective uses of the funds generated in ways that maintain both the forest and the human population.

Dependence of hydropower energy generation on forests in the Amazon Basin at local and regional scales

PubMed Central

Stickler, Claudia M.; Coe, Michael T.; Costa, Marcos H.; Nepstad, Daniel C.; McGrath, David G.; Dias, Livia C. P.; Rodrigues, Hermann O.; Soares-Filho, Britaldo S.

2013-01-01

Tropical rainforest regions have large hydropower generation potential that figures prominently in many nations’ energy growth strategies. Feasibility studies of hydropower plants typically ignore the effect of future deforestation or assume that deforestation will have a positive effect on river discharge and energy generation resulting from declines in evapotranspiration (ET) associated with forest conversion. Forest loss can also reduce river discharge, however, by inhibiting rainfall. We used land use, hydrological, and climate models to examine the local “direct” effects (through changes in ET within the watershed) and the potential regional “indirect” effects (through changes in rainfall) of deforestation on river discharge and energy generation potential for the Belo Monte energy complex, one of the world’s largest hydropower plants that is currently under construction on the Xingu River in the eastern Amazon. In the absence of indirect effects of deforestation, simulated deforestation of 20% and 40% within the Xingu River basin increased discharge by 4–8% and 10–12%, with similar increases in energy generation. When indirect effects were considered, deforestation of the Amazon region inhibited rainfall within the Xingu Basin, counterbalancing declines in ET and decreasing discharge by 6–36%. Under business-as-usual projections of forest loss for 2050 (40%), simulated power generation declined to only 25% of maximum plant output and 60% of the industry’s own projections. Like other energy sources, hydropower plants present large social and environmental costs. Their reliability as energy sources, however, must take into account their dependence on forests. PMID:23671098

Amazon forest structure generates diurnal and seasonal variability in light utilization

Treesearch

Douglas C. Morton; Jeremy Rubio; Bruce D. Cook; Jean-Philippe Gastellu-Etchegorry; Marcos Longo; Hyeungu Choi; Maria Hunter; Michael Keller

2016-01-01

The complex three-dimensional (3-D) structure of tropical forests generates a diversity of light environments for canopy and understory trees. Understanding diurnal and seasonal changes in light availability is critical for interpreting measurements of net ecosystem exchange and improving ecosystem models. Here, we used the Discrete Anisotropic Radiative Transfer (DART...

Loggers and Forest Fragmentation: Behavioral Models of Road Building in the Amazon Basin

NASA Technical Reports Server (NTRS)

Arima, Eugenio Y.; Walker, Robert T.; Perz, Stephen G.; Caldas, Marcellus

2005-01-01

Although a large literature now exists on the drivers of tropical deforestation, less is known about its spatial manifestation. This is a critical shortcoming in our knowledge base since the spatial pattern of land-cover change and forest fragmentation, in particular, strongly affect biodiversity. The purpose of this article is to consider emergent patterns of road networks, the initial proximate cause of fragmentation in tropical forest frontiers. Specifically, we address the road-building processes of loggers who are very active in the Amazon landscape. To this end, we develop an explanation of road expansions, using a positive approach combining a theoretical model of economic behavior with geographic information systems (GIs) software in order to mimic the spatial decisions of road builders. We simulate two types of road extensions commonly found in the Amazon basin in a region: showing the fishbone pattern of fragmentation. Although our simulation results are only partially successful, they call attention to the role of multiple agents in the landscape, the importance of legal and institutional constraints on economic behavior, and the power of GIs as a research tool.

Taxonomical and functional microbial responses to agriculture management of Amazon forest soils

NASA Astrophysics Data System (ADS)

Kuramae, Eiko; Navarrete, Acácio; Mendes, Lucas; de Hollander, Mattias; van Veen, Johannes; Tsai, Siu

2013-04-01

Land-use change is one of the greatest threats to biodiversity worldwide, and one of the most devastating changes in the use of land, especially in the tropics, is the conversion of forest to crop lands. Southeast Amazon region is considered the largest agricultural frontier in the world, where native forests are converted into soybean crop fields, a fact that highlights the social and economic importance of this system to Brazil. This study firstly, focused on the impact of land-use changes and agriculture management of Amazon forest soils on the size and composition of the acidobacterial community. Taxon-specific quantitative real-time PCR (qPCR) and pyrosequencing of 16S rRNA gene were applied to study the acidobacterial community in bulk soil samples from croplands, adjacent native forests and rhizosphere of soybean. Based on qPCR measurements, Acidobacteria accounted for 23%, 18% and 14% of the total bacterial signal in forest soils, cropland soils and soybean rhizosphere samples, respectively. From the sequences of Bacteria domain, the phylum Acidobacteria represented 28%, 16% and 17% of the sequences from forest soils, cropland soils and soybean rhizosphere samples, respectively. Acidobacteria subgroups 2-8, 10, 11, 13, 17, 18, 22 and 25 were detected with subgroup 1 as dominant among them. Subgroups 4, 6 and 7 were significantly higher in cropland soils than in forest soils, which subgroups respond to decrease of soil Aluminium. Subgroups 6 and 7 respond to high content of soil Ca, Mg, Zn, P, Fe, Mn and B. The results showed differential response of the Acidobacteria subgroups to abiotic soil factors, and indicated acidobacterial subgroups as potential early-warning bio-indicators of agricultural soil management effects in the Amazon area. Secondly, using 454 pyrosequencing, we investigated the metabolic diversity of microbial communities colonizing the rhizosphere and the bulk soil associated to soybean. The rhizosphere presented an overrepresentation of functional cores related to metabolism of nitrogen, iron, phosphorus and potassium, with bacterial groups linked to these cores found only in rhizosphere samples. Still, the network involving bacterial groups and metabolisms was less complex in rhizosphere, suggesting the specialization of some specific metabolic pathways. Taken together, these results indicate a rhizosphere effect over the soil functional community with a selection of some metabolic pathways, which could be related to plant benefits as nutrition and development. A better understanding of the functional role of the rhizosphere microbial communities is important to the development of a sustainable agriculture.

Use of morphometric soil aggregates parameters to evaluate the reclamation process in mined areas located at amazon forest - Brazil

NASA Astrophysics Data System (ADS)

Ribeiro, A. I.; Fengler, F. H.; Longo, R. M.; Mello, G. F.; Damame, D. B.; Crowley, D. E.

2015-12-01

Brazil has a high mineral potential that have been explored over the years. A large fraction of these mineral resources are located in Amazon region, which is known for its large biodiversity and world climate importance. As the policies that control the Amazon preservation are relatively new, several mining activities have been exploring the Amazon territory, promoting a large process of degradation. Once the mining activities have a high potential of environmental changes the government created polices to restrain the mining in Amazon forests and obligate mining companies to reclaim theirs minded areas. However, the measurement of reclamation development still is a challenging task for the Professionals involved. The volume and complexity of the variables, allied to the difficulty in identifying the reclamation of ecosystem functionalities are still lack to ensure the reclamation success. In this sense this work aims to investigate the representativeness of morphometric soil aggregates parameters in the understanding of reclamation development. The study area is located in the National Forest of Jamari, State of Rondônia. In the past mining companies explored the region producing eight closed mines that are now in reclamation process. The soil aggregates morphometric measurements: geometric mean diameter (GMD), aggregate circularity index, and aggregate roundness, were choose based in its obtaining facility, and their association to biological activity. To achieve the proposed objective the aggregates of eight sites in reclamation, from different closed mines, where chosen and compared to Amazon forest and open mine soil aggregates. The results were analyzed to one way ANOVA to identifying differences between areas in reclamation, natural ecosystem, and open mine. It was obtained differences for GMD and circularity index. However, only the circularity index allowed to identifying differences between the reclamation sites. The results allowed concluding: (1) Morphometric aggregates measurements can represent the reclamation process in Amazon territory; (2) To validate the results more areas in reclamation process in different ecosystems must be investigated; (3) Roundness didn't represented any differences.Key words: circularity index, ecosystem, geometric mean diameter.

Size and frequency of natural forest disturbances and the Amazon forest carbon balance

PubMed Central

Espírito-Santo, Fernando D.B.; Gloor, Manuel; Keller, Michael; Malhi, Yadvinder; Saatchi, Sassan; Nelson, Bruce; Junior, Raimundo C. Oliveira; Pereira, Cleuton; Lloyd, Jon; Frolking, Steve; Palace, Michael; Shimabukuro, Yosio E.; Duarte, Valdete; Mendoza, Abel Monteagudo; López-González, Gabriela; Baker, Tim R.; Feldpausch, Ted R.; Brienen, Roel J.W.; Asner, Gregory P.; Boyd, Doreen S.; Phillips, Oliver L.

2014-01-01

Forest inventory studies in the Amazon indicate a large terrestrial carbon sink. However, field plots may fail to represent forest mortality processes at landscape-scales of tropical forests. Here we characterize the frequency distribution of disturbance events in natural forests from 0.01 ha to 2,651 ha size throughout Amazonia using a novel combination of forest inventory, airborne lidar and satellite remote sensing data. We find that small-scale mortality events are responsible for aboveground biomass losses of ~1.7 Pg C y−1 over the entire Amazon region. We also find that intermediate-scale disturbances account for losses of ~0.2 Pg C y−1, and that the largest-scale disturbances as a result of blow-downs only account for losses of ~0.004 Pg C y−1. Simulation of growth and mortality indicates that even when all carbon losses from intermediate and large-scale disturbances are considered, these are outweighed by the net biomass accumulation by tree growth, supporting the inference of an Amazon carbon sink. PMID:24643258

Size and frequency of natural forest disturbances and the Amazon forest carbon balance.

PubMed

Espírito-Santo, Fernando D B; Gloor, Manuel; Keller, Michael; Malhi, Yadvinder; Saatchi, Sassan; Nelson, Bruce; Junior, Raimundo C Oliveira; Pereira, Cleuton; Lloyd, Jon; Frolking, Steve; Palace, Michael; Shimabukuro, Yosio E; Duarte, Valdete; Mendoza, Abel Monteagudo; López-González, Gabriela; Baker, Tim R; Feldpausch, Ted R; Brienen, Roel J W; Asner, Gregory P; Boyd, Doreen S; Phillips, Oliver L

2014-03-18

Forest inventory studies in the Amazon indicate a large terrestrial carbon sink. However, field plots may fail to represent forest mortality processes at landscape-scales of tropical forests. Here we characterize the frequency distribution of disturbance events in natural forests from 0.01 ha to 2,651 ha size throughout Amazonia using a novel combination of forest inventory, airborne lidar and satellite remote sensing data. We find that small-scale mortality events are responsible for aboveground biomass losses of ~1.7 Pg C y(-1) over the entire Amazon region. We also find that intermediate-scale disturbances account for losses of ~0.2 Pg C y(-1), and that the largest-scale disturbances as a result of blow-downs only account for losses of ~0.004 Pg C y(-1). Simulation of growth and mortality indicates that even when all carbon losses from intermediate and large-scale disturbances are considered, these are outweighed by the net biomass accumulation by tree growth, supporting the inference of an Amazon carbon sink.

Conversion of the Amazon rainforest to agriculture results in biotic homogenization of soil bacterial communities

PubMed Central

Rodrigues, Jorge L. M.; Pellizari, Vivian H.; Mueller, Rebecca; Baek, Kyunghwa; Jesus, Ederson da C.; Paula, Fabiana S.; Mirza, Babur; Hamaoui, George S.; Tsai, Siu Mui; Feigl, Brigitte; Tiedje, James M.; Bohannan, Brendan J. M.; Nüsslein, Klaus

2013-01-01

The Amazon rainforest is the Earth’s largest reservoir of plant and animal diversity, and it has been subjected to especially high rates of land use change, primarily to cattle pasture. This conversion has had a strongly negative effect on biological diversity, reducing the number of plant and animal species and homogenizing communities. We report here that microbial biodiversity also responds strongly to conversion of the Amazon rainforest, but in a manner different from plants and animals. Local taxonomic and phylogenetic diversity of soil bacteria increases after conversion, but communities become more similar across space. This homogenization is driven by the loss of forest soil bacteria with restricted ranges (endemics) and results in a net loss of diversity. This study shows homogenization of microbial communities in response to human activities. Given that soil microbes represent the majority of biodiversity in terrestrial ecosystems and are intimately involved in ecosystem functions, we argue that microbial biodiversity loss should be taken into account when assessing the impact of land use change in tropical forests. PMID:23271810

Conversion of the Amazon rainforest to agriculture results in biotic homogenization of soil bacterial communities.

PubMed

Rodrigues, Jorge L M; Pellizari, Vivian H; Mueller, Rebecca; Baek, Kyunghwa; Jesus, Ederson da C; Paula, Fabiana S; Mirza, Babur; Hamaoui, George S; Tsai, Siu Mui; Feigl, Brigitte; Tiedje, James M; Bohannan, Brendan J M; Nüsslein, Klaus

2013-01-15

The Amazon rainforest is the Earth's largest reservoir of plant and animal diversity, and it has been subjected to especially high rates of land use change, primarily to cattle pasture. This conversion has had a strongly negative effect on biological diversity, reducing the number of plant and animal species and homogenizing communities. We report here that microbial biodiversity also responds strongly to conversion of the Amazon rainforest, but in a manner different from plants and animals. Local taxonomic and phylogenetic diversity of soil bacteria increases after conversion, but communities become more similar across space. This homogenization is driven by the loss of forest soil bacteria with restricted ranges (endemics) and results in a net loss of diversity. This study shows homogenization of microbial communities in response to human activities. Given that soil microbes represent the majority of biodiversity in terrestrial ecosystems and are intimately involved in ecosystem functions, we argue that microbial biodiversity loss should be taken into account when assessing the impact of land use change in tropical forests.

Drought stress and carbon uptake in an Amazon forest measured with spaceborne imaging spectroscopy

PubMed Central

Asner, Gregory P.; Nepstad, Daniel; Cardinot, Gina; Ray, David

2004-01-01

Amazônia contains vast stores of carbon in high-diversity ecosystems, yet this region undergoes major changes in precipitation affecting land use, carbon dynamics, and climate. The extent and structural complexity of Amazon forests impedes ground studies of ecosystem functions such as net primary production (NPP), water cycling, and carbon sequestration. Traditional modeling and remote-sensing approaches are not well suited to tropical forest studies, because (i) biophysical mechanisms determining drought effects on canopy water and carbon dynamics are poorly known, and (ii) remote-sensing metrics of canopy greenness may be insensitive to small changes in leaf area accompanying drought. New spaceborne imaging spectroscopy may detect drought stress in tropical forests, helping to monitor forest physiology and constrain carbon models. We combined a forest drought experiment in Amazônia with spaceborne imaging spectrometer measurements of this area. With field data on rainfall, soil water, and leaf and canopy responses, we tested whether spaceborne hyperspectral observations quantify differences in canopy water and NPP resulting from drought stress. We found that hyperspectral metrics of canopy water content and light-use efficiency are highly sensitive to drought. Using these observations, forest NPP was estimated with greater sensitivity to drought conditions than with traditional combinations of modeling, remote-sensing, and field measurements. Spaceborne imaging spectroscopy will increase the accuracy of ecological studies in humid tropical forests. PMID:15071182

Are community-based forest enterprises in the tropics financially viable? Case studies from the Brazilian Amazon

Treesearch

Shoana Humphries; Thomas P. Holmes; Karen Kainer; Carlos Gabriel Goncalves Koury; Edson Cruz; Rosana de Miranda Rocha

2012-01-01

Community-based forest management is an integral component of sustainable forest management and conservation in the Brazilian Amazon, where it has been heavily subsidized for the last ten years. Yet knowledge of the financial viability and impact of community-based forest enterprises (CFEs) is lacking. This study evaluates the profitability of three CFEs in the...

Aboveground biomass variability across intact and degraded forests in the Brazilian Amazon

Treesearch

Marcos Longo; Michael Keller; Maiza N. dos-Santos; Veronika Leitold; Ekena R. Pinagé; Alessandro Baccini; Sassan Saatchi; Euler M. Nogueira; Mateus Batistella; Douglas C. Morton

2016-01-01

Deforestation rates have declined in the Brazilian Amazon since 2005, yet degradation from logging, fire, and fragmentation has continued in frontier forests. In this study we quantified the aboveground carbon density (ACD) in intact and degraded forests using the largest data set of integrated forest inventory plots (n = 359) and airborne lidar data (18,000 ha)...

Future forest

NASA Astrophysics Data System (ADS)

2011-11-01

As Brazil debates relaxing its strong forestry laws, Nature Climate Change discusses the implications with Amazon ecologist Thomas Lovejoy, professor of environmental science at George Mason University and Biodiversity Chair at the Heinz Center in Washington DC.

Impact of deforestation and climate on the Amazon Basin's above-ground biomass during 1993-2012.

PubMed

Exbrayat, Jean-François; Liu, Yi Y; Williams, Mathew

2017-11-15

Since the 1960s, large-scale deforestation in the Amazon Basin has contributed to rising global CO 2 concentrations and to climate change. Recent advances in satellite observations enable estimates of gross losses of above-ground biomass (AGB) stocks due to deforestation. However, because of simultaneous regrowth, the net contribution of deforestation emissions to rising atmospheric CO 2 concentrations is poorly quantified. Climate change may also reduce the potential for forest regeneration in previously disturbed regions. Here, we address these points of uncertainty with a machine-learning approach that combines satellite observations of AGB with climate data across the Amazon Basin to reconstruct annual maps of potential AGB during 1993-2012, the above-ground C storage potential of the undisturbed landscape. We derive a 2.2 Pg C loss of AGB over the study period, and, for the regions where these losses occur, we estimate a 0.7 Pg C reduction in potential AGB. Thus, climate change has led to a decline of ~1/3 in the capacity of these disturbed forests to recover and recapture the C lost in disturbances during 1993-2012. Our approach further shows that annual variations in land use change mask the natural relationship between the El Niño/Southern Oscillation and AGB stocks in disturbed regions.

Contrasting the microbiomes from forest rhizosphere and deeper bulk soil from an Amazon rainforest reserve.

PubMed

Fonseca, Jose Pedro; Hoffmann, Luisa; Cabral, Bianca Catarina Azeredo; Dias, Victor Hugo Giordano; Miranda, Marcio Rodrigues; de Azevedo Martins, Allan Cezar; Boschiero, Clarissa; Bastos, Wanderley Rodrigues; Silva, Rosane

2018-02-05

Pristine forest ecosystems provide a unique perspective for the study of plant-associated microbiota since they host a great microbial diversity. Although the Amazon forest is one of the hotspots of biodiversity around the world, few metagenomic studies described its microbial community diversity thus far. Understanding the environmental factors that can cause shifts in microbial profiles is key to improving soil health and biogeochemical cycles. Here we report a taxonomic and functional characterization of the microbiome from the rhizosphere of Brosimum guianense (Snakewood), a native tree, and bulk soil samples from a pristine Brazilian Amazon forest reserve (Cuniã), for the first time by the shotgun approach. We identified several fungi and bacteria taxon significantly enriched in forest rhizosphere compared to bulk soil samples. For archaea, the trend was the opposite, with many archaeal phylum and families being considerably more enriched in bulk soil compared to forest rhizosphere. Several fungal and bacterial decomposers like Postia placenta and Catenulispora acidiphila which help maintain healthy forest ecosystems were found enriched in our samples. Other bacterial species involved in nitrogen (Nitrobacter hamburgensis and Rhodopseudomonas palustris) and carbon cycling (Oligotropha carboxidovorans) were overrepresented in our samples indicating the importance of these metabolic pathways for the Amazon rainforest reserve soil health. Hierarchical clustering based on taxonomic similar microbial profiles grouped the forest rhizosphere samples in a distinct clade separated from bulk soil samples. Principal coordinate analysis of our samples with publicly available metagenomes from the Amazon region showed grouping into specific rhizosphere and bulk soil clusters, further indicating distinct microbial community profiles. In this work, we reported significant shifts in microbial community structure between forest rhizosphere and bulk soil samples from an Amazon forest reserve that are probably caused by more than one environmental factors such as rhizosphere and soil depth. Copyright © 2017 Elsevier B.V. All rights reserved.

Windthrows increase soil carbon stocks in a Central Amazon forest

NASA Astrophysics Data System (ADS)

dos Santos, L. T.; Magnabosco Marra, D.; Trumbore, S.; Camargo, P. B.; Chambers, J. Q.; Negrón-Juárez, R. I.; Lima, A. J. N.; Ribeiro, G. H. P. M.; dos Santos, J.; Higuchi, N.

2015-12-01

Windthrows change forest structure and species composition in Central Amazon forests. However, the effects of widespread tree mortality associated with wind-disturbances on soil properties have not yet been described. In this study, we investigated short-term effects (seven years after disturbance) of a windthrow event on soil carbon stocks and concentrations in a Central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 4.18 Mg ha-1, mean ± standard error) was marginally higher (p = 0.009) than that from undisturbed plots (47.7 ± 6.95 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.08 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.12 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r = 0.575 and p = 0.019) and with tree mortality intensity (r = 0.493 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. Higher nutrient availability in soils from large canopy gaps created by wind disturbance may increase vegetation resilience and favor forest recovery.

Tropical North Atlantic ocean-atmosphere interactions synchronize forest carbon losses from hurricanes and Amazon fires

NASA Astrophysics Data System (ADS)

Chen, Yang; Randerson, James T.; Morton, Douglas C.

2015-08-01

We describe a climate mode synchronizing forest carbon losses from North and South America by analyzing time series of tropical North Atlantic sea surface temperatures (SSTs), landfall hurricanes and tropical storms, and Amazon fires during 1995-2013. Years with anomalously high tropical North Atlantic SSTs during March-June were often followed by a more active hurricane season and a larger number of satellite-detected fires in the southern Amazon during June-November. The relationship between North Atlantic tropical cyclones and southern Amazon fires (r = 0.61, p < 0.003) was stronger than links between SSTs and either cyclones or fires alone, suggesting that fires and tropical cyclones were directly coupled to the same underlying atmospheric dynamics governing tropical moisture redistribution. These relationships help explain why seasonal outlook forecasts for hurricanes and Amazon fires both failed in 2013 and may enable the design of improved early warning systems for drought and fire in Amazon forests.

High-resolution forest carbon stocks and emissions in the Amazon

Treesearch

G. P. Asner; George V. N. Powell; Joseph Mascaro; David E. Knapp; John K. Clark; James Jacobson; Ty Kennedy-Bowdoin; Aravindh Balaji; Guayana Paez-Acosta; Eloy Victoria; Laura Secada; Michael Valqui; R. Flint. Hughes

2010-01-01

Efforts to mitigate climate change through the Reduced Emissions from Deforestation and Degradation (REDD) depend on mapping and monitoring of tropical forest carbon stocks and emissions over large geographic areas. With a new integrated use of satellite imaging, airborne light detection and ranging, and field plots, we mapped aboveground carbon stocks and emissions at...

Light-driven growth in Amazon evergreen forests explained by seasonal variations of vertical canopy structure.

PubMed

Tang, Hao; Dubayah, Ralph

2017-03-07

Light-regime variability is an important limiting factor constraining tree growth in tropical forests. However, there is considerable debate about whether radiation-induced green-up during the dry season is real, or an apparent artifact of the remote-sensing techniques used to infer seasonal changes in canopy leaf area. Direct and widespread observations of vertical canopy structures that drive radiation regimes have been largely absent. Here we analyze seasonal dynamic patterns between the canopy and understory layers in Amazon evergreen forests using observations of vertical canopy structure from a spaceborne lidar. We discovered that net leaf flushing of the canopy layer mainly occurs in early dry season, and is followed by net abscission in late dry season that coincides with increasing leaf area of the understory layer. Our observations of understory development from lidar either weakly respond to or are not correlated to seasonal variations in precipitation or insolation, but are strongly related to the seasonal structural dynamics of the canopy layer. We hypothesize that understory growth is driven by increased light gaps caused by seasonal variations of the canopy. This light-regime variability that exists in both spatial and temporal domains can better reveal the drought-induced green-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.

Integrating the avoidance of forest degradation into systematic conservation planning in the Eastern Amazon

NASA Astrophysics Data System (ADS)

Ferreira, J.; Barlow, J.; Thompson, J.; Berenguer, E.; Aragão, L. E.; Lees, A.; Lennox, G.; Brancalion, P.; Ferraz, S.; Moura, N.; Oliveira, V. H.; Louzada, J.; Solar, R.; Nunes, S.; Parry, L.; Fonseca, T.; Garrett, R.; Vieira, I.; MacNally, R.; Gardner, T.

2017-12-01

Undisturbed forests are becoming increasingly rare in the tropics. The area of forest degraded by some form of disturbance, such as logging or fire, in the Brazilian Amazon now greatly exceeds that which had been deforested. Yet forest policy in the Amazon, as elsewhere in the tropics, remains overwhelmingly focused curbing the rate of forest loss without considering impacts on forest quality. We use a unique data set from the Sustainable Amazon Network (RAS), in the eastern Brazilian Amazon to assess the impacts of forest disturbance on biodiversity and assess the benefits of including avoided degradation measures in conservation planning. Biodiversity data on trees and fauna from two large regions, Santarém and Paragominas, were combined with remote sensing data to model biodiversity patterns as well as estimates of above-ground carbon stocks across a range of land-use types and forest conditions. We found that impact of forest disturbance on biodiversity loss in the state of Pará equates to double that lost from deforestation alone, -the equivalent of losing 92,000-139,000 km2 of primary forest. We found a strong positive relationship between increasing carbon stocks and higher biodiversity in varyingly disturbed forests. Simulations demonstrated that a carbon-focused conservation strategy is least effective at conserving biodiversity in the least disturbed forests, highlighting the importance of on-the-ground biodiversity surveys to prioritise conservation investments in the most species rich forests. We explored trade-offs among management actions to guide priorities for habitat protection, avoided degradation and restoration and found that where restoration imposes significant opportunity and implementation costs, efforts to avoid and reverse the degradation of existing forests can deliver greater returns on investment for biodiversity conservation. Systemic planning of forest management options at regional scales can substantially improve biodiversity outcomes while greatly reducing costs and risks. These results provide new and valuable information for regulators, conservation practitioners and landowners in this biologically unique region.

Coarse woody debris in undisturbed and logged forests in the eastern Brazilian Amazon.

Treesearch

Michael Keller; Michael Palace; Gregory P. Asner; Rodrigo Jr. Pereira; Jose Natalino M. Silva

2004-01-01

Coarse woody debris (CWD) is an important component of the carbon cycle in tropical forests. We measured the volume and density of fallen CWD at two sites, Cauaxi and Tapajós in the Eastern Amazon. At both sites we studied undisturbed forests (UFs) and logged forests 1 year after harvest. Conventional logging (CL) and reduced impact logging (RIL) were...

Biological processes dominate seasonality of remotely sensed canopy greenness in an Amazon evergreen forest.

PubMed

Wu, Jin; Kobayashi, Hideki; Stark, Scott C; Meng, Ran; Guan, Kaiyu; Tran, Ngoc Nguyen; Gao, Sicong; Yang, Wei; Restrepo-Coupe, Natalia; Miura, Tomoaki; Oliviera, Raimundo Cosme; Rogers, Alistair; Dye, Dennis G; Nelson, Bruce W; Serbin, Shawn P; Huete, Alfredo R; Saleska, Scott R

2018-03-01

Satellite observations of Amazon forests show seasonal and interannual variations, but the underlying biological processes remain debated. Here we combined radiative transfer models (RTMs) with field observations of Amazon forest leaf and canopy characteristics to test three hypotheses for satellite-observed canopy reflectance seasonality: seasonal changes in leaf area index, in canopy-surface leafless crown fraction and/or in leaf demography. Canopy RTMs (PROSAIL and FLiES), driven by these three factors combined, simulated satellite-observed seasonal patterns well, explaining c. 70% of the variability in a key reflectance-based vegetation index (MAIAC EVI, which removes artifacts that would otherwise arise from clouds/aerosols and sun-sensor geometry). Leaf area index, leafless crown fraction and leaf demography independently accounted for 1, 33 and 66% of FLiES-simulated EVI seasonality, respectively. These factors also strongly influenced modeled near-infrared (NIR) reflectance, explaining why both modeled and observed EVI, which is especially sensitive to NIR, captures canopy seasonal dynamics well. Our improved analysis of canopy-scale biophysics rules out satellite artifacts as significant causes of satellite-observed seasonal patterns at this site, implying that aggregated phenology explains the larger scale remotely observed patterns. This work significantly reconciles current controversies about satellite-detected Amazon phenology, and improves our use of satellite observations to study climate-phenology relationships in the tropics. No claim to original US Government works New Phytologist © 2017 New Phytologist Trust.

Maximizing Amazonia's Ecosystem Services: Juggling the potential for carbon storage, agricultural yield and biodiversity in the Amazon

NASA Astrophysics Data System (ADS)

O'Connell, C. S.; Foley, J. A.; Gerber, J. S.; Polasky, S.

2011-12-01

The Amazon is not only an exceptionally biodiverse and carbon-rich tract of tropical forest, it is also a case study in land use change. Over the next forty years it will continue to experience pressure from an urbanizing and increasingly affluent populace: under a business-as-usual scenario, global cropland, pasture and biofuels systems will carry on expanding, while the Amazon's carbon storage potential will likely become another viable revenue source under REDD+. Balancing those competing land use pressures ought also take into account Amazonia's high - but heterogeneous - biodiversity. Knowing where Amazonia has opportunities to make efficient or optimal trade offs between carbon storage, agricultural production and biodiversity can allow policymakers to direct or influence LUC drivers. This analysis uses a spatially-explicit model that takes climate and management into account to quantify the potential agricultural yield of both the Amazon's most important agricultural commodities - sugar, soy and maize - as well as several that are going to come into increasing prominence, including palm oil. In addition, it maps the potential for carbon to be stored in forest biomass and relative species richness across Amazonia. We then compare carbon storage, agricultural yield and species richness and identify areas where efficient trade offs occur between food, carbon, and biodiversity - three critical ecosystem goods and services provided by the world's largest tropical forest.

Role of Brazilian Amazon protected areas in climate change mitigation

PubMed Central

Soares-Filho, Britaldo; Moutinho, Paulo; Nepstad, Daniel; Anderson, Anthony; Rodrigues, Hermann; Garcia, Ricardo; Dietzsch, Laura; Merry, Frank; Bowman, Maria; Hissa, Letícia; Silvestrini, Rafaella; Maretti, Cláudio

2010-01-01

Protected areas (PAs) now shelter 54% of the remaining forests of the Brazilian Amazon and contain 56% of its forest carbon. However, the role of these PAs in reducing carbon fluxes to the atmosphere from deforestation and their associated costs are still uncertain. To fill this gap, we analyzed the effect of each of 595 Brazilian Amazon PAs on deforestation using a metric that accounts for differences in probability of deforestation in areas of pairwise comparison. We found that the three major categories of PA (indigenous land, strictly protected, and sustainable use) showed an inhibitory effect, on average, between 1997 and 2008. Of 206 PAs created after the year 1999, 115 showed increased effectiveness after their designation as protected. The recent expansion of PAs in the Brazilian Amazon was responsible for 37% of the region's total reduction in deforestation between 2004 and 2006 without provoking leakage. All PAs, if fully implemented, have the potential to avoid 8.0 ± 2.8 Pg of carbon emissions by 2050. Effectively implementing PAs in zones under high current or future anthropogenic threat offers high payoffs for reducing carbon emissions, and as a result should receive special attention in planning investments for regional conservation. Nevertheless, this strategy demands prompt and predictable resource streams. The Amazon PA network represents a cost of US$147 ± 53 billion (net present value) for Brazil in terms of forgone profits and investments needed for their consolidation. These costs could be partially compensated by an international climate accord that includes economic incentives for tropical countries that reduce their carbon emissions from deforestation and forest degradation. PMID:20505122

Role of Brazilian Amazon protected areas in climate change mitigation.

PubMed

Soares-Filho, Britaldo; Moutinho, Paulo; Nepstad, Daniel; Anderson, Anthony; Rodrigues, Hermann; Garcia, Ricardo; Dietzsch, Laura; Merry, Frank; Bowman, Maria; Hissa, Letícia; Silvestrini, Rafaella; Maretti, Cláudio

2010-06-15

Protected areas (PAs) now shelter 54% of the remaining forests of the Brazilian Amazon and contain 56% of its forest carbon. However, the role of these PAs in reducing carbon fluxes to the atmosphere from deforestation and their associated costs are still uncertain. To fill this gap, we analyzed the effect of each of 595 Brazilian Amazon PAs on deforestation using a metric that accounts for differences in probability of deforestation in areas of pairwise comparison. We found that the three major categories of PA (indigenous land, strictly protected, and sustainable use) showed an inhibitory effect, on average, between 1997 and 2008. Of 206 PAs created after the year 1999, 115 showed increased effectiveness after their designation as protected. The recent expansion of PAs in the Brazilian Amazon was responsible for 37% of the region's total reduction in deforestation between 2004 and 2006 without provoking leakage. All PAs, if fully implemented, have the potential to avoid 8.0 +/- 2.8 Pg of carbon emissions by 2050. Effectively implementing PAs in zones under high current or future anthropogenic threat offers high payoffs for reducing carbon emissions, and as a result should receive special attention in planning investments for regional conservation. Nevertheless, this strategy demands prompt and predictable resource streams. The Amazon PA network represents a cost of US$147 +/- 53 billion (net present value) for Brazil in terms of forgone profits and investments needed for their consolidation. These costs could be partially compensated by an international climate accord that includes economic incentives for tropical countries that reduce their carbon emissions from deforestation and forest degradation.

Extravagance in the commons: Resource exploitation and the frontiers of ecosystem service depletion in the Amazon estuary.

PubMed

de Araujo Barbosa, Caio C; Atkinson, Peter M; Dearing, John A

2016-04-15

Estuaries hold major economic potential due their strategic location, close to seas and inland waterways, thereby supporting intense economic activity. The increasing pace of human development in coastal deltas over the past five decades has also strained local resources and produced extensive changes across both social and ecological systems. The Amazon estuary is located in the Amazon Basin, North Brazil, the largest river basin on Earth and also one of the least understood. A considerable segment of the population living in the estuary is directly dependent on the local extraction of natural resources for their livelihood. Areas sparsely inhabited may be exploited with few negative consequences for the environment. However, recent and increasing pressure on ecosystem services is maximised by a combination of factors such as governance, currency exchange rates, exports of beef and forest products. Here we present a cross methodological approach in identifying the political frontiers of forest cover change in the estuary with consequences for ecosystem services loss. We used a combination of data from earth observation satellites, ecosystem service literature, and official government statistics to produce spatially-explicit relationships linking the Green Vegetation Cover to the availability of ecosystems provided by forests in the estuary. Our results show that the continuous changes in land use/cover and in the economic state have contributed significantly to changes in key ecosystem services, such as carbon sequestration, climate regulation, and the availability of timber over the last thirty years. Copyright © 2016 Elsevier B.V. All rights reserved.

Four decades of land-cover, land-use and hydroclimatology changes in the Itacaiúnas River watershed, southeastern Amazon.

PubMed

Souza-Filho, Pedro Walfir M; de Souza, Everaldo B; Silva Júnior, Renato O; Nascimento, Wilson R; Versiani de Mendonça, Breno R; Guimarães, José Tasso F; Dall'Agnol, Roberto; Siqueira, José Oswaldo

2016-02-01

Long-term human-induced impacts have significantly changed the Amazonian landscape. The most dramatic land cover and land use (LCLU) changes began in the early 1970s with the establishment of the Trans-Amazon Highway and large government projects associated with the expansion of agricultural settlement and cattle ranching, which cleared significant tropical forest cover in the areas of new and accelerated human development. Taking the changes in the LCLU over the past four decades as a basis, this study aims to determine the consequences of land cover (forest and savanna) and land use (pasturelands, mining and urban) changes on the hydroclimatology of the Itacaiúnas River watershed area of the located in the southeastern Amazon region. We analyzed a multi-decadal Landsat dataset from 1973, 1984, 1994, 2004 and 2013 and a 40-yr time series of water discharge from the Itacaiúnas River, as well as air temperature and relative humidity data over this drainage area for the same period. We employed standard Landsat image processing techniques in conjunction with a geographic object-based image analysis and multi-resolution classification approach. With the goal of detecting possible long-term trends, non-parametric Mann-Kendall test was applied, based on a Sen slope estimator on a 40-yr annual PREC, TMED and RH time series, considering the spatial average of the entire watershed. In the 1970s, the region was entirely covered by forest (99%) and savanna (∼0.3%). Four decades later, only ∼48% of the tropical forest remains, while pasturelands occupy approximately 50% of the watershed area. Moreover, in protected areas, nearly 97% of the tropical forest remains conserved, while the forest cover of non-protected areas is quite fragmented and, consequently, unevenly distributed, covering an area of only 30%. Based on observational data analysis, there is evidence that the conversion of forest cover to extensive and homogeneous pasturelands was accompanied by systematic modifications to the hydroclimatology cycle of the Itacaiúnas watershed, thus highlighting drier environmental conditions due to a rise in the region's air temperature, a decrease in the relative humidity, and an increase in river discharge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Separating the Effects of Tropical Atlantic and Pacific SST-driven Climate Variability on Amazon Carbon Exchange

NASA Astrophysics Data System (ADS)

Liptak, J.; Keppel-Aleks, G.

2016-12-01

Amazon forests store an estimated 25% percent of global terrestrial carbon per year1, 2, but the responses of Amazon carbon uptake to climate change is highly uncertain. One source of this uncertainty is tropical sea surface temperature variability driven by teleconnections. El Nino-Southern Oscillation (ENSO) is a key driver of year-to-year Amazon carbon exchange, with associated temperature and precipitation changes favoring net carbon storage in La Nina years, and net carbon release during El Nino years3. To determine how Amazon climate and terrestrial carbon fluxes react to ENSO alone and in concert with other SST-driven teleconnections such as the Atlantic Multidecadal Oscillation (AMO), we force the atmosphere (CAM5) and land (CLM4) components of the CESM(BGC) with prescribed monthly SSTs over the period 1950—2014 in a Historical control simulation. We then run an experiment (PAC) with time-varying SSTs applied only to the tropical equatorial Pacific Ocean, and repeating SST seasonal cycle climatologies elsewhere. Limiting SST variability to the equatorial Pacific indicates that other processes enhance ENSO-driven Amazon climate anomalies. Compared to the Historical control simulation, warming, drying and terrestrial carbon loss over the Amazon during El Nino periods are lower in the PAC simulation, especially prior to 1990 during the cool phase of the AMO. Cooling, moistening, and net carbon uptake during La Nina periods are also reduced in the PAC simulation, but differences are greater after 1990 during the warm phase of the AMO. By quantifying the relationships among climate drivers and carbon fluxes in the Historical and PAC simulations, we both assess the sensitivity of these relationships to the magnitude of ENSO forcing and quantify how other teleconnections affect ENSO-driven Amazon climate feedbacks. We expect that these results will help us improve hypotheses for how Atlantic and Pacific climate trends will affect future Amazon carbon carbon cycling. Pan, Y. et al. A large and persistent carbon sink in the world's forests. Science 333, 988-993 (2011) Brienen, Roel J. W. et al. Long-term decline of the Amazon carbon sink. Nature 519, 344-348 (2015) Botta, A. et al. Long-term variations of climate and carbon fluxes over the Amazon basin. Geophys. Res. Lett. 29 (2002)

Multi-scale assessment of human-induced changes to Amazonian instream habitats

EPA Science Inventory

Context: Land use change and forest degradation have myriad effects on tropical ecosystems. Yet their consequences for low-order streams remain very poorly understood, including in the world´s largest freshwater basin, the Amazon.Objectives: Determine the degree to which ph...

Increased Frequency of Large Blowdown Formation in Years With Hotter Dry Seasons in the Northwestern Amazon

NASA Astrophysics Data System (ADS)

Rifai, S. W.; Anderson, L. O.; Bohlman, S.

2015-12-01

Blowdowns, which are large tree mortality events caused by downbursts, create large pulses of carbon emissions in the short term and alter successional dynamics and species composition of forests, thus affecting long term biogeochemical cycling of tropical forests. Changing climate, especially increasing temperatures and frequency of extreme climate events, may cause changes in the frequency of blowdowns, but there has been little spatiotemporal analysis to associate the interannual variation in the frequency of blowdowns with annual climate parameters. We mapped blowdowns greater than 25 ha using a time series of Landsat images from 1984-2012 in the northwestern Amazon to estimate the annual size distribution of these blowdowns. The difference in forest area affected by blowdowns between the years with the highest and lowest blowdown activity were on the order of 10 - 30 times greater depending on location. Spatially, we found the probability of large blowdowns to be higher in regions with higher annual rainfall. Temporally, we found a positive correlation between the probability of large blowdown events and maximum dry season air temperature (R2 = 0.1-0.46). Mean and maximum blowdown size also increased with maximum dry season air temperature. The strength of these relationships varied between scene locations which may be related to cloud cover obscuring the land surface in the satellite images, or biophysical characteristics of the sites. Potentially, elevated dry season temperatures during the transition from the dry season to the wet season (October - December) may exacerbate atmospheric instabilities, which promote downburst occurrences. Most global circulation models predict dry season air temperatures to increase 2-5 ℃ in the northwestern Amazon by 2050. Should the blowdown disturbance regime continue increasing with elevated dry season temperatures, the northwestern Amazon is likely to experience more catastrophic tree mortality events which has direct consequences for both the carbon emissions and carbon storage capacity of the northwestern Amazon.

Assessing the impact of Amazonia logging with a new ecosystem model

NASA Astrophysics Data System (ADS)

Huang, M.; Asner, G. P.; Keller, M.; Berry, J. A.; Bustamante, M. M.

2006-12-01

Old-growth Amazonian forests play a fundamental role in the global climate and carbon cycle. Land use in old- growth tropical forests contributes to the accumulation of CO2 in the atmosphere and can alter the hydrological cycle, locally, regionally, and globally. Although deforestation, largely for the conversion of land to food crops or pastures, is the major destructive force in tropical forests worldwide (Houghton et al., 2000), other forest disturbances such as the selective logging have also increased in frequency and extent. Selective logging causes widespread collateral damage to remaining trees, sub-canopy vegetation, and soils, with impacts on hydrological processes, erosion, fire, carbon storage, and plant and animal species. In this study, the impact of selective logging on the carbon budget of the Brazil Amazon region is assessed with a new 3-D version of the Carnegie-Ames-Stanford Approach (CASA) ecosystem model, which features: (1) an alternative way of estimating absorbed photosynthetically-active radiation (APAR) by taking advantage of new high-resolution maps of forest canopy gap fraction; (2) a pulse disturbance module to realistically modify the carbon pools after timber harvest; (3) a regrowth module considering changes in community composition; and (4) a radiative transfer module for charactering the dynamic 3-D light environment above the canopy and within gaps after logging. The model was calibrated and validated with field observations from the Large-scale Biosphere Atmosphere Experiment (LBA) and its sensitivity was evaluated with Monte Carlo simulations. The impacts of selected logging on regional carbon budget of the Brazilian Amazon were then assessed under different future climate change scenarios. Results from this study quantify the gross and net carbon storage effects of widespread logging practices throughout the Brazilian Amazon.

River logjams cause frequent large-scale forest die-off events in southwestern Amazonia

NASA Astrophysics Data System (ADS)

Lombardo, Umberto

2017-07-01

This paper investigates the dynamics of logjam-induced floods and alluvial deposition in the Bolivian Amazon and the effects these have on forest disturbance and recovery cycles. It expands on previous work by Gullison et al. (1996) who reported a case of catastrophic floods triggered by logjams in the Chimane Forest in the Bolivian Amazon. No further studies have followed up on this observation and no research has been published on the effects of large wood in tropical lowland rivers. The study is based on the analysis of a time series of Landsat imagery (1984-2016) and field evidence. Results show that logjam-induced floods are a major driver of forest disturbance along the Andean piedmont in the Bolivian Amazon. New logjams form on an almost yearly basis, always further upriver, until an avulsion takes place. Logjam-induced floods are characterized here by the sudden deposition of a thick sand layer and the death of forest in a V-shaped area. The Bolivian Amazon offers a unique opportunity for further research on how large wood affects river behavior in lowland tropical settings and how large and frequent forest disturbance events resulting from river logjams affect forest biodiversity and community successions.

Interpretation of Variations in Modis-Measured Greenness Levels of Amazon Forests During 2000 to 2009

NASA Technical Reports Server (NTRS)

Samanta, Arindam; Ganguly, Sangram; Vermote, Eric; Nemani, Ramakrishna R.; Myneni, Ranga B.

2012-01-01

This work investigates variations in satellite-measured greenness of Amazon forests using ten years of NASA Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI) data. Corruption of optical remote sensing data with clouds and aerosols is prevalent in this region; filtering corrupted data causes spatial sampling constraints, as well as reducing the record length, which introduces large biases in estimates of greenness anomalies. The EVI data, analyzed in multiple ways and taking into account EVI accuracy, consistently show a pattern of negligible changes in the greenness levels of forests both in the area affected by drought in 2005 and outside it. Small random patches of anomalous greening and browning-especially prominent in 2009-appear in all ten years, irrespective of contemporaneous variations in precipitation, but with no persistence over time. The fact that over 90% of the EVI anomalies are insignificantly small-within the envelope of error (95% confidence interval) in EVI-warrants cautious interpretation of these results: there were no changes in the greenness of these forests, or if there were changes, the EVI data failed to capture these either because the constituent reflectances were saturated or the moderate resolution precluded viewing small-scale variations. This suggests a need for more accurate and spatially resolved synoptic views from satellite data and corroborating comprehensive ground sampling to understand the greenness dynamics of these forests.

Vegetation dynamics and rainfall sensitivity of the Amazon.

PubMed

Hilker, Thomas; Lyapustin, Alexei I; Tucker, Compton J; Hall, Forrest G; Myneni, Ranga B; Wang, Yujie; Bi, Jian; Mendes de Moura, Yhasmin; Sellers, Piers J

2014-11-11

We show that the vegetation canopy of the Amazon rainforest is highly sensitive to changes in precipitation patterns and that reduction in rainfall since 2000 has diminished vegetation greenness across large parts of Amazonia. Large-scale directional declines in vegetation greenness may indicate decreases in carbon uptake and substantial changes in the energy balance of the Amazon. We use improved estimates of surface reflectance from satellite data to show a close link between reductions in annual precipitation, El Niño southern oscillation events, and photosynthetic activity across tropical and subtropical Amazonia. We report that, since the year 2000, precipitation has declined across 69% of the tropical evergreen forest (5.4 million km(2)) and across 80% of the subtropical grasslands (3.3 million km(2)). These reductions, which coincided with a decline in terrestrial water storage, account for about 55% of a satellite-observed widespread decline in the normalized difference vegetation index (NDVI). During El Niño events, NDVI was reduced about 16.6% across an area of up to 1.6 million km(2) compared with average conditions. Several global circulation models suggest that a rise in equatorial sea surface temperature and related displacement of the intertropical convergence zone could lead to considerable drying of tropical forests in the 21st century. Our results provide evidence that persistent drying could degrade Amazonian forest canopies, which would have cascading effects on global carbon and climate dynamics.

Vegetation Dynamics and Rainfall Sensitivity of the Amazon

NASA Technical Reports Server (NTRS)

Hilker, Thomas; Lyapustin, Alexei I.; Tucker, Compton J.; Hall, Forrest G.; Myneni, Ranga B.; Wang, Yujie; Bi, Jian; Mendes de Moura, Yhasmin; Sellers, Piers J.

2014-01-01

We show that the vegetation canopy of the Amazon rainforest is highly sensitive to changes in precipitation patterns and that reduction in rainfall since 2000 has diminished vegetation greenness across large parts of Amazonia. Large-scale directional declines in vegetation greenness may indicate decreases in carbon uptake and substantial changes in the energy balance of the Amazon. We use improved estimates of surface reflectance from satellite data to show a close link between reductions in annual precipitation, El Nino southern oscillation events, and photosynthetic activity across tropical and subtropical Amazonia. We report that, since the year 2000, precipitation has declined across 69% of the tropical evergreen forest (5.4 million sq km) and across 80% of the subtropical grasslands (3.3 million sq km). These reductions, which coincided with a decline in terrestrial water storage, account for about 55% of a satellite-observed widespread decline in the normalized difference vegetation index (NDVI). During El Nino events, NDVI was reduced about 16.6% across an area of up to 1.6 million sq km compared with average conditions. Several global circulation models suggest that a rise in equatorial sea surface temperature and related displacement of the intertropical convergence zone could lead to considerable drying of tropical forests in the 21st century. Our results provide evidence that persistent drying could degrade Amazonian forest canopies, which would have cascading effects on global carbon and climate dynamics.

Shifts in the Budyko curve over the past decade in the Amazon basin

NASA Astrophysics Data System (ADS)

Maeda, E. E.; Ma, X.; Liu, Y.; Huete, A. R.

2017-12-01

The Amazon basin has experienced extensive forest loss during the past decades. These changes can exert significant impact on regional water and energy budget, as well as other environmental processes. Here we evaluated how forest loss in the Madeira and Tapajós River basins, between 2002 and 2015, affected the Budyko relationship. The Budyko framework describes the links between climate and hydrological components, where evapotranspiration (ET) is limited by the supply of either water or energy. The framework is composed by two components, the dryness index (DI) and the evaporative index (EI). The DI determines the type and degree of limitation, with values lower than 1 represent energy-limited condition and values higher than 1, water-limited. The EI describes the partitioning of rainfall (P) into ET and runoff (R), with higher values indicating a larger proportion of ET. In this study, we use a modified version of the Budyko framework, which accounts for intra-annual changes in water storage (dS). Hence, the effective rainfall is represented by P-dS, so that EI=ET/(P-dS) and the DI= PET/(P-dS). We show that the Madeira and Tapajós River basins have lost approximately 60000 km2 and 50000km2 of forested area by 2015, respectively. Our results indicate that these changes caused a subtle shift in the Budyko curve in both basins. At the Madeira basin, a reduction in the DI indicate a shift towards lower water limitation, while decreasing EI indicate that a higher proportion of P is being converted into runoff. At the Tapajós basin, we also observe an overall decrease in the DI, but no significant trends in the evaporative index was observed. We expect that the observed shifts provide a new insight on the Amazon forest responses to changes in climate and land use. Further studies will focus in identifying the biophysical mechanisms driving these shifts, as well as seasonal aspects of the changes.

The nitrogen budget for different forest types in the central Congo Basin

NASA Astrophysics Data System (ADS)

Bauters, Marijn; Verbeeck, Hans; Cizungu, Landry; Boeckx, Pascal

2016-04-01

Characterization of fundamental processes in different forest types is vital to understand the interaction of forests with their changing environment. Recent data analyses, as well as modeling activities have shown that the CO2 uptake by terrestrial ecosystems strongly depends on site fertility, i.e. nutrient availability. Accurate projections of future net forest growth and terrestrial CO2 uptake thus necessitate an improved understanding on nutrient cycles and how these are coupled to the carbon (C) cycle in forests. This holds especially for tropical forests, since they represent about 40-50% of the total carbon that is stored in terrestrial vegetation, with the Amazon basin and the Congo basin being the largest two contiguous blocks. However, due to political instability and reduced accessibility in the central Africa region, there is a strong bias in scientific research towards the Amazon basin. Consequently, central African forests are poorly characterized and their role in global change interactions shows distinct knowledge gaps, which is important bottleneck for all efforts to further optimize Earth system models explicitly including this region. Research in the Congo Basin region should combine assessments of both carbon stocks and the underlying nutrient cycles which directly impact the forest productivity. We set up a monitoring network for carbon stocks and nitrogen fluxes in four different forest types in the Congo Basin, which is now operative. With the preliminary data, we can get a glimpse of the differences in nitrogen budget and biogeochemistry of African mixed lowland rainforest, monodominant lowland forest, mixed montane forest and eucalypt plantations.

Carbon Emissions from Deforestation in the Brazilian Amazon Region

NASA Technical Reports Server (NTRS)

Potter, C.; Klooster, S.; Genovese, V.

2009-01-01

A simulation model based on satellite observations of monthly vegetation greenness from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of Brazilian Amazon and Cerrado regions over the period 2000-2002. The NASA-CASA (Carnegie Ames Stanford Approach) model estimates of annual forest production were used for the first time as the basis to generate a prediction for the standing pool of carbon in above-ground biomass (AGB; gC/sq m) for forested areas of the Brazilian Amazon region. Plot-level measurements of the residence time of carbon in wood in Amazon forest from Malhi et al. (2006) were interpolated by inverse distance weighting algorithms and used with CASA to generate a new regional map of AGB. Data from the Brazilian PRODES (Estimativa do Desflorestamento da Amazonia) project were used to map deforested areas. Results show that net primary production (NPP) sinks for carbon varied between 4.25 Pg C/yr (1 Pg=10(exp 15)g) and 4.34 Pg C for the region and were highest across the eastern and northern Amazon areas, whereas deforestation sources of CO2 flux from decomposition of residual woody debris were higher and less seasonal in the central Amazon than in the eastern and southern areas. Increased woody debris from past deforestation events was predicted to alter the net ecosystem carbon balance of the Amazon region to generate annual CO2 source fluxes at least two times higher than previously predicted by CASA modeling studies. Variations in climate, land cover, and forest burning were predicted to release carbon at rates of 0.5 to 1 Pg C/yr from the Brazilian Amazon. When direct deforestation emissions of CO2 from forest burning of between 0.2 and 0.6 Pg C/yr in the Legal Amazon are overlooked in regional budgets, the year-to-year variations in this net biome flux may appear to be large, whereas our model results implies net biome fluxes had actually been relatively consistent from year to year during the period 2000-2002. This is the first study to use MODIS data to model all carbon pools (wood, leaf, root) dynamically in simulations of Amazon forest deforestation from clearing and burning of all kinds.

Land-Cover and Land-Use Change in the Brazilian Amazon: Smallholders, Ranchers and Frontier Stratification

NASA Technical Reports Server (NTRS)

Aldrich, Stephen P.; Walker, Robert T.; Arima, Eugenio Y.; Caldas, Marcellus M.; Browder, John O.; Perz, Stephen

2006-01-01

Tropical deforestation is a significant driver of global environmental change, given its impacts on the carbon cycle and biodiversity. Loss of the Amazon forest, the focus of this article, is of particular concern because of the size and the rapid rate at which the forest is being converted to agricultural use. In this article, we identify what has been the most important driver of deforestation in a specific colonization frontier in the Brazilian Amazon. To this end, we consider (1) the land-use dynamics of smallholder households, (2) the formation of pasture by large-scale ranchers, and (3) structural processes of land aggregation by ranchers. Much has been written about relations between smallholders and ranchers in the Brazilian Amazon, particularly those involving conflict over land, and this article explicates the implications of such social processes for land cover. Toward this end, we draw on panel data (1996-2002) and satellite imagery (1986-1999) to show the deforestation that is attributable to small- and largeholders, and the deforestation that is attributable to aggregations of property arising from a process that we refer to as frontier stratification. Evidently, most of the recent deforestation in the study area has resulted from the household processes of smallholders, not from conversions to pasture pursuant to the appropriations of smallholders' property by well-capitalized ranchers or speculators.

Thresholds of species loss in Amazonian deforestation frontier landscapes.

PubMed

Ochoa-Quintero, Jose Manuel; Gardner, Toby A; Rosa, Isabel; Ferraz, Silvio Frosini de Barros; Sutherland, William J

2015-04-01

In the Brazilian Amazon, private land accounts for the majority of remaining native vegetation. Understanding how land-use change affects the composition and distribution of biodiversity in farmlands is critical for improving conservation strategies in the face of rapid agricultural expansion. Working across an area exceeding 3 million ha in the southwestern state of Rondônia, we assessed how the extent and configuration of remnant forest in replicate 10,000-ha landscapes has affected the occurrence of a suite of Amazonian mammals and birds. In each of 31 landscapes, we used field sampling and semistructured interviews with landowners to determine the presence of 28 large and medium sized mammals and birds, as well as a further 7 understory birds. We then combined results of field surveys and interviews with a probabilistic model of deforestation. We found strong evidence for a threshold response of sampled biodiversity to landscape level forest cover; landscapes with <30-40% forest cover hosted markedly fewer species. Results from field surveys and interviews yielded similar thresholds. These results imply that in partially deforested landscapes many species are susceptible to extirpation following relatively small additional reductions in forest area. In the model of deforestation by 2030 the number of 10,000-ha landscapes under a conservative threshold of 43% forest cover almost doubled, such that only 22% of landscapes would likely to be able to sustain at least 75% of the 35 focal species we sampled. Brazilian law requires rural property owners in the Amazon to retain 80% forest cover, although this is rarely achieved. Prioritizing efforts to ensure that entire landscapes, rather than individual farms, retain at least 50% forest cover may help safeguard native biodiversity in private forest reserves in the Amazon. © 2015 Society for Conservation Biology.

Determining the dynamics of evapotranspiration from fragmented forests under drought in southwestern Amazonia using Landsat imagery

NASA Astrophysics Data System (ADS)

Numata, I.; Khand, K.; Kjaersgaard, J.; Cochrane, M. A.; Silva, S.

2016-12-01

Deforestation in the Amazon has resulted in massive amounts of forest biomass loss and also in extensive forest fragmentation across the region. Fragmented tropical forests are exposed to abrupt environmental changes and experience several biological and ecological changes across distances from forest edges. Extreme droughts in 2005 and 2010 have caused extensive tree mortality across this region. These events may exacerbate edge effects, where already water stressed forest fragments dry more rapidly potentially enabling other disturbances such as forest fire. We analyzed the effects of forest fragmentation and drought on forest evapotranspiration (ET) estimated using the energy balance-based model METRIC with Landsat imagery in Rondônia State in the southwestern Amazon. Forest ET estimates were produced for the dry seasons (June-August) of 2009-2011 thus including the 2010 drought event and pre- and post-event periods. METRIC ET data were combined with forest edge data with edge distances of 100m, 300m, 500m, 1000m, 5000m and >5000m (core forest), generated from Landsat land cover maps for spatiotemporal analysis of forest ET. METRIC ET estimates had an agreement with flux tower ET data from the field of R2 = 0.72. Within the study time period, the 2010 drought year showed the lowest average ET from core forest (2.5mm/day), followed by 2011 (3.0mm/day) and 2009 (3.6mm/day) in the month of August, the mid dry season, while no significant differences were noted among three study years earlier in the dry seasons. In terms of edge effects, the major changes in forest ET occur up to 300 m from the forest edges, with ET decreasees of 30 % at 100 m as compared to further distances. The magnitude of edge-related ET changes became even greater during August of the drought year (2010) and the post-drought year (2011). Annual (drought and non-drought) and seasonal (June-August) forest ET variations were highly significant (p<0.001), while the impact of distance from edge on forest ET was significant only in the drought year (p<0.05).

Modeling the Complex Impacts of Timber Harvests to Find Optimal Management Regimes for Amazon Tidal Floodplain Forests

PubMed Central

Fortini, Lucas B.; Cropper, Wendell P.; Zarin, Daniel J.

2015-01-01

At the Amazon estuary, the oldest logging frontier in the Amazon, no studies have comprehensively explored the potential long-term population and yield consequences of multiple timber harvests over time. Matrix population modeling is one way to simulate long-term impacts of tree harvests, but this approach has often ignored common impacts of tree harvests including incidental damage, changes in post-harvest demography, shifts in the distribution of merchantable trees, and shifts in stand composition. We designed a matrix-based forest management model that incorporates these harvest-related impacts so resulting simulations reflect forest stand dynamics under repeated timber harvests as well as the realities of local smallholder timber management systems. Using a wide range of values for management criteria (e.g., length of cutting cycle, minimum cut diameter), we projected the long-term population dynamics and yields of hundreds of timber management regimes in the Amazon estuary, where small-scale, unmechanized logging is an important economic activity. These results were then compared to find optimal stand-level and species-specific sustainable timber management (STM) regimes using a set of timber yield and population growth indicators. Prospects for STM in Amazonian tidal floodplain forests are better than for many other tropical forests. However, generally high stock recovery rates between harvests are due to the comparatively high projected mean annualized yields from fast-growing species that effectively counterbalance the projected yield declines from other species. For Amazonian tidal floodplain forests, national management guidelines provide neither the highest yields nor the highest sustained population growth for species under management. Our research shows that management guidelines specific to a region’s ecological settings can be further refined to consider differences in species demographic responses to repeated harvests. In principle, such fine-tuned management guidelines could make management more attractive, thus bridging the currently prevalent gap between tropical timber management practice and regulation. PMID:26322896

Modeling the complex impacts of timber harvests to find optimal management regimes for Amazon tidal floodplain forests

USGS Publications Warehouse

Fortini, Lucas B.; Cropper, Wendell P.; Zarin, Daniel J.

2015-01-01

At the Amazon estuary, the oldest logging frontier in the Amazon, no studies have comprehensively explored the potential long-term population and yield consequences of multiple timber harvests over time. Matrix population modeling is one way to simulate long-term impacts of tree harvests, but this approach has often ignored common impacts of tree harvests including incidental damage, changes in post-harvest demography, shifts in the distribution of merchantable trees, and shifts in stand composition. We designed a matrix-based forest management model that incorporates these harvest-related impacts so resulting simulations reflect forest stand dynamics under repeated timber harvests as well as the realities of local smallholder timber management systems. Using a wide range of values for management criteria (e.g., length of cutting cycle, minimum cut diameter), we projected the long-term population dynamics and yields of hundreds of timber management regimes in the Amazon estuary, where small-scale, unmechanized logging is an important economic activity. These results were then compared to find optimal stand-level and species-specific sustainable timber management (STM) regimes using a set of timber yield and population growth indicators. Prospects for STM in Amazonian tidal floodplain forests are better than for many other tropical forests. However, generally high stock recovery rates between harvests are due to the comparatively high projected mean annualized yields from fast-growing species that effectively counterbalance the projected yield declines from other species. For Amazonian tidal floodplain forests, national management guidelines provide neither the highest yields nor the highest sustained population growth for species under management. Our research shows that management guidelines specific to a region’s ecological settings can be further refined to consider differences in species demographic responses to repeated harvests. In principle, such fine-tuned management guidelines could make management more attractive, thus bridging the currently prevalent gap between tropical timber management practice and regulation.

Human impacts on soil carbon dynamics of deep-rooted Amazonian forests and effect of land use change on the carbon cycle in Amazon soils

NASA Technical Reports Server (NTRS)

Nepstad, Daniel; Stone, Thomas; Davidson, Eric; Trumbore, Susan E.

1992-01-01

The main objective of these NASA-funded projects is to improve our understanding of land-use impacts on soil carbon dynamics in the Amazon Basin. Soil contains approximately one half of tropical forest carbon stocks, yet the fate of this carbon following forest impoverishment is poorly studied. Our mechanistics approach draws on numerous techniques for measuring soil carbon outputs, inputs, and turnover time in the soils of adjacent forest and pasture ecosystems at our research site in Paragominas, state of Para, Brazil. We are scaling up from this site-specific work by analyzing Basin-wide patterns in rooting depth and rainfall seasonality, the two factors that we believe should explain much of the variation in tropical soil carbons dynamics. In this report, we summarize ongoing measurements at our Paragominas study site, progress in employing new field data to understand soil C dynamics, and some surprising results from our regional, scale-up work.

Ancient human disturbances may be skewing our understanding of Amazonian forests.

PubMed

McMichael, Crystal N H; Matthews-Bird, Frazer; Farfan-Rios, William; Feeley, Kenneth J

2017-01-17

Although the Amazon rainforest houses much of Earth's biodiversity and plays a major role in the global carbon budget, estimates of tree biodiversity originate from fewer than 1,000 forest inventory plots, and estimates of carbon dynamics are derived from fewer than 200 recensus plots. It is well documented that the pre-European inhabitants of Amazonia actively transformed and modified the forest in many regions before their population collapse around 1491 AD; however, the impacts of these ancient disturbances remain entirely unaccounted for in the many highly influential studies using Amazonian forest plots. Here we examine whether Amazonian forest inventory plot locations are spatially biased toward areas with high probability of ancient human impacts. Our analyses reveal that forest inventory plots, and especially forest recensus plots, in all regions of Amazonia are located disproportionately near archaeological evidence and in areas likely to have ancient human impacts. Furthermore, regions of the Amazon that are relatively oversampled with inventory plots also contain the highest values of predicted ancient human impacts. Given the long lifespan of Amazonian trees, many forest inventory and recensus sites may still be recovering from past disturbances, potentially skewing our interpretations of forest dynamics and our understanding of how these forests are responding to global change. Empirical data on the human history of forest inventory sites are crucial for determining how past disturbances affect modern patterns of forest composition and carbon flux in Amazonian forests.

Loss of nutrients from terrestrial ecosystems to streams and the atmosphere following land use change in Amazonia

NASA Astrophysics Data System (ADS)

Davidson, Eric A.; Neill, Christopher; Krusche, Alex V.; Ballester, Victoria V. R.; Markewitz, Daniel; Figueiredo, Ricardo de O.

Rates of deforestation in the Amazon region have been accelerating, but the quantity and timing of nutrient losses from forested and deforested ecosystems are poorly understood. This paper investigates the broad variation in soil properties of the Amazon Basin as they influence transfers of plant nutrients from the terrestrial biosphere to the atmosphere and the aquatic biosphere. The dominant lowland soils are highly weathered Oxisols and Ultisols, but significant areas of Alfisols also exist, resulting in a wide range of weatherable primary minerals. Despite this considerable variation among Amazonian soils, a common feature in most mature lowland Amazonian forests is a conservative P cycle and excess N availability. In cattle pastures and secondary forests, however, low rates of internal terrestrial N cycling, low N export to streams, and low gaseous N emissions from soils are common, due to significant previous losses of N through repeated fire. Export of P to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Oxisols exhibit very low P export, whereas increased P export to pasture streams has been observed in Ultisols of western Amazonia. Calcium is mostly retained in terrestrial ecosystems following deforestation, although increased inputs to streams can be detected when background fluxes are naturally low. Because soil mineralogy and soil texture are both variable and important, the effects of land-use change on nutrient export to aquatic ecosystems and to the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.

Do dynamic global vegetation models capture the seasonality of carbon fluxes in the Amazon basin? A data-model intercomparison

DOE PAGES

Restrepo-Coupe, Natalia; Levine, Naomi M.; Christoffersen, Bradley O.; ...

2016-08-29

To predict forest response to long-term climate change with high confidence requires that dynamic global vegetation models (DGVMs) be successfully tested against ecosystem response to short-term variations in environmental drivers, including regular seasonal patterns. Here, we used an integrated dataset from four forests in the Brasil flux network, spanning a range of dry-season intensities and lengths, to determine how well four state-of-the-art models (IBIS, ED2, JULES, and CLM3.5) simulated the seasonality of carbon exchanges in Amazonian tropical forests. We found that most DGVMs poorly represented the annual cycle of gross primary productivity (GPP), of photosynthetic capacity (Pc), and of othermore » fluxes and pools. Models simulated consistent dry-season declines in GPP in the equatorial Amazon (Manaus K34, Santarem K67, and Caxiuanã CAX); a contrast to observed GPP increases. Model simulated dry-season GPP reductions were driven by an external environmental factor, ‘soil water stress’ and consequently by a constant or decreasing photosynthetic infrastructure (Pc), while observed dry-season GPP resulted from a combination of internal biological (leaf-flush and abscission and increased Pc) and environmental (incoming radiation) causes. Moreover, we found models generally overestimated observed seasonal net ecosystem exchange (NEE) and respiration (Re) at equatorial locations. In contrast, a southern Amazon forest (Jarú RJA) exhibited dry-season declines in GPP and Re consistent with most DGVMs simulations. While water limitation was represented in models and the primary driver of seasonal photosynthesis in southern Amazonia, changes in internal biophysical processes, light-harvesting adaptations (e.g., variations in leaf area index (LAI) and increasing leaf-level assimilation rate related to leaf demography), and allocation lags between leaf and wood, dominated equatorial Amazon carbon flux dynamics and were deficient or absent from current model formulations. In conclusion, correctly simulating flux seasonality at tropical forests requires a greater understanding and the incorporation of internal biophysical mechanisms in future model developments.« less

Do dynamic global vegetation models capture the seasonality of carbon fluxes in the Amazon basin? A data-model intercomparison

DOE Office of Scientific and Technical Information (OSTI.GOV)

Restrepo-Coupe, Natalia; Levine, Naomi M.; Christoffersen, Bradley O.

To predict forest response to long-term climate change with high confidence requires that dynamic global vegetation models (DGVMs) be successfully tested against ecosystem response to short-term variations in environmental drivers, including regular seasonal patterns. Here, we used an integrated dataset from four forests in the Brasil flux network, spanning a range of dry-season intensities and lengths, to determine how well four state-of-the-art models (IBIS, ED2, JULES, and CLM3.5) simulated the seasonality of carbon exchanges in Amazonian tropical forests. We found that most DGVMs poorly represented the annual cycle of gross primary productivity (GPP), of photosynthetic capacity (Pc), and of othermore » fluxes and pools. Models simulated consistent dry-season declines in GPP in the equatorial Amazon (Manaus K34, Santarem K67, and Caxiuanã CAX); a contrast to observed GPP increases. Model simulated dry-season GPP reductions were driven by an external environmental factor, ‘soil water stress’ and consequently by a constant or decreasing photosynthetic infrastructure (Pc), while observed dry-season GPP resulted from a combination of internal biological (leaf-flush and abscission and increased Pc) and environmental (incoming radiation) causes. Moreover, we found models generally overestimated observed seasonal net ecosystem exchange (NEE) and respiration (Re) at equatorial locations. In contrast, a southern Amazon forest (Jarú RJA) exhibited dry-season declines in GPP and Re consistent with most DGVMs simulations. While water limitation was represented in models and the primary driver of seasonal photosynthesis in southern Amazonia, changes in internal biophysical processes, light-harvesting adaptations (e.g., variations in leaf area index (LAI) and increasing leaf-level assimilation rate related to leaf demography), and allocation lags between leaf and wood, dominated equatorial Amazon carbon flux dynamics and were deficient or absent from current model formulations. In conclusion, correctly simulating flux seasonality at tropical forests requires a greater understanding and the incorporation of internal biophysical mechanisms in future model developments.« less

Amazon soil charcoal: Pyrogenic carbon stock depends of ignition source distance and forest type in Roraima, Brazil.

PubMed

da Silva Carvalho, Lidiany C; Fearnside, Philip M; Nascimento, Marcelo T; Barbosa, Reinaldo I

2018-04-18

Pyrogenic carbon (PyC) derived from charcoal particles (paleo + modern) deposited in the soil column has been little studied in the Amazon, and our understanding of the factors that control the spatial and vertical distribution of these materials in the region's forest soils is still unclear. The objective of this study was to test the effect of forest type and distance from the ignition source on the PyC stocks contained in macroscopic particles of soil charcoal (≥2 mm; 1 m depth) dispersed in ecotone forests of the northern Brazilian Amazon. Thirty permanent plots were set up near a site that had been occupied by pre-Columbian and by modern populations until the late 1970s. The sampled plots represent seasonal and ombrophilous forests that occur under different hydro-edaphic restrictions. Our results indicate that the largest PyC stock was spatially dependent on distance to the ignition source (<3 km), occurring mainly in flood-free ombrophilous forests (3.46 ± 5.22 Mg PyC/ha). The vertical distribution of PyC in the deeper layers of the soil (> 50 cm) in seasonal forests was limited by hydro-edaphic impediments that restricted the occurrence of charcoal. These results suggest that PyC stocks derived from macroscopic charcoal particles in the soil of this Brazilian Amazon ecotone region are controlled by the distance from the ignition source of the fire, and that forest types with higher hydro-edaphic restrictions can inhibit formation and accumulation of charcoal. Making use of these distinctions reduces uncertainty and improves our ability to understand the variability of PyC stocks in forests with a history of fire in the Amazon. © 2018 John Wiley & Sons Ltd.

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

NASA Astrophysics Data System (ADS)

Sanders, Luciana M.; Taffs, Kathryn; Stokes, Debra; Sanders, Christian J.; Enrich-Prast, Alex; Amora-Nogueira, Leonardo; Marotta, Humberto

2018-01-01

Forests along the Amazon Basin produce significant quantities of organic material, a portion of which is deposited in floodplain lakes. Deforestation in the watershed may then have potentially important effects on the carbon fluxes. In this study, a sediment core was extracted from an Amazon floodplain lake to examine the relationship between carbon burial and changing land cover and land use. Historical records from the 1930s and satellite data from the 1970s were used to calculate deforestation rates between 1930 to 1970 and 1970 to 2010 in four zones with different distances from the margins of the lake and its tributaries (100, 500, 1000 and 6000 m buffers). A sediment accumulation rate of ˜ 4 mm yr-1 for the previous ˜ 120 years was determined from the 240+239Pu signatures and the excess 210Pb method. The carbon burial rates ranged between 85 and 298 g C m-2 yr-1, with pulses of high carbon burial in the 1950s, originating from the forest vegetation as indicated by δ13C and δ15N signatures. Our results revealed a potentially important spatial dependence of the organic carbon (OC) burial in Amazon lacustrine sediments in relation to deforestation rates in the catchment. These deforestation rates were more intense in the riparian vegetation (100 m buffer) during the period 1930 to 1970 and the larger open water areas (500, 1000 and 6000 m buffer) during 1970 to 2010. The continued removal of vegetation from the interior of the forest was not related to the peak of OC burial in the lake, but only the riparian deforestation which peaked during the 1950s. Therefore, this supports the conservation priority of riparian forests as an important management practice for Amazon flooded areas. Our findings suggest the importance of abrupt and temporary events in which some of the biomass released by deforestation, especially restricted to areas along open water edges, might reach the depositional environments in the floodplain of the Amazon Basin.

Conversion of Amazon rainforest to agriculture alters community traits of methane-cycling organisms.

PubMed

Meyer, Kyle M; Klein, Ann M; Rodrigues, Jorge L M; Nüsslein, Klaus; Tringe, Susannah G; Mirza, Babur S; Tiedje, James M; Bohannan, Brendan J M

2017-03-01

Land use change is one of the greatest environmental impacts worldwide, especially to tropical forests. The Amazon rainforest has been subject to particularly high rates of land use change, primarily to cattle pasture. A commonly observed response to cattle pasture establishment in the Amazon is the conversion of soil from a methane sink in rainforest, to a methane source in pasture. However, it is not known how the microorganisms that mediate methane flux are altered by land use change. Here, we use the deepest metagenomic sequencing of Amazonian soil to date to investigate differences in methane-cycling microorganisms and their traits across rainforest and cattle pasture soils. We found that methane-cycling microorganisms responded to land use change, with the strongest responses exhibited by methane-consuming, rather than methane-producing, microorganisms. These responses included a reduction in the relative abundance of methanotrophs and a significant decrease in the abundance of genes encoding particulate methane monooxygenase. We also observed compositional changes to methanotroph and methanogen communities as well as changes to methanotroph life history strategies. Our observations suggest that methane-cycling microorganisms are vulnerable to land use change, and this vulnerability may underlie the response of methane flux to land use change in Amazon soils. © 2017 John Wiley & Sons Ltd.

Mapping Canopy Damage from Understory Fires in Amazon Forests Using Annual Time Series of Landsat and MODIS Data

NASA Technical Reports Server (NTRS)

Morton, Douglas C.; DeFries, Ruth S.; Nagol, Jyoteshwar; Souza, Carlos M., Jr.; Kasischke, Eric S.; Hurtt, George C.; Dubayah, Ralph

2011-01-01

Understory fires in Amazon forests alter forest structure, species composition, and the likelihood of future disturbance. The annual extent of fire-damaged forest in Amazonia remains uncertain due to difficulties in separating burning from other types of forest damage in satellite data. We developed a new approach, the Burn Damage and Recovery (BDR) algorithm, to identify fire-related canopy damages using spatial and spectral information from multi-year time series of satellite data. The BDR approach identifies understory fires in intact and logged Amazon forests based on the reduction and recovery of live canopy cover in the years following fire damages and the size and shape of individual understory burn scars. The BDR algorithm was applied to time series of Landsat (1997-2004) and MODIS (2000-2005) data covering one Landsat scene (path/row 226/068) in southern Amazonia and the results were compared to field observations, image-derived burn scars, and independent data on selective logging and deforestation. Landsat resolution was essential for detection of burn scars less than 50 ha, yet these small burns contributed only 12% of all burned forest detected during 1997-2002. MODIS data were suitable for mapping medium (50-500 ha) and large (greater than 500 ha) burn scars that accounted for the majority of all fire-damaged forest in this study. Therefore, moderate resolution satellite data may be suitable to provide estimates of the extent of fire-damaged Amazon forest at a regional scale. In the study region, Landsat-based understory fire damages in 1999 (1508 square kilometers) were an order of magnitude higher than during the 1997-1998 El Nino event (124 square kilometers and 39 square kilometers, respectively), suggesting a different link between climate and understory fires than previously reported for other Amazon regions. The results in this study illustrate the potential to address critical questions concerning climate and fire risk in Amazon forests by applying the BDR algorithm over larger areas and longer image time series.

Windthrows increase soil carbon stocks in a central Amazon forest

NASA Astrophysics Data System (ADS)

dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan; de Camargo, Plínio B.; Negrón-Juárez, Robinson I.; Lima, Adriano J. N.; Ribeiro, Gabriel H. P. M.; dos Santos, Joaquim; Higuchi, Niro

2016-03-01

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha-1, mean ±95 % confidence interval) was marginally higher (p = 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity (r2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.

Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought

Treesearch

Steve Frolking; Stephen Hagen; Bobby Braswell; Tom Milliman; Christina Herrick; Seth Peterson; Dar Roberts; Michael Keller; Michael Palace; Krishna Prasad Vadrevu

2017-01-01

Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon’s vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave...

Biogeochemistry of the Amazon River Basin: the role of aquatic ecosystems in the Amazon functioning

NASA Astrophysics Data System (ADS)

Victoria, R. L.; Ballester, V. R.; Krushe, A. V.; Richey, J. E.; Aufdenkampe, A. K.; Kavaguishi, N. L.; Gomes, B. M.; Victoria, D. D.; Montebello, A. A.; Niell, C.; Deegan, L.

2004-12-01

In this study we present the results of an integrated analysis of physical and anthropogenic controls of river biogeochemistry in Amazônia. At the meso-scale level, our results show that both soil properties and land use are the main drivers of river biogeochemistry and metabolism, with pasture cover and soil exchange cation capacity explaining 99% (p < 0.01) of the variability observed in surface water ions and nutrients concentrations. In small rivers, forest clearing can increase cations, P and C inputs. P and light are the main PPL limiting factors in forested streams, while in pasture streams N becomes limiting. P export to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Pasture streams on Oxisols have very low P export, while on Ultisols P export is increased. Conversions of forest to pasture leads to extensive growth of in channel Paspalum resulting in higher DOC concentrations and respiration rates. Pasture streams have higher DOC fluxes when compared to the forest ones. In pasture areas the soil are compacted, there is less infiltration and higher surface run off, leaching soil superficial layers and caring more DOC to the streams. In forest areas infiltration is deeper into the soils and canopy interaction is higher. Mineralogy and soil properties are key factors determining exports of nutrients to streams. Therefore, land use change effects on nutrient export from terrestrial to aquatic ecosystems and the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.

Lessons from forest FACE experiments provide guidance for Amazon-FACE science plan (Invited)

NASA Astrophysics Data System (ADS)

Norby, R. J.; Lapola, D. M.

2013-12-01

Free-air CO2 enrichment (FACE) experiments have provided novel insights into the ecological mechanisms controlling the cycling and storage of carbon in terrestrial ecosystems, and they provide a strong foundation for next-generation experiments in unexplored biomes. Specific lessons from FACE experiments include: (1) Carbon cycle responses are time-dependent because component processes have different rate constants: for example, net primary productivity is increased by elevated CO2, but the response may diminish with time as N cycling feedbacks become important. (2) Carbon partitioning patterns determine the fate of the extra C taken up by CO2-enriched plants, but partitioning responses remain an important challenge for ecosystem models. (3) The influence of N cycling on plant and ecosystem C cycling continues to be a critical uncertainty, and new experiments, especially in the tropics, must also consider P cycling. (4) Plant community structure can influence the ecosystem response to elevated CO2, but dynamic vegetation effects have not been adequately addressed. These experiences from FACE experiments in temperate forests are now guiding the development of a science plan for a FACE experiment in Amazonia. Models and small-scale experimental results agree that elevated CO2 will affect the metabolism of tropical ecosystems, but the qualitative and quantitative expression of the effects are largely unknown, representing a major source of uncertainty that limits our capacity to assess the vulnerability of the Amazon forest to climate change. Recognizing the high importance of the forests of the Amazon basin on global carbon, water, and energy cycles, biodiversity conservation, and the provision of essential services in Latin America, a consortium of Brazilian researchers and international collaborators have developed a science plan for Amazon-FACE. While the challenges presented both by infrastructure needs (roads, electricity, and provision of CO2) and biology (the size and diversity of the forest) are substantial, preliminary evaluation and past experience from temperate forest FACE experiments have supported the feasibility of an experiment comprising replicated 30-m diameter FACE plots in primary forest. The proposed site is the ZF2 research area 60 km north of Manaus and administered by Brazil's National Institute for Amazonia Research (INPA). The vegetation is representative of a dominant fraction of the forests occurring in the Amazon basin: old-growth closed-canopy terra firme (non-flooded) forest with trees 30-35 m in height on well drained clay soils. The major science questions guiding the experiment are closely informed by results of past FACE experiment and involve carbon metabolism, water use, nutrient cycling, interactions with environmental stressors, and the relationship between plant functional traits and community composition. FACE experiments can define ecological processes and mechanisms of responses for predictive models of ecosystem response, and models of CO2 response can define critical uncertainties and testable hypotheses for experiments; hence, the Amazon FACE experiment will feature a close integration of modeling and experimental approaches.

Optimal use of land surface temperature data to detect changes in tropical forest cover

NASA Astrophysics Data System (ADS)

Van Leeuwen, T. T.; Frank, A. J.; Jin, Y.; Smyth, P.; Goulden, M.; van der Werf, G.; Randerson, J. T.

2011-12-01

Rapid and accurate assessment of global forest cover change is needed to focus conservation efforts and to better understand how deforestation is contributing to the build up of atmospheric CO2. Here we examined different ways to use remotely sensed land surface temperature (LST) to detect changes in tropical forest cover. In our analysis we used monthly 0.05×0.05 degree Terra MODerate Resolution Imaging Spectroradiometer (MODIS) observations of LST and PRODES (Program for the Estimation of Deforestation in the Brazilian Amazon) estimates of forest cover change. We also compared MODIS LST observations with an independent estimate of forest cover loss derived from MODIS and Landsat observations. Our study domain of approximately 10×10 degree included most of the Brazilian state of Mato Grosso. For optimal use of LST data to detect changes in tropical forest cover in our study area, we found that using data sampled during the end of the dry season (~1-2 months after minimum monthly precipitation) had the greatest predictive skill. During this part of the year, precipitation was low, surface humidity was at a minimum, and the difference between day and night LST was the largest. We used this information to develop a simple temporal sampling algorithm appropriate for use in pan-tropical deforestation classifiers. Combined with the normalized difference vegetation index (NDVI), a logistic regression model using day-night LST did moderately well at predicting forest cover change. Annual changes in day-night LST difference decreased during 2006-2009 relative to 2001-2005 in many regions within the Amazon, providing independent confirmation of lower deforestation levels during the latter part of this decade as reported by PRODES. The use of day-night LST differences may be particularly valuable for use with satellites that do not have spectral bands that allow for the estimation of NDVI or other vegetation indices.

Conversion from forests to pastures in the Colombian Amazon leads to differences in dead wood dynamics depending on land management practices.

PubMed

Navarrete, Diego; Sitch, Stephen; Aragão, Luiz E O C; Pedroni, Lucio; Duque, Alvaro

2016-04-15

Dead wood, composed of coarse standing and fallen woody debris (CWD), is an important carbon (C) pool in tropical forests and its accounting is needed to reduce uncertainties within the strategies to mitigate climate change by reducing deforestation and forest degradation (REDD+). To date, information on CWD stocks in tropical forests is scarce and effects of land-cover conversion and land management practices on CWD dynamics remain largely unexplored. Here we present estimates on CWD stocks in primary forests in the Colombian Amazon and their dynamics along 20 years of forest-to-pasture conversion in two sub-regions with different management practices during pasture establishment: high-grazing intensity (HG) and low-grazing intensity (LG) sub-regions. Two 20-year-old chronosequences describing the forest-to-pasture conversion were identified in both sub-regions. The line-intersect and the plot-based methods were used to estimate fallen and standing CWD stocks, respectively. Total necromass in primary forests was similar between both sub-regions (35.6 ± 5.8 Mg ha(-1) in HG and 37.0 ± 7.4 Mg ha(-1) in LG). An increase of ∼124% in CWD stocks followed by a reduction to values close to those at the intact forests were registered after slash-and-burn practice was implemented in both sub-regions during the first two years of forest-to-pasture conversion. Implementation of machinery after using fire in HG pastures led to a reduction of 82% in CWD stocks during the second and fifth years of pasture establishment, compared to a decrease of 41% during the same period in LG where mechanization is not implemented. Finally, average necromass 20 years after forest-to-pasture conversion decreased to 3.5 ± 1.4 Mg ha(-1) in HG and 9.3 ± 3.5 Mg ha(-1) in LG, representing a total reduction of between 90% and 75% in each sub-region, respectively. These results highlight the importance of low-grazing intensity management practices during ranching activities in the Colombian Amazon to reduce C emissions associated with land-cover change from forest to pasture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Asynchronous Amazon forest canopy phenology indicates adaptation to both water and light availability

NASA Astrophysics Data System (ADS)

Jones, Matthew O.; Kimball, John S.; Nemani, Ramakrishna R.

2014-12-01

Amazon forests represent nearly half of all tropical vegetation biomass and, through photosynthesis and respiration, annually process more than twice the amount of estimated carbon (CO2) from fossil fuel emissions. Yet the seasonality of Amazon canopy cover, and the extent to which seasonal fluctuations in water availability and photosynthetically available radiation influence these processes, is still poorly understood. Implementing six remotely sensed data sets spanning nine years (2003-2011), with reported field and flux tower data, we show that southern equatorial Amazon forests exhibit a distinctive seasonal signal. Seasonal timing of water availability, canopy biomass growth and net leaf flush are asynchronous in regions with short dry seasons and become more synchronous across a west-to-east longitudinal moisture gradient of increasing dry season. Forest cover is responsive to seasonal disparities in both water and solar radiation availability, temporally adjusting net leaf flush to maximize use of these generally abundant resources, while reducing drought susceptibility. An accurate characterization of this asynchronous behavior allows for improved understanding of canopy phenology across contiguous tropical forests and their sensitivity to climate variability and drought.

Basin-Wide Amazon Forest Tree Mortality From a Large 2005 Storm

NASA Astrophysics Data System (ADS)

Negron Juarez, R. I.; Chambers, J. Q.; Guimaraes, G.; Zeng, H.; Raupp, C.; Marra, D. M.; Ribeiro, G.; Saatchi, S. S.; Higuchi, N.

2010-12-01

Blowdowns are a recurrent characteristic of Amazon forests and are produced, among others, by squall lines. Squall lines are aligned clusters (typical length of 1000 km, width of 200 km) of deep convective cells that produce heavy rainfall during the dry season and significant rainfall during the wet season. These squall lines (accompanied by intense downbursts from convective cells) have been associated with large blowdowns characterized by uprooted, snapped trees, and trees being dragged down by other falling trees. Most squall lines in Amazonia form along the northeastern coast of South America as sea breeze-induced instability lines and propagate inside the continent. They occur frequently (~4 times per month), and can reach the central and even extreme western parts of Amazonia. Squall lines can also be generated inside the Amazon and propagate toward the equator. In January 2005 a squall line propagated from south to north across the entire Amazon basin producing widespread forest tree mortality and contributed to the elevated mortality observed that year. Over the Manaus region (3.4 x104 km2), disturbed forest patches generated by the squall produced a mortality of 0.3-0.5 million trees, equivalent to 30% of the observed annual deforestation reported in 2005 over the same area. The elevated mortality observed in the Central Amazon in 2005 is unlikely to be related to the 2005 Amazon drought since drought did not affect Central or Eastern Amazonia. Assuming a similar rate of forest mortality across the basin, the squall line could have potentially produced tree mortality estimated at 542 ± 121 million trees, equivalent to 23% of the mean annual biomass accumulation estimated for these forests. Our results highlight the vulnerability of Amazon trees to wind-driven mortality associated with convective storms. This vulnerability is likely to increase in a warming climate with models projecting an increase in storm intensity.

Effect of land use change on the carbon cycle in Amazon soils

NASA Technical Reports Server (NTRS)

Trumbore, Susan E.; Davidson, Eric A.

1994-01-01

The overall goal of this study was to provide a quantitative understanding of the cycling of carbon in the soils associated with deep-rooting Amazon forests. In particular, we wished to apply the understanding gained by answering two questions: (1) what changes will accompany the major land use change in this region, the conversion of forest to pasture? and (2) what is the role of carbon stored deeper than one meter in depth in these soils? To construct carbon budgets for pasture and forest soils we combined the following: measurements of carbon stocks in above-ground vegetation, root biomass, detritus, and soil organic matter; rates of carbon inputs to soil and detrital layers using litterfall collection and sequential coring to estimate fine root turnover; C-14 analyses of fractionated SOM and soil CO2 to estimate residence times; C-13 analyses to estimate C inputs to pasture soils from C-4 grasses; soil pCO2, volumetric water content, and radon gradients to estimate CO2 production as a function of soil depth; soil respiration to estimate total C outputs; and a model of soil C dynamics that defines SOM fractions cycling on annual, decadal, and millennial time scales.

Chemical analysis of rainfall and throughfall in primary forest in the Tapajós National Forest, Belterra, Pará, Brazil

Treesearch

R.C. Oliveira Junior; M. Keller; J. F. da F. Ramos; T.P. Beldini; P.M Crill; P.B. de Camargo; J. van Haren

2015-01-01

The Tapajós National Forest (FLONA Tapajós) has 600,000 hectares of protected forest, and is situated 50 km south of the city of Santarém, Pará, Brazil, a port city of 250,000 inhabitants that is located at the confluence of the Tapajós and Amazon Rivers. There is a lot of farmland in the region, which offers many opportunities to study changes in land use. Selective...

Dispersal limitation induces long-term biomass collapse in overhunted Amazonian forests.

PubMed

Peres, Carlos A; Emilio, Thaise; Schietti, Juliana; Desmoulière, Sylvain J M; Levi, Taal

2016-01-26

Tropical forests are the global cornerstone of biological diversity, and store 55% of the forest carbon stock globally, yet sustained provisioning of these forest ecosystem services may be threatened by hunting-induced extinctions of plant-animal mutualisms that maintain long-term forest dynamics. Large-bodied Atelinae primates and tapirs in particular offer nonredundant seed-dispersal services for many large-seeded Neotropical tree species, which on average have higher wood density than smaller-seeded and wind-dispersed trees. We used field data and models to project the spatial impact of hunting on large primates by ∼ 1 million rural households throughout the Brazilian Amazon. We then used a unique baseline dataset on 2,345 1-ha tree plots arrayed across the Brazilian Amazon to model changes in aboveground forest biomass under different scenarios of hunting-induced large-bodied frugivore extirpation. We project that defaunation of the most harvest-sensitive species will lead to losses in aboveground biomass of between 2.5-5.8% on average, with some losses as high as 26.5-37.8%. These findings highlight an urgent need to manage the sustainability of game hunting in both protected and unprotected tropical forests, and place full biodiversity integrity, including populations of large frugivorous vertebrates, firmly in the agenda of reducing emissions from deforestation and forest degradation (REDD+) programs.

Isotopic values of the Amazon headwaters in Peru: comparison of the wet upper Río Madre de Dios watershed with the dry Urubamba-Apurimac river system.

PubMed

Lambs, L; Horwath, A; Otto, T; Julien, F; Antoine, P-O

2012-04-15

The Amazon River is a huge network of long tributaries, and little is known about the headwaters. Here we present a study of one wet tropical Amazon forest side, and one dry and cold Atiplano plateau, originating from the same cordillera. The aim is to see how this difference affects the water characteristics. Different kind of water (spring, lake, river, rainfall) were sampled to determine their stable isotopes ratios (oxygen 18/16 and hydrogen 2/1) by continuous flow isotope ratio mass spectrometry (IRMS). These ratios coupled with chemical analysis enabled us to determine the origin of the water, the evaporation process and the water recycling over the Amazon plain forest and montane cloud forest. Our study shows that the water flowing in the upper Madre de Dios basin comes mainly from the foothill humid forest, with a characteristic water recycling process signature, and not from higher glacier melt. On the contrary, the water flowing in the Altiplano Rivers is mainly from glacier melts, with a high evaporation process. This snow and glacier are fed mainly by Atlantic moisture which transits over the large Amazon forest. The Atlantic moisture and its recycling over this huge tropical forest display a progressive isotopic gradient, as a function of distance from the ocean. At the level of the montane cloud forest and on the altiplano, respectively, additional water recycling and evaporation occur, but they are insignificant in the total water discharge. Copyright © 2012 John Wiley & Sons, Ltd.

CIMEX: a prototype Instrument to observe from space the amazon forest In the near and shortwave infrared

NASA Astrophysics Data System (ADS)

Guerin, François; Dantes, Didier; Savaria, Eric; Selingardi, Mario Luis; Montes, Amauri Silva

2018-04-01

This paper, "CIMEX: a prototype Instrument to observe from space the amazon forest In the near and shortwave infrared," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

Brazil-U.S. Relations

DTIC Science & Technology

2009-06-03

the Amazon falls within Brazilian borders, making Brazil home to 40% of the world’s remaining tropical forests.96 The Brazilian Amazon was largely...20 Amazon Conservation......................................................................................................... 20 Domestic Efforts...independence in 1822, Brazil occupies almost half of the continent of South America and boasts immense biodiversity, including the vast Amazon

The fate of Amazonian ecosystems over the coming century arising from changes in climate, atmospheric CO2, and land use.

PubMed

Zhang, Ke; de Almeida Castanho, Andrea D; Galbraith, David R; Moghim, Sanaz; Levine, Naomi M; Bras, Rafael L; Coe, Michael T; Costa, Marcos H; Malhi, Yadvinder; Longo, Marcos; Knox, Ryan G; McKnight, Shawna; Wang, Jingfeng; Moorcroft, Paul R

2015-02-20

There is considerable interest in understanding the fate of the Amazon over the coming century in the face of climate change, rising atmospheric CO 2 levels, ongoing land transformation, and changing fire regimes within the region. In this analysis, we explore the fate of Amazonian ecosystems under the combined impact of these four environmental forcings using three terrestrial biosphere models (ED2, IBIS, and JULES) forced by three bias-corrected IPCC AR4 climate projections (PCM1, CCSM3, and HadCM3) under two land-use change scenarios. We assess the relative roles of climate change, CO 2 fertilization, land-use change, and fire in driving the projected changes in Amazonian biomass and forest extent. Our results indicate that the impacts of climate change are primarily determined by the direction and severity of projected changes in regional precipitation: under the driest climate projection, climate change alone is predicted to reduce Amazonian forest cover by an average of 14%. However, the models predict that CO 2 fertilization will enhance vegetation productivity and alleviate climate-induced increases in plant water stress, and, as a result, sustain high biomass forests, even under the driest climate scenario. Land-use change and climate-driven changes in fire frequency are predicted to cause additional aboveground biomass loss and reductions in forest extent. The relative impact of land use and fire dynamics compared to climate and CO 2 impacts varies considerably, depending on both the climate and land-use scenario, and on the terrestrial biosphere model used, highlighting the importance of improved quantitative understanding of all four factors - climate change, CO 2 fertilization effects, fire, and land use - to the fate of the Amazon over the coming century. © 2015 John Wiley & Sons Ltd.

Mining drives extensive deforestation in the Brazilian Amazon.

PubMed

Sonter, Laura J; Herrera, Diego; Barrett, Damian J; Galford, Gillian L; Moran, Chris J; Soares-Filho, Britaldo S

2017-10-18

Mining poses significant and potentially underestimated risks to tropical forests worldwide. In Brazil's Amazon, mining drives deforestation far beyond operational lease boundaries, yet the full extent of these impacts is unknown and thus neglected in environmental licensing. Here we quantify mining-induced deforestation and investigate the aspects of mining operations, which most likely contribute. We find mining significantly increased Amazon forest loss up to 70 km beyond mining lease boundaries, causing 11,670 km 2 of deforestation between 2005 and 2015. This extent represents 9% of all Amazon forest loss during this time and 12 times more deforestation than occurred within mining leases alone. Pathways leading to such impacts include mining infrastructure establishment, urban expansion to support a growing workforce, and development of mineral commodity supply chains. Mining-induced deforestation is not unique to Brazil; to mitigate adverse impacts of mining and conserve tropical forests globally, environmental assessments and licensing must considered both on- and off-lease sources of deforestation.

Space Radar Image of Manaus Region of Brazil

NASA Image and Video Library

1999-05-01

These L-band images of the Manaus region of Brazil were acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour. The left image was acquired on April 12, 1994, and the middle image was acquired on October 3, 1994. The area shown is approximately 8 kilometers by 40 kilometers (5 miles by 25 miles). The two large rivers in this image, the Rio Negro (top) and the Rio Solimoes (bottom), combine at Manaus (west of the image) to form the Amazon River. The image is centered at about 3 degrees south latitude and 61 degrees west longitude. North is toward the top left of the images. The differences in brightness between the images reflect changes in the scattering of the radar channel. In this case, the changes are indicative of flooding. A flooded forest has a higher backscatter at L-band (horizontally transmitted and received) than an unflooded river. The extent of the flooding is much greater in the April image than in the October image, and corresponds to the annual, 10-meter (33-foot) rise and fall of the Amazon River. A third image at right shows the change in the April and October images and was created by determining which areas had significant decreases in the intensity of radar returns. These areas, which appear blue on the third image at right, show the dramatic decrease in the extent of flooded forest, as the level of the Amazon River falls. The flooded forest is a vital habitat for fish and floating meadows are an important source of atmospheric methane. This demonstrates the capability of SIR-C/X-SAR to study important environmental changes that are impossible to see with optical sensors over regions such as the Amazon, where frequent cloud cover and dense forest canopies obscure monitoring of floods. Field studies by boat, on foot and in low-flying aircraft by the University of California at Santa Barbara, in collaboration with Brazil's Instituto Nacional de Pesguisas Estaciais, during the first and second flights of the SIR-C/X-SAR system have validated the interpretation of the radar images. http://photojournal.jpl.nasa.gov/catalog/PIA01740

Evaluating the Effects of Different Vegetation Types on Necrophagous Fly Communities (Diptera: Calliphoridae; Sarcophagidae): Implications for Conservation

PubMed Central

Pereira de Sousa, José Roberto; Carvalho-Filho, Fernando da Silva; Juen, Leandro; Esposito, Maria Cristina

2016-01-01

The present study was conducted in five different phytogeographic zones of the Brazilian state of Maranhão, three of which (the Amazon Forest, Cerrado, and Palm Groves) are more heterogeneous, whereas the other two (Marshlands and Mangroves) are more homogeneous. In each zone, nine sites were visited for the collection of necrophagous flies using bait traps in 2010, 2011, and 2012. The calliphorid and sarcophagid communities observed at each site were compared in terms of species richness, composition, and abundance. The more heterogeneous zones had higher species richness, except in the case of the sarcophagids in the forest habitats. The calliphorids Chloroprocta idioidea (Robineau- Desvoidy, 1830), Mesembrinella bicolor (Fabricius, 1805), Hemilucilia semidiaphana (Rondani, 1850) and Lucilia eximia (Wiedemann, 1819) were more closely associated with the Cerrado, Palm Grove and Amazon Forest zones, and Chrysomya megacephala (Fabricius, 194) with the Mangrove. In the sarcophagids, Peckia (Euboettcheria) subducta (Lopes, 1935) and P. (Pattonella) palidipilosa (Curran & Walley, 1934) were associated with the Amazon Forest, and P. (Sarcodexia) lambens (Wiedemann, 1830) and Tricharaea (Sarcophagula) occidua (Fabricius, 1794) with the Palm Grove and Cerrado zones. In the calliphorids, the greatest dissimilarity was recorded between the Amazon Forest and the Mangrove and Lowland grassland zones. In the sarcophagids, by contrast, the greatest dissimilarities were recorded between the Amazon Forest and all the other four zones. In general, then, the phytogeographic zones with the highest environmental heterogeneity were characterized by the greatest species richness and abundance of necrophagous flies. PMID:27798664

Quantifying edge effect extent and its impacts on carbon stocks across a degraded landscape in the Amazon using airborne lidar.

NASA Astrophysics Data System (ADS)

dos-Santos, M. N.; Keller, M.; Morton, D. C.; Longo, M.; Scaranello, M. A., Sr.; Pinagé, E. R.; Correa Pabon, R.

2017-12-01

Ongoing tropical forest degradation and forest fragmentation increases forest edge area. Forest edges experience hotter, drier, and windier conditions and greater exposure to fires compared to interior areas, which elevate rates of tree mortality. Previous studies have suggested that forests within 100 m from the edge may lose 36% of biomass during the first two decades following fragmentation, although such estimates are based on a limited number of experimental plots. Degraded forests behave differently from intact forests and quantifying edge effect extension in a degraded forest landscape is more challenging compared to experimental studies. To overcome these limitations, we used airborne lidar data to quantify changes in forest structure near 91 edges in a heavily degraded tropical forest in Paragominas Municipality, eastern Brazilian Amazon. Paragominas was a center of timber production in the 1990s. Today, the landscape is a mosaic of different agricultural uses, degraded, secondary and unmanaged forests. A total of 3000 ha of high density (mean density of 17.9 points/m2) lidar data were acquired in August/September 2013 and June/July 2014 over 30 transects (200 x 5000m), systematically distributed over the study area, using the Optech Orion M-200 laser scanning system. We adopted lidar-measured forest heights as the edge effect criteria and found that mean extent of edge effect was highly variable across degraded forests (150 ± 354m) and secondary forest fragments (265 ± 365m). We related the extent of forest edges to the historical disturbances identified in Landsat imagery since 1984. Contrary to previous studies, we found that carbon stocks along forest edges were not significantly lower than forest core biomass when edges were defined by previously estimated range of 100 and 300m. In frontier forests, ecological edge effect may be masked by the cumulative impact of historic forest degradation - an anthropogenic edge effect that extends beyond the scale of changes in forest microclimate from fragmentation.

Land Use and Land Cover Change Dynamics across the Brazilian Amazon: Insights from Extensive Time-Series Analysis of Remote Sensing Data

PubMed Central

Carreiras, João M. B.; Jones, Joshua; Lucas, Richard M.; Gabriel, Cristina

2014-01-01

Throughout the Amazon region, the age of forests regenerating on previously deforested land is determined, in part, by the periods of active land use prior to abandonment and the frequency of reclearance of regrowth, both of which can be quantified by comparing time-series of Landsat sensor data. Using these time-series of near annual data from 1973–2011 for an area north of Manaus (in Amazonas state), from 1984–2010 for south of Santarém (Pará state) and 1984–2011 near Machadinho d’Oeste (Rondônia state), the changes in the area of primary forest, non-forest and secondary forest were documented from which the age of regenerating forests, periods of active land use and the frequency of forest reclearance were derived. At Manaus, and at the end of the time-series, over 50% of regenerating forests were older than 16 years, whilst at Santarém and Machadinho d’Oeste, 57% and 41% of forests respectively were aged 6–15 years, with the remainder being mostly younger forests. These differences were attributed to the time since deforestation commenced but also the greater frequencies of reclearance of forests at the latter two sites with short periods of use in the intervening periods. The majority of clearance for agriculture was also found outside of protected areas. The study suggested that a) the history of clearance and land use should be taken into account when protecting deforested land for the purpose of restoring both tree species diversity and biomass through natural regeneration and b) a greater proportion of the forested landscape should be placed under protection, including areas of regrowth. PMID:25099362

Land use and land cover change dynamics across the Brazilian Amazon: insights from extensive time-series analysis of remote sensing data.

PubMed

Carreiras, João M B; Jones, Joshua; Lucas, Richard M; Gabriel, Cristina

2014-01-01

Throughout the Amazon region, the age of forests regenerating on previously deforested land is determined, in part, by the periods of active land use prior to abandonment and the frequency of reclearance of regrowth, both of which can be quantified by comparing time-series of Landsat sensor data. Using these time-series of near annual data from 1973-2011 for an area north of Manaus (in Amazonas state), from 1984-2010 for south of Santarém (Pará state) and 1984-2011 near Machadinho d'Oeste (Rondônia state), the changes in the area of primary forest, non-forest and secondary forest were documented from which the age of regenerating forests, periods of active land use and the frequency of forest reclearance were derived. At Manaus, and at the end of the time-series, over 50% of regenerating forests were older than 16 years, whilst at Santarém and Machadinho d'Oeste, 57% and 41% of forests respectively were aged 6-15 years, with the remainder being mostly younger forests. These differences were attributed to the time since deforestation commenced but also the greater frequencies of reclearance of forests at the latter two sites with short periods of use in the intervening periods. The majority of clearance for agriculture was also found outside of protected areas. The study suggested that a) the history of clearance and land use should be taken into account when protecting deforested land for the purpose of restoring both tree species diversity and biomass through natural regeneration and b) a greater proportion of the forested landscape should be placed under protection, including areas of regrowth.

New estimates of temperature response of leaf photosynthesis in Amazon forest trees, its acclimation to mean temperature change and consequences for modelling climate response to rain forests.

NASA Astrophysics Data System (ADS)

Kruijt, B.; Jans, W.; Vasconcelos, S.; Tribuzy, E. S.; Felsemburgh, C.; Eliane, M.; Rowland, L.; da Costa, A. C. L.; Meir, P.

2014-12-01

In many dynamic vegetation models, degradation of the tropical forests is induced because they assume that productivity falls rapidly when temperatures rise in the region of 30-40°C. Apart plant respiration, this is due to the assumptions on the temperature optima of photosynthetic capacity, which are low and can differ widely between models, where in fact hardly any empirical information is available for tropical forests. Even less is known about the possibility that photosynthesis will acclimate to changing temperatures. The objective of this study to is to provide better estimates for optima, as well as to determine whether any acclimation to temperature change is to be expected. We present both new and hitherto unpublished data on the temperature response of photosynthesis of Amazon rainforest trees, encompassing three sites, several species and five field campaigns. Leaf photosynthesis and its parameters were determined at a range of temperatures. To study the long-term (seasonal) acclimation of this response, this was combined with an artificial, in situ, multi-season leaf heating experiment. The data show that, on average for all non-heated cases, the photosynthetic parameter Vcmax weakly peaks between 35 and 40 ˚C, while heating does not have a clearly significant effect. Results for Jmax are slightly different, with sharper peaks. Scatter was relatively high, which could indicate weak overall temperature dependence. The combined results were used to fit new parameters to the various temperature response curve functions in a range of DGVMs. The figure shows a typical example: while the default Jules model assumes a temperature optimum for Vcmax at around 33 ˚C, the data suggest that Vcmax keeps rising up to at least 40 ˚C. Of course, calculated photosynthesis, obtained by applying this Vcmax in the Farquhar model, peaks at lower temperature. Finally, the implication of these new model parameters for modelled climate change impact on modelled Amazon forests will be assessed, where it is expected that predicted die-back will be less.

From where does the Amazon forest gets its water?

NASA Astrophysics Data System (ADS)

Miguez-Macho, G.; Fan, Y.

2016-12-01

The Amazon receives abundant annual rainfall but parts of it experience a multi-month dry season. Here we ask: what is the water source that sustains the dry-season ET? Where over the Amazon it is largely local and recent rain (hence ET shutting down in dry season), or past rain that is stored in the deep soils and the groundwater (deep roots tapping deep reservoirs sustaining ET), or is it rain that fell on higher grounds (through topography-driven lateral convergence)? Using synthesis of isotope and other tracer observations and basin-wide inverse modeling (shallow soil, deep soil, with and without groundwater, with and without dynamic rooting depth), we attempt to tease out these components. The results shed light on likely ET sources and how future global change may preferentially impact Amazon ecosystem functioning.

Influence of longer dry seasons in the Southern Amazon on patterns of water vapor transport over northern South America and the Caribbean

NASA Astrophysics Data System (ADS)

Agudelo, Jhoana; Arias, Paola A.; Vieira, Sara C.; Martínez, J. Alejandro

2018-06-01

Several studies have identified a recent lengthening of the dry season over the southern Amazon during the last three decades. Some explanations to this lengthening suggest the influence of changes in the regional circulation over the Atlantic and Pacific oceans, whereas others point to the influence of vegetation changes over the Amazon rainforest. This study aims to understand the implications of more frequent long dry seasons in this forest on atmospheric moisture transport toward northern South America and the Caribbean region. Using a semi-Langrangian model for water vapor tracking, results indicate that longer dry seasons in the southern Amazon relate to reductions of water vapor content over the southern and eastern Amazon basin, due to significant reductions of evaporation and recycled precipitation rates in these regions, especially during the transition from dry to wet conditions in the southern Amazon. On the other hand, longer dry seasons also relate to enhanced atmospheric moisture content over the Caribbean and northern South America regions, mainly due to increased contributions of water vapor from oceanic regions and the increase of surface moisture convergence over the equatorial region. This highlights the importance of understanding the relative role of regional circulation and local surface conditions on modulating water vapor transport toward continental regions.

Vegetation dynamics and rainfall sensitivity of the Amazon

PubMed Central

Hilker, Thomas; Lyapustin, Alexei I.; Tucker, Compton J.; Hall, Forrest G.; Myneni, Ranga B.; Wang, Yujie; Bi, Jian; Mendes de Moura, Yhasmin; Sellers, Piers J.

2014-01-01

We show that the vegetation canopy of the Amazon rainforest is highly sensitive to changes in precipitation patterns and that reduction in rainfall since 2000 has diminished vegetation greenness across large parts of Amazonia. Large-scale directional declines in vegetation greenness may indicate decreases in carbon uptake and substantial changes in the energy balance of the Amazon. We use improved estimates of surface reflectance from satellite data to show a close link between reductions in annual precipitation, El Niño southern oscillation events, and photosynthetic activity across tropical and subtropical Amazonia. We report that, since the year 2000, precipitation has declined across 69% of the tropical evergreen forest (5.4 million km2) and across 80% of the subtropical grasslands (3.3 million km2). These reductions, which coincided with a decline in terrestrial water storage, account for about 55% of a satellite-observed widespread decline in the normalized difference vegetation index (NDVI). During El Niño events, NDVI was reduced about 16.6% across an area of up to 1.6 million km2 compared with average conditions. Several global circulation models suggest that a rise in equatorial sea surface temperature and related displacement of the intertropical convergence zone could lead to considerable drying of tropical forests in the 21st century. Our results provide evidence that persistent drying could degrade Amazonian forest canopies, which would have cascading effects on global carbon and climate dynamics. PMID:25349419

Declining Use of Wild Resources by Indigenous Peoples of the Ecuadorian Amazon.

PubMed

Gray, Clark L; Bozigar, Matthew; Bilsborrow, Richard E

2015-02-01

Wild product harvesting by forest-dwelling peoples, including hunting, fishing, forest product collection and timber harvesting, is believed to be a major threat to the biodiversity of tropical forests worldwide. Despite this threat, few studies have attempted to quantify these activities across time or across large spatial scales. We use a unique longitudinal household survey (n = 480) to describe changes in these activities over time in 32 indigenous communities from five ethnicities in the northern Ecuadorian Amazon. To provide insight into the drivers of these changes, we also estimate multilevel statistical models of these activities as a function of household and community characteristics. These analyses reveal that participation in hunting, fishing, and forest product collection is high but declining across time and across ethnicities, with no evidence for a parallel decline in resource quality. However, participation in timber harvesting did not significantly decline and there is evidence of a decline in resource quality. Multilevel statistical models additionally reveal that household and community characteristics such as ethnicity, demographic characteristics, wealth, livelihood diversification, access to forest, participation in conservation programs and exposure to external markets are significant predictors of wild product harvesting. These characteristics have changed over time but cannot account for declining participation in resource harvesting. This finding suggests that participation is declining due to changes in the regional-scale social and economic context, including urbanization and the expansion of government infrastructure and services. The lesson for conservationists is that macro-scale social and economic conditions can drive reductions in wild product harvesting even in the absence of successful conservation interventions.

Declining Use of Wild Resources by Indigenous Peoples of the Ecuadorian Amazon

PubMed Central

Gray, Clark L.; Bozigar, Matthew; Bilsborrow, Richard E.

2015-01-01

Wild product harvesting by forest-dwelling peoples, including hunting, fishing, forest product collection and timber harvesting, is believed to be a major threat to the biodiversity of tropical forests worldwide. Despite this threat, few studies have attempted to quantify these activities across time or across large spatial scales. We use a unique longitudinal household survey (n = 480) to describe changes in these activities over time in 32 indigenous communities from five ethnicities in the northern Ecuadorian Amazon. To provide insight into the drivers of these changes, we also estimate multilevel statistical models of these activities as a function of household and community characteristics. These analyses reveal that participation in hunting, fishing, and forest product collection is high but declining across time and across ethnicities, with no evidence for a parallel decline in resource quality. However, participation in timber harvesting did not significantly decline and there is evidence of a decline in resource quality. Multilevel statistical models additionally reveal that household and community characteristics such as ethnicity, demographic characteristics, wealth, livelihood diversification, access to forest, participation in conservation programs and exposure to external markets are significant predictors of wild product harvesting. These characteristics have changed over time but cannot account for declining participation in resource harvesting. This finding suggests that participation is declining due to changes in the regional-scale social and economic context, including urbanization and the expansion of government infrastructure and services. The lesson for conservationists is that macro-scale social and economic conditions can drive reductions in wild product harvesting even in the absence of successful conservation interventions. PMID:25620805

Isoprene photochemistry over the Amazon rainforest.

PubMed

Liu, Yingjun; Brito, Joel; Dorris, Matthew R; Rivera-Rios, Jean C; Seco, Roger; Bates, Kelvin H; Artaxo, Paulo; Duvoisin, Sergio; Keutsch, Frank N; Kim, Saewung; Goldstein, Allen H; Guenther, Alex B; Manzi, Antonio O; Souza, Rodrigo A F; Springston, Stephen R; Watson, Thomas B; McKinney, Karena A; Martin, Scot T

2016-05-31

Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO2) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4-0.6. This result implies a ratio of the reaction rate of ISOPOO with HO2 to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.

Isoprene photochemistry over the Amazon rainforest

NASA Astrophysics Data System (ADS)

Liu, Yingjun; Brito, Joel; Dorris, Matthew R.; Rivera-Rios, Jean C.; Seco, Roger; Bates, Kelvin H.; Artaxo, Paulo; Duvoisin, Sergio; Keutsch, Frank N.; Kim, Saewung; Goldstein, Allen H.; Guenther, Alex B.; Manzi, Antonio O.; Souza, Rodrigo A. F.; Springston, Stephen R.; Watson, Thomas B.; McKinney, Karena A.; Martin, Scot T.

2016-05-01

Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO2) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4-0.6. This result implies a ratio of the reaction rate of ISOPOO with HO2 to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.

Ancient human disturbances may be skewing our understanding of Amazonian forests

PubMed Central

McMichael, Crystal N. H.; Matthews-Bird, Frazer; Farfan-Rios, William; Feeley, Kenneth J.

2017-01-01

Although the Amazon rainforest houses much of Earth’s biodiversity and plays a major role in the global carbon budget, estimates of tree biodiversity originate from fewer than 1,000 forest inventory plots, and estimates of carbon dynamics are derived from fewer than 200 recensus plots. It is well documented that the pre-European inhabitants of Amazonia actively transformed and modified the forest in many regions before their population collapse around 1491 AD; however, the impacts of these ancient disturbances remain entirely unaccounted for in the many highly influential studies using Amazonian forest plots. Here we examine whether Amazonian forest inventory plot locations are spatially biased toward areas with high probability of ancient human impacts. Our analyses reveal that forest inventory plots, and especially forest recensus plots, in all regions of Amazonia are located disproportionately near archaeological evidence and in areas likely to have ancient human impacts. Furthermore, regions of the Amazon that are relatively oversampled with inventory plots also contain the highest values of predicted ancient human impacts. Given the long lifespan of Amazonian trees, many forest inventory and recensus sites may still be recovering from past disturbances, potentially skewing our interpretations of forest dynamics and our understanding of how these forests are responding to global change. Empirical data on the human history of forest inventory sites are crucial for determining how past disturbances affect modern patterns of forest composition and carbon flux in Amazonian forests. PMID:28049821

Improving simulated spatial distribution of productivity and biomass in Amazon forests using the ACME land model

NASA Astrophysics Data System (ADS)

Yang, X.; Thornton, P. E.; Ricciuto, D. M.; Shi, X.; Xu, M.; Hoffman, F. M.; Norby, R. J.

2017-12-01

Tropical forests play a crucial role in the global carbon cycle, accounting for one third of the global NPP and containing about 25% of global vegetation biomass and soil carbon. This is particularly true for tropical forests in the Amazon region, as it comprises approximately 50% of the world's tropical forests. It is therefore important for us to understand and represent the processes that determine the fluxes and storage of carbon in these forests. In this study, we show that the implementation of phosphorus (P) cycle and P limitation in the ACME Land Model (ALM) improves simulated spatial pattern of NPP. The P-enabled ALM is able to capture the west-to-east gradient of productivity, consistent with field observations. We also show that by improving the representation of mortality processes, ALM is able to reproduce the observed spatial pattern of above ground biomass across the Amazon region.

Amazon Flooded Forest. Teacher Resource Guide.

ERIC Educational Resources Information Center

Duvall, Todd

This teacher's resource guide was created to accompany the Amazon Flooded Forest exhibit at the Oregon Zoo. The enclosed lessons and activities are designed to extend into several aspects of daily curriculum including science, math, reading, writing, speaking, and geography. The materials are intended for use in grades 3-6 although most activities…

Archaeal Community Changes Associated with Cultivation of Amazon Forest Soil with Oil Palm

PubMed Central

Tupinambá, Daiva Domenech; Cantão, Maurício Egídio; Costa, Ohana Yonara Assis; Bergmann, Jessica Carvalho; Kruger, Ricardo Henrique; Kyaw, Cynthia Maria; Barreto, Cristine Chaves; Quirino, Betania Ferraz

2016-01-01

This study compared soil archaeal communities of the Amazon forest with that of an adjacent area under oil palm cultivation by 16S ribosomal RNA gene pyrosequencing. Species richness and diversity were greater in native forest soil than in the oil palm-cultivated area, and 130 OTUs (13.7%) were shared between these areas. Among the classified sequences, Thaumarchaeota were predominant in the native forest, whereas Euryarchaeota were predominant in the oil palm-cultivated area. Archaeal species diversity was 1.7 times higher in the native forest soil, according to the Simpson diversity index, and the Chao1 index showed that richness was five times higher in the native forest soil. A phylogenetic tree of unclassified Thaumarchaeota sequences showed that most of the OTUs belong to Miscellaneous Crenarchaeotic Group. Several archaeal genera involved in nutrient cycling (e.g., methanogens and ammonia oxidizers) were identified in both areas, but significant differences were found in the relative abundances of Candidatus Nitrososphaera and unclassified Soil Crenarchaeotic Group (prevalent in the native forest) and Candidatus Nitrosotalea and unclassified Terrestrial Group (prevalent in the oil palm-cultivated area). More studies are needed to culture some of these Archaea in the laboratory so that their metabolism and physiology can be studied. PMID:27006640

Where Deforestation Leads to Urbanization: How Resource Extraction is Leading to Urban Growth in the Brazilian Amazon.

PubMed

Richards, Peter; VanWey, Leah

2015-07-01

Developing the Amazon into a major provider of internationally traded mineral and food commodities has dramatically transformed broad expanses of tropical forests to farm and pasturelands, and to mining sites. The environmental impacts of this transformation, as well as the drivers underlying the process, have already been well documented. In this article we turn our analytical lenses to another, less examined effect of Amazon land use and environmental change, namely the creation and development of new urban areas. Here we argue that urban growth in the Amazon is a direct residual of international interest in the production of traded commodities, and of the capacity of local urban residents to capture capital and value before it is extracted from the region. Specifically, we suggest that urban growth is occurring fastest where cities have access to both rural export commodities and export corridors. We also show correlations between urban growth and lower rural population density, and cities' capacities to draw migrants from beyond their immediate rural surroundings. More broadly, we argue that urbanization in the Amazon is better interpreted as a symptom rather than a driver of the region's land use and land cover change.

Where Deforestation Leads to Urbanization: How Resource Extraction is Leading to Urban Growth in the Brazilian Amazon

PubMed Central

VanWey, Leah

2015-01-01

Developing the Amazon into a major provider of internationally traded mineral and food commodities has dramatically transformed broad expanses of tropical forests to farm and pasturelands, and to mining sites. The environmental impacts of this transformation, as well as the drivers underlying the process, have already been well documented. In this article we turn our analytical lenses to another, less examined effect of Amazon land use and environmental change, namely the creation and development of new urban areas. Here we argue that urban growth in the Amazon is a direct residual of international interest in the production of traded commodities, and of the capacity of local urban residents to capture capital and value before it is extracted from the region. Specifically, we suggest that urban growth is occurring fastest where cities have access to both rural export commodities and export corridors. We also show correlations between urban growth and lower rural population density, and cities’ capacities to draw migrants from beyond their immediate rural surroundings. More broadly, we argue that urbanization in the Amazon is better interpreted as a symptom rather than a driver of the region’s land use and land cover change. PMID:26985079

Spatial and temporal dynamics of forest canopy gaps following selective logging in the eastern Amazon.

Treesearch

GREGORY P. ASNER; MICHAEL KELLER; JOSEN M. SILVA

2004-01-01

Selective logging is a dominant form of land use in the Amazon basin and throughout the humid tropics, yet little is known about the spatial variability of forest canopy gap formation and closure following timber harvests. We established chronosequences of large-area (14–158 ha) selective logging sites spanning a 3.5-year period of forest regeneration and two distinct...

Asynchronous Amazon Forest Canopy Phenology Indicates Adaptation to Both Water and Light Availability

NASA Astrophysics Data System (ADS)

Jones, M. O.; Kimball, J. S.; Nemani, R. R.

2015-12-01

Amazon forests represent nearly half of all tropical vegetation biomass and, through photosynthesis and respiration, annually process more than twice the amount of estimated carbon (CO2) from fossil fuel emissions. Yet the seasonality of Amazon canopy cover, and the extent to which seasonal fluctuations in water availability and photosynthetically active radiation influence these processes, is still poorly understood. Implementing six remotely sensed data sets spanning nine years (2003-2011), with reported field and flux tower data, we show that southern equatorial Amazon forests exhibit a distinctive seasonal signal. Seasonal timing of water availability, canopy biomass growth and net leaf flush are asynchronous in regions with short dry seasons and become more synchronous across a west-to-east longitudinal moisture gradient of increasing dry season length. Forest cover is responsive to seasonal disparities in both water and solar radiation availability, temporally adjusting net leaf flush to maximize use of these generally abundant resources, while reducing drought susceptibility. An accurate characterization of this asynchronous behavior allows for improved understanding of canopy phenology across contiguous tropical forests and their sensitivity to climate variability and drought. These insights can also inform land surface models to provide a more accurate representation of seasonal forest carbon allocation strategies responsive to environmental drivers.

Estimating of gross primary production in an Amazon-Cerrado transitional forest using MODIS and Landsat imagery.

PubMed

Danelichen, Victor H M; Biudes, Marcelo S; Velasque, Maísa C S; Machado, Nadja G; Gomes, Raphael S R; Vourlitis, George L; Nogueira, José S

2015-09-01

The acceleration of the anthropogenic activity has increased the atmospheric carbon concentration, which causes changes in regional climate. The Gross Primary Production (GPP) is an important variable in the global carbon cycle studies, since it defines the atmospheric carbon extraction rate from terrestrial ecosystems. The objective of this study was to estimate the GPP of the Amazon-Cerrado Transitional Forest by the Vegetation Photosynthesis Model (VPM) using local meteorological data and remote sensing data from MODIS and Landsat 5 TM reflectance from 2005 to 2008. The GPP was estimated using Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) calculated by MODIS and Landsat 5 TM images. The GPP estimates were compared with measurements in a flux tower by eddy covariance. The GPP measured in the tower was consistent with higher values during the wet season and there was a trend to increase from 2005 to 2008. The GPP estimated by VPM showed the same increasing trend observed in measured GPP and had high correlation and Willmott's coefficient and low error metrics in comparison to measured GPP. These results indicated high potential of the Landsat 5 TM images to estimate the GPP of Amazon-Cerrado Transitional Forest by VPM.

Hydrological and Meteorological Role of Forests: Implications for the Regulation of Water and Energy Balances

NASA Astrophysics Data System (ADS)

Salazar, J. F.; Villegas, J. C.; Bettin, D. M.; Molina, R.; Henao, J. J.; Rodríguez, E.; Rendón, A.; Hoyos, I.; Poveda, G.

2016-12-01

In last decades, there has been increasing debate about the hydrological and meteorological role of forests, particularly regarding its role in the regulation of the energy and water balances. Here we summarize results from an ongoing research program studying this problem. First, we introduce the notion of ecohydrological scaling to show the existence of two alternative states of regulated or unregulated streamflows in the main tributaries of the Amazon river basin. The transition between both states is associated with the loss of forest cover, with a potential critical threshold at around 40% forest loss in the Amazon. These results imply that large-scale forest loss can force the entire Amazon basin system beyond a critical threshold where its natural streamflow regulation is lost. More generally, our proposed framework provides insights for a physical interpretation of the scaling relations in river basins, as well as foundations and tools to develop early warnings of critical transitions in river basins. Second, we show that long-term rainfall-streamflow ratios converge to low values with low spatial variability in forested basins of the world, independent of location, climatic regime, basin size or forest type. We interpret this as evidence that high forest cover provides long-term regulation of the water balance. Third, we examine the linkage between the presence of tropical forests in South America and the long-term spatial distribution of continental precipitation, and found evidence suggesting that the Amazon forests enhance the atmospheric rivers flowing inland from the Atlantic ocean, particularly during the austral and boreal summers. The associated effects on precipitation may be highly relevant for water availability in river basins located downstream such atmospheric rivers, such as the La Plata and the Orinoco river basins. Finally, we explore the linkage between forest-induced temperature inversions and the vertical transport of atmospheric moisture during the wet and dry seasons in the Amazon, and discuss its potential implications for the partitioning of evapotranspiration and the regulation of the surface energy and water balances. Collectively, our findings suggest that forests are more important to the regulation of the surface water and energy balances than generally assumed.

Windthrows increase soil carbon stocks in a central Amazon forest

DOE PAGES

dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan; ...

2016-03-02

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0–30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha -1, mean ±95 % confidence interval) was marginally higher ( p =more » 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha -1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher ( p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content ( r 2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity ( r 2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.« less

Windthrows increase soil carbon stocks in a central Amazon forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0–30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha -1, mean ±95 % confidence interval) was marginally higher ( p =more » 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha -1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher ( p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content ( r 2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity ( r 2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.« less

Prospects for land-use sustainability on the agricultural frontier of the Brazilian Amazon.

PubMed

Galford, Gillian L; Soares-Filho, Britaldo; Cerri, Carlos E P

2013-06-05

The Brazilian Amazon frontier shows how remarkable leadership can work towards increased agricultural productivity and environmental sustainability without new greenhouse gas emissions. This is due to initiatives among various stakeholders, including national and state government and agents, farmers, consumers, funding agencies and non-governmental organizations. Change has come both from bottom-up and top-down actions of these stakeholders, providing leadership, financing and monitoring to foster environmental sustainability and agricultural growth. Goals to reduce greenhouse gas emissions from land-cover and land-use change in Brazil are being achieved through a multi-tiered approach that includes policies to reduce deforestation and initiatives for forest restoration, as well as increased and diversified agricultural production, intensified ranching and innovations in agricultural management. Here, we address opportunities for the Brazilian Amazon in working towards low-carbon rural development and environmentally sustainable landscapes.

Prospects for land-use sustainability on the agricultural frontier of the Brazilian Amazon

PubMed Central

Galford, Gillian L.; Soares-Filho, Britaldo; Cerri, Carlos E. P.

2013-01-01

The Brazilian Amazon frontier shows how remarkable leadership can work towards increased agricultural productivity and environmental sustainability without new greenhouse gas emissions. This is due to initiatives among various stakeholders, including national and state government and agents, farmers, consumers, funding agencies and non-governmental organizations. Change has come both from bottom-up and top-down actions of these stakeholders, providing leadership, financing and monitoring to foster environmental sustainability and agricultural growth. Goals to reduce greenhouse gas emissions from land-cover and land-use change in Brazil are being achieved through a multi-tiered approach that includes policies to reduce deforestation and initiatives for forest restoration, as well as increased and diversified agricultural production, intensified ranching and innovations in agricultural management. Here, we address opportunities for the Brazilian Amazon in working towards low-carbon rural development and environmentally sustainable landscapes. PMID:23610175

Accelerated losses of protected forests from gold mining in the Peruvian Amazon

NASA Astrophysics Data System (ADS)

Asner, Gregory P.; Tupayachi, Raul

2016-09-01

Gold mining in Amazonia involves forest removal, soil excavation, and the use of liquid mercury, which together pose a major threat to biodiversity, water quality, forest carbon stocks, and human health. Within the global biodiversity hotspot of Madre de Dios, Peru, gold mining has continued despite numerous 2012 government decrees and enforcement actions against it. Mining is now also thought to have entered federally protected areas, but the rates of miner encroachment are unknown. Here, we utilize high-resolution remote sensing to assess annual changes in gold mining extent from 1999 to 2016 throughout the Madre de Dios region, including the high-diversity Tambopata National Reserve and buffer zone. Regionally, gold mining-related losses of forest averaged 4437 ha yr-1. A temporary downward inflection in the annual growth rate of mining-related forest loss following 2012 government action was followed by a near doubling of the deforestation rate from mining in 2013-2014. The total estimated area of gold mining throughout the region increased about 40% between 2012 and 2016, including in the Tambopata National Reserve. Our results reveal an urgent need for more socio-environmental effort and law enforcement action to combat illegal gold mining in the Peruvian Amazon.

Biomass burning losses of carbon estimated from ecosystem modeling and satellite data analysis for the Brazilian Amazon region

NASA Astrophysics Data System (ADS)

Potter, Christopher; Brooks Genovese, Vanessa; Klooster, Steven; Bobo, Matthew; Torregrosa, Alicia

To produce a new daily record of gross carbon emissions from biomass burning events and post-burning decomposition fluxes in the states of the Brazilian Legal Amazon (Instituto Brasileiro de Geografia e Estatistica (IBGE), 1991. Anuario Estatistico do Brasil, Vol. 51. Rio de Janeiro, Brazil pp. 1-1024). We have used vegetation greenness estimates from satellite images as inputs to a terrestrial ecosystem production model. This carbon allocation model generates new estimates of regional aboveground vegetation biomass at 8-km resolution. The modeled biomass product is then combined for the first time with fire pixel counts from the advanced very high-resolution radiometer (AVHRR) to overlay regional burning activities in the Amazon. Results from our analysis indicate that carbon emission estimates from annual region-wide sources of deforestation and biomass burning in the early 1990s are apparently three to five times higher than reported in previous studies for the Brazilian Legal Amazon (Houghton et al., 2000. Nature 403, 301-304; Fearnside, 1997. Climatic Change 35, 321-360), i.e., studies which implied that the Legal Amazon region tends toward a net-zero annual source of terrestrial carbon. In contrast, our analysis implies that the total source fluxes over the entire Legal Amazon region range from 0.2 to 1.2 Pg C yr -1, depending strongly on annual rainfall patterns. The reasons for our higher burning emission estimates are (1) use of combustion fractions typically measured during Amazon forest burning events for computing carbon losses, (2) more detailed geographic distribution of vegetation biomass and daily fire activity for the region, and (3) inclusion of fire effects in extensive areas of the Legal Amazon covered by open woodland, secondary forests, savanna, and pasture vegetation. The total area of rainforest estimated annually to be deforested did not differ substantially among the previous analyses cited and our own.

Amazon plant diversity revealed by a taxonomically verified species list.

PubMed

Cardoso, Domingos; Särkinen, Tiina; Alexander, Sara; Amorim, André M; Bittrich, Volker; Celis, Marcela; Daly, Douglas C; Fiaschi, Pedro; Funk, Vicki A; Giacomin, Leandro L; Goldenberg, Renato; Heiden, Gustavo; Iganci, João; Kelloff, Carol L; Knapp, Sandra; Cavalcante de Lima, Haroldo; Machado, Anderson F P; Dos Santos, Rubens Manoel; Mello-Silva, Renato; Michelangeli, Fabián A; Mitchell, John; Moonlight, Peter; de Moraes, Pedro Luís Rodrigues; Mori, Scott A; Nunes, Teonildes Sacramento; Pennington, Terry D; Pirani, José Rubens; Prance, Ghillean T; de Queiroz, Luciano Paganucci; Rapini, Alessandro; Riina, Ricarda; Rincon, Carlos Alberto Vargas; Roque, Nádia; Shimizu, Gustavo; Sobral, Marcos; Stehmann, João Renato; Stevens, Warren D; Taylor, Charlotte M; Trovó, Marcelo; van den Berg, Cássio; van der Werff, Henk; Viana, Pedro Lage; Zartman, Charles E; Forzza, Rafaela Campostrini

2017-10-03

Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests.

Amazon plant diversity revealed by a taxonomically verified species list

PubMed Central

Cardoso, Domingos; Särkinen, Tiina; Alexander, Sara; Amorim, André M.; Bittrich, Volker; Celis, Marcela; Daly, Douglas C.; Fiaschi, Pedro; Funk, Vicki A.; Giacomin, Leandro L.; Heiden, Gustavo; Iganci, João; Kelloff, Carol L.; Knapp, Sandra; Cavalcante de Lima, Haroldo; Machado, Anderson F. P.; dos Santos, Rubens Manoel; Mello-Silva, Renato; Michelangeli, Fabián A.; Mitchell, John; Moonlight, Peter; de Moraes, Pedro Luís Rodrigues; Mori, Scott A.; Nunes, Teonildes Sacramento; Pennington, Terry D.; Pirani, José Rubens; Prance, Ghillean T.; de Queiroz, Luciano Paganucci; Rapini, Alessandro; Rincon, Carlos Alberto Vargas; Roque, Nádia; Shimizu, Gustavo; Sobral, Marcos; Stehmann, João Renato; Stevens, Warren D.; Taylor, Charlotte M.; Trovó, Marcelo; van den Berg, Cássio; van der Werff, Henk; Viana, Pedro Lage; Zartman, Charles E.; Forzza, Rafaela Campostrini

2017-01-01

Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests. PMID:28923966

Drought-induced mortality patterns and rapid biomass recovery in a terra firme forest in the Colombian Amazon.

PubMed

Zuleta, Daniel; Duque, Alvaro; Cardenas, Dairon; Muller-Landau, Helene C; Davies, Stuart J

2017-10-01

Extreme climatic events affecting the Amazon region are expected to become more frequent under ongoing climate change. In this study, we assessed the responses to the 2010 drought of over 14,000 trees ≥10 cm dbh in a 25 ha lowland forest plot in the Colombian Amazon and how these responses varied among topographically defined habitats, with tree size, and with species wood density. Tree mortality was significantly higher during the 2010-2013 period immediately after the drought than in 2007-2010. The post-drought increase in mortality was stronger for trees located in valleys (+243%) than for those located on slopes (+67%) and ridges (+57%). Tree-based generalized linear mixed models showed a significant negative effect of species wood density on mortality and no effect of tree size. Despite the elevated post-drought mortality, aboveground biomass increased from 2007 to 2013 by 1.62 Mg ha -1  yr -1 (95% CI 0.80-2.43 Mg ha -1  yr -1 ). Biomass change varied among habitats, with no significant increase on the slopes (1.05, 95% CI -0.76 to 2.85 Mg ha -1  yr -1 ), a significant increase in the valleys (1.33, 95% CI 0.37-2.34 Mg ha -1  yr -1 ), and a strong increase on the ridges (2.79, 95% CI 1.20-4.21 Mg ha -1  yr -1 ). These results indicate a high carbon resilience of this forest to the 2010 drought due to habitat-associated and interspecific heterogeneity in responses including directional changes in functional composition driven by enhanced performance of drought-tolerant species that inhabit the drier ridges. © 2017 by the Ecological Society of America.

Colloquium paper: how many tree species are there in the Amazon and how many of them will go extinct?

PubMed

Hubbell, Stephen P; He, Fangliang; Condit, Richard; Borda-de-Agua, Luís; Kellner, James; Ter Steege, Hans

2008-08-12

New roads, agricultural projects, logging, and mining are claiming an ever greater area of once-pristine Amazonian forest. The Millennium Ecosystems Assessment (MA) forecasts the extinction of a large fraction of Amazonian tree species based on projected loss of forest cover over the next several decades. How accurate are these estimates of extinction rates? We use neutral theory to estimate the number, relative abundance, and range size of tree species in the Amazon metacommunity and estimate likely tree-species extinctions under published optimistic and nonoptimistic Amazon scenarios. We estimate that the Brazilian portion of the Amazon Basin has (or had) 11,210 tree species that reach sizes >10 cm DBH (stem diameter at breast height). Of these, 3,248 species have population sizes >1 million individuals, and, ignoring possible climate-change effects, almost all of these common species persist under both optimistic and nonoptimistic scenarios. At the rare end of the abundance spectrum, however, neutral theory predicts the existence of approximately 5,308 species with <10,000 individuals each that are expected to suffer nearly a 50% extinction rate under the nonoptimistic deforestation scenario and an approximately 37% loss rate even under the optimistic scenario. Most of these species have small range sizes and are highly vulnerable to local habitat loss. In ensembles of 100 stochastic simulations, we found mean total extinction rates of 20% and 33% of tree species in the Brazilian Amazon under the optimistic and nonoptimistic scenarios, respectively.

Boundary layer ozone - An airborne survey above the Amazon Basin

NASA Technical Reports Server (NTRS)

Gregory, Gerald L.; Browell, Edward V.; Warren, Linda S.

1988-01-01

Ozone data obtained over the forest canopy of the Amazon Basin during July and August 1985 in the course of NASA's Amazon Boundary Layer Experiment 2A are discussed, and ozone profiles obtained during flights from Belem to Tabatinga, Brazil, are analyzed to determine any cross-basin effects. The analyses of ozone data indicate that the mixed layer of the Amazon Basin, for the conditions of undisturbed meteorology and in the absence of biomass burning, is a significant sink for tropospheric ozone. As the coast is approached, marine influences are noted at about 300 km inland, and a transition from a forest-controlled mixed layer to a marine-controlled mixed layer is noted.

Dispersal limitation induces long-term biomass collapse in overhunted Amazonian forests

PubMed Central

Peres, Carlos A.; Emilio, Thaise; Schietti, Juliana; Desmoulière, Sylvain J. M.; Levi, Taal

2016-01-01

Tropical forests are the global cornerstone of biological diversity, and store 55% of the forest carbon stock globally, yet sustained provisioning of these forest ecosystem services may be threatened by hunting-induced extinctions of plant–animal mutualisms that maintain long-term forest dynamics. Large-bodied Atelinae primates and tapirs in particular offer nonredundant seed-dispersal services for many large-seeded Neotropical tree species, which on average have higher wood density than smaller-seeded and wind-dispersed trees. We used field data and models to project the spatial impact of hunting on large primates by ∼1 million rural households throughout the Brazilian Amazon. We then used a unique baseline dataset on 2,345 1-ha tree plots arrayed across the Brazilian Amazon to model changes in aboveground forest biomass under different scenarios of hunting-induced large-bodied frugivore extirpation. We project that defaunation of the most harvest-sensitive species will lead to losses in aboveground biomass of between 2.5–5.8% on average, with some losses as high as 26.5–37.8%. These findings highlight an urgent need to manage the sustainability of game hunting in both protected and unprotected tropical forests, and place full biodiversity integrity, including populations of large frugivorous vertebrates, firmly in the agenda of reducing emissions from deforestation and forest degradation (REDD+) programs. PMID:26811455

Seasonal and interannual variability of climate and vegetation indices across the Amazon.

PubMed

Brando, Paulo M; Goetz, Scott J; Baccini, Alessandro; Nepstad, Daniel C; Beck, Pieter S A; Christman, Mary C

2010-08-17

Drought exerts a strong influence on tropical forest metabolism, carbon stocks, and ultimately the flux of carbon to the atmosphere. Satellite-based studies have suggested that Amazon forests green up during droughts because of increased sunlight, whereas field studies have reported increased tree mortality during severe droughts. In an effort to reconcile these apparently conflicting findings, we conducted an analysis of climate data, field measurements, and improved satellite-based measures of forest photosynthetic activity. Wet-season precipitation and plant-available water (PAW) decreased over the Amazon Basin from 1996-2005, and photosynthetically active radiation (PAR) and air dryness (expressed as vapor pressure deficit, VPD) increased from 2002-2005. Using improved enhanced vegetation index (EVI) measurements (2000-2008), we show that gross primary productivity (expressed as EVI) declined with VPD and PAW in regions of sparse canopy cover across a wide range of environments for each year of the study. In densely forested areas, no climatic variable adequately explained the Basin-wide interannual variability of EVI. Based on a site-specific study, we show that monthly EVI was relatively insensitive to leaf area index (LAI) but correlated positively with leaf flushing and PAR measured in the field. These findings suggest that production of new leaves, even when unaccompanied by associated changes in LAI, could play an important role in Basin-wide interannual EVI variability. Because EVI variability was greatest in regions of lower PAW, we hypothesize that drought could increase EVI by synchronizing leaf flushing via its effects on leaf bud development.

Mixing Carrots and Sticks to Conserve Forests in the Brazilian Amazon: A Spatial Probabilistic Modeling Approach

PubMed Central

Börner, Jan; Marinho, Eduardo; Wunder, Sven

2015-01-01

Annual forest loss in the Brazilian Amazon had in 2012 declined to less than 5,000 sqkm, from over 27,000 in 2004. Mounting empirical evidence suggests that changes in Brazilian law enforcement strategy and the related governance system may account for a large share of the overall success in curbing deforestation rates. At the same time, Brazil is experimenting with alternative approaches to compensate farmers for conservation actions through economic incentives, such as payments for environmental services, at various administrative levels. We develop a spatially explicit simulation model for deforestation decisions in response to policy incentives and disincentives. The model builds on elements of optimal enforcement theory and introduces the notion of imperfect payment contract enforcement in the context of avoided deforestation. We implement the simulations using official deforestation statistics and data collected from field-based forest law enforcement operations in the Amazon region. We show that a large-scale integration of payments with the existing regulatory enforcement strategy involves a tradeoff between the cost-effectiveness of forest conservation and landholder incomes. Introducing payments as a complementary policy measure increases policy implementation cost, reduces income losses for those hit hardest by law enforcement, and can provide additional income to some land users. The magnitude of the tradeoff varies in space, depending on deforestation patterns, conservation opportunity and enforcement costs. Enforcement effectiveness becomes a key determinant of efficiency in the overall policy mix. PMID:25650966

Mixing carrots and sticks to conserve forests in the Brazilian Amazon: a spatial probabilistic modeling approach.

PubMed

Börner, Jan; Marinho, Eduardo; Wunder, Sven

2015-01-01

Annual forest loss in the Brazilian Amazon had in 2012 declined to less than 5,000 sqkm, from over 27,000 in 2004. Mounting empirical evidence suggests that changes in Brazilian law enforcement strategy and the related governance system may account for a large share of the overall success in curbing deforestation rates. At the same time, Brazil is experimenting with alternative approaches to compensate farmers for conservation actions through economic incentives, such as payments for environmental services, at various administrative levels. We develop a spatially explicit simulation model for deforestation decisions in response to policy incentives and disincentives. The model builds on elements of optimal enforcement theory and introduces the notion of imperfect payment contract enforcement in the context of avoided deforestation. We implement the simulations using official deforestation statistics and data collected from field-based forest law enforcement operations in the Amazon region. We show that a large-scale integration of payments with the existing regulatory enforcement strategy involves a tradeoff between the cost-effectiveness of forest conservation and landholder incomes. Introducing payments as a complementary policy measure increases policy implementation cost, reduces income losses for those hit hardest by law enforcement, and can provide additional income to some land users. The magnitude of the tradeoff varies in space, depending on deforestation patterns, conservation opportunity and enforcement costs. Enforcement effectiveness becomes a key determinant of efficiency in the overall policy mix.

Monitoring selective logging in western Amazonia with repeat lidar flights

Treesearch

H.E. Andersen; S.E. Reutebuch; R.J. McGaughey; M.V.N. d' Oliveira; M. Keller

2014-01-01

The objective of this study was to test the use of repeat flight, airborne laser scanning data (lidar) for estimating changes associated with low-impact selective logging (approx. 10-15 m3 ha−1 = 5-7% of total standing volume harvested) in natural tropical forests in the Western Brazilian Amazon. Specifically, we investigated change in area...

Ozone measurements in the Amazon

NASA Astrophysics Data System (ADS)

Kirchhoff, V. W. J. H.

Several scientists of the Brazilian Institute for Space Research (Instituto de Pesquisas Espacias, or INPE; headquarters at Sāo Jose dos Campos, Sao Paulo) went to Manaus (3°S, 60°W), in the central region of the Amazon forest during July-August 1985 to study the atmosphere of the equatorial rainforest. The expedition to the Amazon was part of a large binational atmospheric chemistry field campaign that was organized to measure several atmospheric gases of the forest environment. This was definitely the largest scientific field expedition in this field ever performed on Brazilian territory.

Estimating Unbiased Land Cover Change Areas In The Colombian Amazon Using Landsat Time Series And Statistical Inference Methods

NASA Astrophysics Data System (ADS)

Arevalo, P. A.; Olofsson, P.; Woodcock, C. E.

2017-12-01

Unbiased estimation of the areas of conversion between land categories ("activity data") and their uncertainty is crucial for providing more robust calculations of carbon emissions to the atmosphere, as well as their removals. This is particularly important for the REDD+ mechanism of UNFCCC where an economic compensation is tied to the magnitude and direction of such fluxes. Dense time series of Landsat data and statistical protocols are becoming an integral part of forest monitoring efforts, but there are relatively few studies in the tropics focused on using these methods to advance operational MRV systems (Monitoring, Reporting and Verification). We present the results of a prototype methodology for continuous monitoring and unbiased estimation of activity data that is compliant with the IPCC Approach 3 for representation of land. We used a break detection algorithm (Continuous Change Detection and Classification, CCDC) to fit pixel-level temporal segments to time series of Landsat data in the Colombian Amazon. The segments were classified using a Random Forest classifier to obtain annual maps of land categories between 2001 and 2016. Using these maps, a biannual stratified sampling approach was implemented and unbiased stratified estimators constructed to calculate area estimates with confidence intervals for each of the stable and change classes. Our results provide evidence of a decrease in primary forest as a result of conversion to pastures, as well as increase in secondary forest as pastures are abandoned and the forest allowed to regenerate. Estimating areas of other land transitions proved challenging because of their very small mapped areas compared to stable classes like forest, which corresponds to almost 90% of the study area. Implications on remote sensing data processing, sample allocation and uncertainty reduction are also discussed.

Where do forests influence rainfall?

NASA Astrophysics Data System (ADS)

Wang-Erlandsson, Lan; van der Ent, Ruud; Fetzer, Ingo; Keys, Patrick; Savenije, Hubert; Gordon, Line

2017-04-01

Forests play a major role in hydrology. Not only by immediate control of soil moisture and streamflow, but also by regulating climate through evaporation (i.e., transpiration, interception, and soil evaporation). The process of evaporation travelling through the atmosphere and returning as precipitation on land is known as moisture recycling. Whether evaporation is recycled depends on wind direction and geography. Moisture recycling and forest change studies have primarily focused on either one region (e.g. the Amazon), or one biome type (e.g. tropical humid forests). We will advance this via a systematic global inter-comparison of forest change impacts on precipitation depending on both biome type and geographic location. The rainfall effects are studied for three contemporary forest changes: afforestation, deforestation, and replacement of mature forest by forest plantations. Furthermore, as there are indications in the literature that moisture recycling in some places intensifies during dry years, we will also compare the rainfall impacts of forest change between wet and dry years. We model forest change effects on evaporation using the global hydrological model STEAM and trace precipitation changes using the atmospheric moisture tracking scheme WAM-2layers. This research elucidates the role of geographical location of forest change driven modifications on rainfall as a function of the type of forest change and climatic conditions. These knowledge gains are important at a time of both rapid forest and climate change. Our conclusions nuance our understanding of how forests regulate climate and pinpoint hotspot regions for forest-rainfall coupling.

Carbon emissions risk map from deforestation in the tropical Amazon

NASA Astrophysics Data System (ADS)

Ometto, J.; Soler, L. S.; Assis, T. D.; Oliveira, P. V.; Aguiar, A. P.

2011-12-01

Assis, Pedro Valle This work aims to estimate the carbon emissions from tropical deforestation in the Brazilian Amazon associated to the risk assessment of future land use change. The emissions are estimated by incorporating temporal deforestation dynamics, accounting for the biophysical and socioeconomic heterogeneity in the region, as well secondary forest growth dynamic in abandoned areas. The land cover change model that supported the risk assessment of deforestation, was run based on linear regressions. This method takes into account spatial heterogeneity of deforestation as the spatial variables adopted to fit the final regression model comprise: environmental aspects, economic attractiveness, accessibility and land tenure structure. After fitting a suitable regression models for each land cover category, the potential of each cell to be deforested (25x25km and 5x5 km of resolution) in the near future was used to calculate the risk assessment of land cover change. The carbon emissions model combines high-resolution new forest clear-cut mapping and four alternative sources of spatial information on biomass distribution for different vegetation types. The risk assessment map of CO2 emissions, was obtained by crossing the simulation results of the historical land cover changes to a map of aboveground biomass contained in the remaining forest. This final map represents the risk of CO2 emissions at 25x25km and 5x5 km until 2020, under a scenario of carbon emission reduction target.

Projected increases in the annual flood pulse of the Western Amazon

NASA Astrophysics Data System (ADS)

Zulkafli, Zed; Buytaert, Wouter; Manz, Bastian; Véliz Rosas, Claudia; Willems, Patrick; Lavado-Casimiro, Waldo; Guyot, Jean-Loup; Santini, William

2016-01-01

The impact of a changing climate on the Amazon basin is a subject of intensive research because of its rich biodiversity and the significant role of rainforests in carbon cycling. Climate change has also a direct hydrological impact, and increasing efforts have focused on understanding the hydrological dynamics at continental and subregional scales, such as the Western Amazon. New projections from the Coupled Model Inter-comparison Project Phase 5 ensemble indicate consistent climatic warming and increasing seasonality of precipitation in the Peruvian Amazon basin. Here we use a distributed land surface model to quantify the potential impact of this change in the climate on the hydrological regime of the upper Amazon river. Using extreme value analysis, historical and future projections of the annual minimum, mean, and maximum river flows are produced for a range of return periods between 1 and 100 yr. We show that the RCP 4.5 and 8.5 scenarios of climate change project an increased severity of the wet season flood pulse (7.5% and 12% increases respectively for the 100 yr return floods). These findings agree with previously projected increases in high extremes under the Special Report on Emissions Scenarios climate projections, and are important to highlight due to the potential consequences on reproductive processes of in-stream species, swamp forest ecology, and socio-economy in the floodplain, amidst a growing literature that more strongly emphasises future droughts and their impact on the viability of the rainforest system over greater Amazonia.

Isoprene photochemistry over the Amazon rainforest

DOE PAGES

Liu, Yingjun; Brito, Joel; Dorris, Matthew R.; ...

2016-05-31

Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO 2) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK +more » MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4–0.6. This result implies a ratio of the reaction rate of ISOPOO with HO2 to that with NO of approximately unity. Also, a value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). In conclusion, this abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.« less

Isoprene photochemistry over the Amazon rainforest

PubMed Central

Liu, Yingjun; Brito, Joel; Dorris, Matthew R.; Rivera-Rios, Jean C.; Seco, Roger; Bates, Kelvin H.; Artaxo, Paulo; Duvoisin, Sergio; Keutsch, Frank N.; Kim, Saewung; Goldstein, Allen H.; Guenther, Alex B.; Manzi, Antonio O.; Souza, Rodrigo A. F.; Springston, Stephen R.; Watson, Thomas B.; McKinney, Karena A.

2016-01-01

Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO2) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4–0.6. This result implies a ratio of the reaction rate of ISOPOO with HO2 to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest. PMID:27185928

A long pollen record from lowland Amazonia: Forest and cooling in glacial times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colinvaux, P.A.; Moreno, J.E.; Bush, M.B.

A continuous pollen history of more than 40,000 years was obtained from a lake in the lowland Amazon rain forest. Pollen spectra demonstrate that tropical rain forest occupied the region continuously and that savannas or grasslands were not present during the last glacial maximum. The data suggest that the western Amazon forest was not fragmented into refugia in glacial times and that the lowlands were not a source of dust. Glacial age forests were comparable to modern forests but also included species now restricted to higher evaluations by temperature, suggesting a cooling of the order of 5{degrees} to 6{degrees}C. 23more » refs., 22 tabs.« less

Measurements of atmospheric hydrocarbons and biogenic emission fluxes in the Amazon boundary layer

NASA Technical Reports Server (NTRS)

Zimmerman, P. R.; Greenberg, J. P.; Westberg, C. E.

1988-01-01

Tropospheric mixing ratios of methane, C2-C10 hydrocarbons, and carbon monoxide were measured over the Amazon tropical forest near Manaus, Amazonas, Brazil, in July and August 1985. The measurements, consisting mostly of altitude profiles of these gases, were all made within the atmospheric boundary layer up to an altitude of 1000 m above ground level. Data characterize the diurnal hydrocarbon composition of the boundary layer. Biogenic emissions of isoprene control hydroxyl radical concentrations over the forest. Biogenic emission fluxes of isoprene and terpenes are estimated to be 25,000 micrograms/sq m per day and 5600 micrograms/sq m per day, respectively. This isoprene emission is equivalent to 2 percent of the net primary productivity of the tropical forest. Atmospheric oxidation of biogenic isoprene and terpenes emissions from the Amazon forest may account for daily increases of 8-13 ppb for carbon monoxide in the planetary boundary layer.

Tropical forest carbon balance: effects of field- and satellite-based mortality regimes on the dynamics and the spatial structure of Central Amazon forest biomass

NASA Astrophysics Data System (ADS)

Di Vittorio, Alan V.; Negrón-Juárez, Robinson I.; Higuchi, Niro; Chambers, Jeffrey Q.

2014-03-01

Debate continues over the adequacy of existing field plots to sufficiently capture Amazon forest dynamics to estimate regional forest carbon balance. Tree mortality dynamics are particularly uncertain due to the difficulty of observing large, infrequent disturbances. A recent paper (Chambers et al 2013 Proc. Natl Acad. Sci. 110 3949-54) reported that Central Amazon plots missed 9-17% of tree mortality, and here we address ‘why’ by elucidating two distinct mortality components: (1) variation in annual landscape-scale average mortality and (2) the frequency distribution of the size of clustered mortality events. Using a stochastic-empirical tree growth model we show that a power law distribution of event size (based on merged plot and satellite data) is required to generate spatial clustering of mortality that is consistent with forest gap observations. We conclude that existing plots do not sufficiently capture losses because their placement, size, and longevity assume spatially random mortality, while mortality is actually distributed among differently sized events (clusters of dead trees) that determine the spatial structure of forest canopies.

Combined impacts due to deforestation and the forest fires in the Amazonia and the global climate change on the future climate of South America: a modelling study

NASA Astrophysics Data System (ADS)

de Oliveira, G. S.; Cardoso, M. F.; Sanches, M. B.; Alexandre, F. F.

2014-12-01

Since the late 1980s a large number of numerical experiments with atmospheric general circulation models has been used to assess the impacts of deforestation on global and regional climate, and one of the main motivations is the Amazon rainforest. In the same way, in the last decade several studies have shown that a higher concentration of CO2 in the atmosphere could lead changes in climate in the Amazon region. In this study we performed new analyses to quantify how deforestation, fire and the increase in atmospheric CO2 concentration may combine to affect the climate in Amazonia during this century. For the projection of land use was considered a spatially explicit land use scenario from Aguiar et al. (2013). The scenario was built using LuccME generic modelling framework and the potential of change considering the proximity to previously deforested areas and also spatial drivers (roads and protected areas). In order to quantify the response of Brazilian Earth System Model, with INLAND-IBIS surface model, to climate change, deforestation and forest fire we performed a suite of simulations in two main categories: 1) the model was running under historical and RCP8.5 greenhouse gas concentration, and 2) the model was forced by the same configuration in 1 but also considering the effects of deforestation and forest fire in Amazon. In summary, the most important changes occur in the East/Northeast and South of the Amazonia and are more evident when are considered all effects (climate change, deforestation and fire). The results show warmer near-surface air temperature in all cases compared to the control case. This relative warming of the deforested land surface is consistent with the reduction in evapotranspiration, the lower leaf area and the lower surface roughness length. There is a reduction in annual precipitation in both cases mainly over eastern/northeastern Amazonia. The reduction in precipitation occurs mainly during the dry season (June-November) in both cases, and there is an increase in dry season length that is more evident when are considered all effects. In summary, we conclude that the synergistic combination of deforestation and climate change resulting from global warming may lead to important impacts that add considerably to the vulnerability of tropical forest ecosystems in the region.

Litter and nutrient flows in tropical upland forest flooded by a hydropower plant in the Amazonian basin.

PubMed

Pereira, Guilherme Henrique A; Jordão, Henos Carlos K; Silva, Vanessa Francieli V; Pereira, Marcos Gervasio

2016-12-01

Extensive areas in the Brazilian Amazon have been flooded for the construction of hydroelectric dams. However, the water regime of these areas affects the dynamics of igarapés (streams) in adjacent terra firme (upland forests). When the reservoirs are filled, the water levels of streams rise above the normal levels and upland bank forests are flooded. We investigated how this flooding affects the litterfall and nutrient input in the upland forests upstream of a hydroelectric dam reservoir in the Central Amazonia. When the reservoir was filled, the forests were flooded and produced more than twice the litter (8.80Mg·ha -1 yr -1 ), with three times more leaves (6.36Mg·ha -1 yr -1 ) than when they were not flooded (4.20 and 1.92Mg·ha -1 yr -1 , respectively). During flooding, the decomposition rate was four times lower in flooded forests (0.328g·g -1 yr -1 ) than in control forests (1.460g·g -1 yr -1 ). Despite this, the flooding did not favor litter or nutrient accumulation. Therefore, dam construction changes the organic matter and nutrient cycling in upland Amazon rainforests. This may influence the important role that they play in organic matter dynamics and could have consequences for the regional carbon balance and, ultimately, global climate. Copyright © 2016 Elsevier B.V. All rights reserved.

Implication of Forest-Savanna Dynamics on Biomass and Carbon Stock: Effectiveness of an Amazonian Ecological Station

NASA Astrophysics Data System (ADS)

Couto-Santos, F. R.; Luizao, F. J.

2014-12-01

The forests-savanna advancement/retraction process seems to play an important role in the global carbon cycle and in the climate-vegetation balance maintenance in the Amazon. To contribute with long term carbon dynamics and assess effectiveness of a protected area in reduce carbon emissions in Brazilian Amazon transitional areas, variations in forest-savanna mosaics biomass and carbon stock within Maraca Ecological Station (MES), Roraima/Brazil, and its outskirts non-protected areas were compared. Composite surface soil samples and indirect methods based on regression models were used to estimate aboveground tree biomass accumulation and assess vegetation and soil carbon stock along eleven 0.6 ha transects perpendicular to the forest-savanna limits. Aboveground biomass and carbon accumulation were influenced by vegetation structure, showing higher values within protected area, with great contribution of trees above 40 cm in diameter. In the savanna environments of protected areas, a higher tree density and carbon stock up to 30 m from the border confirmed a forest encroachment. This pointed that MES acts as carbon sink, even under variations in soil fertility gradient, with a potential increase of the total carbon stock from 9 to 150 Mg C ha-1. Under 20 years of fire and disturbance management, the results indicated the effectiveness of this protected area to reduce carbon emissions and mitigate greenhouse and climate change effects in a forest-savanna transitional area in Brazilian Northern Amazon. The contribution of this study in understanding rates and reasons for biomass and carbon variation, under different management strategies, should be considered the first approximation to assist policies of reducing emissions from deforestation and forest degradation (REDD) from underresearched Amazonian ecotone; despite further efforts in this direction are still needed. FINANCIAL SUPPORT: Boticário Group Foundation (Fundação Grupo Boticário); National Council for Scientific and Technological Development (CNPq); Minas Gerais State Research Foundation (FAPEMIG).

Studying the Effects of Amazonian Land Cover Change on Glacier Mass Balance in the Tropical Andes

NASA Astrophysics Data System (ADS)

Mark, B. G.; Fernandez, A.; Gabrielli, P.; Montenegro, A.; Postigo, J.; Hellstrom, R. A.

2017-12-01

Recent research has highlighted several ongoing environmental changes occurring across Tropical South America, including Andean glacier retreat, drought, as well as changes in land-use and land-cover. As the regional climate of the area is mostly characterized by land-ocean interactions, the atmospheric convection in the Amazon, and the effect of the Andes on circulation patterns, it follows that changes in one of those regions may affect the other. Most scholars who have studied the causes of tropical glaciers' fluctuations have not analyzed the linkages with changes in the Amazon with the same attention paid to the influence of Pacific sea surface temperature. Here we study the response of glacier surface mass balance in the Cordillera Blanca, Peru (10°S), to a scenario where the Amazonian rainforest is replaced by savannas. We ran climatic simulations at 2-km spatial resolution utilizing the Weather Research and Forecasting (WRF) model considering two scenarios: (a) control (CRTL), with today's rainforest extent; and (b) land cover change (LCC), where all the rainforest was replaced by savanna. WRF output was in turn ingested into a glacier energy and mass balance (GEMB) model that we validate by reconstructing both the accumulated mass balance from available observations, and the altitudinal distribution of mass balance in the region. Seasonal comparison between CRTL and LCC scenarios indicates that forest replacement by savanna results in more positive glacier mass balance. This shift to more positive mass balance contrasts with a (WRF) modeled rise in the elevation of the freezing line (0°C) between 30 to 120 m for the LCC scenario. Our results are surprising because most previous studies have shown that reducing Amazon forest cover diminishes rainfall and increases temperature, suggesting that glaciers should lose mass. We hypothesize and discuss implications of possible land-atmospheric processes that might drive this tropical glacier response to Amazonian forest change, including: the large-scale influence of Amazonian albedo change on the interaction between the Walker and Hadley cells and the effect of mountain meteorology dynamics.

Volatile isoprenoids as defense compounds during abiotic stress in tropical plants

NASA Astrophysics Data System (ADS)

Jardine, K.

2015-12-01

Emissions of volatile isoprenoids from tropical forests play central roles in atmospheric processes by fueling atmospheric chemistry resulting in modified aerosol and cloud lifecycles and their associated feedbacks with the terrestrial biosphere. However, the identities of tropical isoprenoids, their biological and environmental controls, and functions within plants and ecosystems remain highly uncertain. As part of the DOE ARM program's GoAmazon 2014/15 campaign, extensive field and laboratory observations of volatile isoprenoids are being conducted in the central Amazon. Here we report the results of our completed and ongoing activities at the ZF2 forest reserve in the central Amazon. Among the results of the research are the suprisingly high abundance of light-dependent volatile isoprenoid emissions across abundant tree genera in the Amazon in both primary and secondary forests, the discovery of highly reactive monoterpene emissions from Amazon trees, and evidence for the importance of volatile isoprenoids in protecting photosynthesis during oxidative stress under elevated temperatures including energy consumption and direct antioxidant functions and a tight connection betwen volatile isoprenoid emissions, photorespiration, and CO2 recycling within leaves. The results highlight the need to model allocation of carbon to isoprenoids during elevated temperature stress in the tropics.

The future of the Amazon: new perspectives from climate, ecosystem and social sciences.

PubMed

Betts, Richard A; Malhi, Yadvinder; Roberts, J Timmons

2008-05-27

The potential loss or large-scale degradation of the tropical rainforests has become one of the iconic images of the impacts of twenty-first century environmental change and may be one of our century's most profound legacies. In the Amazon region, the direct threat of deforestation and degradation is now strongly intertwined with an indirect challenge we are just beginning to understand: the possibility of substantial regional drought driven by global climate change. The Amazon region hosts more than half of the world's remaining tropical forests, and some parts have among the greatest concentrations of biodiversity found anywhere on Earth. Overall, the region is estimated to host about a quarter of all global biodiversity. It acts as one of the major 'flywheels' of global climate, transpiring water and generating clouds, affecting atmospheric circulation across continents and hemispheres, and storing substantial reserves of biomass and soil carbon. Hence, the ongoing degradation of Amazonia is a threat to local climate stability and a contributor to the global atmospheric climate change crisis. Conversely, the stabilization of Amazonian deforestation and degradation would be an opportunity for local adaptation to climate change, as well as a potential global contributor towards mitigation of climate change. However, addressing deforestation in the Amazon raises substantial challenges in policy, governance, sustainability and economic science. This paper introduces a theme issue dedicated to a multidisciplinary analysis of these challenges.

Multi-stage approach to estimate forest biomass in degraded area by fire and selective logging

NASA Astrophysics Data System (ADS)

Santos, E. G.; Shimabukuro, Y. E.; Arai, E.; Duarte, V.; Jorge, A.; Gasparini, K.

2017-12-01

The Amazon forest has been the target of several threats throughout the years. Anthropogenic disturbances in the region can significantly alter this environment, affecting directly the dynamics and structure of tropical forests. Monitoring these threats of forest degradation across the Amazon is of paramount to understand the impacts of disturbances in the tropics. With the advance of new technologies such as Light Detection and Ranging (LiDAR) the quantification and development of methodologies to monitor forest degradation in the Amazon is possible and may bring considerable contributions to this topic. The objective of this study was to use remote sensing data to assess and estimate the aboveground biomass (AGB) across different levels of degradation (fire and selective logging) using multi-stage approach between airborne LiDAR and orbital image. The study area is in the northern part of the state of Mato Grosso, Brazil. It is predominantly characterized by agricultural land and remnants of the Amazon Forest intact and degraded by either anthropic or natural reasons (selective logging and/or fire). More specifically, the study area corresponds to path/row 226/69 of OLI/Landsat 8 image. With a forest mask generated from the multi-resolution segmentation, agriculture and forest areas, forest biomass was calculated from LiDAR data and correlated with texture images, vegetation indices and fraction images by Linear Spectral Unmixing of OLI/Landsat 8 image and extrapolated to the entire scene 226/69 and validated with field inventories. The results showed that there is a moderate to strong correlation between forest biomass and texture data, vegetation indices and fraction images. With that, it is possible to extract biomass information and create maps using optical data, specifically by combining vegetation indices, which contain forest greening information with texture data that contains forest structure information. Then it was possible to extrapolate the biomass to the entire scene (226/69) from the optical data and to obtain an overview of the biomass distribution throughout the area.

Floodplains as an Achilles’ heel of Amazonian forest resilience

PubMed Central

Flores, Bernardo M.; Holmgren, Milena; van Nes, Egbert H.; Jakovac, Catarina C.; Mesquita, Rita C. G.; Scheffer, Marten

2017-01-01

The massive forests of central Amazonia are often considered relatively resilient against climatic variation, but this view is challenged by the wildfires invoked by recent droughts. The impact of such fires that spread from pervasive sources of ignition may reveal where forests are less likely to persist in a drier future. Here we combine field observations with remotely sensed information for the whole Amazon to show that the annually inundated lowland forests that run through the heart of the system may be trapped relatively easily into a fire-dominated savanna state. This lower forest resilience on floodplains is suggested by patterns of tree cover distribution across the basin, and supported by our field and remote sensing studies showing that floodplain fires have a stronger and longer-lasting impact on forest structure as well as soil fertility. Although floodplains cover only 14% of the Amazon basin, their fires can have substantial cascading effects because forests and peatlands may release large amounts of carbon, and wildfires can spread to adjacent uplands. Floodplains are thus an Achilles’ heel of the Amazon system when it comes to the risk of large-scale climate-driven transitions. PMID:28396440

Drought impact on forest carbon dynamics and fluxes in Amazonia.

PubMed

Doughty, Christopher E; Metcalfe, D B; Girardin, C A J; Amézquita, F Farfán; Cabrera, D Galiano; Huasco, W Huaraca; Silva-Espejo, J E; Araujo-Murakami, A; da Costa, M C; Rocha, W; Feldpausch, T R; Mendoza, A L M; da Costa, A C L; Meir, P; Phillips, O L; Malhi, Y

2015-03-05

In 2005 and 2010 the Amazon basin experienced two strong droughts, driven by shifts in the tropical hydrological regime possibly associated with global climate change, as predicted by some global models. Tree mortality increased after the 2005 drought, and regional atmospheric inversion modelling showed basin-wide decreases in CO2 uptake in 2010 compared with 2011 (ref. 5). But the response of tropical forest carbon cycling to these droughts is not fully understood and there has been no detailed multi-site investigation in situ. Here we use several years of data from a network of thirteen 1-ha forest plots spread throughout South America, where each component of net primary production (NPP), autotrophic respiration and heterotrophic respiration is measured separately, to develop a better mechanistic understanding of the impact of the 2010 drought on the Amazon forest. We find that total NPP remained constant throughout the drought. However, towards the end of the drought, autotrophic respiration, especially in roots and stems, declined significantly compared with measurements in 2009 made in the absence of drought, with extended decreases in autotrophic respiration in the three driest plots. In the year after the drought, total NPP remained constant but the allocation of carbon shifted towards canopy NPP and away from fine-root NPP. Both leaf-level and plot-level measurements indicate that severe drought suppresses photosynthesis. Scaling these measurements to the entire Amazon basin with rainfall data, we estimate that drought suppressed Amazon-wide photosynthesis in 2010 by 0.38 petagrams of carbon (0.23-0.53 petagrams of carbon). Overall, we find that during this drought, instead of reducing total NPP, trees prioritized growth by reducing autotrophic respiration that was unrelated to growth. This suggests that trees decrease investment in tissue maintenance and defence, in line with eco-evolutionary theories that trees are competitively disadvantaged in the absence of growth. We propose that weakened maintenance and defence investment may, in turn, cause the increase in post-drought tree mortality observed at our plots.

Basin-wide variations in Amazon forest structure and function are mediated by both soils and climate

NASA Astrophysics Data System (ADS)

Quesada, C. A.; Phillips, O. L.; Schwarz, M.; Czimczik, C. I.; Baker, T. R.; Patiño, S.; Fyllas, N. M.; Hodnett, M. G.; Herrera, R.; Almeida, S.; Alvarez Dávila, E.; Arneth, A.; Arroyo, L.; Chao, K. J.; Dezzeo, N.; Erwin, T.; di Fiore, A.; Higuchi, N.; Honorio Coronado, E.; Jimenez, E. M.; Killeen, T.; Lezama, A. T.; Lloyd, G.; López-González, G.; Luizão, F. J.; Malhi, Y.; Monteagudo, A.; Neill, D. A.; Núñez Vargas, P.; Paiva, R.; Peacock, J.; Peñuela, M. C.; Peña Cruz, A.; Pitman, N.; Priante Filho, N.; Prieto, A.; Ramírez, H.; Rudas, A.; Salomão, R.; Santos, A. J. B.; Schmerler, J.; Silva, N.; Silveira, M.; Vásquez, R.; Vieira, I.; Terborgh, J.; Lloyd, J.

2012-06-01

Forest structure and dynamics vary across the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. Soil samples were collected in a total of 59 different forest plots across the Amazon Basin and analysed for exchangeable cations, carbon, nitrogen and pH, with several phosphorus fractions of likely different plant availability also quantified. Physical properties were additionally examined and an index of soil physical quality developed. Bivariate relationships of soil and climatic properties with above-ground wood productivity, stand-level tree turnover rates, above-ground wood biomass and wood density were first examined with multivariate regression models then applied. Both forms of analysis were undertaken with and without considerations regarding the underlying spatial structure of the dataset. Despite the presence of autocorrelated spatial structures complicating many analyses, forest structure and dynamics were found to be strongly and quantitatively related to edaphic as well as climatic conditions. Basin-wide differences in stand-level turnover rates are mostly influenced by soil physical properties with variations in rates of coarse wood production mostly related to soil phosphorus status. Total soil P was a better predictor of wood production rates than any of the fractionated organic- or inorganic-P pools. This suggests that it is not only the immediately available P forms, but probably the entire soil phosphorus pool that is interacting with forest growth on longer timescales. A role for soil potassium in modulating Amazon forest dynamics through its effects on stand-level wood density was also detected. Taking this into account, otherwise enigmatic variations in stand-level biomass across the Basin were then accounted for through the interacting effects of soil physical and chemical properties with climate. A hypothesis of self-maintaining forest dynamic feedback mechanisms initiated by edaphic conditions is proposed. It is further suggested that this is a major factor determining endogenous disturbance levels, species composition, and forest productivity across the Amazon Basin.

Applications of AMS {sup 14}C on Climate and Archaeology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomes, P. R. S.

2007-10-26

We describe the Accelerator Mass Spectrometry (AMS) technique and two distinct applications of its use with {sup 14}C to study environmental problems in Brazil, such as forest fires and climate changes in the Amazon region and archaeological studies on the early settlements in the Southeast Brazilian coast.

C-13/C-12 of atmospheric CO2 in the Amazon basin - Forest and river sources

NASA Technical Reports Server (NTRS)

Quay, Paul; King, Stagg; Wilbur, Dave; Richey, Jeffrey; Wofsy, Steven

1989-01-01

Results are presented of measurements of the CO2 concentrations and C-13/C-12 ratios in CO2 in air samples collected from within the Amazonian rain forest and over the Amazon river between 1982 and 1987. Results indicate the presence of a diurnal cycle in the CO2 concentration and the C-13/C-12 ratio. It was found that the CO2 input to air in the forest was derived from the soil respiration, and the CO2 input to air over the Amazon river was derived from the degassing of CO2 from the river. It was also found that plants growing at heights lower than 7 m assimilate soil-derived CO2 with a low C-13/C-12 ratio.

The spatial pattern and dominant drivers of woody cover change in Latin America and Caribbean from 2001 to 2010

NASA Astrophysics Data System (ADS)

Clark, M.; Aide, T.; Riner, G.; Redo, D.; Grau, H.; Bonilla-Moheno, M.; Lopez-Carr, D.; Levy, M.

2011-12-01

Change in woody vegetation (i.e., forests, shrublands) is a major component of global environmental change: it directly affects biodiversity, the global carbon budget, and ecosystem function. For several decades, remote sensing technology has been used to document deforestation in Latin America and the Caribbean (LAC), although mostly at local to regional scales (e.g., moist forests of the Amazon basin). Most studies have focused on forest loss, some local-scale studies have mapped forest recovery, with contrasting forest dynamics attributed to shifting demographic and socio-economic factors. For example, local population change (rural-urban migration) can stimulate forest recovery on abandoned land, while increasing global food demand may drive regional expansion of mechanized agriculture. However, there are no studies in LAC that simultaneously map both loss and gain in woody vegetation at continental, national, and municipality scales with consistent data sources, methods and accuracy; and thus, we lack a comprehensive assessment of the spatial distribution of woody vegetation change and the relative importance of the multi-scale drivers of this change. We overcame this limitation by producing annual land-cover maps between 2001 and 2010 for each of the >16,000 municipalities in LAC. We focused on mapping municipality-scale trends in three broad classes: woody vegetation, mixed woody/plantations, and agriculture/herbaceous vegetation. Our area estimates show that woody vegetation change during the past decade was dominated by deforestation, or loss (-541,830 km2), particularly in the Amazon basin moist forest and the tropical-subtropical Cerrado and Chaco ecoregions, where large swaths of forest have been transformed to pastures and agricultural lands. Extensive areas (362,431 km2) in LAC also gained woody vegetation, particularly in regions too dry or too steep for modern agriculture, including the desert/xeric shrub biome in NE Brazil and northern Mexico, the conifer forest and tropical dry forest biomes in Central America, and Andean montane areas. We used Random Forests regression, a non-linear and non-parametric analytical technique, as a means to assess the relative importance of demographic and environmental variables in explaining trends in woody vegetation at the municipality scale. We found no association between population change and woody vegetation change at this scale, suggesting that global demand for food (e.g., soybean production for export to China) is a more important driver of deforestation than local population change. Our results emphasize that both loss and gain (i.e., deforestation and reforestation) need to be addressed in a research framework that links multiple spatial scales of land change with global drivers of change.

The Net Carbon Flux due to Deforestation and Forest Re-Growth in the Brazilian Amazon: Analysis using a Process-Based Model

NASA Technical Reports Server (NTRS)

Hirsch, A. I.; Little, W. S.; Houghton, R. A.; Scott, N. A.; White, J. D.

2004-01-01

We developed a process-based model of forest growth, carbon cycling, and land cover dynamics named CARLUC (for CARbon and Land Use Change) to estimate the size of terrestrial carbon pools in terra firme (non-flooded) forests across the Brazilian Legal Amazon and the net flux of carbon resulting from forest disturbance and forest recovery from disturbance. Our goal in building the model was to construct a relatively simple ecosystem model that would respond to soil and climatic heterogeneity that allows us to study of the impact of Amazonian deforestation, selective logging, and accidental fire on the global carbon cycle. This paper focuses on the net flux caused by deforestation and forest re-growth over the period from 1970-1998. We calculate that the net flux to the atmosphere during this period reached a maximum of approx. 0.35 PgC/yr (1PgC = 1 x 10(exp I5) gC) in 1990, with a cumulative release of approx. 7 PgC from 1970- 1998. The net flux is higher than predicted by an earlier study by a total of 1 PgC over the period 1989-1 998 mainly because CARLUC predicts relatively high mature forest carbon storage compared to the datasets used in the earlier study. Incorporating the dynamics of litter and soil carbon pools into the model increases the cumulative net flux by approx. 1 PgC from 1970-1998, while different assumptions about land cover dynamics only caused small changes. The uncertainty of the net flux, calculated with a Monte-Carlo approach, is roughly 35% of the mean value (1 SD).

An integrated remote sensing and GIS approach for monitoring areas affected by selective logging: A case study in northern Mato Grosso, Brazilian Amazon

NASA Astrophysics Data System (ADS)

Grecchi, Rosana Cristina; Beuchle, René; Shimabukuro, Yosio Edemir; Aragão, Luiz E. O. C.; Arai, Egidio; Simonetti, Dario; Achard, Frédéric

2017-09-01

Forest cover disturbances due to processes such as logging and forest fires are a widespread issue especially in the tropics, and have heavily affected forest biomass and functioning in the Brazilian Amazon in the past decades. Satellite remote sensing has played a key role for assessing logging activities in this region; however, there are still remaining challenges regarding the quantification and monitoring of these processes affecting forested lands. In this study, we propose a new method for monitoring areas affected by selective logging in one of the hotspots of Mato Grosso state in the Brazilian Amazon, based on a combination of object-based and pixel-based classification approaches applied on remote sensing data. Logging intensity and changes over time are assessed within grid cells of 300 m × 300 m spatial resolution. Our method encompassed three main steps: (1) mapping forest/non-forest areas through an object-based classification approach applied to a temporal series of Landsat images during the period 2000-2015, (2) mapping yearly logging activities from soil fraction images on the same Landsat data series, and (3) integrating information from previous steps within a regular grid-cell of 300 m × 300 m in order to monitor disturbance intensities over this 15-years period. The overall accuracy of the baseline forest/non-forest mask (year 2000) and of the undisturbed vs disturbed forest (for selected years) were 93% and 84% respectively. Our results indicate that annual forest disturbance rates, mainly due to logging activities, were higher than annual deforestation rates during the whole period of study. The deforested areas correspond to circa 25% of the areas affected by forest disturbances. Deforestation rates were highest from 2001 to 2005 and then decreased considerably after 2006. In contrast, the annual forest disturbance rates show high temporal variability with a slow decrease over the 15-year period, resulting in a significant increase of the ratio between disturbed and deforested areas. Although the majority of the areas, which have been affected by selective logging during the period 2000-2014, were not deforested by 2015, more than 70% of the deforested areas in 2015 had been at least once identified as disturbed forest during that period.

An integrated remote sensing and GIS approach for monitoring areas affected by selective logging: A case study in northern Mato Grosso, Brazilian Amazon.

PubMed

Grecchi, Rosana Cristina; Beuchle, René; Shimabukuro, Yosio Edemir; Aragão, Luiz E O C; Arai, Egidio; Simonetti, Dario; Achard, Frédéric

2017-09-01

Forest cover disturbances due to processes such as logging and forest fires are a widespread issue especially in the tropics, and have heavily affected forest biomass and functioning in the Brazilian Amazon in the past decades. Satellite remote sensing has played a key role for assessing logging activities in this region; however, there are still remaining challenges regarding the quantification and monitoring of these processes affecting forested lands. In this study, we propose a new method for monitoring areas affected by selective logging in one of the hotspots of Mato Grosso state in the Brazilian Amazon, based on a combination of object-based and pixel-based classification approaches applied on remote sensing data. Logging intensity and changes over time are assessed within grid cells of 300 m × 300 m spatial resolution. Our method encompassed three main steps: (1) mapping forest/non-forest areas through an object-based classification approach applied to a temporal series of Landsat images during the period 2000-2015, (2) mapping yearly logging activities from soil fraction images on the same Landsat data series, and (3) integrating information from previous steps within a regular grid-cell of 300 m × 300 m in order to monitor disturbance intensities over this 15-years period. The overall accuracy of the baseline forest/non-forest mask (year 2000) and of the undisturbed vs disturbed forest (for selected years) were 93% and 84% respectively. Our results indicate that annual forest disturbance rates, mainly due to logging activities, were higher than annual deforestation rates during the whole period of study. The deforested areas correspond to circa 25% of the areas affected by forest disturbances. Deforestation rates were highest from 2001 to 2005 and then decreased considerably after 2006. In contrast, the annual forest disturbance rates show high temporal variability with a slow decrease over the 15-year period, resulting in a significant increase of the ratio between disturbed and deforested areas. Although the majority of the areas, which have been affected by selective logging during the period 2000-2014, were not deforested by 2015, more than 70% of the deforested areas in 2015 had been at least once identified as disturbed forest during that period.

The Spatial Distribution of Forest Biomass in the Brazilian Amazon: A Comparison of Estimates

NASA Technical Reports Server (NTRS)

Houghton, R. A.; Lawrence, J. L.; Hackler, J. L.; Brown, S.

2001-01-01

The amount of carbon released to the atmosphere as a result of deforestation is determined, in part, by the amount of carbon held in the biomass of the forests converted to other uses. Uncertainty in forest biomass is responsible for much of the uncertainty in current estimates of the flux of carbon from land-use change. We compared several estimates of forest biomass for the Brazilian Amazon, based on spatial interpolations of direct measurements, relationships to climatic variables, and remote sensing data. We asked three questions. First, do the methods yield similar estimates? Second, do they yield similar spatial patterns of distribution of biomass? And, third, what factors need most attention if we are to predict more accurately the distribution of forest biomass over large areas? Amazonian forests (including dead and below-ground biomass) vary by more than a factor of two, from a low of 39 PgC to a high of 93 PgC. Furthermore, the estimates disagree as to the regions of high and low biomass. The lack of agreement among estimates confirms the need for reliable determination of aboveground biomass over large areas. Potential methods include direct measurement of biomass through forest inventories with improved allometric regression equations, dynamic modeling of forest recovery following observed stand-replacing disturbances (the approach used in this research), and estimation of aboveground biomass from airborne or satellite-based instruments sensitive to the vertical structure plant canopies.

Seasonal and interannual variability of climate and vegetation indices across the Amazon

PubMed Central

Brando, Paulo M.; Goetz, Scott J.; Baccini, Alessandro; Nepstad, Daniel C.; Beck, Pieter S. A.; Christman, Mary C.

2010-01-01

Drought exerts a strong influence on tropical forest metabolism, carbon stocks, and ultimately the flux of carbon to the atmosphere. Satellite-based studies have suggested that Amazon forests green up during droughts because of increased sunlight, whereas field studies have reported increased tree mortality during severe droughts. In an effort to reconcile these apparently conflicting findings, we conducted an analysis of climate data, field measurements, and improved satellite-based measures of forest photosynthetic activity. Wet-season precipitation and plant-available water (PAW) decreased over the Amazon Basin from 1996−2005, and photosynthetically active radiation (PAR) and air dryness (expressed as vapor pressure deficit, VPD) increased from 2002–2005. Using improved enhanced vegetation index (EVI) measurements (2000–2008), we show that gross primary productivity (expressed as EVI) declined with VPD and PAW in regions of sparse canopy cover across a wide range of environments for each year of the study. In densely forested areas, no climatic variable adequately explained the Basin-wide interannual variability of EVI. Based on a site-specific study, we show that monthly EVI was relatively insensitive to leaf area index (LAI) but correlated positively with leaf flushing and PAR measured in the field. These findings suggest that production of new leaves, even when unaccompanied by associated changes in LAI, could play an important role in Basin-wide interannual EVI variability. Because EVI variability was greatest in regions of lower PAW, we hypothesize that drought could increase EVI by synchronizing leaf flushing via its effects on leaf bud development. PMID:20679201

Variability of carbon and water fluxes following climate extremes over a tropical forest in southwestern Amazonia.

PubMed

Zeri, Marcelo; Sá, Leonardo D A; Manzi, Antônio O; Araújo, Alessandro C; Aguiar, Renata G; von Randow, Celso; Sampaio, Gilvan; Cardoso, Fernando L; Nobre, Carlos A

2014-01-01

The carbon and water cycles for a southwestern Amazonian forest site were investigated using the longest time series of fluxes of CO2 and water vapor ever reported for this site. The period from 2004 to 2010 included two severe droughts (2005 and 2010) and a flooding year (2009). The effects of such climate extremes were detected in annual sums of fluxes as well as in other components of the carbon and water cycles, such as gross primary production and water use efficiency. Gap-filling and flux-partitioning were applied in order to fill gaps due to missing data, and errors analysis made it possible to infer the uncertainty on the carbon balance. Overall, the site was found to have a net carbon uptake of ≈5 t C ha(-1) year(-1), but the effects of the drought of 2005 were still noticed in 2006, when the climate disturbance caused the site to become a net source of carbon to the atmosphere. Different regions of the Amazon forest might respond differently to climate extremes due to differences in dry season length, annual precipitation, species compositions, albedo and soil type. Longer time series of fluxes measured over several locations are required to better characterize the effects of climate anomalies on the carbon and water balances for the whole Amazon region. Such valuable datasets can also be used to calibrate biogeochemical models and infer on future scenarios of the Amazon forest carbon balance under the influence of climate change.

Variability of Carbon and Water Fluxes Following Climate Extremes over a Tropical Forest in Southwestern Amazonia

PubMed Central

Zeri, Marcelo; Sá, Leonardo D. A.; Manzi, Antônio O.; Araújo, Alessandro C.; Aguiar, Renata G.; von Randow, Celso; Sampaio, Gilvan; Cardoso, Fernando L.; Nobre, Carlos A.

2014-01-01

The carbon and water cycles for a southwestern Amazonian forest site were investigated using the longest time series of fluxes of CO2 and water vapor ever reported for this site. The period from 2004 to 2010 included two severe droughts (2005 and 2010) and a flooding year (2009). The effects of such climate extremes were detected in annual sums of fluxes as well as in other components of the carbon and water cycles, such as gross primary production and water use efficiency. Gap-filling and flux-partitioning were applied in order to fill gaps due to missing data, and errors analysis made it possible to infer the uncertainty on the carbon balance. Overall, the site was found to have a net carbon uptake of ≈5 t C ha−1 year−1, but the effects of the drought of 2005 were still noticed in 2006, when the climate disturbance caused the site to become a net source of carbon to the atmosphere. Different regions of the Amazon forest might respond differently to climate extremes due to differences in dry season length, annual precipitation, species compositions, albedo and soil type. Longer time series of fluxes measured over several locations are required to better characterize the effects of climate anomalies on the carbon and water balances for the whole Amazon region. Such valuable datasets can also be used to calibrate biogeochemical models and infer on future scenarios of the Amazon forest carbon balance under the influence of climate change. PMID:24558378

Projections of future meteorological drought and wet periods in the Amazon

PubMed Central

Duffy, Philip B.; Brando, Paulo; Asner, Gregory P.; Field, Christopher B.

2015-01-01

Future intensification of Amazon drought resulting from climate change may cause increased fire activity, tree mortality, and emissions of carbon to the atmosphere across large areas of Amazonia. To provide a basis for addressing these issues, we examine properties of recent and future meteorological droughts in the Amazon in 35 climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that the CMIP5 climate models, as a group, simulate important properties of historical meteorological droughts in the Amazon. In addition, this group of models reproduces observed relationships between Amazon precipitation and regional sea surface temperature anomalies in the tropical Pacific and the North Atlantic oceans. Assuming the Representative Concentration Pathway 8.5 scenario for future drivers of climate change, the models project increases in the frequency and geographic extent of meteorological drought in the eastern Amazon, and the opposite in the West. For the region as a whole, the CMIP5 models suggest that the area affected by mild and severe meteorological drought will nearly double and triple, respectively, by 2100. Extremes of wetness are also projected to increase after 2040. Specifically, the frequency of periods of unusual wetness and the area affected by unusual wetness are projected to increase after 2040 in the Amazon as a whole, including in locations where annual mean precipitation is projected to decrease. Our analyses suggest that continued emissions of greenhouse gases will increase the likelihood of extreme events that have been shown to alter and degrade Amazonian forests. PMID:26460046

Fire and Deforestation Dynamics in South America over the Past 50 Years

NASA Astrophysics Data System (ADS)

van Marle, M.; Field, R. D.; van der Werf, G.

2015-12-01

Fires play an important role in the Earth system and are one of the major sources of greenhouse gases and aerosols. Satellites have been key to understand their spatial and temporal variability in space and time, but the most frequently used satellite datasets start only in 1995. There are still large uncertainties about the frequency and intensity of fires in the pre-satellite time period, especially in regions with active deforestation, which may have changed dramatically in intensity in the past decades influencing fire dynamics. We used two datasets to extend the record of fires and deforestation in the Amazon region back in time: 1) annual forest loss rates starting in 1990 derived from Vegetation Optical Depth (VOD), which is a satellite-based vegetation product that can be used as proxy for forest loss, and 2) horizontal visibility as proxy for fire emissions, reported by weather stations and airports in the Amazon, which started around 1940, and having widespread coverage since 1973. We show that these datasets overlap with fire emission estimates from the Global Fire Emissions Database (GFED) enabling us to estimate fire emissions over the last 50 years. We will discuss how fires have varied over time in this region with globally significant emissions, how droughts have influenced fire activity and deforestation rates, and what the impact is of land-use change caused by fire on emissions in the Amazon region.

Sensitivity of Regional Climate to Deforestation in the Amazon Basin

NASA Technical Reports Server (NTRS)

Eltahir, Elfatih A. B.; Bras, Rafael L.

1994-01-01

The deforestation results in several adverse effect on the natural environment. The focus of this paper is on the effects of deforestation on land-surface processes and regional climate of the Amazon basin. In general, the effect of deforestation on climate are likely to depend on the scale of the defrosted area. In this study, we are interested in the effects due to deforestation of areas with a scale of about 250 km. Hence, a meso-scale climate model is used in performing numerical experiments on the sensitivity of regional climate to deforestation of areas with that size. It is found that deforestation results in less net surface radiation, less evaporation, less rainfall, and warmer surface temperature. The magnitude of the of the change in temperature is of the order 0.5 C, the magnitudes of the changes in the other variables are of the order of IO%. In order to verify some of he results of the numerical experiments, the model simulations of net surface radiation are compared to recent observations of net radiation over cleared and undisturbed forest in the Amazon. The results of the model and the observations agree in the following conclusion: the difference in net surface radiation between cleared and undisturbed forest is, almost, equally partioned between net solar radiation and net long-wave radiation. This finding contributes to our understanding of the basic physics in the deforestation problem.

Storm intensity and old-growth forest disturbances in the Amazon region

Treesearch

F.D.B. Espírito-Santo; M. Keller; B. Braswell; B.W. Nelson; S. Frolking; G. Vicente

2010-01-01

We analyzed the pattern of large forest disturbances or blow‐downs apparently caused by severe storms in a mostly unmanaged portion of the Brazilian Amazon using 27 Landsat images and daily precipitation estimates from NOAA satellite data. For each Landsat a spectral mixture analysis (SMA) was applied. Based on SMA, we detected and mapped 279 patches (from 5 ha to 2,...

A source of methane from upland forests in the Brazilian Amazon.

Treesearch

Janaina Braga do Carmo; Michael Keller; Jadson Dezincourt Dias; Plinio Barbosa de Camargo; Patrick Crill

2006-01-01

We sampled air in the canopy layer of undisturbed upland forests during wet and dry seasons at three sites in the Brazilian Amazon region and found that both methane(CH4) and carbon dioxide (CO2) mixing ratios increased at night. Such increases were consistent across sites and seasons. A canopy layer budget model based on measured soil-atmosphere fluxes of CO2 was...

The Amazon at sea: Onset and stages of the Amazon River from a marine record, with special reference to Neogene plant turnover in the drainage basin

NASA Astrophysics Data System (ADS)

Hoorn, Carina; Bogotá-A, Giovanni R.; Romero-Baez, Millerlandy; Lammertsma, Emmy I.; Flantua, Suzette G. A.; Dantas, Elton L.; Dino, Rodolfo; do Carmo, Dermeval A.; Chemale, Farid

2017-06-01

The Amazon submarine fan is a large sediment apron situated offshore Pará (Brazil) and represents the most distal extent of the Amazon River. The age of onset of this transcontinental river remains debated, yet is of great importance for understanding biotic evolutionary processes on land and at sea. Here we present new geochemical and palynological data from a borehole drilled at the continental slope and dated based on nannofossil biostratigraphy. We found that sediments of mixed source (craton and adjacent) occur at least from the late Oligocene (NP25) to late Miocene (NN9), and that the earliest Andes-derived sediments occur in NN10 (late Miocene). Our geochemical record indicates an onset of the transcontinental Amazon River between 9.4 and 9 Ma, which postdates the regional unconformity by 1 to 1.5 My. The shift in sediment geochemistry is more gradually replicated in the palynological record by a change from coastal plain and tropical lowland taxa to a mixture of tropical lowland, and montane forest to open Andean taxa. In particular, the appearance of taxa such as Jamesonia and Huperzia, followed by Valeriana, Polylepis-Acaena, Lysipomia and Plantago (with a current altitudinal range from 3200 to 4000 m) suggests the development of open, treeless, vegetation between 9.5 and 5.4 Ma, and highlight the presence of a high Andes in the late Miocene hinterland. Poaceae progressively increased from 9 Ma, with a notable rise from 4 Ma onwards, and percentages well above post-glacial and modern values, particularly between 2.6 and 0.8 Ma. We hypothesize that the rise of the grasses is a basin-wide phenomenon, but that the Plio-Pleistocene expansion of open, treeless vegetation on the Andean slopes and foothills are the main contributor. This rise in grasses was likely caused by climatic fluctuations, and subsequent changes in relief and erosion rates. We conclude that the onset of the Amazon River is coupled with Neogene Andean tectonism and that subsequent developments, both of river and biota, are closely linked to the Plio-Pleistocene climatic fluctuations. From latest Neogene onwards these major landscape changes determined the composition of the montane and lowland forest in the Andes-Amazonian system.

Surface Soil Changes Following Selective Logging in an Eastern Amazon Forest

NASA Technical Reports Server (NTRS)

Olander, Lydia P.; Bustamante, Mercedes M.; Asner, Gregory P.; Telles, Everaldo; Prado, Zayra; Camargo, Plinio B.

2005-01-01

In the Brazilian Amazon, selective logging is second only to forest conversion in its extent. Conversion to pasture or agriculture tends to reduce soil nutrients and site productivity over time unless fertilizers are added. Logging removes nutrients in bole wood, enough that repeated logging could deplete essential nutrients over time. After a single logging event, nutrient losses are likely to be too small to observe in the large soil nutrient pools, but disturbances associated with logging also alter soil properties. Selective logging, particularly reduced-impact logging, results in consistent patterns of disturbance that may be associated with particular changes in soil properties. Soil bulk density, pH, carbon (C), nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), aluminum (Al), delta(sup 3)C, delta(sup 15)N, and P fractionations were measured on the soils of four different types of loggingrelated disturbances: roads, decks, skids, and treefall gaps. Litter biomass and percent bare ground were also determined in these areas. To evaluate the importance of fresh foliage inputs from downed tree crowns in treefall gaps, foliar nutrients for mature forest trees were also determined and compared to that of fresh litterfall. The immediate impacts of logging on soil properties and how these might link to the longer-term estimated nutrient losses and the observed changes in soils were studied.

Effects of selective logging on bat communities in the southeastern Amazon.

PubMed

Peters, Sandra L; Malcolm, Jay R; Zimmerman, Barbara L

2006-10-01

Although extensive areas of tropical forest are selectively logged each year, the responses of bat communities to this form of disturbance have rarely been examined. Our objectives were to (1) compare bat abundance, species composition, and feeding guild structure between unlogged and low-intensity selectively logged (1-4 logged stems/ha) sampling grids in the southeastern Amazon and (2) examine correlations between logging-induced changes in bat communities and forest structure. We captured bats in understory and canopy mist nets set in five 1-ha study grids in both logged and unlogged forest. We captured 996 individuals, representing 5 families, 32 genera, and 49 species. Abundances of nectarivorous and frugivorous taxa (Glossophaginae, Lonchophyllinae, Stenodermatinae, and Carolliinae) were higher at logged sites, where canopy openness and understory foliage density were greatest. In contrast, insectivorous and omnivorous species (Emballonuridae, Mormoopidae, Phyllostominae, and Vespertilionidae) were more abundant in unlogged sites, where canopy foliage density and variability in the understory stratum were greatest. Multivariate analyses indicated that understory bat species composition differed strongly between logged and unlogged sites but provided little evidence of logging effects for the canopy fauna. Different responses among feeding guilds and taxonomic groups appeared to be related to foraging and echolocation strategies and to changes in canopy cover and understory foliage densities. Our results suggest that even low-intensity logging modifies habitat structure, leading to changes in bat species composition.

Cost-effectiveness of reducing emissions from tropical deforestation, 2016-2050

NASA Astrophysics Data System (ADS)

Busch, Jonah; Engelmann, Jens

2017-12-01

Reducing tropical deforestation is potentially a large-scale and low-cost strategy for mitigating climate change. Yet previous efforts to project the cost-effectiveness of policies to reduce greenhouse gas emissions from future deforestation across the tropics were hampered by crude available data on historical forest loss. Here we use recently available satellite-based maps of annual forest loss between 2001-2012, along with information on topography, accessibility, protected status, potential agricultural revenue, and an observed inverted-U-shaped relationship between forest cover loss and forest cover, to project tropical deforestation from 2016-2050 under alternative policy scenarios and to construct new marginal abatement cost curves for reducing emissions from tropical deforestation. We project that without new forest conservation policies 289 million hectares of tropical forest will be cleared from 2016-2050, releasing 169 GtCO2. A carbon price of US20/tCO2 (50/tCO2) across tropical countries would avoid 41 GtCO2 (77 GtCO2) from 2016-2050. By comparison, we estimate that Brazil’s restrictive policies in the Amazon between 2004-2012 successfully decoupled potential agricultural revenue from deforestation and reduced deforestation by 47% below what would have otherwise occurred, preventing the emission of 5.2 GtCO2. All tropical countries enacting restrictive anti-deforestation policies as effective as those in the Brazilian Amazon between 2004-2012 would avoid 58 GtCO2 from 2016-2050.

Widespread Amazon forest tree mortality from a single cross-basin squall line event

NASA Astrophysics Data System (ADS)

Negrón-Juárez, Robinson I.; Chambers, Jeffrey Q.; Guimaraes, Giuliano; Zeng, Hongcheng; Raupp, Carlos F. M.; Marra, Daniel M.; Ribeiro, Gabriel H. P. M.; Saatchi, Sassan S.; Nelson, Bruce W.; Higuchi, Niro

2010-08-01

Climate change is expected to increase the intensity of extreme precipitation events in Amazonia that in turn might produce more forest blowdowns associated with convective storms. Yet quantitative tree mortality associated with convective storms has never been reported across Amazonia, representing an important additional source of carbon to the atmosphere. Here we demonstrate that a single squall line (aligned cluster of convective storm cells) propagating across Amazonia in January, 2005, caused widespread forest tree mortality and may have contributed to the elevated mortality observed that year. Forest plot data demonstrated that the same year represented the second highest mortality rate over a 15-year annual monitoring interval. Over the Manaus region, disturbed forest patches generated by the squall followed a power-law distribution (scaling exponent α = 1.48) and produced a mortality of 0.3-0.5 million trees, equivalent to 30% of the observed annual deforestation reported in 2005 over the same area. Basin-wide, potential tree mortality from this one event was estimated at 542 ± 121 million trees, equivalent to 23% of the mean annual biomass accumulation estimated for these forests. Our results highlight the vulnerability of Amazon trees to wind-driven mortality associated with convective storms. Storm intensity is expected to increase with a warming climate, which would result in additional tree mortality and carbon release to the atmosphere, with the potential to further warm the climate system.

Soil carbon dynamics

NASA Astrophysics Data System (ADS)

Trumbore, Susan; Barbosa de Camargo, Plínio

The amount of organic carbon (C) stored in the upper meter of mineral soils in the Amazon Basin (˜40 Pg C) represents ˜3% of the estimated global store of soil carbon. Adding surface detrital C stocks and soil carbon deeper than 1 m can as much as quadruple this estimate. The potential for Amazon soil carbon to respond to changes in land use, climate, or atmospheric composition depends on the form and dynamics of soil carbon. Much (˜30% in the top ˜10 cm but >85% in soils to 1 m depth) of the carbon in mineral soils of the Oxisols and Ultisols that are the predominant soil types in the Amazon Basin is in forms that are strongly stabilized, with mean ages of centuries to thousands of years. Measurable changes in soil C stocks that accompany land use/land cover change occur in the upper meter of soil, although the presence of deep roots in forests systems drives an active C cycle at depths >1 m. Credible estimates of the potential for changes in Amazon soil C stocks with future land use and climate change are much smaller than predictions of aboveground biomass change. Soil organic matter influences fertility and other key soil properties, and thus is important independent of its role in the global C cycle. Most work on C dynamics is limited to upland soils, and more is needed to investigate C dynamics in poorly drained soils. Work is also needed to relate cycles of C with water, N, P, and other elements.

Campaign datasets for Observations and Modeling of the Green Ocean Amazon (GOAMAZON)

DOE Data Explorer

Martin,Scot; Mei,Fan; Alexander,Lizabeth; Artaxo,Paulo; Barbosa,Henrique; Bartholomew,Mary Jane; Biscaro,Thiago; Buseck,Peter; Chand,Duli; Comstock,Jennifer; Dubey,Manvendra; Godstein,Allen; Guenther,Alex; Hubbe,John; Jardine,Kolby; Jimenez,Jose-Luis; Kim,Saewung; Kuang,Chongai; Laskin,Alexander; Long,Chuck; Paralovo,Sarah; Petaja,Tuukka; Powers,Heath; Schumacher,Courtney; Sedlacek,Arthur; Senum,Gunnar; Smith,James; Shilling,John; Springston,Stephen; Thayer,Mitchell; Tomlinson,Jason; Wang,Jian; Xie,Shaocheng

2016-05-30

The hydrologic cycle of the Amazon Basin is one of the primary heat engines of the Southern Hemisphere. Any accurate climate model must succeed in a good description of the Basin, both in its natural state and in states perturbed by regional and global human activities. At the present time, however, tropical deep convection in a natural state is poorly understood and modeled, with insufficient observational data sets for model constraint. Furthermore, future climate scenarios resulting from human activities globally show the possible drying and the eventual possible conversion of rain forest to savanna in response to global climate change. Based on our current state of knowledge, the governing conditions of this catastrophic change are not defined. Human activities locally, including the economic development activities that are growing the population and the industry within the Basin, also have the potential to shift regional climate, most immediately by an increment in aerosol number and mass concentrations, and the shift is across the range of values to which cloud properties are most sensitive. The ARM Climate Research Facility in the Amazon Basin seeks to understand aerosol and cloud life cycles, particularly the susceptibility to cloud aerosol precipitation interactions, within the Amazon Basin.

Lidar-based multinomial classification algorithms for tropical forest degradation status: Implications for biomass estimation

NASA Astrophysics Data System (ADS)

Duffy, P.; Keller, M.; Longo, M.; Morton, D. C.; dos-Santos, M. N.; Pinagé, E. R.

2017-12-01

There is an urgent need to quantify the effects of land use and land cover change on carbon stocks in tropical forests to support REDD+ policies and improve characterization of global carbon budgets. This need is underscored by the fact that the variability in forest biomass estimates from global forest carbon maps is artificially low relative to estimates generated from forest inventory and high-resolution airborne lidar data. Both deforestation and degradation processes (e.g. logging, fire, and fragmentation) affect carbon fluxes at varying spatial and temporal scales. While the spatial extent and impact of deforestation has been relatively well characterized, the quantification of degradation processes is still poorly constrained. In the Brazilian Amazon, the largest source of uncertainty in CO2 emissions estimates is data on changes in tropical forest carbon stocks through time, followed closely by incomplete information on the carbon losses from forest degradation. In this work, we present a method for classifying the degradation status of tropical forests using higher order moments (skewness and kurtosis) of lidar return distributions aggregated at grids with resolution ranging from 50 m to 250 m. Across multiple spatial resolutions, we quantify the strength of the functional relationship between the lidar returns and the classification based on historical time series of Landsat imagery. Our results show that the higher order moments of the lidar return distributions provide sufficient information to build multinomial models that accurately classify the landscape into intact, logged, and burned forests. Model fit improved with coarser spatial resolution with Kappa statistics of 0.70 at 50 m, and 0.77 at 250 m. In addition, multi-class AUC was estimated as 0.87 at 50 m, and 0.95 at 250 m. This classification provides important information regarding the applicability of the use of lidar data for regional monitoring of recent logging, as well as the trajectory of the carbon budget. Differentiating between the biomass changes associated with deforestation and degradation processes is critical for accurate accounting of disturbance impacts on carbon cycling within the Brazilian Amazon and global tropical forests.

Species richness and composition of epiphytic bryophytes in flooded forests of Caxiuanã National Forest, Eastern Amazon, Brazil.

PubMed

Cerqueira, Gabriela R; Ilkiu-Borges, Anna Luiza; Ferreira, Leandro V

2017-01-01

This study aimed to compare the richness and composition of the epiphytic bryoflora between várzea and igapó forests in Caxiuanã National Forest, Brazilian Amazon. Bryophytes were collected on 502 phorophytes of Virola surinamensis. Average richness per phorophyte and composition between forests and between dry and rainy periods was tested by two-way analysis and by cluster analysis, respectively. In total, 54 species of 13 families were identified. Richness was greater in igapó forest (44 species) compared to várzea forest (38 species). There was no significant difference in the number of species between the studied periods. Cluster analysis showed the bryoflora composition was different between várzea and igapó, but not between dry and rainy periods. Results did not corroborate the hypothesis that várzea forests harbor higher species richness than igapó forests.

Structure and tree species composition in different habitats of savanna used by indigenous people in the Northern Brazilian Amazon.

PubMed

de Oliveira, Rodrigo Leonardo Costa; Farias, Hugo Leonardo Sousa; Perdiz, Ricardo de Oliveira; Scudeller, Veridiana Vizoni; Imbrozio Barbosa, Reinaldo

2017-01-01

Woody plant diversity from the Amazonian savannas has been poorly quantified. In order to improve the knowledge on wood plants of these regional ecosystems, a tree inventory was carried out in four different habitats used by indigenous people living in the savanna areas of the Northern Brazilian Amazon. The habitats were divided into two types (or groups) of vegetation formations: forest (riparian forest, forest island, and buritizal = Mauritia palm formation) and non-forest (typical savanna). The inventory was carried out in two hectares established in the Darora Indigenous Community region, north of the state of Roraima. The typical savanna is the most densely populated area (709 stems ha -1 ); however, it has the lowest tree species richness (nine species, seven families) in relation to typical forest habitats: riparian forest (22 species, 13 families and 202 stems ha -1 ), forest islands (13 species, 10 families and 264 stems ha -1 ), and buritizal (19 species, 15 families and 600 stems ha -1 ). The tree structure (density and dominance) of the forest habitats located in the savanna areas studied in this work is smaller in relation to forest habitats derived from continuous areas of other parts of the Amazon. These environments are derived from Paleoclimatic fragmentation, and are currently affected by the impact of intensive use of natural resources as timberselective logging and some land conversion for agriculture.

Pervasive Rise of Small-scale Deforestation in Amazonia.

PubMed

Kalamandeen, Michelle; Gloor, Emanuel; Mitchard, Edward; Quincey, Duncan; Ziv, Guy; Spracklen, Dominick; Spracklen, Benedict; Adami, Marcos; Aragão, Luiz E O C; Galbraith, David

2018-01-25

Understanding forest loss patterns in Amazonia, the Earth's largest rainforest region, is critical for effective forest conservation and management. Following the most detailed analysis to date, spanning the entire Amazon and extending over a 14-year period (2001-2014), we reveal significant shifts in deforestation dynamics of Amazonian forests. Firstly, hotspots of Amazonian forest loss are moving away from the southern Brazilian Amazon to Peru and Bolivia. Secondly, while the number of new large forest clearings (>50 ha) has declined significantly over time (46%), the number of new small clearings (<1 ha) increased by 34% between 2001-2007 and 2008-2014. Thirdly, we find that small-scale low-density forest loss expanded markedly in geographical extent during 2008-2014. This shift presents an important and alarming new challenge for forest conservation, despite reductions in overall deforestation rates.

Assessing Impacts of Selective Logging on Water, Energy, and Carbon Fluxes in Amazon Forests Using the Functionally Assembled Terrestrial Ecosystem Simulator (FATES)

NASA Astrophysics Data System (ADS)

Xu, Y.; Huang, M.; Keller, M. M.; Longo, M.; Knox, R. G.; Koven, C.; Fisher, R.

2016-12-01

As a key component in the climate system, old-growth tropical forests act as carbon sinks that remove CO2 from the atmosphere. However, these forests could be easily turned into C sources when disturbed. In fact, over half of tropical forests have been cleared or logged, and almost half of standing primary tropical forests are designated for timber production. Existing literature suggests that timber harvests alone could contribute up to 25% as much C losses as deforestation in Amazon. Yet, the spatial extent and recovery trajectory of disturbed forests in a changing climate are highly uncertain. This study constitutes our first attempt to quantify impacts of selective logging on water, energy, and carbon budgets in Amazon forests using the Functionally Assembled Terrestrial Ecosystem Simulator (FATES). The Community Land Model version 4.5 (CLM4.5), with and without FATES turned on, are configured to run at two flux towers established in the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA). One tower is located at in an old-growth forest (i.e. KM67) and the other is located in a selectively logged site (i.e., KM83). The three CLM4.5 options, (1) Satellite Phenology (CLM4.5-SP), (2) Century-based biogeochemical cycling with prognostic phenology (CLM4.5-BGC), and (3) CLM4.5-FATES, are spun up to equilibrium by recycling the observed meteorology at the towers, respectively. The simulated fluxes (i.e., sensible heat, latent heat, and net ecosystem exchange) are then compared to observations at KM67 to evaluate the capability of the models in capturing water and carbon dynamics in old-growth tropical forests. Our results suggest that all three models perform reasonably well in capturing the fluxes but demographic features simulated by FATES, such as distributions of diameter at breast height (DBH) and stem density (SD), are skewed heavily toward extremely large trees (e.g., > 100 cm in DBH) when compared to site surveys at the forest plots. Efforts are underway to evaluate parametric sensitivity in FATES to improve simulations in old-growth forests, and to implement parameterization to represent pulse disturbance to carbon pools created by logging events at different intensities, and follow-up recovery closely related to gap-phase regeneration and competition for lights within the gaps.

Carbon emissions from deforestation and forest fragmentation in the Brazilian Amazon

NASA Astrophysics Data System (ADS)

Numata, Izaya; Cochrane, Mark A.; Souza, Carlos M., Jr.; Sales, Marcio H.

2011-10-01

Forest-fragmentation-related edge effects are one of the major causes of forest degradation in Amazonia and their spatio-temporal dynamics are highly influenced by annual deforestation patterns. Rapid biomass collapse due to edge effects in forest fragments has been reported in the Brazilian Amazon; however the collective impacts of this process on Amazonian carbon fluxes are poorly understood. We estimated biomass loss and carbon emissions from deforestation and forest fragmentation related to edge effects on the basis of the INPE (Brazilian National Space Research Institute) PRODES deforestation data and forest biomass volume data. The areas and ages of edge forests were calculated annually and the corresponding biomass loss and carbon emissions from these forest edges were estimated using published rates of biomass decay and decomposition corresponding to the areas and ages of edge forests. Our analysis estimated carbon fluxes from deforestation (4195 Tg C) and edge forest (126-221 Tg C) for 2001-10 in the Brazilian Amazon. The impacts of varying rates of deforestation on regional forest fragmentation and carbon fluxes were also investigated, with the focus on two periods: 2001-5 (high deforestation rates) and 2006-10 (low deforestation rates). Edge-released carbon accounted for 2.6-4.5% of deforestation-related carbon emissions. However, the relative importance of carbon emissions from forest fragmentation increased from 1.7-3.0% to 3.3-5.6% of the respective deforestation emissions between the two contrasting deforestation rates. Edge-related carbon fluxes are of increasing importance for basin-wide carbon accounting, especially as regards ongoing reducing emissions from deforestation and forest degradation (REDD) efforts in Brazilian Amazonia.

Isotopic analysis of Bothrops atrox in Amazonian forest

NASA Astrophysics Data System (ADS)

Martinez, M. G.; Silva, A. M.; Chalkidis, H.; de Oliveira Júnior, R. C.; Camargo, P. B.

2012-12-01

The poisoning of snakes is considered a public health problem, especially in populations from rural areas of tropical and subtropical countries. In Brazil, the 26,000 snakebites, 90% are of the genus Bothrops, and Bothrops atrox species predominant in the Amazon region including all the Brazilian Amazon. Research shows that using stable isotopes, we can verify the isotopic composition of tissues of animals that depend mainly on food, water ingested and inhaled gases. For this study, samples taken from Bothrops atrox (B. atrox), in forest using pitfall traps and fall ("Pitt-fall traps with drift fence"). The analyzes were performed by mass spectrometry, where the analytical error is 0.3‰ for carbon and 0.5‰ to nitrogen. The results of the forest animals are significantly different from results of animal vivarium. The average values of the tissues and venoms of snakes of the forest for carbon-13 and nitrogen-15 are: δ13C = -24.68‰ and δ15N = 14.22‰ and mean values of tissue and poisons snakes vivarium (Instituto Butantan) to carbon-13 and nitrogen-15 are δ13C = -20.47‰ and δ15N = 8.36‰, with a significantly different due to different sources of food animals. Based on all results isotopic δ13C and δ15N, we can suggest that changes as the power of the serpent, (nature and captivity), changes occur in relation to diet and environment as the means of the isotopic data are quite distinct, showing that these changes can also cause metabolic changes in the body of the animal itself and the different periods of turnover of each tissue analyzed.

Model gives a 3-month warning of Amazonian forest fires

NASA Astrophysics Data System (ADS)

Schultz, Colin

2011-08-01

The widespread drought suffered by the Amazon rain forest in the summer of 2005 was heralded at the time as the drought of the century. Because of the dehydrated conditions, supplemented by slash and burn agricultural practices, the drought led to widespread forest fires throughout the western Amazon, a portion of the rain forest usually too lush to support spreading wildfires. Only 5 years later, the 2005 season was outdone by even more widespread drought, with fires decimating more than 3000 square kilometers of western Amazonian rain forest. Blame for the wildfires has been consistently laid on deforestation and agricultural practices, but a convincing climatological explanation exists as well. (Geophysical Research Letters, doi:10.1029/2011GL047392, 2011)

Combining global land cover datasets to quantify agricultural expansion into forests in Latin America: Limitations and challenges

PubMed Central

Persson, U. Martin

2017-01-01

While we know that deforestation in the tropics is increasingly driven by commercial agriculture, most tropical countries still lack recent and spatially-explicit assessments of the relative importance of pasture and cropland expansion in causing forest loss. Here we present a spatially explicit quantification of the extent to which cultivated land and grassland expanded at the expense of forests across Latin America in 2001–2011, by combining two “state-of-the-art” global datasets (Global Forest Change forest loss and GlobeLand30-2010 land cover). We further evaluate some of the limitations and challenges in doing this. We find that this approach does capture some of the major patterns of land cover following deforestation, with GlobeLand30-2010’s Grassland class (which we interpret as pasture) being the most common land cover replacing forests across Latin America. However, our analysis also reveals some major limitations to combining these land cover datasets for quantifying pasture and cropland expansion into forest. First, a simple one-to-one translation between GlobeLand30-2010’s Cultivated land and Grassland classes into cropland and pasture respectively, should not be made without caution, as GlobeLand30-2010 defines its Cultivated land to include some pastures. Comparisons with the TerraClass dataset over the Brazilian Amazon and with previous literature indicates that Cultivated land in GlobeLand30-2010 includes notable amounts of pasture and other vegetation (e.g. in Paraguay and the Brazilian Amazon). This further suggests that the approach taken here generally leads to an underestimation (of up to ~60%) of the role of pasture in replacing forest. Second, a large share (~33%) of the Global Forest Change forest loss is found to still be forest according to GlobeLand30-2010 and our analysis suggests that the accuracy of the combined datasets, especially for areas with heterogeneous land cover and/or small-scale forest loss, is still too poor for deriving accurate quantifications of land cover following forest loss. PMID:28704510

Combining global land cover datasets to quantify agricultural expansion into forests in Latin America: Limitations and challenges.

PubMed

Pendrill, Florence; Persson, U Martin

2017-01-01

While we know that deforestation in the tropics is increasingly driven by commercial agriculture, most tropical countries still lack recent and spatially-explicit assessments of the relative importance of pasture and cropland expansion in causing forest loss. Here we present a spatially explicit quantification of the extent to which cultivated land and grassland expanded at the expense of forests across Latin America in 2001-2011, by combining two "state-of-the-art" global datasets (Global Forest Change forest loss and GlobeLand30-2010 land cover). We further evaluate some of the limitations and challenges in doing this. We find that this approach does capture some of the major patterns of land cover following deforestation, with GlobeLand30-2010's Grassland class (which we interpret as pasture) being the most common land cover replacing forests across Latin America. However, our analysis also reveals some major limitations to combining these land cover datasets for quantifying pasture and cropland expansion into forest. First, a simple one-to-one translation between GlobeLand30-2010's Cultivated land and Grassland classes into cropland and pasture respectively, should not be made without caution, as GlobeLand30-2010 defines its Cultivated land to include some pastures. Comparisons with the TerraClass dataset over the Brazilian Amazon and with previous literature indicates that Cultivated land in GlobeLand30-2010 includes notable amounts of pasture and other vegetation (e.g. in Paraguay and the Brazilian Amazon). This further suggests that the approach taken here generally leads to an underestimation (of up to ~60%) of the role of pasture in replacing forest. Second, a large share (~33%) of the Global Forest Change forest loss is found to still be forest according to GlobeLand30-2010 and our analysis suggests that the accuracy of the combined datasets, especially for areas with heterogeneous land cover and/or small-scale forest loss, is still too poor for deriving accurate quantifications of land cover following forest loss.

Leaf ontogeny and demography explain photosynthetic seasonality in Amazon evergreen forests

NASA Astrophysics Data System (ADS)

Wu, J.; Albert, L.; Lopes, A. P.; Restrepo-Coupe, N.; Hayek, M.; Wiedemann, K. T.; Guan, K.; Stark, S. C.; Prohaska, N.; Tavares, J. V.; Marostica, S. F.; Kobayashi, H.; Ferreira, M. L.; Campos, K.; Silva, R. D.; Brando, P. M.; Dye, D. G.; Huxman, T. E.; Huete, A. R.; Nelson, B. W.; Saleska, S. R.

2015-12-01

Photosynthetic seasonality couples the evolutionary ecology of plant leaves to large-scale rhythms of carbon and water exchanges that are important feedbacks to climate. However, the extent, magnitude, and controls on photosynthetic seasonality of carbon-rich tropical forests are poorly resolved, controversial in the remote sensing literature, and inadequately represented in most earth system models. Here we show that ecosystem-scale phenology (measured by photosynthetic capacity), rather than environmental seasonality, is the primary driver of photosynthetic seasonality at four Amazon evergreen forests spanning gradients in rainfall seasonality, forest composition, and flux seasonality. We further demonstrate that leaf ontogeny and demography explain most of this ecosystem phenology at two central Amazon evergreen forests, using a simple leaf-cohort canopy model that integrates eddy covariance-derived CO2 fluxes, novel near-surface camera-detected leaf phenology, and ground observations of litterfall and leaf physiology. The coordination of new leaf growth and old leaf divestment (litterfall) during the dry season shifts canopy composition towards younger leaves with higher photosynthetic efficiency, driving large seasonal increases (~27%) in ecosystem photosynthetic capacity. Leaf ontogeny and demography thus reconciles disparate observations of forest seasonality from leaves to eddy flux towers to satellites. Strategic incorporation of such whole-plant coordination processes as phenology and ontogeny will improve ecological, evolutionary and earth system theories describing tropical forests structure and function, allowing more accurate representation of forest dynamics and feedbacks to climate in earth system models.

The carbon debt from Amazon forest degradation: integrating airborne lidar, field measurements, and an ecosystem demography model.

NASA Astrophysics Data System (ADS)

Longo, M.; Keller, M. M.; dos-Santos, M. N.; Scaranello, M. A., Sr.; Pinagé, E. R.; Leitold, V.; Morton, D. C.

2016-12-01

Amazon deforestation has declined over the last decade, yet forest degradation from logging, fire, and fragmentation continue to impact forest carbon stocks and fluxes. The magnitude of this impact remains uncertain, and observation-based studies are often limited by short time intervals or small study areas. To better understand the long-term impact of forest degradation and recovery, we have been developing a framework that integrates field plot measurements and airborne lidar surveys into an individual- and process-based model (Ecosystem Demography model, ED). We modeled forest dynamics for three forest landscapes in the Amazon with diverse degradation histories: conventional and reduced-impact logging, logging and burning, and multiple burns. Based on the initialization with contemporary forest structure and composition, model results suggest that degraded forests rapidly recover (30 years) water and energy fluxes compared with old-growth, even at sites that were affected by multiple fires. However, degraded forests maintained different carbon stocks and fluxes even after 100 years without further disturbances, because of persistent differences in forest structure and composition. Recurrent disturbances may hinder the recovery of degraded forests. Simulations using a simple fire model entirely dependent on environmental controls indicate that the most degraded forests would take much longer to reach biomass typical of old-growth forests, because drier conditions near the ground make subsequent fires more intense and more recurrent. Fires in tropical forests are also closely related to nearby human activities; while results suggest an important feedback between fires and the microenvironment, additional work is needed to improve how the model represents the human impact on current and future fire regimes. Our study highlights that recovery of degraded forests may act as an important carbon sink, but efficient recovery depends on controlling future disturbances.

Short term effects of fire on soil respiration in Peruvian Amazon

NASA Astrophysics Data System (ADS)

Suarez, L. F.; Kruijt, B.

2008-05-01

Severe changes are affecting the role of Amazon in the Earth system. One of these possible effects could be the modification of the role of soils in the carbon cycle due to land use and land cover change activities mainly involving the change of forest by crops. In this sense, fire is the main tool used by farmers for land use and also is an important factor for mobilizing C from the soil to the atmosphere, mainly as CO2. This could have an important effect in the global warming. This proposal will evaluate the variation of the soil respiration related to the seasonality and the fire effects on soils in the Amazon of Peru and Brazil. In experimental locations of Peru with different vegetation cover (forest and pasture), we measured soil respiration along with the organic carbon and the microbial biomass of soils during campaigns covering wet and dry seasons. Complementary measurements of soil temperature, water and nutrient content were performed. Also, we reproduced a fire experiment simulating agricultural local activity by the technique of "slash and burn" to evaluate fire effects on soil respiration. Measurements were taken after the soil cooled and at least 3 days after the fire. Additionally, the carbon stocks of the subplots were evaluated. Evaluation of the variations of CO2 fluxes and the capacity of adaptation to fire and water content are discussed through the comparisons of the different locations, type of soils and concentration of available N (nitrate and ammonium) as an indicator of nutrient content.

Evapotranspiration estimation using a parameter-parsimonious energy partition model over Amazon basin

NASA Astrophysics Data System (ADS)

Xu, D.; Agee, E.; Wang, J.; Ivanov, V. Y.

2017-12-01

The increased frequency and severity of droughts in the Amazon region have emphasized the potential vulnerability of the rainforests to heat and drought-induced stresses, highlighting the need to reduce the uncertainty in estimates of regional evapotranspiration (ET) and quantify resilience of the forest. Ground-based observations for estimating ET are resource intensive, making methods based on remotely sensed observations an attractive alternative. Several methodologies have been developed to estimate ET from satellite data, but challenges remained in model parameterization and satellite limited coverage reducing their utility for monitoring biodiverse regions. In this work, we apply a novel surface energy partition method (Maximum Entropy Production; MEP) based on Bayesian probability theory and nonequilibrium thermodynamics to derive ET time series using satellite data for Amazon basin. For a large, sparsely monitored region such as the Amazon, this approach has the advantage methods of only using single level measurements of net radiation, temperature, and specific humidity data. Furthermore, it is not sensitive to the uncertainty of the input data and model parameters. In this first application of MEP theory for a tropical forest biome, we assess its performance at various spatiotemporal scales against a diverse field data sets. Specifically, the objective of this work is to test this method using eddy flux data for several locations across the Amazonia at sub-daily, monthly, and annual scales and compare the new estimates with those using traditional methods. Analyses of the derived ET time series will contribute to reducing the current knowledge gap surrounding the much debated response of the Amazon Basin region to droughts and offer a template for monitoring the long-term changes in global hydrologic cycle due to anthropogenic and natural causes.

Amazon collapse in the next century: exploring the sensitivity to climate and model formulation uncertainties

NASA Astrophysics Data System (ADS)

Booth, B.; Collins, M.; Harris, G.; Chris, H.; Jones, C.

2007-12-01

A number of recent studies have highlighted the risk of abrupt dieback of the Amazon Rain Forest as the result of climate changes over the next century. The recent 2005 Amazon drought brought wider acceptance of the idea that that climate drivers will play a significant role in future rain forest stability, yet that stability is still subject to considerable degree of uncertainty. We present a study which seeks to explore some of the underlying uncertainties both in the climate drivers of dieback and in the terrestrial land surface formulation used in GCMs. We adopt a perturbed physics approach which forms part of a wider project which is covered in an accompanying abstract submitted to the multi-model ensembles session. We first couple the same interactive land surface model to a number of different versions of the Hadley Centre atmosphere-ocean model that exhibit a wide range of different physical climate responses in the future. The rainforest extent is shown to collapse in all model cases but the timing of the collapse is dependent on the magnitude of the climate drivers. In the second part, we explore uncertainties in the terrestrial land surface model using the perturbed physics ensemble approach, perturbing uncertain parameters which have an important role in the vegetation and soil response. Contrasting the two approaches enables a greater understanding of the relative importance of climatic and land surface model uncertainties in Amazon dieback.

Lessons from the Rain Forest.

ERIC Educational Resources Information Center

Phillips, Shelley

2002-01-01

Presents a first-grade art project after students learned about the rain forest and heard the story, "The Great Kapok Tree: A Tale of the Amazon Rain Forest" (Lynn Cherry). Explains that the students created pictures of the rain forest. (CMK)

Evapotranspiration seasonality across the Amazon Basin

NASA Astrophysics Data System (ADS)

Eiji Maeda, Eduardo; Ma, Xuanlong; Wagner, Fabien Hubert; Kim, Hyungjun; Oki, Taikan; Eamus, Derek; Huete, Alfredo

2017-06-01

Evapotranspiration (ET) of Amazon forests is a main driver of regional climate patterns and an important indicator of ecosystem functioning. Despite its importance, the seasonal variability of ET over Amazon forests, and its relationship with environmental drivers, is still poorly understood. In this study, we carry out a water balance approach to analyse seasonal patterns in ET and their relationships with water and energy drivers over five sub-basins across the Amazon Basin. We used in situ measurements of river discharge, and remotely sensed estimates of terrestrial water storage, rainfall, and solar radiation. We show that the characteristics of ET seasonality in all sub-basins differ in timing and magnitude. The highest mean annual ET was found in the northern Rio Negro basin (˜ 1497 mm year-1) and the lowest values in the Solimões River basin (˜ 986 mm year-1). For the first time in a basin-scale study, using observational data, we show that factors limiting ET vary across climatic gradients in the Amazon, confirming local-scale eddy covariance studies. Both annual mean and seasonality in ET are driven by a combination of energy and water availability, as neither rainfall nor radiation alone could explain patterns in ET. In southern basins, despite seasonal rainfall deficits, deep root water uptake allows increasing rates of ET during the dry season, when radiation is usually higher than in the wet season. We demonstrate contrasting ET seasonality with satellite greenness across Amazon forests, with strong asynchronous relationships in ever-wet watersheds, and positive correlations observed in seasonally dry watersheds. Finally, we compared our results with estimates obtained by two ET models, and we conclude that neither of the two tested models could provide a consistent representation of ET seasonal patterns across the Amazon.

Modeling seasonal and interannual variability in ecosystem carbon cycling for the Brazilian Amazon region

NASA Astrophysics Data System (ADS)

Potter, Christopher; Klooster, Steven; de Carvalho, Claudio Reis; Genovese, Vanessa Brooks; Torregrosa, Alicia; Dungan, Jennifer; Bobo, Matthew; Coughlan, Joseph

2001-05-01

Previous field measurements have implied that undisturbed Amazon forests may represent a substantial terrestrial sink for atmospheric carbon dioxide. We investigated this hypothesis using a regional ecosystem model for net primary production (NPP) and soil biogeochemical cycling. Seasonal and interannual controls on net ecosystem production (NEP) were studied with integration of high-resolution (8-km) multiyear satellite data to characterize Amazon land surface properties over time. Background analysis of temporal and spatial relationships between regional rainfall patterns and satellite observations (for vegetation land cover, fire counts, and smoke aerosol effects) reveals several notable patterns in the model driver data. Autocorrelation analysis for monthly vegetation "greenness" index (normalized difference vegetation index, NDVI) from the advanced very high resolution radiometer (AVHRR) and monthly rainfall indicates a significant lag time correlation of up to 12 months. At lag times approaching 36 months, autocorrelation function (ACF) values did not exceed the 95% confidence interval at locations west of about 47°W, which is near the transition zone of seasonal tropical forest and other (nonforest) vegetation types. Even at lag times of 12 months or less, the location near Manaus (approximately 60°W) represents the farthest western point in the Amazon region where seasonality of rainfall accounts significantly for monthly variations in forest phenology, as observed using NDVI. Comparisons of NDVI seasonal profiles in areas of the eastern Amazon widely affected by fires (as observed from satellite) suggest that our adjusted AVHRR-NDVI captures year-to-year variation in land cover greenness with minimal interference from small fires and smoke aerosols. Ecosystem model results using this newly generated combination of regional forcing data from satellite suggest that undisturbed Amazon forests can be strong net sinks for atmospheric carbon dioxide, particularly during wet (non El Niño) years. However, drought effects during El Niño years can reduce NPP in primary forests of the eastern Amazon by 10-20%, compared to long-term average estimates of regional productivity. Annual NEP for the region is predicted to range from -0.4 Pg C yr-1 (net CO2 source) to 0.5 Pg C yr-1 (net CO2 sink), with large interannual variability over the states of Pará, Maranhao, and Amazonas. As in the case of predicted NPP, it appears that periods of relatively high solar surface irradiance combined with several months of adequate rainfall are required to sustain the forest carbon sink for positive yearly NEP estimates.

Sensitivity of ALOS/PALSAR imagery to forest degradation by fire in northern Amazon

NASA Astrophysics Data System (ADS)

Martins, Flora da Silva Ramos Vieira; dos Santos, João Roberto; Galvão, Lênio Soares; Xaud, Haron Abrahim Magalhães

2016-07-01

We evaluated the sensitivity of the full polarimetric Phased Array type L-band Synthetic Aperture Radar (PALSAR), onboard the Advanced Land Observing Satellite (ALOS), to forest degradation caused by fires in northern Amazon, Brazil. We searched for changes in PALSAR signal and tri-dimensional polarimetric responses for different classes of fire disturbance defined by fire frequency and severity. Since the aboveground biomass (AGB) is affected by fire, multiple regression models to estimate AGB were obtained for the whole set of coherent and incoherent attributes (general model) and for each set separately (specific models). The results showed that the polarimetric L-band PALSAR attributes were sensitive to variations in canopy structure and AGB caused by forest fire. However, except for the unburned and thrice burned classes, no single PALSAR attribute was able to discriminate between the intermediate classes of forest degradation by fire. Both the coherent and incoherent polarimetric attributes were important to explain AGB variations in tropical forests affected by fire. The HV backscattering coefficient, anisotropy, double-bounce component, orientation angle, volume index and HH-VV phase difference were PALSAR attributes selected from multiple regression analysis to estimate AGB. The general regression model, combining phase and power radar metrics, presented better results than specific models using coherent or incoherent attributes. The polarimetric responses indicated the dominance of VV-oriented backscattering in primary forest and lightly burned forests. The HH-oriented backscattering predominated in heavily and frequently burned forests. The results suggested a greater contribution of horizontally arranged constituents such as fallen trunks or branches in areas severely affected by fire.

Natural and drought scenarios in an east central Amazon forest: Fidelity of the Community Land Model 3.5 with three biogeochemical models

NASA Astrophysics Data System (ADS)

Sakaguchi, Koichi; Zeng, Xubin; Christoffersen, Bradley J.; Restrepo-Coupe, Natalia; Saleska, Scott R.; Brando, Paulo M.

2011-03-01

Recent development of general circulation models involves biogeochemical cycles: flows of carbon and other chemical species that circulate through the Earth system. Such models are valuable tools for future projections of climate, but still bear large uncertainties in the model simulations. One of the regions with especially high uncertainty is the Amazon forest where large-scale dieback associated with the changing climate is predicted by several models. In order to better understand the capability and weakness of global-scale land-biogeochemical models in simulating a tropical ecosystem under the present day as well as significantly drier climates, we analyzed the off-line simulations for an east central Amazon forest by the Community Land Model version 3.5 of the National Center for Atmospheric Research and its three independent biogeochemical submodels (CASA', CN, and DGVM). Intense field measurements carried out under Large Scale Biosphere-Atmosphere Experiment in Amazonia, including forest response to drought from a throughfall exclusion experiment, are utilized to evaluate the whole spectrum of biogeophysical and biogeochemical aspects of the models. Our analysis shows reasonable correspondence in momentum and energy turbulent fluxes, but it highlights three processes that are not in agreement with observations: (1) inconsistent seasonality in carbon fluxes, (2) biased biomass size and allocation, and (3) overestimation of vegetation stress to short-term drought but underestimation of biomass loss from long-term drought. Without resolving these issues the modeled feedbacks from the biosphere in future climate projections would be questionable. We suggest possible directions for model improvements and also emphasize the necessity of more studies using a variety of in situ data for both driving and evaluating land-biogeochemical models.

Regional Eco-hydrologic Sensitivity to Projected Amazonian Land Use Scenarios

NASA Astrophysics Data System (ADS)

Knox, R. G.; Longo, M.; Zhang, K.; Levine, N. M.; Moorcroft, P. R.; Bras, R. L.

2011-12-01

Given business as usual land-use practices, it is estimated that by 2050 roughly half of the Amazon's pre-anthropogenic closed-canopy forest stands would remain. Of this, eight of the Amazon's twelve major hydrologic basins would lose more than half of their forest cover to deforestation. With the availability of these land-use projections, we may start to question the associated response of the region's hydrologic climate to significant land-cover change. Here the Ecosystem-Demography Model 2 (EDM2, a dynamic and spatially distributed terrestrial model of plant structure and composition, succession, disturbance and thermodynamic transfer) is coupled with the Brazilian Regional Atmospheric Model (BRAMS, a three-dimensional limited area model of the atmospheric fluid momentum equations and physics parameterizations for closing the system of equations at the lower boundary, convection, radiative transfer, microphysics, etc). This experiment conducts decadal simulations, framed with high-reliability lateral boundary conditions of reanalysis atmospheric data (ERA-40 interim) and variable impact of land-use scenarios (SimAmazonia). This is done by initializing the regional ecosystem structure with both aggressive and conservationist deforestation scenarios, and also by differentially allowing and not-allowing dynamic vegetation processes. While the lateral boundaries of the simulation will not reflect the future climate in the region, reanalysis data has provided improved realism as compared to results derived from GCM boundary data. Therefore, the ecosystem response (forest composition and structure) and the time-space patterns of hydrologic information (soil moisture, rainfall, evapotranspiration) are objectively compared in the context of a sensitivity experiment, as opposed to a forecast. The following questions are addressed. How do aggressive and conservative scenarios of Amazonian deforestation effect the regional patterning of hydrologic information in the Amazon and South American Convergence Zone, and does forest response in these regions influence that patterning of hydrologic information?

Using ALS and MODIS data to evaluate degradation in different forests types over the Xingu basin - Brazilian Amazon

NASA Astrophysics Data System (ADS)

Moura, Y.; Aragão, L. E.; Galvão, L. S.; Dalagnol, R.; Lyapustin, A.; Santos, E. G.; Espirito-Santo, F.

2017-12-01

Degradation of Amazon rainforests represents a vital threat to carbon storage, climate regulation and biodiversity; however its effect on tropical ecosystems is largely unknown. In this study we evaluate the effects of forest degradation on forest structure and functioning over the Xingu Basin in the Brazilian Amazon. The vegetation types in the area is dominated by Open Ombrophilous Forest (Asc), Semi-decidiuous Forest (Fse) and Dense Ombrophilous Forest (Dse). We used Airborne Laser Scanning (ALS) data together with time series of optical remote sensing images from the Moderate Resolution Imaging Spectroradiometer (MODIS) bi-directional corrected using the Multi-Angle Implementation for Atmospheric Correction (MAIAC). We derive time-series (2008 to 2016) of the Enhanced Vegetation Index (EVI) and Green-Red Normalized Difference (GRND) to analyze the dynamics of degraded areas with related changes in canopy structure and greenness values, respectively. Airborne ALS measurements showed the largest tree heights in the Dse class with values up to 40m tall. Asc and Fse vegetation types reached up to 30m and 25m in height, respectively. Differences in canopy structure were also evident from the analysis of canopy volume models (CVMs). Asc showed higher proportion of sunlit, as expected for open forest types. Fse showed gaps predominantly in lower height levels, and a higher overall proportion of shaded crown. Full canopy closure was reached at about15 m height for both Asc and Dse, and at about 20 m height for Fse. We also used a base map of degraded areas (available from Imazon - Instituto do Homen e Meio Ambiente da Amazônia) to follow these regions throughout time using EVI and GRND from MODIS. All three forest types displayed seasonal cycles. Notable differences in amplitude were detected during the periods when degradation occurred and both indexes showed a decrease in their response. However, there were marked differences in timing and amplitude depending on forest type. These responses were influenced by the spatial resolution of 1km of the MODIS images, limited the ability to observe small degraded regions. In conclusion, ASL together with optical remote sensing used in a straight multi-scale approach may contribute to understand the impacts of degradation in the structure and functioning of tropical forest.

Civil-Military Collaboration to Address Adaptation to Climate Change in South America

DTIC Science & Technology

2011-03-01

drought, water scarcity and soil degradation, intensify land use conflicts (especially in the Andean and Amazon Regions) and trigger environmentally...of the territories , climatic variability, and food scarcity are common problems for many of the countries of the region, which are in dire need to...resource conflicts. Because climate change can further affect such environmental issues as water, forests , soil fertility, hunger, disease, health, and

Physical, chemical, and biological properties of soil under soybean cultivation and at an adjacent rainforest in Amazonia

Treesearch

T.P. Beldini; R.C. Oliveira Junior; Michael Keller; P.B. de Camargo; P.M. Crill; A. Damasceno da Silva; D. Bentes dos Santos; D. Rocha de Oliveira

2015-01-01

Land-use change in the Amazon basin has occurred at an accelerated pace during the last decade, and it is important that the effects induced by these changes on soil properties are better understood. This study investigated the chemical, physical, and biological properties of soil in a field under cultivation of soy and rice, and at an adjacent primary rain forest....

Multi-scale assessment of human-induced changes to ...

EPA Pesticide Factsheets

Context: Land use change and forest degradation have myriad effects on tropical ecosystems. Yet their consequences for low-order streams remain very poorly understood, including in the world´s largest freshwater basin, the Amazon.Objectives: Determine the degree to which physical and chemical characteristics of the instream habitat of low-order Amazonian streams change in response to past local- and catchment-level anthropogenic disturbances. Methods: To do so, we collected field instream habitat (i.e., physical habitat and water quality) and landscape data from 99 stream sites in two eastern Brazilian Amazon regions. We used random forest regression trees to assess the relative importance of different predictor variables in determining changes in instream habitat response variables. Adaptations the USEPA’s National Aquatic Resource Survey (NARS) designs, field methods, and approaches for assessing ecological condition have been applied in state and basin stream surveys throughout the U.S., and also in countries outside of the U.S. These applications not only provide valuable tests of the NARS approaches, but generate new understandings of natural and anthropogenic controls on biota and physical habitat in streams. Results from applications in Brazil, for example, not only aid interpretation of the condition of Brazilian streams, but also refine approaches for interpreting aquatic resource surveys in the U.S. and elsewhere. In this article, the authors des

Long-term decline of the Amazon carbon sink.

PubMed

Brienen, R J W; Phillips, O L; Feldpausch, T R; Gloor, E; Baker, T R; Lloyd, J; Lopez-Gonzalez, G; Monteagudo-Mendoza, A; Malhi, Y; Lewis, S L; Vásquez Martinez, R; Alexiades, M; Álvarez Dávila, E; Alvarez-Loayza, P; Andrade, A; Aragão, L E O C; Araujo-Murakami, A; Arets, E J M M; Arroyo, L; Aymard C, G A; Bánki, O S; Baraloto, C; Barroso, J; Bonal, D; Boot, R G A; Camargo, J L C; Castilho, C V; Chama, V; Chao, K J; Chave, J; Comiskey, J A; Cornejo Valverde, F; da Costa, L; de Oliveira, E A; Di Fiore, A; Erwin, T L; Fauset, S; Forsthofer, M; Galbraith, D R; Grahame, E S; Groot, N; Hérault, B; Higuchi, N; Honorio Coronado, E N; Keeling, H; Killeen, T J; Laurance, W F; Laurance, S; Licona, J; Magnussen, W E; Marimon, B S; Marimon-Junior, B H; Mendoza, C; Neill, D A; Nogueira, E M; Núñez, P; Pallqui Camacho, N C; Parada, A; Pardo-Molina, G; Peacock, J; Peña-Claros, M; Pickavance, G C; Pitman, N C A; Poorter, L; Prieto, A; Quesada, C A; Ramírez, F; Ramírez-Angulo, H; Restrepo, Z; Roopsind, A; Rudas, A; Salomão, R P; Schwarz, M; Silva, N; Silva-Espejo, J E; Silveira, M; Stropp, J; Talbot, J; ter Steege, H; Teran-Aguilar, J; Terborgh, J; Thomas-Caesar, R; Toledo, M; Torello-Raventos, M; Umetsu, R K; van der Heijden, G M F; van der Hout, P; Guimarães Vieira, I C; Vieira, S A; Vilanova, E; Vos, V A; Zagt, R J

2015-03-19

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.

Observations of atmospheric monoaromatic hydrocarbons at urban, semi-urban and forest environments in the Amazon region

NASA Astrophysics Data System (ADS)

Paralovo, Sarah L.; Borillo, Guilherme C.; Barbosa, Cybelli G. G.; Godoi, Ana Flavia L.; Yamamoto, Carlos I.; de Souza, Rodrigo A. F.; Andreoli, Rita V.; Costa, Patrícia S.; Almeida, Gerson P.; Manzi, Antonio O.; Pöhlker, Christopher; Yáñez-Serrano, Ana M.; Kesselmeier, Jürgen; Godoi, Ricardo H. M.

2016-03-01

The Amazon region is one of the most significant natural ecosystems on the planet. Of special interest as a major study area is the interface between the forest and Manaus city, a state capital in Brazil embedded in the heart of the Amazon forest. In view of the interactions between natural and anthropogenic processes, an integrated experiment was conducted measuring the concentrations of the volatile organic compounds (VOCs) benzene, toluene, ethylbenzene and meta, ortho, para-xylene (known as BTEX), all of them regarded as pollutants with harmful effects on human health and vegetation and acting also as important precursors of tropospheric ozone. Furthermore, these compounds also take part in the formation of secondary organic aerosols, which can influence the pattern of cloud formation, and thus the regional water cycle and climate. The samples were collected in 2012/2013 at three different sites: (i) The Amazon Tall Tower Observatory (ATTO), a pristine rain forest region in the central Amazon Basin; (ii) Manacapuru, a semi-urban site located southwest and downwind of Manaus as a preview of the Green Ocean Amazon Experiment (GoAmazon 2014/15); and (iii) the city of Manaus (distributed over three sites). Results indicate that there is an increase in pollutant concentrations with increasing proximity to urban areas. For instance, the benzene concentration ranges were 0.237-19.6 (Manaus), 0.036-0.948 (Manacapuru) and 0.018-0.313 μg m-3 (ATTO). Toluene ranges were 0.700-832 (Manaus), 0.091-2.75 μg m-3 (Manacapuru) and 0.011-4.93 (ATTO). For ethylbenzene, they were 0.165-447 (Manaus), 0.018-1.20 μg m-3 (Manacapuru) and 0.047-0.401 (ATTO). Some indication was found for toluene to be released from the forest. No significant difference was found between the BTEX levels measured in the dry season and the wet seasons. Furthermore, it was observed that, in general, the city of Manaus seems to be less impacted by these pollutants than other cities in Brazil and in other countries, near the coastline or on the continent. A risk analysis for the health of Manaus' population was performed and indicated that the measured concentrations posed a risk for development of chronic diseases and cancer for the population of Manaus.

Trading forests for yields in the Peruvian Amazon

NASA Astrophysics Data System (ADS)

Gibbs, Holly

2012-03-01

Our knowledge of how agriculture expands, and the types of land it replaces, is remarkably limited across the tropics. Most remote-sensing studies focus on the net gains and losses in forests and agricultural land rather than the land-use transition pathways (Gibbs et al 2010). Only a handful of studies identify land sources for new croplands or plantations, and then only for farming systems aggregated together (e.g., Koh and Wilcove 2008, Morton et al 2006, Gibbs et al 2010). Gutiérrez-Vélez et al (2011), however, have taken a leap forward by tracking the different expansion pathways for smallholder and industrial oil palm plantations. Using a combination of Landsat, MODIS and field surveys, they investigate whether higher yields in new agricultural lands spare forests in the Peruvian Amazon and in a smaller focus area in the Ucayali region. Across the Peruvian Amazon, they show that between 2000 and 2010, new high-yield oil palm plantations replaced forests 72% of the time and accounted for 1.3% of total deforestation, with most expansion occurring after 2006. Gutiérrez-Vélez et al went further in the Ucayali region and compared land sources for new high-yield and low-yield plantations. Expansion of higher-yield agricultural lands should logically reduce the total area needed for production, thus potentially sparing forests. In the Ucayali focus area, expansion of high-yield oil palm did convert less total land area but more forest was cleared than with low-yield expansion. Smaller-scale plantations tended to expand into already cleared areas while industrial-scale plantations traded their greater yields for forests, leading to higher land-clearing carbon emissions per production unit (Gibbs et al 2008). Gutiérrez-Vélez et al show that higher yields may require less land for production but more forest may be lost in the process, and they emphasize the need for stronger incentives for land sparing. The potential land-saving nature of these high-yield plantations could be further analyzed by considering whether they help depress global prices, reducing incentives to expand elsewhere (Angelsen and Kaimowitz 2001). The significance of the study goes well beyond the bounds of Ucayli, and highlights risks to Amazonian forests from oil palm expansion (Butler and Laurance 2010). Oil palm is an astoundingly profitable and productive crop, with typical oil yields more than ten times that of soy. Some have even argued that oil palm is innately land sparing because it would take substantially more land for all other oil-bearing crops to provide the same output. However, most production gains from oil palm have occurred through increased area rather than increased yield, and in many cases expansion has been through forest clearing (Koh and Wilcove 2008, Gibbs et al 2010). The findings of Gutiérrez-Vélez et al (2011) are particularly significant considering that the booming palm oil sectors in Indonesia and Malaysia, which currently produce over 80% of the world's product, are facing a host of pressures that constrain future area expansion. Malaysia has little remaining land suited for plantations and Indonesia faces intensifying international scrutiny over the future of their forestlands. Consequently, the Amazon basin is widely considered the new frontier, with more than half of its forest area suitable for palm oil cultivation (Butler and Laurance 2010) and growing incentives from Brazil's Program for the Sustainable Production of Oil Palm, which aims to utilize degraded lands and spur reforestation efforts. Their results also illuminate another key issue, namely the constraints faced by large-scale producers when they seek to expand plantation area. Emerging demand-side conservation efforts, such as the Roundtable for Sustainable Palm Oil (RSPO), assume that already cleared and non-forested lands are freely available. Gutiérrez-Vélez et al (2011) hint at the obstacles to using such cleared lands, which is that they are inhabited and often have contested land tenure. We must carefully consider our consumption of these commodities in the face of growing land scarcity (Lambin and Meyfroidt 2011). If high-yield plantations displace low-yield plantations they too may follow the path of industrial agriculture and resume destruction of the forests that conservation efforts aim to protect. Without clear incentives to spare land, we could be trading forest for higher yields. References Angelsen A and Kaimowitz D 2001 Agricultural Technologies and Tropical Deforestation (New York: CABI Publishing) (www.cifor.org/publications/pdf files/books/bangelsen0101e0.pdf) Butler R and Laurance W 2010 Is oil palm the next emerging threat to the Amazon? Trop. Conserv. Sci. 2 1-10 Gibbs H K, Johnston M, Foley J A, Holloway T, Monfreda C, Ramankutty N and Zaks D 2008 Carbon payback times for crop-based biofuel expansion in the tropics: the effects of changing yield and technology Environ. Res. Lett. 3 034001 Gibbs H K, Ruesch A S, Achard F, Clayton M K, Holmgren P, Ramankutty N and Foley J A 2010 Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s Proc. Natl Acad. Sci. 107 16732-7 Gutiérrez-Vélez V H, DeFries R, Pinedo-Vásquez M, Uriarte M, Padoch C, Baethgen W, Fernandes K and Lim Y 2011 High-yield oil palm expansion spares land at the expense of forests in the Peruvian Amazon Environ. Res. Lett. 6 044029 Koh L and Wilcove D 2008 Is oil palm agriculture really destroying tropical biodiversity? Conserv. Lett. 1 60-4 Lambin E and Meyfroidt P 2011 Inaugural article: global land use change, economic globalization, and the looming land scarcity Proc. Natl Acad. Sci. 108 93465-72 Morton D C et al 2006 Cropland expansion changes deforestation dynamics in the southern Brazilian Amazon Proc. Natl Acad. Sci. USA 103 14637-41

Testing the Amazon savannization hypothesis: fire effects on invasion of a neotropical forest by native cerrado and exotic pasture grasses

PubMed Central

Silvério, Divino V.; Brando, Paulo M.; Balch, Jennifer K.; Putz, Francis E.; Nepstad, Daniel C.; Oliveira-Santos, Claudinei; Bustamante, Mercedes M. C.

2013-01-01

Changes in climate and land use that interact synergistically to increase fire frequencies and intensities in tropical regions are predicted to drive forests to new grass-dominated stable states. To reveal the mechanisms for such a transition, we established 50 ha plots in a transitional forest in the southwestern Brazilian Amazon to different fire treatments (unburned, burned annually (B1yr) or at 3-year intervals (B3yr)). Over an 8-year period since the commencement of these treatments, we documented: (i) the annual rate of pasture and native grass invasion in response to increasing fire frequency; (ii) the establishment of Brachiaria decumbens (an African C4 grass) as a function of decreasing canopy cover and (iii) the effects of grass fine fuel on fire intensity. Grasses invaded approximately 200 m from the edge into the interiors of burned plots (B1yr: 4.31 ha; B3yr: 4.96 ha) but invaded less than 10 m into the unburned plot (0.33 ha). The probability of B. decumbens establishment increased with seed availability and decreased with leaf area index. Fine fuel loads along the forest edge were more than three times higher in grass-dominated areas, which resulted in especially intense fires. Our results indicate that synergies between fires and invasive C4 grasses jeopardize the future of tropical forests. PMID:23610179

A Slippery Slope: Children's Perceptions of Their Role in Environmental Preservation in the Peruvian Amazon

ERIC Educational Resources Information Center

Galeano, Rebecca

2013-01-01

Despite international attention and attempts to preserve the environmental diversity of the Amazon, it is an accepted fact that those who inhabit the forest must be the ones who preserve it. This article presents an analysis of how children in small rural riverine communities along the Amazon understand the importance of environmental preservation…

Comparative Phylogeography of Neotropical Birds

DTIC Science & Technology

2009-05-01

of lowland Neotropical rainforest birds that have populations isolated on either side of the Andes, Amazon River, and Madeira River. I found widely...Unlike canopy species, understory birds were structured at smaller spatial scales, particularly across riverine barriers of the Amazon basin...expansive complementary forest of the Amazon Basin. This divide is relatively young as the northern Andes were only half their present elevation

Estimating the risk of Amazonian forest dieback.

PubMed

Rammig, Anja; Jupp, Tim; Thonicke, Kirsten; Tietjen, Britta; Heinke, Jens; Ostberg, Sebastian; Lucht, Wolfgang; Cramer, Wolfgang; Cox, Peter

2010-08-01

*Climate change will very likely affect most forests in Amazonia during the course of the 21st century, but the direction and intensity of the change are uncertain, in part because of differences in rainfall projections. In order to constrain this uncertainty, we estimate the probability for biomass change in Amazonia on the basis of rainfall projections that are weighted by climate model performance for current conditions. *We estimate the risk of forest dieback by using weighted rainfall projections from 24 general circulation models (GCMs) to create probability density functions (PDFs) for future forest biomass changes simulated by a dynamic vegetation model (LPJmL). *Our probabilistic assessment of biomass change suggests a likely shift towards increasing biomass compared with nonweighted results. Biomass estimates range between a gain of 6.2 and a loss of 2.7 kg carbon m(-2) for the Amazon region, depending on the strength of CO(2) fertilization. *The uncertainty associated with the long-term effect of CO(2) is much larger than that associated with precipitation change. This underlines the importance of reducing uncertainties in the direct effects of CO(2) on tropical ecosystems.

Combined effects of climate change and forest clearing on the Amazon vegetation: Projections for 2080-2100

NASA Astrophysics Data System (ADS)

Cook, K. H.; Vizy, E. K.

2007-05-01

A regional climate model with resolution of 60 km coupled with a potential vegetation model is used to simulate future vegetation distributions over South America. The coupled model, which produces an accurate representation of today's climate and vegetation, is forced with increasing atmospheric CO2 concentrations, sea surface temperature from a global model, and scenarios of future land use practices to predict climate and vegetation distributions for the last 2 decades of the 21st century. When only climate change is considered, under a business-as-usual scenario for global emissions, the extent of the Amazon rainforest is reduced by about 70 per cent by the end of this century, and the shrubland (caatinga) vegetation of Brazil's Nordeste region spreads westward and southward. Reductions in annual mean precipitation are widespread and rainfall becomes insufficient to support the rainforest in these regions, but some areas receive more precipitation. The length of the dry season increases in the central and southern Amazon in association with changes in the large-scale tropical circulation. Without this change in seasonality, local refugia of Amazon vegetation would be preserved and the retreat of the rainforest would be somewhat less extensive. Including various projections of future land use practices in addition to climate change may accelerate the unrecoverable demise of the rainforest and feedback to modify climate on regional space scales. The portions of the rainforest that are most vulnerable to climate change are the same as those that are under the most pressure from human activity, presenting a remarkable competition.

Response of the Amazon rainforest to late Pleistocene climate variability

NASA Astrophysics Data System (ADS)

Häggi, Christoph; Chiessi, Cristiano M.; Merkel, Ute; Mulitza, Stefan; Prange, Matthias; Schulz, Michael; Schefuß, Enno

2017-12-01

Variations in Amazonian hydrology and forest cover have major consequences for the global carbon and hydrological cycles as well as for biodiversity. Yet, the climate and vegetation history of the lowland Amazon basin and its effect on biogeography remain debated due to the scarcity of suitable high-resolution paleoclimate records. Here, we use the isotopic composition (δD and δ13C) of plant-waxes from a high-resolution marine sediment core collected offshore the Amazon River to reconstruct the climate and vegetation history of the integrated lowland Amazon basin for the period from 50,000 to 12,800 yr before present. Our results show that δD values from the Last Glacial Maximum were more enriched than those from Marine Isotope Stage (MIS) 3 and the present-day. We interpret this trend to reflect long-term changes in precipitation and atmospheric circulation, with overall drier conditions during the Last Glacial Maximum. Our results thus suggest a dominant glacial forcing of the climate in lowland Amazonia. In addition to previously suggested thermodynamic mechanisms of precipitation change, which are directly related to temperature, we conclude that changes in atmospheric circulation are crucial to explain the temporal evolution of Amazonian rainfall variations, as demonstrated in climate model experiments. Our vegetation reconstruction based on δ13C values shows that the Amazon rainforest was affected by intrusions of savannah or more open vegetation types in its northern sector during Heinrich Stadials, while it was resilient to glacial drying. This suggests that biogeographic patterns in tropical South America were affected by Heinrich Stadials in addition to glacial-interglacial climate variability.

Analysis of normalized radar cross section (sigma-O) signature of Amazon rain forest using SEASAT scatterometer data

NASA Technical Reports Server (NTRS)

Bracalente, E. M.; Sweet, J. L.

1984-01-01

The normalized radar cross section (NRCS) signature of the Amazon rain forest was SEASAT scatterometer data. Statistics of the measured (NRCS) values were determined from multiple orbit passes for three local time periods. Plots of mean normalized radar cross section, dB against incidence angle as a function of beam and polarization show that less than 0.3 dB relative bias exists between all beams over a range of incidence angle from 30 deg to 53 deg. The backscattered measurements analyzed show the Amazon rain forest to be relatively homogeneous, azimuthally isotropic and insensitive to polarization. The return from the rain forest target appears relatively consistent and stable, except for the small diurnal variation (0.75 dB) that occurs at sunrise. Because of the relative stability of the rain forest target and the scatterometer instrument, the response of versus incidence angle was able to detect errors in the estimated yaw altitude angle. Also, small instrument gain biases in some of the processing channels were detected. This led to the development of an improved NRCS algorithm, which uses a more accurate method for estimating the system noise power.

Aboveground Biomass Variability Across Intact and Degraded Forests in the Brazilian Amazon

NASA Technical Reports Server (NTRS)

Longo, Marcos; Keller, Michael; Dos-Santos, Maiza N.; Leitold, Veronika; Pinage, Ekena R.; Baccini, Alessandro; Saatchi, Sassan; Nogueira, Euler M.; Batistella, Mateus; Morton, Douglas C.

2016-01-01

Deforestation rates have declined in the Brazilian Amazon since 2005, yet degradation from logging, re, and fragmentation has continued in frontier forests. In this study we quantified the aboveground carbon density (ACD) in intact and degraded forests using the largest data set of integrated forest inventory plots (n 359) and airborne lidar data (18,000 ha) assembled to date for the Brazilian Amazon. We developed statistical models relating inventory ACD estimates to lidar metrics that explained70 of the variance across forest types. Airborne lidar-ACD estimates for intact forests ranged between 5.0 +/- 2.5 and 31.9 +/- 10.8 kg C m(exp -2). Degradation carbon losses were large and persistent. Sites that burned multiple times within a decade lost up to 15.0 +/- 0.7 kg C m(-2)(94%) of ACD. Forests that burned nearly15 years ago had between 4.1 +/- 0.5 and 6.8 +/- 0.3 kg C m(exp -2) (22-40%) less ACD than intact forests. Even for low-impact logging disturbances, ACD was between 0.7 +/- 0.3 and 4.4 +/- 0.4 kg C m(exp -2)(4-21%) lower than unlogged forests. Comparing biomass estimates from airborne lidar to existing biomass maps, we found that regional and pan-tropical products consistently overestimated ACD in degraded forests, under-estimated ACD in intact forests, and showed little sensitivity to res and logging. Fine-scale heterogeneity in ACD across intact and degraded forests highlights the benefits of airborne lidar for carbon mapping. Differences between airborne lidar and regional biomass maps underscore the need to improve and update biomass estimates for dynamic land use frontiers, to better characterize deforestation and degradation carbon emissions for regional carbon budgets and Reduce Emissions from Deforestation and forest Degradation(REDD+).

Fifty-thousand-year vegetation and climate history of Noel Kempff Mercado National Park, Bolivian Amazon

NASA Astrophysics Data System (ADS)

Burbridge, Rachel E.; Mayle, Francis E.; Killeen, Timothy J.

2004-03-01

Pollen and charcoal records from two large, shallow lakes reveal that throughout most of the past 50,000 yr Noel Kempff Mercado National Park, in northeastern lowland Bolivia (southwestern Amazon Basin), was predominantly covered by savannas and seasonally dry semideciduous forests. Lowered atmospheric CO 2 concentrations, in combination with a longer dry season, caused expansion of dry forests and savannas during the last glacial period, especially at the last glacial maximum. These ecosystems persisted until the mid-Holocene, although they underwent significant species reassortment. Forest communities containing a mixture of evergreen and semideciduous species began to expand between 6000 and 3000 14C yr B.P. Humid evergreen rain forests expanded to cover most of the area within the past 2000 14C yr B.P., coincident with a reduction in fire frequencies. Comparisons between modern pollen spectra and vegetation reveal that the Moraceae-dominated rain forest pollen spectra likely have a regional source area at least 2-3 km beyond the lake shore, whereas the grass- and sedge-dominated savanna pollen spectra likely have a predominantly local source area. The Holocene vegetation changes are consistent with independent paleoprecipitation records from the Bolivian Altiplano and paleovegetation records from other parts of southwestern Amazonia. The progressive expansion in rain forests through the Holocene can be largely attributed to enhanced convective activity over Amazonia, due to greater seasonality of insolation in the Southern Hemisphere tropics driven by the precession cycle according to the Milankovitch Astronomical Theory.

Erosion of particulate organic material from an Andean river and its delivery to the Amazon Basin

NASA Astrophysics Data System (ADS)

Clark, Kathryn; Hilton, Robert; West, A. Joshua; Robles Caceres, Arturo; Grocke, Darren; Marthews, Toby; Asner, Greg; New, Mark; Mahli, Yadvinder

2016-04-01

Organic carbon and nutrients discharged by mountainous rivers can play an important role in biogeochemical cycles from regional to global scales. The eastern Andes host productive forests on steep, rapidly eroding slopes, a combination that is primed to deliver sediment, carbon and nutrients to the lowland Amazon River. We quantify clastic sediment and particulate organic carbon (POC) discharge for the Kosñipata River, Peru, an Andean tributary of the Madre de Dios River, using suspended sediment samples and discharge measurements over one year at two gauging stations. Calculations of sediment yield on the basis of this data suggest that the Madre de Dios basin may have erosion rates ˜10 times greater than the Amazon Basin average. The total POC yield over the sampling period was up to five times higher than the yield in the lowland Amazon Basin, with most POC (70-80%) exported between December and March in the wet season. We use radiocarbon, stable C isotopes and C/N ratios to distinguish between the erosion and discharge of POC from sedimentary rocks (petrogenic POC) and POC eroded from the modern terrestrial biosphere, from vegetation and soil (biospheric POC). We find that biospheric POC discharge was significantly enhanced during flood events, over that of clastic sediment and petrogenic POC. The ultimate fate of the eroded POC may play a central role in the net carbon budget of Andean forest. In these forests, net productivity minus heterotrophic respiration is close to zero at the scale of forest plots, and the erosion of biospheric POC by this Andean river is sufficiently rapid that its fate downstream (sedimentary burial/preservation versus oxidation/degradation) may determine whether the mountain forest is a carbon sink or source to the atmosphere. In addition, the measured discharge of petrogenic POC suggests that fluxes from the Andes may be considerably higher than measured downstream in the Madeira River. If this petrogenic POC is oxidised rather than stored in the Amazon River floodplains, it could contribute an important release of CO2 which is not considered in forest-plot scale measurements. Overall, our results suggest that the erosion of biospheric and petrogenic POC from the Andes and its discharge by rivers comprise an important part of the organic carbon budget of the Amazon River Basin, one that depends on the fate of material delivered to the lowlands.

Phylogeography of the dark fruit-eating bat Artibeus obscurus in the Brazilian Amazon.

PubMed

Ferreira, Wallax Augusto Silva; Borges, Bárbara do Nascimento; Rodrigues-Antunes, Symara; de Andrade, Fernanda Atanaena Gonçalves; Aguiar, Gilberto Ferreira de Souza; de Sousa e Silva-Junior, José; Marques-Aguiar, Suely Aparecida; Harada, Maria Lúcia

2014-01-01

Artibeus obscurus (Mammalia: Chiroptera) is endemic to South America, being found in at least 18 Brazilian states. Recent studies revealed that different populations of this genus present distinct phylogeographic patterns; however, very little is known on the population genetics structure of A. obscurus in the Amazon rainforest. Here, using a fragment (1010bp) of the mitochondrial gene cytochrome b from 87 samples, we investigated patterns of genetic divergence among populations of A. obscurus from different locations in the Brazilian Amazon rainforest and compared them with other Brazilian and South American regions. Analysis of molecular variance (AMOVA), fixation index (Fst) analysis, and phylogeographic patterns showed divergence between two major monophyletic groups, each one corresponding to a geographic region associated with the Atlantic and Amazon forest biomes. The Atlantic forest clusters formed a monophyletic group with a high bootstrap support and a fragmented distribution that follows the pattern predicted by the Refuge Theory. On the other hand, a different scenario was observed for the Amazon forest, where no fragmentation was identified. The AMOVA results revealed a significant geographic heterogeneity in the distribution of genetic variation, with 70% found within populations across the studied populations (Fst values ranging from 0.05864 to 0.09673; φST = 0.55). The intrapopulational analysis revealed that one population (Bragança) showed significant evidence of population expansion, with the formation of 2 distinct phylogroups, suggesting the occurrence of a subspecies or at least a different population in this region. These results also suggest considerable heterogeneity for A. obscurus in the Amazon region.

Seasonality of Central Amazon Forest Leaf Flush Using Tower-Mounted RGB Camera

NASA Astrophysics Data System (ADS)

Wu, J.; Nelson, B. W.; Tavares, J. V.; Valeriano, D. M.; Lopes, A. P.; Marostica, S. F.; Martins, G.; Prohaska, N.; Albert, L.; De Araujo, A. C.; Manzi, A. O.; Saleska, S. R.; Huete, A. R.

2014-12-01

Tower-mounted RGB cameras can contribute data to the debate on seasonality of photosynthesis in Amazon upland forests and to improved modelling of forest response to climate change. In late 2010 we began monitoring upper crown surfaces of ~65 living trees or vines from a 54m tall eddy-flux tower on a well-drained clay-soil plateau. This Central Amazon site (60.2091 W, 2.6092 S) is in a large forest reserve. We deployed a Stardot Netcam XL RGB camera with a 1024 x 768 resolution CMOS sensor, 66o HFOV lens, fixed oblique south view, fixed iris, fixed white balance and auto-exposure. Images were logged every 15 seconds to a passively cooled FitPC2i with heat-tolerant SSD drive. Camera and PC automatically rebooted after power outages. Here we report results for two full years, from 1 Dec 2011 through 30 Nov 2013. Images in six day intervals were selected near local noon for homogeneous diffuse lighting under cloudy sky and for a standard reflected radiance (± 10%). Crowns showing two easily recognized phenophases were tallied: (1) massive flushing of new light-green leaves and (2) complete or nearly complete leaf loss. On average, 60% of live crowns flushed a massive amount of new leaves each year. Each crown flush was completed within 30 days. During the five driest months (Jun-Oct), 44% of all live crowns, on average, exhibited such massive leaf flush. In the five wettest months (Dec-Apr) only 11% of live crowns mass-flushed new leaves. In each year 23% of all live crowns became deciduous, usually a brief (1-2 week) preamble to flushing. Additional crowns lost old dark-green leaves partially and more gradually, becoming semi-deciduous prior to flushing. From these two years of camera data we infer that highly efficient leaves of 2-6 months age (high maximum carboxylation rate) are most abundant from the late dry season (October) through the mid wet season (March). This coincides with peak annual photosynthesis (Gross Ecosystem Productivity) reported for this same Central Amazon site using eddy flux methods.

Modelling basin-wide variations in Amazon forest photosynthesis

NASA Astrophysics Data System (ADS)

Mercado, Lina; Lloyd, Jon; Domingues, Tomas; Fyllas, Nikolaos; Patino, Sandra; Dolman, Han; Sitch, Stephen

2010-05-01

Given the importance of Amazon rainforest in the global carbon and hydrological cycles, there is a need to use parameterized and validated ecosystem gas exchange and vegetation models for this region in order to adequately simulate present and future carbon and water balances. Recent research has found major differences in above-ground net primary productivity (ANPP), above ground biomass and tree dynamics across Amazonia. West Amazonia is more dynamic, with younger trees, higher stem growth rates and lower biomass than central and eastern Amazon (Baker et al. 2004; Malhi et al. 2004; Phillips et al. 2004). A factor of three variation in above-ground net primary productivity has been estimated across Amazonia by Malhi et al. (2004). Different hypotheses have been proposed to explain the observed spatial variability in ANPP (Malhi et al. 2004). First, due to the proximity to the Andes, sites from western Amazonia tend to have richer soils than central and eastern Amazon and therefore soil fertility could possibly be highly related to the high wood productivity found in western sites. Second, if GPP does not vary across the Amazon basin then different patterns of carbon allocation to respiration could also explain the observed ANPP gradient. However since plant growth depends on the interaction between photosynthesis, transport of assimilates, plant respiration, water relations and mineral nutrition, variations in plant gross photosynthesis (GPP) could also explain the observed variations in ANPP. In this study we investigate whether Amazon GPP can explain variations of observed ANPP. We use a sun and shade canopy gas exchange model that has been calibrated and evaluated at five rainforest sites (Mercado et al. 2009) to simulate gross primary productivity of 50 sites across the Amazon basin during the period 1980-2001. Such simulation differs from the ones performed with global vegetation models (Cox et al. 1998; Sitch et al. 2003) where i) single plant functional type parameter values are assigned and assumed invariant with environmental condition but also ii) these models use leaf N as a factor that limit photosynthesis. Instead, since leaf P may also limit photosynthesis of the tropical forest (Reich et al. 2009), we use a more specific description of photosynthetic capacity across the basin based on the model evaluation done in Mercado et al. (2009) in which canopy photosynthetic capacity is related to foliar P but also using the relationships derived between canopy photosynthesis and leaf nutrients (N and P) from measurements in tropical trees (Domingues et al.In review). A study of this kind can inform the global vegetation/climate community as to the need for variability in key model parameters in order to accurately simulate carbon fluxes across the Amazon basin. Baker, T. R., et al. 2004. Increasing biomass in Amazonian forest plots. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359 (1443):353-365. Phillips, O. L. et al. 2004. Pattern and process in Amazon tree turnover, 1976-2001. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359 (1443):381-407. Malhi, Y. et al. 2004. The above-ground coarse wood productivity of 104 Neotropical forest plots. Global Change Biology 10 (5):563-591. Mercado, L.M. et al. 2009. Impact of changes in diffuse radiation on the global land carbon sink. Nature 458 (7241), 1014. Cox, P. M. et al. 1998. A canopy conductance and photosynthesis model for use in a GCM land surface scheme. Journal of Hydrology 213 (1-4):79-9 Sitch, S. et al. 2003. Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model. Global Change Biology 9 (2):161-185. Reich B. R. et al. 2009. Leaf phosphorus influences the photosynhtesis-nitrogen relation: a cross-biome analysis of 314 species. Oecologia, doi 10.1007/s00442-009-1291-3. Domingues, T. et al. In review. Co-limitation of photosynthetic capacity by nitrogen and phosphorus along a precipitation gradient in West Africa. Plant Cell and Environment.

Land-Use Change, Soil Process and Trace Gas Fluxes in the Brazilian Amazon Basin

NASA Technical Reports Server (NTRS)

Melillo, Jerry M.; Steudler, Paul A.

1997-01-01

We measured changes in key soil processes and the fluxes of CO2, CH4 and N2O associated with the conversion of tropical rainforest to pasture in Rondonia, a state in the southwest Amazon that has experienced rapid deforestation, primarily for cattle ranching, since the late 1970s. These measurements provide a comprehensive quantitative picture of the nature of surface soil element stocks, C and nutrient dynamics, and trace gas fluxes between soils and the atmosphere during the entire sequence of land-use change from the initial cutting and burning of native forest, through planting and establishment of pasture grass and ending with very old continuously-pastured land. All of our work is done in cooperation with Brazilian scientists at the Centro de Energia Nuclear na Agricultura (CENA) through an extant official bi-lateral agreement between the Marine Biological Laboratory and the University of Sao Paulo, CENA's parent institution.

Leaf development and demography explain photosynthetic seasonality in Amazon evergreen forests

USGS Publications Warehouse

Wu, Jin; Albert, Lauren; Lopes, Aline; Restrepo-Coupe, Natalia; Hayek, Matthew; Wiedemann, Kenia T.; Guan, Kaiyu; Stark, Scott C.; Christoffersen, Bradley; Prohaska, Neill; Tavares, Julia V.; Marostica, Suelen; Kobayashi, Hideki; Ferreira, Maurocio L.; Campos, Kleber Silva; da Silva, Rodrigo; Brando, Paulo M.; Dye, Dennis G.; Huxman, Travis E.; Huete, Alfredo; Nelson, Bruce; Saleska, Scott

2016-01-01

In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality in these forests. Specifically, synchronization of new leaf growth with dry season litterfall shifts canopy composition toward younger, more light-use efficient leaves, explaining large seasonal increases (~27%) in ecosystem photosynthesis. Coordinated leaf development and demography thus reconcile seemingly disparate observations at different scales and indicate that accounting for leaf-level phenology is critical for accurately simulating ecosystem-scale responses to climate change.

Spatial Pattern of Standing Timber Value across the Brazilian Amazon

PubMed Central

Ahmed, Sadia E.; Ewers, Robert M.

2012-01-01

The Amazon is a globally important system, providing a host of ecosystem services from climate regulation to food sources. It is also home to a quarter of all global diversity. Large swathes of forest are removed each year, and many models have attempted to predict the spatial patterns of this forest loss. The spatial patterns of deforestation are determined largely by the patterns of roads that open access to frontier areas and expansion of the road network in the Amazon is largely determined by profit seeking logging activities. Here we present predictions for the spatial distribution of standing value of timber across the Amazon. We show that the patterns of timber value reflect large-scale ecological gradients, determining the spatial distribution of functional traits of trees which are, in turn, correlated with timber values. We expect that understanding the spatial patterns of timber value across the Amazon will aid predictions of logging movements and thus predictions of potential future road developments. These predictions in turn will be of great use in estimating the spatial patterns of deforestation in this globally important biome. PMID:22590520

Cropland expansion changes deforestation dynamics in the southern Brazilian Amazon

PubMed Central

Morton, Douglas C.; DeFries, Ruth S.; Shimabukuro, Yosio E.; Anderson, Liana O.; Arai, Egidio; del Bon Espirito-Santo, Fernando; Freitas, Ramon; Morisette, Jeff

2006-01-01

Intensive mechanized agriculture in the Brazilian Amazon grew by >3.6 million hectares (ha) during 2001–2004. Whether this cropland expansion resulted from intensified use of land previously cleared for cattle ranching or new deforestation has not been quantified and has major implications for future deforestation dynamics, carbon fluxes, forest fragmentation, and other ecosystem services. We combine deforestation maps, field surveys, and satellite-based information on vegetation phenology to characterize the fate of large (>25-ha) clearings as cropland, cattle pasture, or regrowing forest in the years after initial clearing in Mato Grosso, the Brazilian state with the highest deforestation rate and soybean production since 2001. Statewide, direct conversion of forest to cropland totaled >540,000 ha during 2001–2004, peaking at 23% of 2003 annual deforestation. Cropland deforestation averaged twice the size of clearings for pasture (mean sizes, 333 and 143 ha, respectively), and conversion occurred rapidly; >90% of clearings for cropland were planted in the first year after deforestation. Area deforested for cropland and mean annual soybean price in the year of forest clearing were directly correlated (R2 = 0.72), suggesting that deforestation rates could return to higher levels seen in 2003–2004 with a rebound of crop prices in international markets. Pasture remains the dominant land use after forest clearing in Mato Grosso, but the growing importance of larger and faster conversion of forest to cropland defines a new paradigm of forest loss in Amazonia and refutes the claim that agricultural intensification does not lead to new deforestation. PMID:16973742

A Simulation Model of Carbon Cycling and Methane Emissions in Amazon Wetlands

NASA Technical Reports Server (NTRS)

Potter, Christopher; Melack, John; Hess, Laura; Forsberg, Bruce; Novo, Evlyn Moraes; Klooster, Steven

2004-01-01

An integrative carbon study is investigating the hypothesis that measured fluxes of methane from wetlands in the Amazon region can be predicted accurately using a combination of process modeling of ecosystem carbon cycles and remote sensing of regional floodplain dynamics. A new simulation model has been build using the NASA- CASA concept for predicting methane production and emission fluxes in Amazon river and floodplain ecosystems. Numerous innovations area being made to model Amazon wetland ecosystems, including: (1) prediction of wetland net primary production (NPP) as the source for plant litter decomposition and accumulation of sediment organic matter in two major vegetation classes - flooded forests (varzea or igapo) and floating macrophytes, (2) representation of controls on carbon processing and methane evasion at the diffusive boundary layer, through the lake water column, and in wetland sediments as a function of changes in floodplain water level, (3) inclusion of surface emissions controls on wetland methane fluxes, including variations in daily surface temperature and of hydrostatic pressure linked to water level fluctuations. A model design overview and early simulation results are presented.

Effects of Natural and Experimental Drought on Growth and Water Use Efficiency in Amazon trees

NASA Astrophysics Data System (ADS)

Vadeboncoeur, M. A.; Brum, M., Jr.; Oliveira, R. S.; Moutinho, V. H. P.; Flores, C. F.; Llerena, C. A.; Palace, M. W.; Asbjornsen, H.

2016-12-01

Severe regional droughts in the Amazon basin, mostly associated with El Nino events, have attracted considerable attention over the past decade, especially with regard to their effects on tree mortality, vulnerability to fire, and changes in the terrestrial budgets of carbon, water, and energy. Understanding the complex responses of forest ecosystems to such droughts is key to predicting how these globally critical forest ecosystems will respond to a changing climate with higher temperatures and greater precipitation variability. Though tree rings are not formed by all tropical tree species, they offer a unique retrospective approach for investigating patterns of climatic responses in both carbon cycling (primary production inferred from diameter growth) and water cycling (water use efficiency calculated from stable C isotope ratios). We sampled increment cores from 40 tree species at the Tapajos National Forest in Brazil, as well as the Cocha Cashu Biological Station in Peru, for an isotopic dendrochronological investigation into the effects of past droughts on the growth and water-use efficiency of canopy and mid-story tree species. We found that many but not all trees responded to drought years with periods of reduced growth lasting 2-3 years. Forthcoming data on carbon isotope ratios will allow us to compare the sensitivity of species and sites in terms of water use under drought conditions.

Tall Amazonian forests are less sensitive to precipitation variability

NASA Astrophysics Data System (ADS)

Giardina, Francesco; Konings, Alexandra G.; Kennedy, Daniel; Alemohammad, Seyed Hamed; Oliveira, Rafael S.; Uriarte, Maria; Gentine, Pierre

2018-06-01

Climate change is altering the dynamics, structure and function of the Amazon, a biome deeply connected to the Earth's carbon cycle. Climate factors that control the spatial and temporal variations in forest photosynthesis have been well studied, but the influence of forest height and age on this controlling effect has rarely been considered. Here, we present remote sensing observations of solar-induced fluorescence (a proxy for photosynthesis), precipitation, vapour-pressure deficit and canopy height, together with estimates of forest age and aboveground biomass. We show that photosynthesis in tall Amazonian forests, that is, forests above 30 m, is three times less sensitive to precipitation variability than in shorter (less than 20 m) forests. Taller Amazonian forests are also found to be older, have more biomass and deeper rooting systems1, which enable them to access deeper soil moisture and make them more resilient to drought. We suggest that forest height and age are an important control of photosynthesis in response to interannual precipitation fluctuations. Although older and taller trees show less sensitivity to precipitation variations, they are more susceptible to fluctuations in vapour-pressure deficit. Our findings illuminate the response of Amazonian forests to water stress, droughts and climate change.

Large seasonal swings in leaf area of Amazon rainforests

PubMed Central

Myneni, Ranga B.; Yang, Wenze; Nemani, Ramakrishna R.; Huete, Alfredo R.; Dickinson, Robert E.; Knyazikhin, Yuri; Didan, Kamel; Fu, Rong; Negrón Juárez, Robinson I.; Saatchi, Sasan S.; Hashimoto, Hirofumi; Ichii, Kazuhito; Shabanov, Nikolay V.; Tan, Bin; Ratana, Piyachat; Privette, Jeffrey L.; Morisette, Jeffrey T.; Vermote, Eric F.; Roy, David P.; Wolfe, Robert E.; Friedl, Mark A.; Running, Steven W.; Votava, Petr; El-Saleous, Nazmi; Devadiga, Sadashiva; Su, Yin; Salomonson, Vincent V.

2007-01-01

Despite early speculation to the contrary, all tropical forests studied to date display seasonal variations in the presence of new leaves, flowers, and fruits. Past studies were focused on the timing of phenological events and their cues but not on the accompanying changes in leaf area that regulate vegetation–atmosphere exchanges of energy, momentum, and mass. Here we report, from analysis of 5 years of recent satellite data, seasonal swings in green leaf area of ≈25% in a majority of the Amazon rainforests. This seasonal cycle is timed to the seasonality of solar radiation in a manner that is suggestive of anticipatory and opportunistic patterns of net leaf flushing during the early to mid part of the light-rich dry season and net leaf abscission during the cloudy wet season. These seasonal swings in leaf area may be critical to initiation of the transition from dry to wet season, seasonal carbon balance between photosynthetic gains and respiratory losses, and litterfall nutrient cycling in moist tropical forests. PMID:17360360

Ecological Niche Modelling Predicts Southward Expansion of Lutzomyia (Nyssomyia) flaviscutellata (Diptera: Psychodidae: Phlebotominae), Vector of Leishmania (Leishmania) amazonensis in South America, under Climate Change.

PubMed

Carvalho, Bruno M; Rangel, Elizabeth F; Ready, Paul D; Vale, Mariana M

2015-01-01

Vector borne diseases are susceptible to climate change because distributions and densities of many vectors are climate driven. The Amazon region is endemic for cutaneous leishmaniasis and is predicted to be severely impacted by climate change. Recent records suggest that the distributions of Lutzomyia (Nyssomyia) flaviscutellata and the parasite it transmits, Leishmania (Leishmania) amazonensis, are expanding southward, possibly due to climate change, and sometimes associated with new human infection cases. We define the vector's climatic niche and explore future projections under climate change scenarios. Vector occurrence records were compiled from the literature, museum collections and Brazilian Health Departments. Six bioclimatic variables were used as predictors in six ecological niche model algorithms (BIOCLIM, DOMAIN, MaxEnt, GARP, logistic regression and Random Forest). Projections for 2050 used 17 general circulation models in two greenhouse gas representative concentration pathways: "stabilization" and "high increase". Ensemble models and consensus maps were produced by overlapping binary predictions. Final model outputs showed good performance and significance. The use of species absence data substantially improved model performance. Currently, L. flaviscutellata is widely distributed in the Amazon region, with records in the Atlantic Forest and savannah regions of Central Brazil. Future projections indicate expansion of the climatically suitable area for the vector in both scenarios, towards higher latitudes and elevations. L. flaviscutellata is likely to find increasingly suitable conditions for its expansion into areas where human population size and density are much larger than they are in its current locations. If environmental conditions change as predicted, the range of the vector is likely to expand to southeastern and central-southern Brazil, eastern Paraguay and further into the Amazonian areas of Bolivia, Peru, Ecuador, Colombia and Venezuela. These areas will only become endemic for L. amazonensis, however, if they have competent reservoir hosts and transmission dynamics matching those in the Amazon region.

Ecological Niche Modelling Predicts Southward Expansion of Lutzomyia (Nyssomyia) flaviscutellata (Diptera: Psychodidae: Phlebotominae), Vector of Leishmania (Leishmania) amazonensis in South America, under Climate Change

PubMed Central

Carvalho, Bruno M.; Ready, Paul D.

2015-01-01

Vector borne diseases are susceptible to climate change because distributions and densities of many vectors are climate driven. The Amazon region is endemic for cutaneous leishmaniasis and is predicted to be severely impacted by climate change. Recent records suggest that the distributions of Lutzomyia (Nyssomyia) flaviscutellata and the parasite it transmits, Leishmania (Leishmania) amazonensis, are expanding southward, possibly due to climate change, and sometimes associated with new human infection cases. We define the vector’s climatic niche and explore future projections under climate change scenarios. Vector occurrence records were compiled from the literature, museum collections and Brazilian Health Departments. Six bioclimatic variables were used as predictors in six ecological niche model algorithms (BIOCLIM, DOMAIN, MaxEnt, GARP, logistic regression and Random Forest). Projections for 2050 used 17 general circulation models in two greenhouse gas representative concentration pathways: “stabilization” and “high increase”. Ensemble models and consensus maps were produced by overlapping binary predictions. Final model outputs showed good performance and significance. The use of species absence data substantially improved model performance. Currently, L. flaviscutellata is widely distributed in the Amazon region, with records in the Atlantic Forest and savannah regions of Central Brazil. Future projections indicate expansion of the climatically suitable area for the vector in both scenarios, towards higher latitudes and elevations. L. flaviscutellata is likely to find increasingly suitable conditions for its expansion into areas where human population size and density are much larger than they are in its current locations. If environmental conditions change as predicted, the range of the vector is likely to expand to southeastern and central-southern Brazil, eastern Paraguay and further into the Amazonian areas of Bolivia, Peru, Ecuador, Colombia and Venezuela. These areas will only become endemic for L. amazonensis, however, if they have competent reservoir hosts and transmission dynamics matching those in the Amazon region. PMID:26619186

Environment Industry, Industry Study, Spring 2008

DTIC Science & Technology

2008-01-01

challenge is deforestation of the Amazon rainforest due to illegal logging, cattle ranching, commercial agriculture and settlement/ subsistence farming...Since the Amazon accounts for thirty percent of all remaining tropical forest in the world, the challenge is immense.24 Understandably, Brazil is a

Emergent Hydrological Regimes in Amazonia Determine Vegetation Productivity and Structure.

NASA Astrophysics Data System (ADS)

Ahlström, A.; Canadell, J.; Schurgers, G.; Berry, J. A.; Guan, K.; Jackson, R. B.

2016-12-01

The Amazon rain forest has a disproportionate significance for global CO2 storage and biodiversity. Earth system models (ESMs) that estimate future climate and vegetation show little agreement in simulations in Amazonia. Here we show that evapotranspiration (ET), gross primary productivity (GPP) and above ground biomass in both models and empirical data align on an emergent hydrologically determined relationship that describes a functional relationship with annual precipitation (P). The physical relationship describes the potential for plant productivity and has a breakpoint at 2000 mm annual precipitation, where the system transitions between water and radiation limitation of annual ET. While ESM GPP is generally underestimated due to a low-bias in their internally generated P, their response to annual precipitation generally matches empirical data. It is different for biomass: ESMs show some ability in capturing biomass levels in the energy-limited wet hydrological regime above 2000 mm annual precipitation but they do not fully capture the biomass structure tipping point found in empirical data at the hydrological regime breakpoint that coincide with the forest-savanna transition. This discrepancy is likely due to the relatively simple representation of disturbances, primarily fires, and vegetation dynamics found in ESMs, and implies that ESMs likely overestimate the resilience to a potential future drying of the Amazon. Future elevated CO2 may increase plant water use efficiency and shift GPP upwards, but it will not affect the breakpoint between the regimes or the susceptibility of the forest which are both determined by precipitation and its role in determining the hydrological regime. This analysis reconciles and explains the findings of many studies on the Amazon. Our results suggests that future Amazonian biomass is governed by changes in precipitation, vegetation dynamics and disturbances, none of which are well predicted and represented by ESMs. Improvements of these processes are the most pressing challenges for more accurate future predictions on the fate of the Amazon and the global tropics.

Early Hg mobility in cultivated tropical soils one year after slash-and-burn of the primary forest, in the Brazilian Amazon.

PubMed

Béliveau, Annie; Lucotte, Marc; Davidson, Robert; Lopes, Luis Otávio do Canto; Paquet, Serge

2009-07-15

In the Brazilian Amazon, forest conversion to agricultural lands (slash-and-burn cultivation) contributes to soil mercury (Hg) release and to aquatic ecosystem contamination. Recent studies have shown that soil Hg loss occurs rapidly after deforestation, suggesting that Hg mobility could be related to the massive cation input resulting from biomass burning. The objective of this research was to determine the effects of the first year of slash-and-burn agriculture on soil Hg levels at the regional scale of the Tapajós River, in the state of Pará, Brazilian Amazon. A total of 429 soil samples were collected in 26 farms of five riparian communities of the Tapajós basin. In September 2004, soil samples were collected from primary forest sites planned for slash-and-burn cultivation. In August 2005, one year after the initial burning, a second campaign was held and the exact same sites were re-sampled. Our results showed that total Hg levels in soils did not change significantly during the first year following slash-and-burn, suggesting no immediate release of soil Hg at that point in time. However, an early Hg mobility was detected near the surface (0-5 cm), reflected by a significant shift in Hg distribution in soil fractions. Indeed, a transfer of Hg from fine to coarser soil particles was observed, indicating that chemical bonds between Hg and fine particles could have been altered. A correspondence analysis (CA) showed that this process could be linked to a chemical competition caused by cation enrichment. The regional dimension of the study highlighted the prevailing importance of soil types in Hg dynamics, as shown by differentiated soil responses following deforestation according to soil texture. Confirming an early Hg mobility and indicating an eventual Hg release out of the soil, our results reinforce the call for the development of more sustainable agricultural practices in the Amazon.

A large-scale deforestation experiment: Effects of patch area and isolation on Amazon birds

USGS Publications Warehouse

Ferraz, G.; Nichols, J.D.; Hines, J.E.; Stouffer, P.C.; Bierregaard, R.O.; Lovejoy, T.E.

2007-01-01

As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

A multi-approach and multi-scale study on water quantity and quality changes in the Tapajós River basin, Amazon

NASA Astrophysics Data System (ADS)

Bezerra Nóbrega, Rodolfo Luiz; Lamparter, Gabriele; Hughes, Harold; Chenjerayi Guzha, Alphonce; Santos Silva Amorim, Ricardo; Gerold, Gerhard

2018-04-01

We analyzed changes in water quantity and quality at different spatial scales within the Tapajós River basin (Amazon) based on experimental fieldwork, hydrological modelling, and statistical time-trend analysis. At a small scale, we compared the river discharge (Q) and suspended-sediment concentrations (SSC) of two adjacent micro-catchments ( < 1 km2) with similar characteristics but contrasting land uses (forest vs. pasture) using empirical data from field measurements. At an intermediary scale, we simulated the hydrological responses of a sub-basin of the Tapajós (Jamanxim River basin, 37 400 km2), using a hydrological model (SWAT) and land-use change scenario in order to quantify the changes in the water balance components due to deforestation. At the Tapajós' River basin scale, we investigated trends in Q, sediments, hydrochemistry, and geochemistry in the river using available data from the HYBAM Observation Service. The results in the micro-catchments showed a higher runoff coefficient in the pasture (0.67) than in the forest catchment (0.28). At this scale, the SSC were also significantly greater during stormflows in the pasture than in the forest catchment. At the Jamanxim watershed scale, the hydrological modelling results showed a 2 % increase in Q and a 5 % reduction of baseflow contribution to total Q after a conversion of 22 % of forest to pasture. In the Tapajós River, however, trend analysis did not show any significant trend in discharge and sediment concentration. However, we found upward trends in dissolved organic carbon and NO3- over the last 20 years. Although the magnitude of anthropogenic impact has shown be scale-dependent, we were able to find changes in the Tapajós River basin in streamflow, sediment concentration, and water quality across all studied scales.

A case study of carbon fluxes from land change in the southwest Brazilian Amazon

USGS Publications Warehouse

Barrett, K.; Rogan, J.; Eastman, J.R.

2009-01-01

Worldwide, land change is responsible for one-fifth of anthropogenic carbon emissions. In Brazil, three-quarters of carbon emissions originate from land change. This study represents a municipal-scale study of carbon fluxes from vegetation in Rio Branco, Brazil. Land-cover maps of pasture, forest, and secondary growth from 1993, 1996, 1999, and 2003 were produced using an unsupervised classification method (overall accuracy = 89%). Carbon fluxes from land change over the decade of imagery were estimated from transitions between land-cover categories for each time interval. This article presents new methods for estimating emissions reductions from carbon stored in the vegetation that replaces forests (e.g., pasture) and sequestration by new (>10-15 years) forests, which reduced gross emissions by 16, 15, and 22% for the period of 1993-1996, 1996-1999, and 1999-2003, respectively. The methods used in the analysis are broadly applicable and provide a comprehensive characterization of regional-scale carbon fluxes from land change.

Modeling Diurnal and Seasonal 3D Light Profiles in Amazon Forests

NASA Astrophysics Data System (ADS)

Morton, D. C.; Rubio, J.; Gastellu-Etchegorry, J.; Cook, B. D.; Hunter, M. O.; Yin, T.; Nagol, J. R.; Keller, M. M.

2013-12-01

The complex horizontal and vertical structure in tropical forests generates a diversity of light environments for canopy and understory trees. These 3D light profiles are dynamic on diurnal and seasonal time scales based on changes in solar illumination and the fraction of diffuse light. Understanding this variability is critical for improving ecosystem models and interpreting optical and LiDAR remote sensing data from tropical forests. Here, we initialized the Discrete Anisotropic Radiative Transfer (DART) model using dense airborne LiDAR data (>20 returns m2) from three forest sites in the central and eastern Amazon. Forest scenes derived from airborne LiDAR data were tested using modeled and observed large-footprint LiDAR data from the ICESat-GLAS sensor. Next, diurnal and seasonal profiles of photosynthetically active radiation (PAR) for each forest site were simulated under clear sky and cloudy conditions using DART. Incident PAR was summarized for canopy, understory, and ground levels. Our study illustrates the importance of realistic canopy models for accurate representation of LiDAR and optical radiative transfer. In particular, canopy rugosity and ground topography information from airborne LiDAR data provided critical 3D information that cannot be recreated using stem maps and allometric relationships for crown dimensions. The spatial arrangement of canopy trees altered PAR availability, even for dominant individuals, compared to downwelling measurements from nearby eddy flux towers. Pseudo-realistic branch and leaf architecture was also essential for recreating multiple scattering within canopies at near-infrared wavelengths commonly used for LiDAR remote sensing and quantifying PAR attenuation from shading within and between canopies. These findings point to the need for more spatial information on forest structure to improve the representation of light availability in models of tropical forest productivity.

Fire in the Brazilian Amazon : 3. Dynamics of biomass, C, and nutrient pools in regenerating forests.

PubMed

Hughes, R F; Kauffman, J B; Cummings, D L

2000-09-01

Regenerating forests have become a common land-cover type throughout the Brazilian Amazon. However, the potential for these systems to accumulate and store C and nutrients, and the fluxes resulting from them when they are cut, burned, and converted back to croplands and pastures have not been well quantified. In this study, we quantified pre- and post-fire pools of biomass, C, and nutrients, as well as the emissions of those elements, at a series of second- and third-growth forests located in the states of Pará and Rondônia, Brazil. Total aboveground biomass (TAGB) of second- and third-growth forests averaged 134 and 91 Mg ha -1 , respectively. Rates of aboveground biomass accumulation were rapid in these systems, but were not significantly different between second- and third-growth forests, ranging from 9 to 16 Mg ha -1 year -1 . Residual pools of biomass originating from primary forest vegetation accounted for large portions of TAGB in both forest types and were primarily responsible for TAGB differences between the two forest types. In second-growth forests this pool (82 Mg ha -1 ) represented 58% of TAGB, and in third-growth forests (40 Mg ha -1 ) it represented 40% of TAGB. Amounts of TAGB consumed by burning of second- and third-growth forests averaged 70 and 53 Mg ha -1 , respectively. Aboveground pre-fire pools in second- and third-growth forests averaged 67 and 45 Mg C ha -1 , 821 and 707 kg N ha -1 , 441 and 341 kg P ha -1 , and 46 and 27 kg Ca ha -1 , respectively. While pre-fire pools of C, N, S and K were not significantly different between second- and third-growth forests, pools of both P and Ca were significantly higher in second-growth forests. This suggests that increasing land use has a negative impact on these elemental pools. Site losses of elements resulting from slashing and burning these sites were highly variable: losses of C ranged from 20 to 47 Mg ha -1 ; N losses ranged from 306 to 709 kg ha -1 ; Ca losses ranged from 10 to 145 kg ha -1 ; and P losses ranged from 2 to 20 kg ha -1 . Elemental losses were controlled to a large extent by the relative distribution of elemental mass within biomass components of varying susceptibilities to combustion and the temperatures of volatilization of each element. Due to a relatively low temperature of volatilization and its concentration in highly combustible biomass pools, site losses of N averaged 70% of total pre-fire pools. In contrast, site losses of P and Ca resulting from burning were 33 and 20% of total pre-fire pools, respectively, as much of the mass of those elements was deposited on site as ash. Pre- and post-fire biomass and elemental pools of second- and third-growth forests, as well as the emissions from those systems, were intermediate between those of primary forests and pastures in the Brazilian Amazon. Overall, regenerating forests have the capacity to act as either large terrestrial sinks or sources of C and nutrients, depending on the course of land-use patterns within the Brazilian Amazon. Combining remote sensing techniques with field measures of aboveground C accumulation in regenerating forests and C fluxes from those forests when they are cut and burned, we estimate that during 1990-1991 roughly 104 Tg of C was accumulated by regenerating forests across the Brazilian Amazon. Further, we estimate that approximately 103 Tg of C was lost via the cutting and burning of regenerating forests across the Brazilian Amazon during this same period. Since average C accumulations (5.5 Mg ha -1 year -1 ) in regenerating forests were 19% of the C lost when such forests are cut and burned (29.3 Mg ha -1 ), our results suggest that when less than 19% of the total area accounted for by secondary forests is cut and burned in a given year, those forests will be net accumulators of C during that year. Conversely, when more than 19% of regenerating forests are burned, those forests will be a net source of C to the atmosphere.

Trends in entropy production during ecosystem development in the Amazon Basin.

PubMed

Holdaway, Robert J; Sparrow, Ashley D; Coomes, David A

2010-05-12

Understanding successional trends in energy and matter exchange across the ecosystem-atmosphere boundary layer is an essential focus in ecological research; however, a general theory describing the observed pattern remains elusive. This paper examines whether the principle of maximum entropy production could provide the solution. A general framework is developed for calculating entropy production using data from terrestrial eddy covariance and micrometeorological studies. We apply this framework to data from eight tropical forest and pasture flux sites in the Amazon Basin and show that forest sites had consistently higher entropy production rates than pasture sites (0.461 versus 0.422 W m(-2) K(-1), respectively). It is suggested that during development, changes in canopy structure minimize surface albedo, and development of deeper root systems optimizes access to soil water and thus potential transpiration, resulting in lower surface temperatures and increased entropy production. We discuss our results in the context of a theoretical model of entropy production versus ecosystem developmental stage. We conclude that, although further work is required, entropy production could potentially provide a much-needed theoretical basis for understanding the effects of deforestation and land-use change on the land-surface energy balance.

Reconstruction of the Amazon Basin effective moisture availability over the past 14,000 years.

PubMed

Maslin, M A; Burns, S J

2000-12-22

Quantifying the moisture history of the Amazon Basin is essential for understanding the cause of rain forest diversity and its potential as a methane source. We reconstructed the Amazon River outflow history for the past 14,000 years to provide a moisture budget for the river drainage basin. The oxygen isotopic composition of planktonic foraminifera recovered from a marine sediment core in a region of Amazon River discharge shows that the Amazon Basin was extremely dry during the Younger Dryas, with the discharge reduced by at least 40% as compared with that of today. After the Younger Dryas, a meltwater-driven discharge event was followed by a steady increase in the Amazon Basin effective moisture throughout the Holocene.

Off-nadir antenna bias correction using Amazon rain forest sigma deg data. [Brazil

NASA Technical Reports Server (NTRS)

Birrer, I. J.; Bracalente, E. M.; Dome, G. J.; Sweet, J.; Berthold, G.; Moore, R. K. (Principal Investigator)

1981-01-01

The radar response from the Amazon rain forest was studied to determine the suitability of this region for use as a standard target to calibrate a scatterometer like that proposed for the National Ocean Satellite System (NOSS). Backscattering observations made by the SEASAT-1 scatterometer system show the Amazon rain forest to be a homogeneous, azimuthally-isotropic, radar target which is insensitive to polarization. The variation with angle of incidence may be adequately modeled as sigma deg (dB) = alpha theta + beta with typical values for the incidence-angle coefficient from 0.07 dB deg to 0.15 dB/deg. A small diurnal effect occurs, with measurements at sunrise being 0.5 dB to 1 dB higher than the rest of the day. Maximum likelihood estimation algorithms are presented which permit determination of relative bias and true pointing angle for each beam. Specific implementation of these algorithms for the proposed NOSS scatterometer system is also discussed.

Brazil-USA Collaborative Research: Modifications by Anthropogenic Pollution of the Natural Atmospheric Chemistry and Particle Microphysics of the Tropical Rain Forest During the GoAmazon Intensive Operating Periods (IOPs)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Saewung

Manaus, a city of nearly two million people, represents an isolated urban area having a distinct urban pollution plume within the otherwise pristine Amazon Basin. The plume has high concentrations of oxides of nitrogen and sulfur, carbon monoxide, particle concentrations, and soot, among other pollutants. Critically, the distinct plume in the setting of the surrounding tropical rain forest serves as a natural laboratory to allow direct comparisons between periods of pollution influence to those of pristine conditions. The funded activity of this report is related to the Brazil-USA collaborative project during the two Intensive Operating Periods (wet season, 1 Febmore » - 31 Mar 2014; dry season, 15 Aug - 15 Oct 2014) of GoAmazon2014/5. The project addresses key science questions regarding the modification of the natural atmospheric chemistry and particle microphysics of the forest by present and future anthropogenic pollution.« less

The Green Ocean Amazon Experiment (GoAmazon2014/5) Observes Pollution Affecting Gases, Aerosols, Clouds, and Rainfall over the Rain Forest

DOE PAGES

Martin, S. T.; Artaxo, P.; Machado, L.; ...

2017-05-15

The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across 2 years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied temperate regions of Earth. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the United States, employed an unparalleled suite of measurements at nine ground sites and on board two aircraftmore » to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Here in this paper, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.« less

The Green Ocean Amazon Experiment (GoAmazon2014/5) Observes Pollution Affecting Gases, Aerosols, Clouds, and Rainfall over the Rain Forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, S. T.; Artaxo, P.; Machado, L.

The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across 2 years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied temperate regions of Earth. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the United States, employed an unparalleled suite of measurements at nine ground sites and on board two aircraftmore » to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Here in this paper, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.« less

Eo-1 Hyperion Measures Canopy Drought Stress In Amazonia

NASA Technical Reports Server (NTRS)

Asner, Gregory P.; Nepstad, Daniel; Cardinot, Gina; Moutinho, Paulo; Harris, Thomas; Ray, David

2004-01-01

The central, south and southeast portions of the Amazon Basin experience a period of decreased cloud cover and precipitation from June through November. There are likely important effects of seasonal and interannual rainfall variation on forest leaf area index, canopy water stress, productivity and regional carbon cycling in the Amazon. While both ground and spaceborne studies of precipitation continue to improve, there has been almost no progress made in observing forest canopy responses to rainfall variability in the humid tropics. This shortfall stems from the large stature of the vegetation and great spatial extent of tropical forests, both of which strongly impede field studies of forest responses to water availability. Those few studies employing satellite measures of canopy responses to seasonal and interannual drought (e.g., Bohlman et al. 1998, Asner et al. 2000) have been limited by the spectral resolution and sampling available from Landsat and AVHRR sensors. We report on a study combining the first landscape-level, managed drought experiment in Amazon tropical forest with the first spaceborne imaging spectrometer observations of this experimental area. Using extensive field data on rainfall inputs, soil water content, and both leaf and canopy responses, we test the hypothesis that spectroscopic signatures unique to hyperspectral observations can be used to quantify relative differences in canopy stress resulting from water availability.

Deforestation and Malaria on the Amazon Frontier: Larval Clustering of Anopheles darlingi (Diptera: Culicidae) Determines Focal Distribution of Malaria

PubMed Central

Barros, Fábio S. M.; Honório, Nildimar A.

2015-01-01

We performed bimonthly mosquito larval collections during 1 year, in an agricultural settlement in the Brazilian Amazon, as well as an analysis of malaria incidence in neighboring houses. Water collections located at forest fringes were more commonly positive for Anopheles darlingi larvae and Kulldorff spatial analysis pinpointed significant larval clusters at sites directly beneath forest fringes, which were called larval “hotspots.” Remote sensing identified 43 “potential” hotspots. Sampling of these areas revealed an 85.7% positivity rate for A. darlingi larvae. Malaria was correlated with shorter distances to potential hotpots and settlers living within 400 m of potential hotspots had a 2.60 higher risk of malaria. Recently arrived settlers, usually located closer to the tip of the triangularly shaped deforestation imprints of side roads, may be more exposed to malaria due to their proximity to the forest fringe. As deforestation progresses, transmission decreases. However, forest remnants inside deforested areas conferred an increased risk of malaria. We propose a model for explaining frontier malaria in the Amazon: because of adaptation of A. darlingi to the forest fringe ecotone, humans are exposed to an increased transmission risk when in proximity to these areas, especially when small dams are created on naturally running water collections. PMID:26416110

Titling indigenous communities protects forests in the Peruvian Amazon.

PubMed

Blackman, Allen; Corral, Leonardo; Lima, Eirivelthon Santos; Asner, Gregory P

2017-04-18

Developing countries are increasingly decentralizing forest governance by granting indigenous groups and other local communities formal legal title to land. However, the effects of titling on forest cover are unclear. Rigorous analyses of titling campaigns are rare, and related theoretical and empirical research suggests that they could either stem or spur forest damage. We analyze such a campaign in the Peruvian Amazon, where more than 1,200 indigenous communities comprising some 11 million ha have been titled since the mid-1970s. We use community-level longitudinal data derived from high-resolution satellite images to estimate the effect of titling between 2002 and 2005 on contemporaneous forest clearing and disturbance. Our results indicate that titling reduces clearing by more than three-quarters and forest disturbance by roughly two-thirds in a 2-y window spanning the year title is awarded and the year afterward. These results suggest that awarding formal land titles to local communities can advance forest conservation.

Titling indigenous communities protects forests in the Peruvian Amazon

PubMed Central

Blackman, Allen; Corral, Leonardo; Lima, Eirivelthon Santos; Asner, Gregory P.

2017-01-01

Developing countries are increasingly decentralizing forest governance by granting indigenous groups and other local communities formal legal title to land. However, the effects of titling on forest cover are unclear. Rigorous analyses of titling campaigns are rare, and related theoretical and empirical research suggests that they could either stem or spur forest damage. We analyze such a campaign in the Peruvian Amazon, where more than 1,200 indigenous communities comprising some 11 million ha have been titled since the mid-1970s. We use community-level longitudinal data derived from high-resolution satellite images to estimate the effect of titling between 2002 and 2005 on contemporaneous forest clearing and disturbance. Our results indicate that titling reduces clearing by more than three-quarters and forest disturbance by roughly two-thirds in a 2-y window spanning the year title is awarded and the year afterward. These results suggest that awarding formal land titles to local communities can advance forest conservation. PMID:28373565

Niche partitioning among frugivorous fishes in response to fluctuating resources in the Amazonian floodplain forest.

PubMed

Correa, Sandra Bibiana; Winemiller, Kirk O

2014-01-01

In response to temporal changes in the quality and availability of food resources, consumers should adjust their foraging behavior in a manner that maximizes energy and nutrient intake and, when resources are limiting, minimizes dietary overlap with other consumers. Floodplains of the Amazon and its lowland tributaries are characterized by strong, yet predictable, hydrological seasonality, seasonal availability of fruits, seeds, and other food resources of terrestrial origin, and diverse assemblages of frugivorous fishes, including morphologically similar species of several characiform families. Here, we investigated how diets of frugivorous fishes in the Amazon change in response to fluctuations in food availability, and how this influences patterns of interspecific dietary overlap. We tested predictions from classical theories of foraging and resource competition by estimating changes in diet breadth and overlap across seasons. We monitored fruiting phenology to assess food availability, and surveyed local fish populations during three hydrological seasons in an oligotrophic river and an adjacent oxbow lake in the Colombian Amazon. We analyzed stomach contents and stable isotope data to evaluate temporal and interspecific relationships for dietary composition, breadth, and overlap. Diets of six species of characiform fishes representing three genera changed according to seasonal fluctuations in food availability, and patterns of diet breadth and interspecific overlap during the peak flood pulse were consistent with predictions of optimal foraging theory. During times of high fruit abundance, fishes consumed items to which their functional morphological traits seemed best adapted, potentially enhancing net energy and nutritional gains. As the annual flood pulse subsided and availability of forest food resources in aquatic habitats changed, there was not a consistent pattern of diet breadth expansion or compression. Nonetheless, shifts in both diet composition and stable isotope ratios of consumer tissues during this period resulted in trophic niche segregation in a pattern consistent with competition theory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yingjun; Brito, Joel; Dorris, Matthew R.

Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO 2) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK +more » MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4–0.6. This result implies a ratio of the reaction rate of ISOPOO with HO2 to that with NO of approximately unity. Also, a value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). In conclusion, this abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.« less

Predictive modelling of contagious deforestation in the Brazilian Amazon.

PubMed

Rosa, Isabel M D; Purves, Drew; Souza, Carlos; Ewers, Robert M

2013-01-01

Tropical forests are diminishing in extent due primarily to the rapid expansion of agriculture, but the future magnitude and geographical distribution of future tropical deforestation is uncertain. Here, we introduce a dynamic and spatially-explicit model of deforestation that predicts the potential magnitude and spatial pattern of Amazon deforestation. Our model differs from previous models in three ways: (1) it is probabilistic and quantifies uncertainty around predictions and parameters; (2) the overall deforestation rate emerges "bottom up", as the sum of local-scale deforestation driven by local processes; and (3) deforestation is contagious, such that local deforestation rate increases through time if adjacent locations are deforested. For the scenarios evaluated-pre- and post-PPCDAM ("Plano de Ação para Proteção e Controle do Desmatamento na Amazônia")-the parameter estimates confirmed that forests near roads and already deforested areas are significantly more likely to be deforested in the near future and less likely in protected areas. Validation tests showed that our model correctly predicted the magnitude and spatial pattern of deforestation that accumulates over time, but that there is very high uncertainty surrounding the exact sequence in which pixels are deforested. The model predicts that under pre-PPCDAM (assuming no change in parameter values due to, for example, changes in government policy), annual deforestation rates would halve between 2050 compared to 2002, although this partly reflects reliance on a static map of the road network. Consistent with other models, under the pre-PPCDAM scenario, states in the south and east of the Brazilian Amazon have a high predicted probability of losing nearly all forest outside of protected areas by 2050. This pattern is less strong in the post-PPCDAM scenario. Contagious spread along roads and through areas lacking formal protection could allow deforestation to reach the core, which is currently experiencing low deforestation rates due to its isolation.

The effects of land use change on mercury distribution in soils of Alta Floresta, Southern Amazon.

PubMed

Lacerda, Luiz D; de Souza, Margareth; Ribeiro, Mario G

2004-05-01

This study presents the spatial distribution, degree of contamination and storage capacity of Hg in surface forest and pasture soils from Alta Floresta, Southern Amazon, a significant gold mining site from 1980 to 1996. During that period, average annual gold production was about 6.5 tons, with an estimated Hg annual emission to the environment of about 8.8 tons, 60-80% of it being emitted to the atmosphere. Mercury sources to the region are mining sites and gold-dealer shops at the city of Alta Floresta, where gold is smelted and commercialized. Mercury concentrations in forest soils (15-248 ng g(-1), average=61.9 ng g(-1)) were 1.5-3.0 times higher than in pasture soils (10-74 ng g(-1), average=33.8 ng g(-1)), suggesting strong re-mobilization after deforestation. Highest Hg concentrations were found within a distance of 20-30 km from mining sites in both soil types. The influence of the refining operations within the city of Alta Floresta, however, was less clear. Somewhat higher concentrations were observed only within a 5 km radius from the city center where gold-dealer shops are located. Wind direction controls the spatial distribution of Hg. Background concentrations (15-50 ng g(-1)) were generally found at the outer perimeter of the sampling grid, about 40 km from sources. This suggests that Hg released from mining and refining activities undergoes rapid deposition. Estimated cumulative Hg burdens for the first 10 cm of soil averaged 8.3 mg m(-2) and 4.9 mg m(-2), for forest and pasture soils respectively and compare well with ultisols and hydromorphic oxisols, but were lower than those found in yellow-red and yellow latosols and podsols from other Amazonian areas. Our results show that changing land use in the Amazon is a strong re-mobilizing agent of Hg deposited on soils from the atmosphere.

Predictive Modelling of Contagious Deforestation in the Brazilian Amazon

PubMed Central

Rosa, Isabel M. D.; Purves, Drew; Souza, Carlos; Ewers, Robert M.

2013-01-01

Tropical forests are diminishing in extent due primarily to the rapid expansion of agriculture, but the future magnitude and geographical distribution of future tropical deforestation is uncertain. Here, we introduce a dynamic and spatially-explicit model of deforestation that predicts the potential magnitude and spatial pattern of Amazon deforestation. Our model differs from previous models in three ways: (1) it is probabilistic and quantifies uncertainty around predictions and parameters; (2) the overall deforestation rate emerges “bottom up”, as the sum of local-scale deforestation driven by local processes; and (3) deforestation is contagious, such that local deforestation rate increases through time if adjacent locations are deforested. For the scenarios evaluated–pre- and post-PPCDAM (“Plano de Ação para Proteção e Controle do Desmatamento na Amazônia”)–the parameter estimates confirmed that forests near roads and already deforested areas are significantly more likely to be deforested in the near future and less likely in protected areas. Validation tests showed that our model correctly predicted the magnitude and spatial pattern of deforestation that accumulates over time, but that there is very high uncertainty surrounding the exact sequence in which pixels are deforested. The model predicts that under pre-PPCDAM (assuming no change in parameter values due to, for example, changes in government policy), annual deforestation rates would halve between 2050 compared to 2002, although this partly reflects reliance on a static map of the road network. Consistent with other models, under the pre-PPCDAM scenario, states in the south and east of the Brazilian Amazon have a high predicted probability of losing nearly all forest outside of protected areas by 2050. This pattern is less strong in the post-PPCDAM scenario. Contagious spread along roads and through areas lacking formal protection could allow deforestation to reach the core, which is currently experiencing low deforestation rates due to its isolation. PMID:24204776

Spatial and temporal dimensions of landscape fragmentation across the Brazilian Amazon.

PubMed

Rosa, Isabel M D; Gabriel, Cristina; Carreiras, Joāo M B

2017-01-01

The Brazilian Amazon in the past decades has been suffering severe landscape alteration, mainly due to anthropogenic activities, such as road building and land clearing for agriculture. Using a high-resolution time series of land cover maps (classified as mature forest, non-forest, secondary forest) spanning from 1984 through 2011, and four uncorrelated fragmentation metrics (edge density, clumpiness index, area-weighted mean patch size and shape index), we examined the temporal and spatial dynamics of forest fragmentation in three study areas across the Brazilian Amazon (Manaus, Santarém and Machadinho d'Oeste), inside and outside conservation units. Moreover, we compared the impacts on the landscape of: (1) different land uses (e.g. cattle ranching, crop production), (2) occupation processes (spontaneous vs. planned settlements) and (3) implementation of conservation units. By 2010/2011, municipalities located along the Arc of Deforestation had more than 55% of the remaining mature forest strictly confined to conservation units. Further, the planned settlement showed a higher rate of forest loss, a more persistent increase in deforested areas and a higher relative incidence of deforestation inside conservation units. Distinct agricultural activities did not lead to significantly different landscape structures; the accessibility of the municipality showed greater influence in the degree of degradation of the landscapes. Even with a high proportion of the landscapes covered by conservation units, which showed a strong inhibitory effect on forest fragmentation, we show that dynamic agriculturally driven economic activities, in municipalities with extensive road development, led to more regularly shaped, heavily fragmented landscapes, with higher densities of forest edge.

[Ants’ higher taxa as surrogates of species richness in a chronosequence of fallows, old-grown forests and agroforestry systems in the Eastern Amazon, Brazil].

PubMed

Muñoz Gutiérrez, Jhonatan Andrés; Roussea, Guillaume Xavier; Andrade-Silva, Joudellys; Delabie, Jacques Hubert Charles

2017-03-01

Deforestation in Amazon forests is one of the main causes for biodiversity loss worldwide. Ants are key into the ecosystem because act like engineers; hence, the loss of ants’ biodiversity may be a guide to measure the loss of essential functions into the ecosystems. The aim of this study was to evaluate soil ant’s richness and to estimate whether higher taxa levels (Subfamily and Genus) can be used as surrogates of species richness in different vegetation types (fallows, old-growth forests and agroforestry systems) in Eastern Amazon. The samples were taken in 65 areas in the Maranhão and Pará States in the period 2011-2014. The sampling scheme followed the procedure of Tropical Soil Biology and Fertility (TSBF). Initially, the vegetation types were characterized according to their age and estimated species richness. Linear and exponential functions were applied to evaluate if higher taxa can be used as surrogates and correlated with the Pearson coefficient. In total, 180 species distributed in 60 genera were identified. The results showed that ant species richness was higher in intermediate fallows (88) and old secondary forest (76), and was lower in agroforestry systems (38) and mature riparian forest (35). The genus level was the best surrogate to estimate the ant’s species richness across the different vegetation types, and explained 72-97 % (P < 0.001) of the total species variability. The results confirmed that the genus level is an excellent surrogate to estimate the ant’s species richness in the region and that both fallows and agroforestry systems may contribute in the conservation of Eastern Amazon ant community.

Soluble iron nutrients in Saharan dust over the central Amazon rainforest

NASA Astrophysics Data System (ADS)

Rizzolo, Joana A.; Barbosa, Cybelli G. G.; Borillo, Guilherme C.; Godoi, Ana F. L.; Souza, Rodrigo A. F.; Andreoli, Rita V.; Manzi, Antônio O.; Sá, Marta O.; Alves, Eliane G.; Pöhlker, Christopher; Angelis, Isabella H.; Ditas, Florian; Saturno, Jorge; Moran-Zuloaga, Daniel; Rizzo, Luciana V.; Rosário, Nilton E.; Pauliquevis, Theotonio; Santos, Rosa M. N.; Yamamoto, Carlos I.; Andreae, Meinrat O.; Artaxo, Paulo; Taylor, Philip E.; Godoi, Ricardo H. M.

2017-02-01

The intercontinental transport of aerosols from the Sahara desert plays a significant role in nutrient cycles in the Amazon rainforest, since it carries many types of minerals to these otherwise low-fertility lands. Iron is one of the micronutrients essential for plant growth, and its long-range transport might be an important source for the iron-limited Amazon rainforest. This study assesses the bioavailability of iron Fe(II) and Fe(III) in the particulate matter over the Amazon forest, which was transported from the Sahara desert (for the sake of our discussion, this term also includes the Sahel region). The sampling campaign was carried out above and below the forest canopy at the ATTO site (Amazon Tall Tower Observatory), a near-pristine area in the central Amazon Basin, from March to April 2015. Measurements reached peak concentrations for soluble Fe(III) (48 ng m-3), Fe(II) (16 ng m-3), Na (470 ng m-3), Ca (194 ng m-3), K (65 ng m-3), and Mg (89 ng m-3) during a time period of dust transport from the Sahara, as confirmed by ground-based and satellite remote sensing data and air mass backward trajectories. Dust sampled above the Amazon canopy included primary biological aerosols and other coarse particles up to 12 µm in diameter. Atmospheric transport of weathered Saharan dust, followed by surface deposition, resulted in substantial iron bioavailability across the rainforest canopy. The seasonal deposition of dust, rich in soluble iron, and other minerals is likely to assist both bacteria and fungi within the topsoil and on canopy surfaces, and especially benefit highly bioabsorbent species. In this scenario, Saharan dust can provide essential macronutrients and micronutrients to plant roots, and also directly to plant leaves. The influence of this input on the ecology of the forest canopy and topsoil is discussed, and we argue that this influence would likely be different from that of nutrients from the weathered Amazon bedrock, which otherwise provides the main source of soluble mineral nutrients.

Following Saharan Dust Outbreak Toward The Amazon Basin

NASA Astrophysics Data System (ADS)

Ben Ami, Y.; Koren, I.; Rudich, Y.; Flores, M.

2008-12-01

The role of the Amazon rainforest on earth climatic system is well recognized. To keep forest wellbeing and the fragile balance between the rainforest and the atmosphere, the Amazon must contain a satisfactory amount of nutrients to support the plants. The extensive rain and floods wash most of the soluble nutrients from the rainforest soil, leaving behind acidic kaolinite clay or sandy soil, with limited minerals for plant growth. It was suggested that lack of mineral in the soil may be replenished by deposition of Saharan mineral dust. Using remote sensing data (from the A-train satellites constellation) following with in-situ measurements (as part of the AMazonian Aerosol CharacteriZation Experiment (AMZE) campaign), ground-based data (from AErosol RObotic NETwork (AERONET)) and back trajectory calculations, we analyzed Saharan dust transport toward the Amazon basin during the AMZE period (Feb 7 to Mar 14, 2008). Dust mass, sink, vertical distribution and surface wind speeds were analyzed over the Bodele depression (located in Chad), where most of the dust is emitted, along the Atlantic Ocean and near the Brazilian coastline. Using an integrated data analysis approach we followed dust packages from their emission in the Sahara to their sink in the Amazon forest.

Aerial and surface rivers: downwind impacts on water availability from land use changes in Amazonia

NASA Astrophysics Data System (ADS)

Weng, Wei; Luedeke, Matthias K. B.; Zemp, Delphine C.; Lakes, Tobia; Kropp, Juergen P.

2018-02-01

The abundant evapotranspiration provided by the Amazon forests is an important component of the hydrological cycle, both regionally and globally. Since the last century, deforestation and expanding agricultural activities have been changing the ecosystem and its provision of moisture to the atmosphere. However, it remains uncertain how the ongoing land use change will influence rainfall, runoff, and water availability as findings from previous studies differ. Using moisture tracking experiments based on observational data, we provide a spatially detailed analysis recognizing potential teleconnection between source and sink regions of atmospheric moisture. We apply land use scenarios in upwind moisture sources and quantify the corresponding rainfall and runoff changes in downwind moisture sinks. We find spatially varying responses of water regimes to land use changes, which may explain the diverse results from previous studies. Parts of the Peruvian Amazon and western Bolivia are identified as the sink areas most sensitive to land use change in the Amazon and we highlight the current water stress by Amazonian land use change on these areas in terms of the water availability. Furthermore, we also identify the influential source areas where land use change may considerably reduce a given target sink's water reception (from our example of the Ucayali River basin outlet, rainfall by 5-12 % and runoff by 19-50 % according to scenarios). Sensitive sinks and influential sources are therefore suggested as hotspots for achieving sustainable land-water management.

Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought.

PubMed

Frolking, Steve; Hagen, Stephen; Braswell, Bobby; Milliman, Tom; Herrick, Christina; Peterson, Seth; Roberts, Dar; Keller, Michael; Palace, Michael

2017-01-01

Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon's vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999-2009, and low morning backscatter persisted for 2006-2009, after which the instrument failed. The persistent low backscatter has been suggested to be indicative of increased forest vulnerability to future drought. To better ascribe the cause of the low post-drought backscatter, we analyzed multiyear, gridded remote sensing data sets of precipitation, land surface temperature, forest cover and forest cover loss, and microwave backscatter over the 2005 drought region in the southwestern Amazon Basin (4°-12°S, 66°-76°W) and in adjacent 8°x10° regions to the north and east. We found moderate to weak correlations with the spatial distribution of persistent low backscatter for variables related to three groups of forest impacts: the 2005 drought itself, loss of forest cover, and warmer and drier dry seasons in the post-drought vs. the pre-drought years. However, these variables explained only about one quarter of the variability in depressed backscatter across the southwestern drought region. Our findings indicate that drought impact is a complex phenomenon and that better understanding can only come from more extensive ground data and/or analysis of frequent, spatially-comprehensive, high-resolution data or imagery before and after droughts.

Birds of the Tapajos National Forest, Brazilian Amazon: a preliminary assessment.

Treesearch

L. M. P. Henr¡ques; J.M. Wunderle Jr.; M. R. Willig

2003-01-01

This study describes the avifauna of the Tapajos National forest, an area on the east bank of the Tapajos River where controlled resource exploitation occurs. Here we provide a near complete species list for terra firme forest with an incomplete list of species from less comprehensively surveyed habitats such as "varzea" forest.

Create a Rain Forest in the Gym.

ERIC Educational Resources Information Center

Kane, Karen

1995-01-01

Describes a creative interdisciplinary program for K-3 students that involves setting up a rain forest in the gymnasium to teach students gymnastic skills in the context of the Amazon rain forest. The paper describes how to set up the rain forest and teach a variety of classes. Rainforest resources are included. (SM)

Millennial-Scale ITCZ Variability in the Tropical Atlantic and Dynamics of Amazonian Rain Forest

NASA Astrophysics Data System (ADS)

Wang, X.; Auler, A. S.; Edwards, R. L.; Cheng, H.; Shen, C.; Smart, P. L.; Richards, D. A.

2003-12-01

Precipitation in the Amazon Basin is largely related to the intertropical convergence zone (ITCZ) in the tropical Atlantic which undergoes a regular seasonal migration. We chose a site south of the present day rainforest in semiarid northeastern Brazil, in order to study the timing of pluvial periods when the southern extend of the ITCZ would have been much further south than today. Shifts in the ITCZ position may have influenced the dynamics of rain forest and species diversity. We collected speleothems from northern Bahia state, located southeast of Amazonia. Age determinations with U-series dating methods show that samples grew rapidly during relatively short intervals (several hundreds of years) of glacial periods in the last 210 kyr. In addition, paleopluvial phases delineated by speleothem growth intervals show millennial-scale variations. Pluvial phases coincide with the timing of weak East Asian summer monsoon intensities (Wang et al., 2001, Science 294: 2345-2348), which have been correlated to the timing of stadials in Greenland ice core records and Heinrich events (Bond and Lotti, 1995, Science 267: 1005-1010). Furthermore, these intervals correspond to the periods of light color reflectance of Cariaco Basin sediments from ODP Hole 1002C (Peterson et al., 2000, Science, 290: 1947-1951), which was suggested to be caused by a southward shift of the northernmost position of the ITCZ and decreased rainfall in this region. Abrupt precipitation changes in northeastern Brazil may be due to the southward displacement of the southernmost position of the ITCZ associated with atmosphere-ocean circulation changes caused by (1) an increase in northern high latitude-tropical temperature gradient (Chiang et al., 2003, Paleoceanography, in press), and/or (2) the bipolar seesaw mechanism (Broecker et al., 1998, Paleoceanography 13: 119-121) during these Heinrich events. Pluvial phases are also coincident with higher insolation at 10° S during austral autumn. This association implies that insolation may contribute to the southward shift of the ITCZ and enhanced precipitation in northeastern Brazil. The mean latitudinal migration of the ITCZ in the tropical Atlantic may force Amazon rain forest dynamics. Fossils and geomorphologic evidence found nearby indicate much wetter climates and possible tropical rainforest expansion to this locality in the past (Auler and Smart, 2001, Quaternary Research 55: 159-167). Furthermore, low δ 13C (around -11‰ ) values in speleothems suggest an extensive C3 forest coverage, different from current drought-resistant caatinga vegetation. During time of high rainfall, northeastern Brazil may act as a migration corridor between two species-rich communities, the Amazon Rain Forest and the Atlantic Rain Forest.

Does deforestation promote or inhibit malaria transmission in the Amazon? A systematic literature review and critical appraisal of current evidence

PubMed Central

Tucker Lima, Joanna M.; Vittor, Amy; Rifai, Sami

2017-01-01

Considerable interest in the relationship between biodiversity and disease has recently captured the attention of the research community, with important public policy implications. In particular, malaria in the Amazon region is often cited as an example of how forest conservation can improve public health outcomes. However, despite a growing body of literature and an increased understanding of the relationship between malaria and land use / land cover change (LULC) in Amazonia, contradictions have emerged. While some studies report that deforestation increases malaria risk, others claim the opposite. Assessing malaria risk requires examination of dynamic processes among three main components: (i) the environment (i.e. LULC and landscape transformations), (ii) vector biology (e.g. mosquito species distributions, vector activity and life cycle, plasmodium infection rates), and (iii) human populations (e.g. forest-related activity, host susceptibility, movement patterns). In this paper, we conduct a systematic literature review on malaria risk and deforestation in the Amazon focusing on these three components. We explore key features that are likely to generate these contrasting results using the reviewed articles and our own data from Brazil and Peru, and conclude with suggestions for productive avenues in future research. This article is part of the themed issue ‘Conservation, biodiversity and infectious disease: scientific evidence and policy implications'. PMID:28438914

Does deforestation promote or inhibit malaria transmission in the Amazon? A systematic literature review and critical appraisal of current evidence.

PubMed

Tucker Lima, Joanna M; Vittor, Amy; Rifai, Sami; Valle, Denis

2017-06-05

Considerable interest in the relationship between biodiversity and disease has recently captured the attention of the research community, with important public policy implications. In particular, malaria in the Amazon region is often cited as an example of how forest conservation can improve public health outcomes. However, despite a growing body of literature and an increased understanding of the relationship between malaria and land use / land cover change (LULC) in Amazonia, contradictions have emerged. While some studies report that deforestation increases malaria risk, others claim the opposite. Assessing malaria risk requires examination of dynamic processes among three main components: (i) the environment (i.e. LULC and landscape transformations), (ii) vector biology (e.g. mosquito species distributions, vector activity and life cycle, plasmodium infection rates), and (iii) human populations (e.g. forest-related activity, host susceptibility, movement patterns). In this paper, we conduct a systematic literature review on malaria risk and deforestation in the Amazon focusing on these three components. We explore key features that are likely to generate these contrasting results using the reviewed articles and our own data from Brazil and Peru, and conclude with suggestions for productive avenues in future research.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'. © 2017 The Authors.

Long-term observations of cloud condensation nuclei in the Amazon rain forest

NASA Astrophysics Data System (ADS)

Pöhlker, Mira L.; Pöhlker, Christopher; Ditas, Florian; Klimach, Thomas; Hrabe de Angelis, Isabella; Brito, Joel; Carbone, Samara; Cheng, Yafang; Martin, Scot T.; Moran-Zuloaga, Daniel; Rose, Diana; Saturno, Jorge; Su, Hang; Thalman, Ryan; Walter, David; Wang, Jian; Barbosa, Henrique; Artaxo, Paulo; Andreae, Meinrat O.; Pöschl, Ulrich

2017-04-01

Size-resolved long-term measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a full seasonal cycle (Mar 2014 - Feb 2015). The measurements provide a climatology of CCN properties characteristic of a remote central Amazonian rain forest site [1,2]. The CCN measurements were continuously cycled through 10 levels of supersaturation (S = 0.11 to 1.10 %) and span the aerosol particle size range from 20 to 245 nm. The particle hygroscopicity exhibits a pronounced size dependence with lower values for the Aitken mode (κAit = 0.14 ± 0.03), higher values for the accumulation mode (κAcc = 0.22 ± 0.05), and an overall mean value of κmean = 0.17 ± 0.06, consistent with high fractions of organic aerosol. The hygroscopicity parameter, κ, exhibits remarkably little temporal variability: no pronounced diurnal cycles, only weak seasonal trends, and few short-term variations during long-range transport events. In contrast, the CCN number concentrations exhibit a pronounced seasonal cycle, tracking the pollution-related seasonality in total aerosol concentration. We find that the variability in the CCN concentrations in the central Amazon is mostly driven by aerosol particle number concentration and size distribution, while variations in aerosol hygroscopicity and chemical composition matter only during a few episodes. For modelling purposes, we compare different approaches of predicting CCN number concentration and present a novel parameterization, which allows accurate CCN predictions based on a small set of input data. In addition, we analyzed the CCN short-term variability in relation to air mass changes as well as aerosol emission and transformation processes. The CCN short term variability is presented for selected case studies, which analyze particularly interesting and characteristic events/conditions in the Amazon region. References: [1] Andreae, M. O., et al. (2015), Atmos. Chem. Phys., 15, 10723-10776. [2] Pöhlker, M. L.., et al. (2016), Atmos. Chem. Phys., 16, 15709-15740.

21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions.

PubMed

Aragão, Luiz E O C; Anderson, Liana O; Fonseca, Marisa G; Rosan, Thais M; Vedovato, Laura B; Wagner, Fabien H; Silva, Camila V J; Silva Junior, Celso H L; Arai, Egidio; Aguiar, Ana P; Barlow, Jos; Berenguer, Erika; Deeter, Merritt N; Domingues, Lucas G; Gatti, Luciana; Gloor, Manuel; Malhi, Yadvinder; Marengo, Jose A; Miller, John B; Phillips, Oliver L; Saatchi, Sassan

2018-02-13

Tropical carbon emissions are largely derived from direct forest clearing processes. Yet, emissions from drought-induced forest fires are, usually, not included in national-level carbon emission inventories. Here we examine Brazilian Amazon drought impacts on fire incidence and associated forest fire carbon emissions over the period 2003-2015. We show that despite a 76% decline in deforestation rates over the past 13 years, fire incidence increased by 36% during the 2015 drought compared to the preceding 12 years. The 2015 drought had the largest ever ratio of active fire counts to deforestation, with active fires occurring over an area of 799,293 km 2 . Gross emissions from forest fires (989 ± 504 Tg CO 2 year -1 ) alone are more than half as great as those from old-growth forest deforestation during drought years. We conclude that carbon emission inventories intended for accounting and developing policies need to take account of substantial forest fire emissions not associated to the deforestation process.

Andean settlers rush for Amazonia.

PubMed

Serra-vega, J

1990-01-01

Governments of Andean countries (Peru, Bolivia, Colombia, Ecuador, and Venezuela) have encouraged migration to the Amazon Basin, which has contributed to its destruction. Population pressure, landlessness, and poverty are the inducements to migrate. Efforts to populate the Amazon forest were begun as early as 1964 in Peru without international notice. By 1980, logging was allowed in Peru, and Brazil considered colonization of the Amazon essential to national sovereignty. By 1986, outside of Lima, Peru, a development project originally funded by the World Bank, the InterAmerican Development Bank, and the US, resulted in conflicts between settlers and Indians, in loggers indiscriminately cutting, and in farmers using slash and burn techniques to clear forests. Elsewhere the Peruvian Amazon, in San Ignacio, the population was growing by 5.5%/year. The jungle road that had been started but never completed, Carretera Marginal, destroyed 5 million hectares of primary forest, and much of the 600,000 hectares of arable land gained by the road suffered from inappropriate farming practices which caused massive erosion and laterization of the soils. Food crop production declined, and production of coca for cocaine increased. Coca crops are controlled by the Shining Path guerrillas, who are trying to overthrow the Peruvian government. Devastation of Ecuador around Lago Agrio continues. In Colombia, east of Bogota, forests have disappeared and hills have eroded and silted up rivers and dams. The Andean piedmont in Bolivia has also been devastated by loggers and by slash and burn farming. Southeastern Bolivian forests have been cleared for soya bean cultivation on poor soils. Social and economic crises propel people into the remaining forests. The solution is to ease foreign debt, transfer appropriate technology at affordable prices, refuse to finance destructive development, and help to educate and train scientific researchers. Family planning services are also urgently needed. Basic facts on population, biodiversity, the greenhouse effect, deforestation, roads, iron, gold, and Indians is provided.

Drought-induced changes in Amazon forest structure from repeat airborne lidar

NASA Astrophysics Data System (ADS)

Morton, D. C.; Leitold, V.; Longo, M.; Keller, M.; dos-Santos, M. N.; Scaranello, M. A., Sr.

2017-12-01

Drought events in tropical forests, including the 2015-2016 El Niño, may reduce net primary productivity and increase canopy tree mortality, thereby altering the short and long-term net carbon balance of tropical forests. Given the broad extent of drought impacts, forest inventory plots or eddy flux towers may not capture regional variability in forest response to drought. Here, we analyzed repeat airborne lidar data to evaluate canopy turnover from branch and tree fall before (2013-2014) and during (2014-2016) the recent El Niño drought in the eastern and central Brazilian Amazon. Coincident field surveys for a 16-ha subset of the lidar coverage provided complementary information to classify turnover areas by mechanism (branch, multiple branch, tree fall, multiple tree fall) and estimate the total coarse woody debris volume from canopy and understory tree mortality. Annualized rates of canopy turnover increased by 50%, on average, during the drought period in both intact and fragmented forests near Santarém, Pará. Turnover increased uniformly across all size classes, and there was limited evidence that taller trees contributed a greater proportion of turnover events in any size class in 2014-2016 compared to 2013-2014. This short-term increase in canopy turnover differs from findings in multi-year rainfall exclusion experiments that large trees were more sensitive to drought impacts. Field measurements confirmed the separability of the smallest (single branch) and largest damage classes (multiple tree falls), but single tree and multiple branch fall events generated similar coarse woody debris production and lidar-derived changes in canopy volume. Large-scale sampling possible with repeat airborne lidar data also captured strong local and regional gradients in canopy turnover. Differences in slope partially explained the north-south gradient in canopy turnover dynamics near Santarém, with larger increases in turnover on flatter terrain. Regional variability in canopy turnover in response to drought conditions highlights the need for a mechanistic representation of branch and tree fall dynamics in ecosystem models to resolve changes in net carbon balance from the increase in coarse woody debris production and reorganization of canopy light environments during drought years.

Mouth of the Amazon River as seen from STS-58

NASA Image and Video Library

1993-10-30

STS058-107-083 (18 Oct.-1 Nov. 1993) --- A near-nadir view of the mouth of the Amazon River, that shows all signs of being a relatively healthy system, breathing and exhaling. The well-developed cumulus field over the forested areas on both the north and south sides of the river (the view is slightly to the west) shows that good evapotranspiration is underway. The change in the cloud field from the moisture influx from the Atlantic (the cloud fields over the ocean are parallel to the wind direction) to perpendicular cloud fields over the land surface are normal. This change in direction is caused by the increased surface roughness over the land area. The plume of the river, although turbid, is no more or less turbid than it has been reported since the Portuguese first rounded Brasil's coast at the end of the 15th Century.

Seasonal Distribution, Biology, and Human Attraction Patterns of Mosquitoes (Diptera: Culicidae) in a Rural Village and Adjacent Forested Site Near Iquitos, Peru

DTIC Science & Technology

2008-11-01

and malarial activity in the Amazon Basin, Loreto Department, Peru , to determine the relative abundance, species diversity, and seasonal and vertical...populations. KEY WORDS Anopheles, bionomics, mosquito ecology, Amazon Basin, Peru Malaria and other arthropod-vectored diseases are on the increase...in the Amazon Basin region of Peru to date. The Puerto Almendra area was selected because human cases of dengue, malaria, Mayaro, Oropouche

The impact of forest structure and light utilization on carbon cycling in tropical forests

NASA Astrophysics Data System (ADS)

Morton, D. C.; Longo, M.; Leitold, V.; Keller, M. M.

2015-12-01

Light competition is a fundamental organizing principle of forest ecosystems, and interactions between forest structure and light availability provide an important constraint on forest productivity. Tropical forests maintain a dense, multi-layered canopy, based in part on abundant diffuse light reaching the forest understory. Climate-driven changes in light availability, such as more direct illumination during drought conditions, therefore alter the potential productivity of forest ecosystems during such events. Here, we used multi-temporal airborne lidar data over a range of Amazon forest conditions to explore the influence of forest structure on gross primary productivity (GPP). Our analysis combined lidar-based observations of canopy illumination and turnover in the Ecosystem Demography model (ED, version 2.2). The ED model was updated to specifically account for regional differences in canopy and understory illumination using lidar-derived measures of canopy light environments. Model simulations considered the influence of forest structure on GPP over seasonal to decadal time scales, including feedbacks from differential productivity between illuminated and shaded canopy trees on mortality rates and forest composition. Finally, we constructed simple scenarios with varying diffuse and direct illumination to evaluate the potential for novel plant-climate interactions under scenarios of climate change. Collectively, the lidar observations and model simulations underscore the need to account for spatial heterogeneity in the vertical structure of tropical forests to constrain estimates of tropical forest productivity under current and future climate conditions.

Climatically-mediated landcover change: impacts on Brazilian territory.

PubMed

Zanin, Marina; Tessarolo, Geiziane; Machado, Nathália; Albernaz, Ana Luisa M

2017-01-01

In the face of climate change threats, governments are drawing attention to policies for mitigating its effects on biodiversity. However, the lack of distribution data makes predictions at species level a difficult task, mainly in regions of higher biodiversity. To overcome this problem, we use native landcover as a surrogate biodiversity, because it can represent specialized habitat for species, and investigate the effects of future climate change on Brazilian biomes. We characterize the climatic niches of native landcover and use ecological niche modeling to predict the potential distribution under current and future climate scenarios. Our results highlight expansion of the distribution of open vegetation and the contraction of closed forests. Drier Brazilian biomes, like Caatinga and Cerrado, are predicted to expand their distributions, being the most resistant to climate change impacts. However, these would also be affected by losses of their closed forest enclaves and their habitat-specific or endemic species. Replacement by open vegetation and overall reductions are a considerable risk for closed forest, threatening Amazon and Atlantic forest biomes. Here, we evidence the impacts of climate change on Brazilian biomes, and draw attention to the necessity for management and attenuation plans to guarantee the future of Brazilian biodiversity.

[Distribution of potentially nitrogen-fixing bacteria and its relationship with physicochemical parameters in soils with three vegetation types in the southern Colombian Amazon region].

PubMed

Mantilla-Paredes, Andrea J; Cardona, Gladys I; Peña-Venegas, Clara P; Murcia, Uriel; Rodríguez, Mariana; Zambrano, Maria M

2009-12-01

Potentially nitrogen-fixing microaerobic and aerobic bacteria were isolated from several Colombian Amazon soils (forest, pastures and chagras) and two landscapes (floodable and non floodable areas). The abundance and distribution of bacteria were evaluated, as well as their relationship with soil physical and chemical characteristics. Landscape had a direct influence on the abundance of the microaerobic bacteria, with higher numbers in forest and pasture soils in non-floodable zones. The aerobic isolates (N=51) were grouped into 19 morphologies, with the highest numbers found in forest soil in floodable zones. A higher number of aerobic morphologies was shared among forest sites (Nonmetric Multidimensional Scaling and Analysis of Similarity p<0.05), and 40% of the distribution was explained by lime percentage and Al concentration.

The Green Ocean Amazon Experiment (GoAmazon2014/5) Observes Pollution Affecting Gases, Aerosols, Clouds, and Rainfall over the Rain Forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, S. T.; Artaxo, P.; Machado, L.

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across two years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied USA, employed an unparalleled suite of measurements at nine ground sites and onboard two aircraft to investigate the flow of background air into Manaus, the emissions into the air over themore » city, and the advection of the pollution downwind of the city. Herein, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.« less

Climate change, allergy and asthma, and the role of tropical forests.

PubMed

D'Amato, Gennaro; Vitale, Carolina; Rosario, Nelson; Neto, Herberto Josè Chong; Chong-Silva, Deborah Carla; Mendonça, Francisco; Perini, Josè; Landgraf, Loraine; Solé, Dirceu; Sánchez-Borges, Mario; Ansotegui, Ignacio; D'Amato, Maria

2017-01-01

Tropical forests cover less than 10 per cent of all land area (1.8 × 107 km 2 ) and over half of the tropical-forest area (1.1 × 107 Km 2 ) is represented by humid tropical forests (also called tropical rainforests). The Amazon basin contains the largest rainforest on Earth, almost 5.8 million km 2 , and occupies about 40% of South America; more than 60% of the basin is located in Brazil and the rest in Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela. Over the past decade the positive role of tropical rainforests in capturing large amounts of atmospheric carbon dioxide (CO 2 ) has been demonstrated. In response to the increase in atmospheric CO 2 concentration, tropical forests act as a global carbon sink. Accumulation of carbon in the tropical terrestrial biosphere strongly contributes to slowing the rate of increase of CO 2 into the atmosphere, thus resulting in the reduction of greenhouse gas effect. Tropical rainforests have been estimated to account for 32-36% of terrestrial Net Primary Productivity (NPP) that is the difference between total forest photosynthesis and plant respiration. Tropical rainforests have been acting as a strong carbon sink in this way for decades. However, over the past years, increased concentrations of greenhouse gases, and especially CO 2 , in the atmosphere have significantly affected the net carbon balance of tropical rainforests, and have warmed the planet substantially driving climate changes through more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods. The role of tropical forests in mitigating climate change is therefore critical. Over the past 30 years almost 600,000 km 2 have been deforested in Brazil alone due to the rapid development of Amazonia, this is the reason why currently the region is one of the 'hotspots' of global environmental change on the planet. Deforestation represents the second largest anthropogenic source of CO 2 to the atmosphere, after fossil fuel combustion. There are many causes of deforestation, including socioeconomic and natural factors, such as clear-cutting for agriculture, ranching and development, unsustainable logging for timber, as well as droughts, fires and degradation due to climate change. About natural causes of forest degradation, in the context of the Amazon, the major agent of change in the forest ecosystem would most likely be decreased dry-season precipitation. Of the 23 global climate models employed by the Intergovernmental Panel on Climate Change (IPCC) in their 2007 report, 50-70% predict a substantial (above 20%) reduction of dry-season rainfall in eastern Amazonia under mid-range greenhouse gas emissions scenarios, 40% in central Amazonia and 20% in the west. While annual carbon emissions from fossil-fuel combustion have been continually increasing since 1960s, historical trends of deforestation and associated carbon emissions have remained poorly understood.

Getting REDD-y: conservation and climate change in Latin America.

PubMed

Hall, Anthony

2011-01-01

Deforestation in Latin America, especially in the Amazon basin, is a major source of greenhouse gases such as carbon dioxide that contribute to global warming. Protected areas play a vital role in minimizing forest loss and in supplying key environmental services, including carbon sequestration and rainfall regulation, which mitigate the adverse impacts of climate change amid a rising tide of economic development in the region. The area of protected forest has expanded rapidly since 1980 to cover one-fifth of Latin America and more than two-fifths of Amazonia, a region whose rain forest captures some 40 percent of Latin America's carbon emissions. The reserve sector has traditionally suffered from severe underfunding, but the possibility of new resources being generated through financial compensation for "reduced emissions from deforestation and forest degradation" (REDD) or "avoided deforestation" under a new Kyoto protocol after 2012 could help strengthen the environmental and social roles of protected areas. However, a number of major implementation and governance challenges will need to be addressed.

Solar radiation and functional traits explain the decline of forest primary productivity along a tropical elevation gradient.

PubMed

Fyllas, Nikolaos M; Bentley, Lisa Patrick; Shenkin, Alexander; Asner, Gregory P; Atkin, Owen K; Díaz, Sandra; Enquist, Brian J; Farfan-Rios, William; Gloor, Emanuel; Guerrieri, Rossella; Huasco, Walter Huaraca; Ishida, Yoko; Martin, Roberta E; Meir, Patrick; Phillips, Oliver; Salinas, Norma; Silman, Miles; Weerasinghe, Lasantha K; Zaragoza-Castells, Joana; Malhi, Yadvinder

2017-06-01

One of the major challenges in ecology is to understand how ecosystems respond to changes in environmental conditions, and how taxonomic and functional diversity mediate these changes. In this study, we use a trait-spectra and individual-based model, to analyse variation in forest primary productivity along a 3.3 km elevation gradient in the Amazon-Andes. The model accurately predicted the magnitude and trends in forest productivity with elevation, with solar radiation and plant functional traits (leaf dry mass per area, leaf nitrogen and phosphorus concentration, and wood density) collectively accounting for productivity variation. Remarkably, explicit representation of temperature variation with elevation was not required to achieve accurate predictions of forest productivity, as trait variation driven by species turnover appears to capture the effect of temperature. Our semi-mechanistic model suggests that spatial variation in traits can potentially be used to estimate spatial variation in productivity at the landscape scale. © 2017 John Wiley & Sons Ltd/CNRS.

Space Radar Image of Manaus region of Brazil

NASA Technical Reports Server (NTRS)

1994-01-01

These L-band images of the Manaus region of Brazil were acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour. The left image was acquired on April 12, 1994, and the middle image was acquired on October 3, 1994. The area shown is approximately 8 kilometers by 40 kilometers (5 miles by 25 miles). The two large rivers in this image, the Rio Negro (top) and the Rio Solimoes (bottom), combine at Manaus (west of the image) to form the Amazon River. The image is centered at about 3 degrees south latitude and 61 degrees west longitude. North is toward the top left of the images. The differences in brightness between the images reflect changes in the scattering of the radar channel. In this case, the changes are indicative of flooding. A flooded forest has a higher backscatter at L-band (horizontally transmitted and received) than an unflooded river. The extent of the flooding is much greater in the April image than in the October image, and corresponds to the annual, 10-meter (33-foot) rise and fall of the Amazon River. A third image at right shows the change in the April and October images and was created by determining which areas had significant decreases in the intensity of radar returns. These areas, which appear blue on the third image at right, show the dramatic decrease in the extent of flooded forest, as the level of the Amazon River falls. The flooded forest is a vital habitat for fish and floating meadows are an important source of atmospheric methane. This demonstrates the capability of SIR-C/X-SAR to study important environmental changes that are impossible to see with optical sensors over regions such as the Amazon, where frequent cloud cover and dense forest canopies obscure monitoring of floods. Field studies by boat, on foot and in low-flying aircraft by the University of California at Santa Barbara, in collaboration with Brazil's Instituto Nacional de Pesguisas Estaciais, during the first and second flights of the SIR-C/X-SAR system have validated the interpretation of the radar images. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR.

Consistency of vegetation index seasonality across the Amazon rainforest

NASA Astrophysics Data System (ADS)

Maeda, Eduardo Eiji; Moura, Yhasmin Mendes; Wagner, Fabien; Hilker, Thomas; Lyapustin, Alexei I.; Wang, Yujie; Chave, Jérôme; Mõttus, Matti; Aragão, Luiz E. O. C.; Shimabukuro, Yosio

2016-10-01

Vegetation indices (VIs) calculated from remotely sensed reflectance are widely used tools for characterizing the extent and status of vegetated areas. Recently, however, their capability to monitor the Amazon forest phenology has been intensely scrutinized. In this study, we analyze the consistency of VIs seasonal patterns obtained from two MODIS products: the Collection 5 BRDF product (MCD43) and the Multi-Angle Implementation of Atmospheric Correction algorithm (MAIAC). The spatio-temporal patterns of the VIs were also compared with field measured leaf litterfall, gross ecosystem productivity and active microwave data. Our results show that significant seasonal patterns are observed in all VIs after the removal of view-illumination effects and cloud contamination. However, we demonstrate inconsistencies in the characteristics of seasonal patterns between different VIs and MODIS products. We demonstrate that differences in the original reflectance band values form a major source of discrepancy between MODIS VI products. The MAIAC atmospheric correction algorithm significantly reduces noise signals in the red and blue bands. Another important source of discrepancy is caused by differences in the availability of clear-sky data, as the MAIAC product allows increased availability of valid pixels in the equatorial Amazon. Finally, differences in VIs seasonal patterns were also caused by MODIS collection 5 calibration degradation. The correlation of remote sensing and field data also varied spatially, leading to different temporal offsets between VIs, active microwave and field measured data. We conclude that recent improvements in the MAIAC product have led to changes in the characteristics of spatio-temporal patterns of VIs seasonality across the Amazon forest, when compared to the MCD43 product. Nevertheless, despite improved quality and reduced uncertainties in the MAIAC product, a robust biophysical interpretation of VIs seasonality is still missing.

Consistency of Vegetation Index Seasonality Across the Amazon Rainforest

NASA Technical Reports Server (NTRS)

Maeda, Eduardo Eiji; Moura, Yhasmin Mendes; Wagner, Fabien; Hilker, Thomas; Lyapustin, Alexei I.; Wang, Yujie; Chave, Jerome; Mottus, Matti; Aragao, Luiz E.O.C.; Shimabukuro, Yosio

2016-01-01

Vegetation indices (VIs) calculated from remotely sensed reflectance are widely used tools for characterizing the extent and status of vegetated areas. Recently, however, their capability to monitor the Amazon forest phenology has been intensely scrutinized. In this study, we analyze the consistency of VIs seasonal patterns obtained from two MODIS products: the Collection 5 BRDF product (MCD43) and the Multi-Angle Implementation of Atmospheric Correction algorithm (MAIAC). The spatio-temporal patterns of the VIs were also compared with field measured leaf litterfall, gross ecosystem productivity and active microwave data. Our results show that significant seasonal patterns are observed in all VIs after the removal of view-illumination effects and cloud contamination. However, we demonstrate inconsistencies in the characteristics of seasonal patterns between different VIs and MODIS products. We demonstrate that differences in the original reflectance band values form a major source of discrepancy between MODIS VI products. The MAIAC atmospheric correction algorithm significantly reduces noise signals in the red and blue bands. Another important source of discrepancy is caused by differences in the availability of clear-sky data, as the MAIAC product allows increased availability of valid pixels in the equatorial Amazon. Finally, differences in VIs seasonal patterns were also caused by MODIS collection 5 calibration degradation. The correlation of remote sensing and field data also varied spatially, leading to different temporal offsets between VIs, active microwave and field measured data. We conclude that recent improvements in the MAIAC product have led to changes in the characteristics of spatio-temporal patterns of VIs seasonality across the Amazon forest, when compared to the MCD43 product. Nevertheless, despite improved quality and reduced uncertainties in the MAIAC product, a robust biophysical interpretation of VIs seasonality is still missing.

Forest policy reform in Brazil

Treesearch

S. Bauch; E. Sills; L.C. Rodriguez Estraviz; K. McGinley; F. Cubbage

2009-01-01

Rapid deforestation in the Brazilian Amazon, caused by economic, social, and policy factors, has focused global and national attention on protecting this valuable forest resource. In response, Brazil reformed its federal forest laws in 2006, creating new regulatory, development, and incentive policy instruments and institutions. Federal forestry responsibilities are...

Edge effects on growth and biomass partitioning of an Amazonian understory herb (Heliconia acuminata; Heliconiaceae).

PubMed

Bruna, Emilio M; de Andrade, Ana Segalin

2011-10-01

After deforestation, environmental changes in the remaining forest fragments are often most intense near the forest edge, but few studies have evaluated plant growth or plasticity of plant growth in response to edge effects. In a 2-year common garden experiment, we compared biomass allocation and growth of Heliconia acuminata with identical genotypes grown in 50 × 35 m common gardens on a 25-year-old edge and in a forest interior site. Genetically identical plants transplanted to the forest edge and understory exhibited different patterns of growth and biomass allocation. However, individuals with identical genotypes in the same garden often had very different responses. Plants on forest edges also had higher growth rates and increased biomass at the end of the experiment, almost certainly due to the increased light on the forest edge. With over 70000 km of forest edge created annually in the Brazilian Amazon, phenotypic plasticity may play an important role in mediating plant responses to these novel environmental conditions.

Naming and Shaming for Conservation: Evidence from the Brazilian Amazon

PubMed Central

Cisneros, Elías; Zhou, Sophie Lian; Börner, Jan

2015-01-01

Deforestation in the Brazilian Amazon has dropped substantially after a peak of over 27 thousand square kilometers in 2004. Starting in 2008, the Brazilian Ministry of the Environment has regularly published blacklists of critical districts with high annual forest loss. Farms in blacklisted districts face additional administrative hurdles to obtain authorization for clearing forests. In this paper we add to the existing literature on evaluating the Brazilian anti-deforestation policies by specifically quantifying the impact of blacklisting on deforestation. We first use spatial matching techniques using a set of covariates that includes official blacklisting criteria to identify control districts. We then explore the effect of blacklisting on change in deforestation in double difference regressions with panel data covering the period from 2002 to 2012. Multiple robustness checks are conducted including an analysis of potential causal mechanisms behind the success of the blacklist. We find that the blacklist has considerably reduced deforestation in the affected districts even after controlling for the potential mechanism effects of field-based enforcement, environmental registration campaigns, and rural credit. PMID:26398096

A database for the monitoring of thermal anomalies over the Amazon forest and adjacent intertropical oceans

PubMed Central

Jiménez-Muñoz, Juan C.; Mattar, Cristian; Sobrino, José A.; Malhi, Yadvinder

2015-01-01

Advances in information technologies and accessibility to climate and satellite data in recent years have favored the development of web-based tools with user-friendly interfaces in order to facilitate the dissemination of geo/biophysical products. These products are useful for the analysis of the impact of global warming over different biomes. In particular, the study of the Amazon forest responses to drought have recently received attention by the scientific community due to the occurrence of two extreme droughts and sustained warming over the last decade. Thermal Amazoni@ is a web-based platform for the visualization and download of surface thermal anomalies products over the Amazon forest and adjacent intertropical oceans using Google Earth as a baseline graphical interface (http://ipl.uv.es/thamazon/web). This platform is currently operational at the servers of the University of Valencia (Spain), and it includes both satellite (MODIS) and climatic (ERA-Interim) datasets. Thermal Amazoni@ is composed of the viewer system and the web and ftp sites with ancillary information and access to product download. PMID:26029379

A database for the monitoring of thermal anomalies over the Amazon forest and adjacent intertropical oceans.

PubMed

Jiménez-Muñoz, Juan C; Mattar, Cristian; Sobrino, José A; Malhi, Yadvinder

2015-01-01

Advances in information technologies and accessibility to climate and satellite data in recent years have favored the development of web-based tools with user-friendly interfaces in order to facilitate the dissemination of geo/biophysical products. These products are useful for the analysis of the impact of global warming over different biomes. In particular, the study of the Amazon forest responses to drought have recently received attention by the scientific community due to the occurrence of two extreme droughts and sustained warming over the last decade. Thermal Amazoni@ is a web-based platform for the visualization and download of surface thermal anomalies products over the Amazon forest and adjacent intertropical oceans using Google Earth as a baseline graphical interface (http://ipl.uv.es/thamazon/web). This platform is currently operational at the servers of the University of Valencia (Spain), and it includes both satellite (MODIS) and climatic (ERA-Interim) datasets. Thermal Amazoni@ is composed of the viewer system and the web and ftp sites with ancillary information and access to product download.

High overlap between traditional ecological knowledge and forest conservation found in the Bolivian Amazon.

PubMed

Paneque-Gálvez, Jaime; Pérez-Llorente, Irene; Luz, Ana Catarina; Guèze, Maximilien; Mas, Jean-François; Macía, Manuel J; Orta-Martínez, Martí; Reyes-García, Victoria

2018-03-12

It has been suggested that traditional ecological knowledge (TEK) may play a key role in forest conservation. However, empirical studies assessing to what extent TEK is associated with forest conservation compared with other variables are rare. Furthermore, to our knowledge, the spatial overlap of TEK and forest conservation has not been evaluated at fine scales. In this paper, we address both issues through a case study with Tsimane' Amerindians in the Bolivian Amazon. We sampled 624 households across 59 villages to estimate TEK and used remote sensing data to assess forest conservation. We ran statistical and spatial analyses to evaluate whether TEK was associated and spatially overlapped with forest conservation at the village level. We find that Tsimane' TEK is significantly and positively associated with forest conservation although acculturation variables bear stronger and negative associations with forest conservation. We also find a very significant spatial overlap between levels of Tsimane' TEK and forest conservation. We discuss the potential reasons underpinning our results, which provide insights that may be useful for informing policies in the realms of development, conservation, and climate. We posit that the protection of indigenous cultural systems is vital and urgent to create more effective policies in such realms.

Space Radar Image of Manaus, Brazil

NASA Image and Video Library

1999-05-01

These two false-color images of the Manaus region of Brazil in South America were acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar on board the space shuttle Endeavour. The image at left was acquired on April 12, 1994, and the image at right was acquired on October 3, 1994. The area shown is approximately 8 kilometers by 40 kilometers (5 miles by 25 miles). The two large rivers in this image, the Rio Negro (at top) and the Rio Solimoes (at bottom), combine at Manaus (west of the image) to form the Amazon River. The image is centered at about 3 degrees south latitude and 61 degrees west longitude. North is toward the top left of the images. The false colors were created by displaying three L-band polarization channels: red areas correspond to high backscatter, horizontally transmitted and received, while green areas correspond to high backscatter, horizontally transmitted and vertically received. Blue areas show low returns at vertical transmit/receive polarization; hence the bright blue colors of the smooth river surfaces can be seen. Using this color scheme, green areas in the image are heavily forested, while blue areas are either cleared forest or open water. The yellow and red areas are flooded forest or floating meadows. The extent of the flooding is much greater in the April image than in the October image and appears to follow the 10-meter (33-foot) annual rise and fall of the Amazon River. The flooded forest is a vital habitat for fish, and floating meadows are an important source of atmospheric methane. These images demonstrate the capability of SIR-C/X-SAR to study important environmental changes that are impossible to see with optical sensors over regions such as the Amazon, where frequent cloud cover and dense forest canopies block monitoring of flooding. Field studies by boat, on foot and in low-flying aircraft by the University of California at Santa Barbara, in collaboration with Brazil's Instituto Nacional de Pesguisas Estaciais, during the first and second flights of the SIR-C/X-SAR system have validated the interpretation of the radar images. http://photojournal.jpl.nasa.gov/catalog/PIA01735

Survival, growth and reproduction by big-leaf mahogany (Swietenia macrophylla) in open clearing vs. forested conditions in Brazil

Treesearch

James Grogan; Mark Schulze; Jurandir Galvao

2010-01-01

Big-leaf mahogany (Swietenia macrophylla) trees are often retained in agricultural fields and pastures for seed and timber production after selective logging and forest clearing in the Brazilian Amazon. At a forest management site in southeast Para´, we censused trees growing scattered across a large open clearing after forest removal and in heavily disturbed forest...

Climatic impact of Amazon deforestation - a mechanistic model study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ning Zeng; Dickinson, R.E.; Xubin Zeng

1996-04-01

Recent general circulation model (GCM) experiments suggest a drastic change in the regional climate, especially the hydrological cycle, after hypothesized Amazon basinwide deforestation. To facilitate the theoretical understanding os such a change, we develop an intermediate-level model for tropical climatology, including atmosphere-land-ocean interaction. The model consists of linearized steady-state primitive equations with simplified thermodynamics. A simple hydrological cycle is also included. Special attention has been paid to land-surface processes. It generally better simulates tropical climatology and the ENSO anomaly than do many of the previous simple models. The climatic impact of Amazon deforestation is studied in the context of thismore » model. Model results show a much weakened Atlantic Walker-Hadley circulation as a result of the existence of a strong positive feedback loop in the atmospheric circulation system and the hydrological cycle. The regional climate is highly sensitive to albedo change and sensitive to evapotranspiration change. The pure dynamical effect of surface roughness length on convergence is small, but the surface flow anomaly displays intriguing features. Analysis of the thermodynamic equation reveals that the balance between convective heating, adiabatic cooling, and radiation largely determines the deforestation response. Studies of the consequences of hypothetical continuous deforestation suggest that the replacement of forest by desert may be able to sustain a dry climate. Scaling analysis motivated by our modeling efforts also helps to interpret the common results of many GCM simulations. When a simple mixed-layer ocean model is coupled with the atmospheric model, the results suggest a 1{degrees}C decrease in SST gradient across the equatorial Atlantic Ocean in response to Amazon deforestation. The magnitude depends on the coupling strength. 66 refs., 16 figs., 4 tabs.« less

High-resolution mapping of forest carbon stocks in the Colombian Amazon

NASA Astrophysics Data System (ADS)

Asner, G. P.; Clark, J. K.; Mascaro, J.; Galindo García, G. A.; Chadwick, K. D.; Navarrete Encinales, D. A.; Paez-Acosta, G.; Cabrera Montenegro, E.; Kennedy-Bowdoin, T.; Duque, Á.; Balaji, A.; von Hildebrand, P.; Maatoug, L.; Bernal, J. F. Phillips; Yepes Quintero, A. P.; Knapp, D. E.; García Dávila, M. C.; Jacobson, J.; Ordóñez, M. F.

2012-07-01

High-resolution mapping of tropical forest carbon stocks can assist forest management and improve implementation of large-scale carbon retention and enhancement programs. Previous high-resolution approaches have relied on field plot and/or light detection and ranging (LiDAR) samples of aboveground carbon density, which are typically upscaled to larger geographic areas using stratification maps. Such efforts often rely on detailed vegetation maps to stratify the region for sampling, but existing tropical forest maps are often too coarse and field plots too sparse for high-resolution carbon assessments. We developed a top-down approach for high-resolution carbon mapping in a 16.5 million ha region (> 40%) of the Colombian Amazon - a remote landscape seldom documented. We report on three advances for large-scale carbon mapping: (i) employing a universal approach to airborne LiDAR-calibration with limited field data; (ii) quantifying environmental controls over carbon densities; and (iii) developing stratification- and regression-based approaches for scaling up to regions outside of LiDAR coverage. We found that carbon stocks are predicted by a combination of satellite-derived elevation, fractional canopy cover and terrain ruggedness, allowing upscaling of the LiDAR samples to the full 16.5 million ha region. LiDAR-derived carbon maps have 14% uncertainty at 1 ha resolution, and the regional map based on stratification has 28% uncertainty in any given hectare. High-resolution approaches with quantifiable pixel-scale uncertainties will provide the most confidence for monitoring changes in tropical forest carbon stocks. Improved confidence will allow resource managers and decision makers to more rapidly and effectively implement actions that better conserve and utilize forests in tropical regions.

High-resolution Mapping of Forest Carbon Stocks in the Colombian Amazon

NASA Astrophysics Data System (ADS)

Asner, G. P.; Clark, J. K.; Mascaro, J.; Galindo García, G. A.; Chadwick, K. D.; Navarrete Encinales, D. A.; Paez-Acosta, G.; Cabrera Montenegro, E.; Kennedy-Bowdoin, T.; Duque, Á.; Balaji, A.; von Hildebrand, P.; Maatoug, L.; Bernal, J. F. Phillips; Knapp, D. E.; García Dávila, M. C.; Jacobson, J.; Ordóñez, M. F.

2012-03-01

High-resolution mapping of tropical forest carbon stocks can assist forest management and improve implementation of large-scale carbon retention and enhancement programs. Previous high-resolution approaches have relied on field plot and/or Light Detection and Ranging (LiDAR) samples of aboveground carbon density, which are typically upscaled to larger geographic areas using stratification maps. Such efforts often rely on detailed vegetation maps to stratify the region for sampling, but existing tropical forest maps are often too coarse and field plots too sparse for high resolution carbon assessments. We developed a top-down approach for high-resolution carbon mapping in a 16.5 million ha region (>40 %) of the Colombian Amazon - a remote landscape seldom documented. We report on three advances for large-scale carbon mapping: (i) employing a universal approach to airborne LiDAR-calibration with limited field data; (ii) quantifying environmental controls over carbon densities; and (iii) developing stratification- and regression-based approaches for scaling up to regions outside of LiDAR coverage. We found that carbon stocks are predicted by a combination of satellite-derived elevation, fractional canopy cover and terrain ruggedness, allowing upscaling of the LiDAR samples to the full 16.5 million ha region. LiDAR-derived carbon mapping samples had 14.6 % uncertainty at 1 ha resolution, and regional maps based on stratification and regression approaches had 25.6 % and 29.6 % uncertainty, respectively, in any given hectare. High-resolution approaches with reported local-scale uncertainties will provide the most confidence for monitoring changes in tropical forest carbon stocks. Improved confidence will allow resource managers and decision-makers to more rapidly and effectively implement actions that better conserve and utilize forests in tropical regions.

Along the Rio Negro: Brazilian Children's Environmental Views and Values.

ERIC Educational Resources Information Center

Howe, Daniel C.; And Others

1996-01-01

Interviews with fifth graders living in rural and urban parts of the Brazilian Amazon region revealed that children were aware of environmental problems, believed that throwing garbage into the Rio Negro harmed the environment and violated a moral obligation, cared about environmental harm, and supported conservation of the Amazon rain forest. (BC)

Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere

NASA Technical Reports Server (NTRS)

Devol, Allan H.; Richey, Jeffrey E.; Forsberg, Bruce R.; Martinelli, Luiz A.

1990-01-01

Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 mg CH4/sq m per day and were significantly lower than similar emissions determined previously for the high-water period, 184 mg CH4/sq m per day (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emission from eight lakes located in the central Amazon basis showed similar results. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg/yr, which indicates the importance of the area in global atmospheric chemistry.

Does Tropical Forest Fragmentation Increase Long-Term Variability of Butterfly Communities?

PubMed Central

Leidner, Allison K.; Haddad, Nick M.; Lovejoy, Thomas E.

2010-01-01

Habitat fragmentation is a major driver of biodiversity loss. Yet, the overall effects of fragmentation on biodiversity may be obscured by differences in responses among species. These opposing responses to fragmentation may be manifest in higher variability in species richness and abundance (termed hyperdynamism), and in predictable changes in community composition. We tested whether forest fragmentation causes long-term hyperdynamism in butterfly communities, a taxon that naturally displays large variations in species richness and community composition. Using a dataset from an experimentally fragmented landscape in the central Amazon that spanned 11 years, we evaluated the effect of fragmentation on changes in species richness and community composition through time. Overall, adjusted species richness (adjusted for survey duration) did not differ between fragmented forest and intact forest. However, spatial and temporal variation of adjusted species richness was significantly higher in fragmented forests relative to intact forest. This variation was associated with changes in butterfly community composition, specifically lower proportions of understory shade species and higher proportions of edge species in fragmented forest. Analysis of rarefied species richness, estimated using indices of butterfly abundance, showed no differences between fragmented and intact forest plots in spatial or temporal variation. These results do not contradict the results from adjusted species richness, but rather suggest that higher variability in butterfly adjusted species richness may be explained by changes in butterfly abundance. Combined, these results indicate that butterfly communities in fragmented tropical forests are more variable than in intact forest, and that the natural variability of butterflies was not a buffer against the effects of fragmentation on community dynamics. PMID:20224772

Nitrous oxide emissions from forests and pastures of various ages in the Brazilian Amazon

NASA Astrophysics Data System (ADS)

Melillo, J. M.; Steudler, P. A.; Feigl, B. J.; Neill, C.; Garcia, D.; Piccolo, M. C.; Cerri, C. C.; Tian, H.

2001-12-01

Nitrous oxide emissions from tropical forest soils are thought to account for 2.2-3.7 Tg N yr-1 of the total annual global production of 10-17 Tg N yr-1. Recent research suggests that clearing of tropical forest for pasture can increase N2O emissions but that the period of elevated emissions may be limited and fluxes from older pastures may be lower than from the original forest. Here we report N2O emissions from two land-use sequences in the Brazilian Amazon's state of Rondônia. Each sequence includes a forest and a set of pastures of different ages. One sequence contains a newly created pasture that we studied intensively through its first 2 years, including forest cutting, burning, and the planting of forage grasses. Emissions from the newly created pasture were about two and one half times the forest emissions during the first 2 years (5.0 kg N2O-N ha-1 yr-1 versus 1.9 kg N2O-N ha-1 yr-1). Nitrous oxide fluxes from pastures older than 3 years were on average about one third lower than fluxes from uncut forest (1.4 kg N2O-N ha-1 yr-1 versus 1.9 kg N2O-N ha-1 yr-1). The best predictor of N2O flux across the chronosequences was the magnitude of the NO3 pool in the upper 10 cm of soil measured at the time of gas sampling. Using a simple cohort model combined with deforestation rates estimated from satellite images by Brazil's Instituto de Pesquisas Espaciais (INPE) for the period 1978 through 1997, we estimate that for the Brazilian Amazon the basin-wide flux of N2O-N from pasture soils was 0.06 Tg in 1997. This is ˜8% of the combined forest plus pasture flux of 0.78 Tg N2O-N we estimate for the Brazilian part of the basin in 1997. In the absence of any forest-to-pasture conversion in the Brazilian part of the basin, we estimate that the basin-wide flux of N2O-N would have been only slightly larger: 0.80 Tg in 1997. Through a second modeling analysis we estimate that for the whole of the Amazon Basin, including parts of the basin outside of Brazil, the N2O-N emissions from forests averaged 1.3 Tg yr-1 over the period 1978-1995.

Time Series of Tropical-Forest Structure from TanDEM-X, Transformed to Time Series of Biomass by MODIS

NASA Astrophysics Data System (ADS)

Treuhaft, R. N.; Baccini, A.; Goncalves, F. G.; Lei, Y.; Keller, M.; Walker, W. S.

2017-12-01

Tropical forests account for about 50% of the world's forested biomass, and play a critical role in the control of atmospheric carbon dioxide. Large-scale (1000's of km) changes in forest structure and biomass bear on global carbon source-sink dynamics, while small-scale (< 100 m) changes bear on deforestation and degradation monitoring. After describing the interferometric SAR (InSAR) phase-height observation, we show forest phase-height time series from the TanDEM-X radar interferometer at X-band (3 cm), taken with monthly and sub-hectare temporal and spatial resolution, respectively. The measurements were taken with more than 30 TanDEM-X passes over Tapajós National Forest in the Brazilian Amazon between 2011 and 2014. The transformation of phase-height rates into aboveground biomass (AGB) rates is based on the idea that the change in AGB due to a change in phase-height depends on the plot's AGB. Plots with higher AGB will produce more AGB for a given increase in height or phase-height. Postulating a power-law dependence of plot-level mass density on physical height, we previously found that the best conversion factors for transforming phase-height rate to AGB rate were indeed dependent on AGB. For 78 plots, we demonstrated AGB rates from InSAR phase-height rates using AGB from field measurements. For regional modeling of the Amazon Basin, field measurements of AGB, to specify the conversion factors, is impractical. Conversion factors from InSAR phase-height rate to AGB rate in this talk will be based on AGB derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). AGB measurement from MODIS is based on the spectral reflectance of 7 bands from the visible to short wave infrared, and auxiliary metrics describing the variance in reflectance. The mapping of MODIS reflectance to AGB is enabled by training a machine learning algorithm with lidar-derived AGB data, which are in turn trained by field measurements for small areas. The performance of TanDEM-X AGB rate from MODIS-derived conversion factors will be compared to that derived from field-based conversion factors. We will also attempt to improve phase-height rate to AGB rate transformation by deriving improved models of mass density dependences on height, based on the aggregation of single-stem allometrics.

Measurement of deforestation in the Brazilian Amazon using satellite remote sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skole, D.L.

1992-01-01

Understanding of the role of the biota in the global carbon cycle is limited by an absence of accurate measurements of deforestation rates in the tropics. This study measures the rate and extent of deforestation in the Brazilian Amazon, the largest extant tropical forest biome in the world. The study uses remote sensing measurements of deforestation rates, the area of secondary vegetation, and tabular data to document deforestation. The analysis concludes: (1) AVHRR will greatly overestimate deforestation and be highly variable; the use of a brightness temperature threshold is highly sensitive and unreliable. The upward bias of AVHRR is amore » function of the density of deforestation. (2) Accurate measurement of deforestation requires Landsat TM data, and can be accomplished using low cost visual interpretation of photographic products at 1:250,000 scales. (3) Secondary growth in the Brazilian Amazon represents a large fraction of the total deforested area, and the abandonment of agricultural land is an important land cover transition. Abandonment rates were 70--83% of clearing rates from primary forests. At any one point in time, approximately 30% of the deforested area is in some stage of abandonment, and quite likely nearly all deforested land becomes abandoned after approximately 5 years. (4) Previous estimates of the total area deforested in the Amazon, as well as deforestation rates, have been too high by as much as 4-fold. A complete assessment of the entire Legal Amazon using over 200 Landsat images measures 251 [times] 10[sup 3] km[sup 2] deforestation as of 1988, or approximately 6% of the closed forests of the region. The average annual rate of deforestation between 1978 and 1988 was 18 [times] 10[sup 3] km[sup 2] yr[sup [minus]1]. These findings suggest the estimates of carbon emissions from the Amazon for the late 1980s have been too high, since the area of regrowth is large and rates of deforestation are lower than previously believed.« less

Seeing through the Canopy: Relationship between Coarse Woody Debris and Forest Structure measured by Airborne Lidar in the Brazilian Amazon

NASA Astrophysics Data System (ADS)

Scaranello, M. A., Sr.; Keller, M. M.; dos-Santos, M. N.; Longo, M.; Pinagé, E. R.; Leitold, V.

2016-12-01

Coarse woody debris is an important but infrequently quantified carbon pool in tropical forests. Based on studies at 12 sites spread across the Brazilian Amazon, we quantified coarse woody debris stocks in intact forests and forests affected by different intensities of degradation by logging and/or fire. Measurement were made in-situ and for the first time field measurements of coarse woody debris were related to structural metrics derived from airborne lidar. Using the line-intercept method we established 84 transects for sampling fallen coarse woody debris and associated inventory plots for sampling standing dead wood in intact, conventional logging, reduced impact logging, burned and burned after logging forests. Overall mean and standard deviation of total coarse woody debris were 50.0 Mg ha-1 and 26.4 Mg ha-1 respectively. Forest degradation increased coarse woody debris stocks compared to intact forests by a factor of 1.7 in reduced impact logging forests and up to 3-fold in burned forests, in a side-by-side comparison of nearby areas. The ratio between coarse woody debris and biomass increased linearly with number of degradation events (R²: 0.67, p<0.01). Individual lidar-derived structural variables strongly correlated with coarse woody debris in intact and reduced impact logging forests: the 5th percentile of last returns for in intact forests (R²: 0.78, p<0.01) and forest gap area, mapped using lidar-derived canopy height model, for reduced impact logging forests (R²: 0.63, p<0.01). Individual gap area also played a weak but significant role in determining coarse woody debris in burned forests (R2: 0.21, p<0.05), but with contrasting trend. Both degradation-specific and general multiple models using lidar-derived variables were good predictor of coarse woody debris stocks in different degradation levels in the Brazilian Amazon. The strong relation of coarse woody debris with lidar derived structural variables suggests an approach for quantifying infrequently measured coarse woody debris over large areas.

Gender-specific out-migration, deforestation and urbanization in the Ecuadorian Amazon

NASA Astrophysics Data System (ADS)

Barbieri, Alisson F.; Carr, David L.

2005-07-01

The Ecuadorian Amazon, one of the richest reserves of biodiversity in the world, has faced one of the highest rates of deforestation of any Amazonian nation. Most of this forest elimination has been caused by agricultural colonization that followed the discovery of oil fields in 1967. Since the 1990s, an increasing process of urbanization has also engendered new patterns of population mobility within the Amazon, along with traditional ways by which rural settlers make their living. However, while very significant in its effects on deforestation, urbanization and regional development, population mobility within the Amazon has hardly been studied at all, as well as the distinct migration patterns between men and women. This paper uses a longitudinal dataset of 250 farm households in the Northern Ecuadorian Amazon to understand differentials between men and women migrants to urban and rural destinations and between men and women non-migrants. First, we use hazard analysis based on the Kaplan-Meier (KM) estimator to obtain the cumulative probability that an individual living in the study area in 1990 or at time t, will out-migrated at some time, t+ n, before 1999. Results indicate that out-migration to other rural areas in the Amazon, especially pristine areas is considerably greater than out-migration to the growing, but still incipient, Amazonian urban areas. Furthermore, men are more likely to out-migrate to rural areas than women, while the reverse occurs for urban areas. Difference-of-means tests were employed to examine potential factors accounting for differentials between male and female out-migration to urban and rural areas. Among the key results, relative to men younger women are more likely to out-migrate to urban areas; more difficult access from farms to towns and roads constrains women's migration; and access to new lands in the Amazon-an important cause of further deforestation-is more associated with male out-migration. Economic factors such as engagement in on-farm work, increasing resource scarcity-measured by higher population density at the farm and reduction in farm land on forest and crops-and increase in pasture land are more associated with male out-migration to rural areas. On the other hand, increasing resource scarcity, higher population density and weaker migration networks are more associated with female out-migration to urban areas. Thus, a "vicious cycle" is created: Pressure over land leads to deforestation in most or all farm forest areas and reduces the possibilities for further agricultural extensification (deforestation); out-migration, especially male out-migration, occurs to other rural or forest areas in the Amazon (with women being more likely to choose urban destinations); and, giving continuing population growth and pressures in the new settled areas, new pressures promote further out-migration to rural destinations and unabated deforestation.

Rapid tree carbon stock recovery in managed Amazonian forests.

PubMed

Rutishauser, Ervan; Hérault, Bruno; Baraloto, Christopher; Blanc, Lilian; Descroix, Laurent; Sotta, Eleneide Doff; Ferreira, Joice; Kanashiro, Milton; Mazzei, Lucas; d'Oliveira, Marcus V N; de Oliveira, Luis C; Peña-Claros, Marielos; Putz, Francis E; Ruschel, Ademir R; Rodney, Ken; Roopsind, Anand; Shenkin, Alexander; da Silva, Katia E; de Souza, Cintia R; Toledo, Marisol; Vidal, Edson; West, Thales A P; Wortel, Verginia; Sist, Plinio

2015-09-21

While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production. Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity. Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al. found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin to assess the main drivers of time-to-recovery of post-logging tree carbon (Table S1). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Regional aerosol chemistry of the Amazon Basin during the dry season

NASA Technical Reports Server (NTRS)

Talbot, R. W.; Harriss, R. C.; Andreae, M. O.; Andreae, T. W.

1988-01-01

The distribution and chemical composition of the atmospheric aerosol over the Amazon Basin forest were determined during the 1985 July-August dry season, using data on the aerosol chemical constituent concentration collected during the NASA Global Tropospheric Experiment Amazon Boundary Layer Experiment 2A mission. The results of the analyses suggest that there is a remarkable compositional and spatial homogeneity of the atmospheric aerosol on an extensive regional scale. Particulate organic carbon is the dominant component of the atmospheric aerosol, exhibiting an average concentration of about 740 nmol/cu m in the mixed layer and about 220 nmol/cu m in free tropospheric air. Oxalate and SO4(2-) exhibited the greatest enrichment in the mixed layer, while Cl(-) showed essentially no enrichment. The aerosol in the Amazonian atmosphere is essentially acid-base neutral, primarily as a result of incorporation of NH(+), which is presumably derived from NH3 released by the forest ecosystem.

Dispersal assembly of rain forest tree communities across the Amazon basin

PubMed Central

Lavin, Mathew; Torke, Benjamin M.; Twyford, Alex D.; Kursar, Thomas A.; Coley, Phyllis D.; Drake, Camila; Hollands, Ruth; Pennington, R. Toby

2017-01-01

We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus Inga. We compare our results with those for three other ecologically important, diverse, and abundant Amazonian tree lineages, Swartzia, Protieae, and Guatteria. Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure, and show that local communities of Inga and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of Inga and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance, and that allopatric isolation following dispersal may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales, the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin. PMID:28213498

Dispersal assembly of rain forest tree communities across the Amazon basin.

PubMed

Dexter, Kyle G; Lavin, Mathew; Torke, Benjamin M; Twyford, Alex D; Kursar, Thomas A; Coley, Phyllis D; Drake, Camila; Hollands, Ruth; Pennington, R Toby

2017-03-07

We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus Inga We compare our results with those for three other ecologically important, diverse, and abundant Amazonian tree lineages, Swartzia , Protieae, and Guatteria Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure, and show that local communities of Inga and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of Inga and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance, and that allopatric isolation following dispersal may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales, the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin.

Off-nadir antenna bias correction using Amazon rain sigma(0) data

NASA Technical Reports Server (NTRS)

Birrer, I. J.; Dome, G. J.; Sweet, J.; Berthold, G.; Moore, R. K.

1982-01-01

The radar response from the Amazon rain forest was studied to determine the suitability of this region for use as a standard target to calibrate a scatterometer like that proposed for the National Oceanic Satellite System (NOSS). Backscattering observations made by the SEASAT Scatterometer System (SASS) showed the Amazon rain forest to be a homogeneous, azimuthally-isotropic, radar target which was insensitive to polarization. The variation with angle of incidence was adequately modeled as scattering coefficient (dB) = a theta b with typical values for the incidence-angle coefficient from 0.07 to 0.15 dB/deg. A small diurnal effect occurs, with measurements at sunrise being 0.5 dB to 1 dB higher than the rest of the day. Maximum-likelihood estimation algorithms presented here permit determination of relative bias and true pointing angle for each beam. Specific implementation of these algorithms for the proposed NOSS scatterometer system is also discussed.

Origin and processing of terrestrial organic carbon in the Amazon system: lignin phenols in river, shelf, and fan sediments

NASA Astrophysics Data System (ADS)

Sun, Shuwen; Schefuß, Enno; Mulitza, Stefan; Chiessi, Cristiano M.; Sawakuchi, André O.; Zabel, Matthias; Baker, Paul A.; Hefter, Jens; Mollenhauer, Gesine

2017-05-01

The Amazon River transports large amounts of terrestrial organic carbon (OCterr) from the Andean and Amazon neotropical forests to the Atlantic Ocean. In order to compare the biogeochemical characteristics of OCterr in the fluvial sediments from the Amazon drainage basin and in the adjacent marine sediments, we analysed riverbed sediments from the Amazon mainstream and its main tributaries as well as marine surface sediments from the Amazon shelf and fan for total organic carbon (TOC) content, organic carbon isotopic composition (δ13CTOC), and lignin phenol compositions. TOC and lignin content exhibit positive correlations with Al / Si ratios (indicative of the sediment grain size) implying that the grain size of sediment discharged by the Amazon River plays an important role in the preservation of TOC and leads to preferential preservation of lignin phenols in fine particles. Depleted δ13CTOC values (-26.1 to -29.9 ‰) in the main tributaries consistently correspond with the dominance of C3 vegetation. Ratios of syringyl to vanillyl (S / V) and cinnamyl to vanillyl (C / V) lignin phenols suggest that non-woody angiosperm tissues are the dominant source of lignin in the Amazon basin. Although the Amazon basin hosts a rich diversity of vascular plant types, distinct regional lignin compositions are not observed. In the marine sediments, the distribution of δ13CTOC and Λ8 (sum of eight lignin phenols in organic carbon (OC), expressed as mg/100 mg OC) values implies that OCterr discharged by the Amazon River is transported north-westward by the North Brazil Current and mostly deposited on the inner shelf. The lignin compositions in offshore sediments under the influence of the Amazon plume are consistent with the riverbed samples suggesting that processing of OCterr during offshore transport does not change the encoded source information. Therefore, the lignin compositions preserved in these offshore sediments can reliably reflect the vegetation in the Amazon River catchment. In sediments from the Amazon fan, low lignin content, relatively depleted δ13CTOC values and high (Ad / Al)V ratios indicating highly degraded lignin imply that a significant fraction of the deposited OCterr is derived from petrogenic (sourced from ancient rocks) sources.

Technical and institutional innovation in agroforestry for protected areas management in the Brazilian Amazon: opportunities and limitations.

PubMed

Schroth, Götz; da Mota, Maria do Socorro S

2013-08-01

Tropical forest countries are struggling with the partially conflicting policy objectives of socioeconomic development, forest conservation, and safeguarding the livelihoods of local forest-dependent people. We worked with communities in the lower Tapajós region of the central Brazilian Amazon for over 10 years to understand their traditional and present land use practices, the constraints, and decision making processes imposed by their biophysical, socioeconomic, and political environment, and to facilitate development trajectories to improve the livelihoods of forest communities while conserving the forest on the farms and in the larger landscape. The work focused on riverine communities initially in the Tapajós National Forest and then in the Tapajós-Arapiuns Extractive Reserve. These communities have a century-old tradition of planting rubber agroforests which despite their abandonment during the 1990s still widely characterize the vegetation of the river banks, especially in the two protected areas where they are safe from the recent expansion of mechanized rice and soybean agriculture. The project evolved from the capacity-building of communities in techniques to increase the productivity of the rubber agroforests without breaking their low-input and low-risk logic, to the establishment of a community enterprise that allowed reserve inhabitants to reforest their own land with tree species of their choice and sell reforestation (not carbon) credits to local timber companies while retaining the ownership of the trees. By making land use practices economically more viable and ecologically more appropriate for protected areas, the project shows ways to strengthen the system of extractive and sustainable development reserves that protects millions of hectares of Amazon forest with the consent of the communities that inhabit them.

Technical and Institutional Innovation in Agroforestry for Protected Areas Management in the Brazilian Amazon: Opportunities and Limitations

NASA Astrophysics Data System (ADS)

Schroth, Götz; da Mota, Maria do Socorro S.

2013-08-01

Tropical forest countries are struggling with the partially conflicting policy objectives of socioeconomic development, forest conservation, and safeguarding the livelihoods of local forest-dependent people. We worked with communities in the lower Tapajós region of the central Brazilian Amazon for over 10 years to understand their traditional and present land use practices, the constraints, and decision making processes imposed by their biophysical, socioeconomic, and political environment, and to facilitate development trajectories to improve the livelihoods of forest communities while conserving the forest on the farms and in the larger landscape. The work focused on riverine communities initially in the Tapajós National Forest and then in the Tapajós-Arapiuns Extractive Reserve. These communities have a century-old tradition of planting rubber agroforests which despite their abandonment during the 1990s still widely characterize the vegetation of the river banks, especially in the two protected areas where they are safe from the recent expansion of mechanized rice and soybean agriculture. The project evolved from the capacity-building of communities in techniques to increase the productivity of the rubber agroforests without breaking their low-input and low-risk logic, to the establishment of a community enterprise that allowed reserve inhabitants to reforest their own land with tree species of their choice and sell reforestation (not carbon) credits to local timber companies while retaining the ownership of the trees. By making land use practices economically more viable and ecologically more appropriate for protected areas, the project shows ways to strengthen the system of extractive and sustainable development reserves that protects millions of hectares of Amazon forest with the consent of the communities that inhabit them.

Effect of oil palm on the Plecoptera and Trichoptera (Insecta) assemblages in streams of eastern Amazon.

PubMed

de Paiva, Carina Kaory Sasahara; de Faria, Ana Paula Justino; Calvão, Lenize Batista; Juen, Leandro

2017-08-01

The production of oil palm is expected to increase in the Amazon region. However, expansion of oil palm plantation leads to significant changes in the physical structure of aquatic ecosystems, mainly through the reduction of riparian vegetation that is essential for aquatic biodiversity. Here, we evaluated the effects of oil palm on the physical habitat structure of Amazonian stream environments and assemblages of Plecoptera and Trichoptera (PT), ​both found in these streams. We compared streams sampled in oil palm plantations (n = 13) with natural forest areas ("reference" streams, n = 8), located in the eastern Amazon, Brazil. Our results showed that oil palm streams were more likely to be in close proximity to roads, had higher pH values, and higher amounts of fine substrate deposited in the channel than reference streams. Further, these environmental changes had important effects on the aquatic invertebrate assemblages, reducing the abundance and richness of PT. Nevertheless, the genera composition of the assemblages did not differ between reference and oil palm (PERMANOVA, pseudo-F (1,19)  = 1.891; p = 0.111). We conclude that oil palm production has clear negative impacts on aquatic environments and PT assemblages in Amazonian streams. We recommend that oil palm producers invest more in planning of road networks to avoid the construction of roads near to the riparian vegetation. This planning can minimize impacts of oil palm production on aquatic systems in the Amazon.

Trends in nitrogen and phosphorus cycling are consistent and constrained during tropical secondary forest succession: is secondary forest young primary forest from a nutrient perspective?

NASA Astrophysics Data System (ADS)

Sullivan, B. W.; Nasto, M.; Alvarez-Clare, S.; Cole, R. J.; Reed, S.; Chazdon, R.; Davidson, E. A.; Cleveland, C. C.

2015-12-01

Extensive deforestation of tropical rainforest often leads to agricultural abandonment and secondary forest regeneration. The land area of secondary rainforest is soon likely to exceed that of primary forest, highlighting the importance of secondary tropical rainforest in the global carbon (C) cycle. Secondary forests often grow rapidly, but the role soil nutrients play in regulating secondary forest productivity remains unsettled. Consistent with biogeochemical theory, a landmark study from a set of sites in the Amazon Basin showed that secondary forests had low nitrogen (N) availability and relatively higher phosphorus (P) availability immediately after abandonment, but that as succession proceeded, N availability "recuperated" and there was relatively less P available. To address whether such changes in N and P availability during secondary forest growth are common, we reviewed 38 studies in lowland tropical rainforest that reported changes in 23 different metrics of N and P cycling during secondary succession. We calculated slopes (rates of change) during secondary succession for each metric in each study, and analyzed patterns in these rates of change. Significant trends during secondary succession were more evident in soils than in plants, but in most cases, the variability among studies was surprisingly low. Both soil N and P availability increased through succession, at least in surface soil. Such consistent changes imply substantial biogeochemical resilience of tropical forest soils in spite of differing land use histories and species compositions among studies. In most cases, slopes were similar whether primary forest was included in, or excluded from, our analysis, suggesting that secondary succession eventually leads to similar biogeochemical conditions as those found in primary forest. Our results suggesting consistent changes in N and P availability during succession provide a biogeochemical rationale for the conservation and restoration value of tropical secondary forests, and may be of utility to coupled C-nutrient models projecting primary productivity in a dynamic tropical biome.

Rock, Paper, Protest: The Fight for the Boreal Forest

ERIC Educational Resources Information Center

Gunz, Sally; Whittaker, Linda

2016-01-01

Canada's boreal forests are second only to the Amazon in producing life-giving oxygen and providing a habitat for thousands of species, from the large woodland caribou to the smallest organisms. The boreal forests are the lifeblood of many Aboriginal communities and the thousands of workers, Aboriginal and non-Aboriginal, who harvest and process…

Perceptions of environmental change and use of traditional knowledge to plan riparian forest restoration with relocated communities in Alcântara, Eastern Amazon.

PubMed

Celentano, Danielle; Rousseau, Guillaume Xavier; Engel, Vera Lex; Façanha, Cristiane Lima; Oliveira, Elivaldo Moreira de; Moura, Emanoel Gomes de

2014-01-27

Riparian forests provide ecosystem services that are essential for human well-being. The Pepital River is the main water supply for Alcântara (Brazil) and its forests are disappearing. This is affecting water volume and distribution in the region. Promoting forest restoration is imperative. In deprived regions, restoration success depends on the integration of ecology, livelihoods and traditional knowledge (TEK). In this study, an interdisciplinary research framework is proposed to design riparian forest restoration strategies based on ecological data, TEK and social needs. This study takes place in a region presenting a complex history of human relocation and land tenure. Local populations from seven villages were surveyed to document livelihood (including 'free-listing' of agricultural crops and homegarden tree species). Additionally, their perceptions toward environmental changes were explored through semi-structured interviews (n = 79). Ethnobotanical information on forest species and their uses were assessed by local-specialists (n = 19). Remnants of conserved forests were surveyed to access ecological information on tree species (three plots of 1,000 m2). Results included descriptive statistics, frequency and Smith’s index of salience of the free-list results. The local population depends primarily on slash-and-burn subsistence agriculture to meet their needs. Interviewees showed a strong empirical knowledge about the environmental problems of the river, and of their causes, consequences and potential solutions. Twenty-four tree species (dbh > 10 cm) were found at the reference sites. Tree density averaged 510 individuals per hectare (stdv = 91.6); and 12 species were considered the most abundant (density > 10ind/ha). There was a strong consensus among plant-specialists about the most important trees. The species lists from reference sites and plant-specialists presented an important convergence. Slash-and-burn agriculture is the main source of livelihood but also the main driver of forest degradation. Effective restoration approaches must transform problems into solutions by empowering local people. Successional agroforestry combining annual crops and trees may be a suitable transitional phase for restoration. The model must be designed collectively and include species of ecological, cultural, and socioeconomic value. In deprived communities of the Amazon, forest restoration must be a process that combines environmental and social gains.

Perceptions of environmental change and use of traditional knowledge to plan riparian forest restoration with relocated communities in Alcântara, Eastern Amazon

PubMed Central

2014-01-01

Background Riparian forests provide ecosystem services that are essential for human well-being. The Pepital River is the main water supply for Alcântara (Brazil) and its forests are disappearing. This is affecting water volume and distribution in the region. Promoting forest restoration is imperative. In deprived regions, restoration success depends on the integration of ecology, livelihoods and traditional knowledge (TEK). In this study, an interdisciplinary research framework is proposed to design riparian forest restoration strategies based on ecological data, TEK and social needs. Methods This study takes place in a region presenting a complex history of human relocation and land tenure. Local populations from seven villages were surveyed to document livelihood (including ‘free-listing’ of agricultural crops and homegarden tree species). Additionally, their perceptions toward environmental changes were explored through semi-structured interviews (n = 79). Ethnobotanical information on forest species and their uses were assessed by local-specialists (n = 19). Remnants of conserved forests were surveyed to access ecological information on tree species (three plots of 1,000 m2). Results included descriptive statistics, frequency and Smith’s index of salience of the free-list results. Results The local population depends primarily on slash-and-burn subsistence agriculture to meet their needs. Interviewees showed a strong empirical knowledge about the environmental problems of the river, and of their causes, consequences and potential solutions. Twenty-four tree species (dbh > 10 cm) were found at the reference sites. Tree density averaged 510 individuals per hectare (stdv = 91.6); and 12 species were considered the most abundant (density > 10ind/ha). There was a strong consensus among plant-specialists about the most important trees. The species lists from reference sites and plant-specialists presented an important convergence. Conclusions Slash-and-burn agriculture is the main source of livelihood but also the main driver of forest degradation. Effective restoration approaches must transform problems into solutions by empowering local people. Successional agroforestry combining annual crops and trees may be a suitable transitional phase for restoration. The model must be designed collectively and include species of ecological, cultural, and socioeconomic value. In deprived communities of the Amazon, forest restoration must be a process that combines environmental and social gains. PMID:24468421

Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements

NASA Astrophysics Data System (ADS)

Gatti, L. V.; Gloor, M.; Miller, J. B.; Doughty, C. E.; Malhi, Y.; Domingues, L. G.; Basso, L. S.; Martinewski, A.; Correia, C. S. C.; Borges, V. F.; Freitas, S.; Braz, R.; Anderson, L. O.; Rocha, H.; Grace, J.; Phillips, O. L.; Lloyd, J.

2014-02-01

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48+/-0.18 petagrams of carbon per year (PgCyr-1) during the dry year but was carbon neutral (0.06+/-0.1PgCyr-1) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25+/-0.14PgCyr-1, which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39+/-0.10PgCyr-1 previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.

Dust transport and deposition observed from the Terra-MODIS space observations

NASA Astrophysics Data System (ADS)

Kaufman, Y. J.; Koren, I.; Tanre, D.; Fan, S.; Remer, L.; Ginoux, P.

2003-12-01

Meteorological observations, in situ data and satellite images of dust episodes were used already in the 1970s to estimate that 100 tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but deteriorates air quality and caries pathogens as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport and deposition. The Terra spacecraft launched at the dawn of the last millennium provides first systematic well calibrated multispectral measurements from the MODIS instrument, for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and evaluate the African dust column concentration, transport and deposition. We found that 230 80 tg of dust are transported annually from Africa to the Atlantic Ocean, 30 tg return to Africa and Europe, 70 tg reach the Caribbean, 45 tg fertilize the Amazon Basin, 4 times as previous estimates thus explaining a paradox regarding the source of nutrition to the Amazon forest, and 120 40 tg are deposited in the Atlantic Ocean. The results are compared favorably with dust transport models for particle radius * 12 m. This study is a first example of quantitative use of MODIS aerosol for a geophysical study.

Predicting potential ranges of primary malaria vectors and malaria in northern South America based on projected changes in climate, land cover and human population.

PubMed

Alimi, Temitope O; Fuller, Douglas O; Qualls, Whitney A; Herrera, Socrates V; Arevalo-Herrera, Myriam; Quinones, Martha L; Lacerda, Marcus V G; Beier, John C

2015-08-20

Changes in land use and land cover (LULC) as well as climate are likely to affect the geographic distribution of malaria vectors and parasites in the coming decades. At present, malaria transmission is concentrated mainly in the Amazon basin where extensive agriculture, mining, and logging activities have resulted in changes to local and regional hydrology, massive loss of forest cover, and increased contact between malaria vectors and hosts. Employing presence-only records, bioclimatic, topographic, hydrologic, LULC and human population data, we modeled the distribution of malaria and two of its dominant vectors, Anopheles darlingi, and Anopheles nuneztovari s.l. in northern South America using the species distribution modeling platform Maxent. Results from our land change modeling indicate that about 70,000 km(2) of forest land would be lost by 2050 and 78,000 km(2) by 2070 compared to 2010. The Maxent model predicted zones of relatively high habitat suitability for malaria and the vectors mainly within the Amazon and along coastlines. While areas with malaria are expected to decrease in line with current downward trends, both vectors are predicted to experience range expansions in the future. Elevation, annual precipitation and temperature were influential in all models both current and future. Human population mostly affected An. darlingi distribution while LULC changes influenced An. nuneztovari s.l. distribution. As the region tackles the challenge of malaria elimination, investigations such as this could be useful for planning and management purposes and aid in predicting and addressing potential impediments to elimination.

Does Evapotranspiration Increase When Forests are converted to Grasslands?

NASA Astrophysics Data System (ADS)

Varcoe, Robert; Sterling, Shannon

2017-04-01

The conversion of forests to grasslands (FGC) is a widespread land cover change (LCC) and is also among the most commonly studied changes with respect to its impact on ET; such research employs a variety of experimental approaches, including, paired catchment (PC), Budyko and land surface models (LSM), and measurement methods, including the catchment water balance (CWB), eddy covariance (EC) and remote sensing (RS). Until recently, there has been consensus in the scientific literature that rates of ET decrease when a forest is converted to grassland; however, this consensus has recently come into question. Williams (2012) applied the Budyko framework to a global network of eddy covariance measurements with the results that grasslands have a 9% greater evaporative index than forests. In addition, HadGEM2, a recent Hadley Centre LSM, produced increased ET in the northern Amazon Basin after simulating global scale tropical deforestation (Brovkin et al., 2015). Here we present an analysis of available estimates of how ET rates change with FGC to increase our understanding of the forest - grassland-ET paradigm. We used two datasets to investigate the impacts land cover change on ET. I compiled a dataset of change in ET with land cover change (ΔETLCC) using published experiments that compare forest and grassland ET under conditions controlled for meteorological and landscape influences. Using the ΔETLCC dataset, we show that, in all cases, forest ET is higher than grassland under controlled conditions. Results suggest that the eddy covariance method measures smaller changes in ET when forests are converted to grasslands, though more data are needed for this result to be statistically significant. Finally, GETA2.0, a new global dataset of annual ET, projects that forest ET is greater than grassland, except at high latitudes and areas where orography influences precipitation (P). The data included in this study represent the data available on forest and grassland ET comparison and reveal an important gap in the scientific literature: the lack of data available regarding forest to grassland LCC.

Gross changes in forest area shape the future carbon balance of tropical forests

NASA Astrophysics Data System (ADS)

Li, Wei; Ciais, Philippe; Yue, Chao; Gasser, Thomas; Peng, Shushi; Bastos, Ana

2018-01-01

Bookkeeping models are used to estimate land-use and land-cover change (LULCC) carbon fluxes (ELULCC). The uncertainty of bookkeeping models partly arises from data used to define response curves (usually from local data) and their representativeness for application to large regions. Here, we compare biomass recovery curves derived from a recent synthesis of secondary forest plots in Latin America by Poorter et al. (2016) with the curves used previously in bookkeeping models from Houghton (1999) and Hansis et al. (2015). We find that the two latter models overestimate the long-term (100 years) vegetation carbon density of secondary forest by about 25 %. We also use idealized LULCC scenarios combined with these three different response curves to demonstrate the importance of considering gross forest area changes instead of net forest area changes for estimating regional ELULCC. In the illustrative case of a net gain in forest area composed of a large gross loss and a large gross gain occurring during a single year, the initial gross loss has an important legacy effect on ELULCC so that the system can be a net source of CO2 to the atmosphere long after the initial forest area change. We show the existence of critical values of the ratio of gross area change over net area change (γAnetAgross), above which cumulative ELULCC is a net CO2 source rather than a sink for a given time horizon after the initial perturbation. These theoretical critical ratio values derived from simulations of a bookkeeping model are compared with observations from the 30 m resolution Landsat Thematic Mapper data of gross and net forest area change in the Amazon. This allows us to diagnose areas in which current forest gains with a large land turnover will still result in LULCC carbon emissions in 20, 50 and 100 years.

Vegetation and climate variability in tropical and subtropical South America during the late Quaternary

NASA Astrophysics Data System (ADS)

Behling, H.

2013-05-01

Detailed palynological studies from different ecosystems in tropical and subtropical South America reflect interesting vegetation and climate dynamics, in particular during glacial and late glacial times. Records from ecosystems such as the Amazon rainforest, savanna, Caatinga, Atlantic rainforest, Araucaria forest and grasslands provide interesting insight of past climate variability. The influence of events such as Dansgaard-Oeschger, Heinnrich stadials, changes in the thermohaline circulation (THC) will be discussed. In particular the Younger Dryas (YD) period shows at different places distinct vegetational changes, revealing unexpected past climatic conditions.

Airborne laser-guided imaging spectroscopy to map forest trait diversity and guide conservation.

PubMed

Asner, G P; Martin, R E; Knapp, D E; Tupayachi, R; Anderson, C B; Sinca, F; Vaughn, N R; Llactayo, W

2017-01-27

Functional biogeography may bridge a gap between field-based biodiversity information and satellite-based Earth system studies, thereby supporting conservation plans to protect more species and their contributions to ecosystem functioning. We used airborne laser-guided imaging spectroscopy with environmental modeling to derive large-scale, multivariate forest canopy functional trait maps of the Peruvian Andes-to-Amazon biodiversity hotspot. Seven mapped canopy traits revealed functional variation in a geospatial pattern explained by geology, topography, hydrology, and climate. Clustering of canopy traits yielded a map of forest beta functional diversity for land-use analysis. Up to 53% of each mapped, functionally distinct forest presents an opportunity for new conservation action. Mapping functional diversity advances our understanding of the biosphere to conserve more biodiversity in the face of land use and climate change. Copyright © 2017, American Association for the Advancement of Science.

A Behavioral Model of Landscape Change in the Amazon Basin: The Colonist Case

NASA Technical Reports Server (NTRS)

Walker, R. A.; Drzyzga, S. A.; Li, Y. L.; Wi, J. G.; Caldas, M.; Arima, E.; Vergara, D.

2004-01-01

This paper presents the prototype of a predictive model capable of describing both magnitudes of deforestation and its spatial articulation into patterns of forest fragmentation. In a departure from other landscape models, it establishes an explicit behavioral foundation for algorithm development, predicated on notions of the peasant economy and on household production theory. It takes a 'bottom-up' approach, generating the process of land-cover change occurring at lot level together with the geography of a transportation system to describe regional landscape change. In other words, it translates the decentralized decisions of individual households into a collective, spatial impact. In so doing, the model unites the richness of survey research on farm households with the analytical rigor of spatial analysis enabled by geographic information systems (GIs). The paper describes earlier efforts at spatial modeling, provides a critique of the so-called spatially explicit model, and elaborates a behavioral foundation by considering farm practices of colonists in the Amazon basin. It then uses, insight from the behavioral statement to motivate a GIs-based model architecture. The model is implemented for a long-standing colonization frontier in the eastern sector of the basin, along the Trans-Amazon Highway in the State of Para, Brazil. Results are subjected to both sensitivity analysis and error assessment, and suggestions are made about how the model could be improved.

Avian distribution in treefall gaps and understorey of terra firme forest in the lowland Amazon

Treesearch

JR WUNDERLE; MICHAEL R. WILLIG; LUIZA MAGALLI PINTO HENRIQUES

2005-01-01

We compared the bird distributions in the understorey of treefall gaps and sites with intact canopy in Amazonian terra firme forest in Brazil. We compiled 2216 mist-net captures (116 species) in 32 gap and 32 forest sites over 22.3 months. Gap habitats differed from forest habitats in having higher capture rates, total captures, species richness and diversity....

Necromass in undisturbed and logged forests in the Brazilian Amazon.

Treesearch

Michael Palace; Michael Keller; Gregory P. Asner; Jose Natalino M. Silva; Carlos Passos

2007-01-01

Necromass is an important stock of carbon in tropical forests. We estimated volume, density, and mass of fallen and standing necromass in undisturbed and selectively logged forests at Juruena, Mato Grosso, Brazil (10.488S, 58.478W). We also measured standing dead trees at the Tapajos National Forest, Para, Brazil (3.088S, 54.948W) complementing our earlier study there...

Shifts in indigenous culture relate to forest tree diversity: a case study from the Tsimane', Bolivian Amazon.

PubMed

Guèze, Maximilien; Luz, Ana Catarina; Paneque-Gálvez, Jaime; Macía, Manuel J; Orta-Martínez, Martí; Pino, Joan; Reyes-García, Victoria

2015-06-01

Understanding how indigenous peoples' management practices relate to biological diversity requires addressing contemporary changes in indigenous peoples' way of life. This study explores the association between cultural change among a Bolivian Amazonian indigenous group, the Tsimane', and tree diversity in forests surrounding their villages. We interviewed 86 informants in six villages about their level of attachment to traditional Tsimane' values, our proxy for cultural change. We estimated tree diversity (Fisher's Alpha index) by inventorying trees in 48 0.1-ha plots in old-growth forests distributed in the territory of the same villages. We used multivariate models to assess the relation between cultural change and alpha tree diversity. Cultural change was associated with alpha tree diversity and the relation showed an inverted U-shape, thus suggesting that tree alpha diversity peaked in villages undergoing intermediate cultural change. Although the results do not allow for testing the direction of the relation, we propose that cultural change relates to tree diversity through the changes in practices and behaviors that affect the traditional ecological knowledge of Tsimane' communities; further research is needed to determine the causality. Our results also find support in the intermediate disturbance hypothesis, and suggest that indigenous management can be seen as an intermediate form of anthropogenic disturbance affecting forest communities in a subtle, non-destructive way.

Shifts in indigenous culture relate to forest tree diversity: a case study from the Tsimane’, Bolivian Amazon

PubMed Central

Guèze, Maximilien; Luz, Ana Catarina; Paneque-Gálvez, Jaime; Macía, Manuel J.; Orta-Martínez, Martí; Pino, Joan; Reyes-García, Victoria

2015-01-01

Understanding how indigenous peoples’ management practices relate to biological diversity requires addressing contemporary changes in indigenous peoples’ way of life. This study explores the association between cultural change among a Bolivian Amazonian indigenous group, the Tsimane’, and tree diversity in forests surrounding their villages. We interviewed 86 informants in six villages about their level of attachment to traditional Tsimane’ values, our proxy for cultural change. We estimated tree diversity (Fisher’s Alpha index) by inventorying trees in 48 0.1-ha plots in old-growth forests distributed in the territory of the same villages. We used multivariate models to assess the relation between cultural change and alpha tree diversity. Cultural change was associated with alpha tree diversity and the relation showed an inverted U-shape, thus suggesting that tree alpha diversity peaked in villages undergoing intermediate cultural change. Although the results do not allow for testing the direction of the relation, we propose that cultural change relates to tree diversity through the changes in practices and behaviors that affect the traditional ecological knowledge of Tsimane’ communities; further research is needed to determine the causality. Our results also find support in the intermediate disturbance hypothesis, and suggest that indigenous management can be seen as an intermediate form of anthropogenic disturbance affecting forest communities in a subtle, non-destructive way. PMID:26097240

Estimating forest biomass and identifying low-intensity logging areas using airborne scanning lidar in Antimary State Forest, Acre State, Western Brazilian Amazon

Treesearch

Marcus V.N. d' Oliveira; Stephen E. Reutebuch; Robert J. McGaughey; Hans-Erik. Andersen

2012-01-01

The objectives of this study were to estimate above ground forest biomass and identify areas disturbed by selective logging in a 1000 ha Brazilian tropical forest in the Antimary State Forest using airborne lidar data. The study area consisted of three management units, two of which were unlogged, while the third unit was selectively logged at a low intensity. A...

Public policies and communication affecting forest cover in the Amazon

NASA Astrophysics Data System (ADS)

Kawakami Savaget, E.; Batistella, M.; Aguiar, A. P. D.

2014-12-01

The research program Amazalert was based on information delivered by the IPCC through its 2007 report, which indicates forest degradation processes in the Amazonian region as a consequence of anthropogenic actions. Such processes affecting the structural and functional characteristics of ecosystems would harm environmental services that guarantee, for example, the regulation of climate and the provision of fresh water. A survey was organized, through a multidisciplinary perspective, on the main policies and programs that can affect forest cover in the Amazon. These rules and norms seek to regulate societal actions by defining a developmental model for the region. Although deforestation rates in the Brazilian Amazon have decreased significantly since 2004, some locations maintain high levels of deforestation. In 2013, for example, the municipalities of Monte Alegre, Óbidos, Alenquer, Oriximiná, Curuá and Almeirin, in the northern region of the state of Para, showed the highest rates of deforestation in the Amazon. Managers and stakeholders within these areas are being interviewed to provide insights on how policies are interpreted and applied locally. There is an understanding delay between discourses normalized by federal governmental institutions and claims of local societies. The possible lack of clarity in official discourses added to the absence of a local communicative dynamics cause the phenomenon of incomplete information. Conflicts often occur in local institutional arenas resulting in violence and complex social and historical dissonances, enhanced by other public policies idealized in different temporal and spatial conditions.

Imaging Laser Altimetry in the Amazon: Mapping Large Areas of Topography, Vegetation Height and Structure, and Biomass

NASA Technical Reports Server (NTRS)

Blair, J. Bryan; Nelson, B.; dosSantos, J.; Valeriano, D.; Houghton, R.; Hofton, M.; Lutchke, S.; Sun, Q.

2002-01-01

A flight mission of NASA GSFC's Laser Vegetation Imaging Sensor (LVIS) is planned for June-August 2003 in the Amazon region of Brazil. The goal of this flight mission is to map the vegetation height and structure and ground topography of a large area of the Amazon. This data will be used to produce maps of true ground topography, vegetation height, and estimated above-ground biomass and for comparison with and potential calibration of Synthetic Aperture Radar (SAR) data. Approximately 15,000 sq. km covering various regions of the Amazon will be mapped. The LVIS sensor has the unique ability to accurately sense the ground topography beneath even the densest of forest canopies. This is achieved by using a high signal-to-noise laser altimeter to detect the very weak reflection from the ground that is available only through small gaps in between leaves and between tree canopies. Often the amount of ground signal is 1% or less of the total returned echo. Once the ground elevation is identified, that is used as the reference surface from which we measure the vertical height and structure of the vegetation. Test data over tropical forests have shown excellent correlation between LVIS measurements and biomass, basal area, stem density, ground topography, and canopy height. Examples of laser altimetry data over forests and the relationships to biophysical parameters will be shown. Also, recent advances in the LVIS instrument will be discussed.

The Amazon hydrometeorology: Climatology, variability and links to changes in weather patterns

NASA Astrophysics Data System (ADS)

Fernandes, Katia De Avila

My thesis focuses on improving the quantification of the hydrological cycle and understanding the atmospheric processes that link weather to climate in the Amazon River basin. By using ERA40 and independent observations, I assess how well we can estimate the surface water budget in the Amazon River basin. I find that ERA40 basin wide annual precipitation (P) overall agrees with observations showing a slight underestimation of 10% in average, whereas runoff (R) is underestimated by a larger margin (˜25%). Observed residual of precipitation and runoff (denoted as P-R) is better estimated by ERA40 P-R than actual ET which includes soil moisture nudging. The causes for said discrepancies were found to partly relate to soil moisture nudging that needs to be applied during the dry season to produce realistic ET and compensate for the low soil moisture recharge during the previous wet season. Insufficient recharge may in part be caused by underestimation of rainfall amount and intensity; moreover the shallow root layer in the model does not represent the deep soil water reservoir characteristic of the Amazonian forest. Whether the hydrological cycle and weather patterns in the Amazon have changed during the past few decades is a highly debatable but central question for detecting climate change in the region. The second part of my thesis focus on the physical links between rainfall changes detected in observations, and changes of synoptic scale systems as represented by ERA40. My results suggest that an observed delayed wet season onset is consistent with a decreasing number of cold air incursion (CAI) days in southern Amazon for the period 1979--2001. The variability of CAI into southern Amazon is related to the variability of SST upstream of South America in the tropical Pacific and Indian Oceans. A Singular Value Decomposition Analysis (SVD) between CAI days and global SST reveal three main modes of co-variability. The first mode describes the effect of the El Nino-Southern Oscillation. During El Nino (La Nina) a strong (weak) subtropical jet stream over South America tends to prevent transient systems from moving to southern Amazon, resulting in decreased (increased) CAI days during SON. The second mode of co-variability shows an anomalously warm western Indian Ocean also related to strong subtropical jet stream, except the jet is positioned farther north in South America, which along with the absence of a well defined subpolar jet stream, favors the northward displacement of transient waves into central South America, but show little response in southern Amazon. The CAI days reconstructed from the first and second modes do not present any significant trend in southern Amazon. CAI days reconstructed from the third mode of co-variability on the other hand, reproduces the SON observed trend in almost its entirety. The third mode of co-variability describes negative (positive) anomalies in CAI days associated with cold (warm) SST anomalies in the eastern tropical Pacific, anomalous wavetrain in the Southern Hemisphere and Walker Cell displacement that are unfavorable (favorable) to the incursion of CAI into southern Amazon. The temporal evolution of this mode correlates negatively with the Pacific Decadal Oscillation, suggesting that the recent gradual shift in PDO polarity reflected on the interannual response of Southern Pacific atmospheric patterns, hence on the behavior of transients propagation. The negative PDO index and its related atmospheric patterns are in agreement with the reduced observed CAI days, which also related to a delayed wet season onset in the southern Amazon.

Response of Amazon Fires to the 2015/2016 El Niño and Evaluation of a Seasonal Fire Season Severity Forecast

NASA Astrophysics Data System (ADS)

Randerson, J. T.

2016-12-01

Recent work has established that year-to-year variability in drought and fire within the Amazon responds to a dual forcing from ocean-atmosphere interactions in the tropical Pacific and North Atlantic. Teleconnections between the Pacific and the Amazon are strongest between October and March, when El Niño contributes to below-average precipitation during the wet season. A reduced build-up of soil moisture during the wet season, in turn, may limit water availability and transpiration in tropical forests during the following dry season, lowering surface humidity, drying fuels, and allowing fires to spread more easily through the understory. The delayed influence of soil moisture through this land - atmosphere coupling provides a means to predict fire season severity 3-6 months before the onset of the dry season. With the aim of creating new opportunities for forest conservation, we have developed an experimental seasonal fire forecasting system for the Amazon. The 2016 fire season severity forecast, released in June by UCI and NASA, predicts unusually high risk across eastern Peru, northern Bolivia, and Brazil. Several surface and satellite data streams confirm that El Niño teleconnections had a significant impact on wet season hydrology within the Amazon. Rainfall observations from the Global Precipitation Climatology Centre provided evidence that cumulative precipitation deficits during August-April were 1 to 2 standard deviations below the long-term mean for most of the basin. These observations were corroborated by strong negative terrestrial water storage anomalies measured by the Gravity Recovery and Climate Experiment, and by fluorescence and vegetation index observations from other sensors that indicated elevated canopy stress. By August 3rd, satellite observations showed above average fire activity in most, but not all, forecast regions. Using additional satellite observations that become available later this year, we plan to describe the full spatial and temporal pattern of fires within the Amazon during the 2016 dry season and evaluate the success of our forecast. As a part of this analysis, we will compare fires from 2016 with other years of extreme drought (i.e., 2005 and 2010), and assess how trends in land use, including regional changes in deforestation, modify El Niño-driven fire risk.

Estimating Canopy Structure in an Amazon Forest from Laser Range Finder and IKONOS Satellite Observations

Treesearch

Gregory P. Asner; Michael Palace; Michael Keller; Rodrigo Pereira Jr.; Jose N. M. Silva; Johan C. Zweede

2002-01-01

Canopy structural data can be used for biomass estimation and studies of carbon cycling, disturbance, energy balance, and hydrological processes in tropical forest ecosystems. Scarce information on canopy dimensions reflects the difficulties associated with measuring crown height, width, depth, and area in tall, humid tropical forests. New field and spaceborne...

Financial and ecological indicators of reduced impact logging performance in the eastern Amazon

Treesearch

Thomas P. Holmes; Geoffrey M. Blate; Johan C. Zweede; Rodrigo Pereira; Paulo Barreto; Frederick Boltz; Roberto Bauch

2002-01-01

Reduced impact logging (RIL) systems are currently being promoted in Brazil and other tropical countries in response to domestic and international concern over the ecological and economic sustainability of harvesting natural tropical forests. RIL systems are necessary, but not sufficient, for sustainable forest management because they reduce damage to the forest...

Restoration of tropical moist forest on bauxite mined lands in the Brazilian Amazon

Treesearch

John A Parrotta; Oliver H. Knowles

1999-01-01

We evaluated forest structure and composition in 9- to 13-year-old stands established on a bauxite-mined site at Trombetas (Pará), Brazil, using four different reforestation techniques following initial site preparation and topsoil replacement. These techniques included reliance on natural forest regeneration, mixed commercial species plantings of mostly exotic timber...

Analysis of Chromobacterium sp. natural isolates from different Brazilian ecosystems

PubMed Central

Lima-Bittencourt, Cláudia I; Astolfi-Filho, Spartaco; Chartone-Souza, Edmar; Santos, Fabrício R; Nascimento, Andréa MA

2007-01-01

Background Chromobacterium violaceum is a free-living bacterium able to survive under diverse environmental conditions. In this study we evaluate the genetic and physiological diversity of Chromobacterium sp. isolates from three Brazilian ecosystems: Brazilian Savannah (Cerrado), Atlantic Rain Forest and Amazon Rain Forest. We have analyzed the diversity with molecular approaches (16S rRNA gene sequences and amplified ribosomal DNA restriction analysis) and phenotypic surveys of antibiotic resistance and biochemistry profiles. Results In general, the clusters based on physiological profiles included isolates from two or more geographical locations indicating that they are not restricted to a single ecosystem. The isolates from Brazilian Savannah presented greater physiologic diversity and their biochemical profile was the most variable of all groupings. The isolates recovered from Amazon and Atlantic Rain Forests presented the most similar biochemical characteristics to the Chromobacterium violaceum ATCC 12472 strain. Clusters based on biochemical profiles were congruent with clusters obtained by the 16S rRNA gene tree. According to the phylogenetic analyses, isolates from the Amazon Rain Forest and Savannah displayed a closer relationship to the Chromobacterium violaceum ATCC 12472. Furthermore, 16S rRNA gene tree revealed a good correlation between phylogenetic clustering and geographic origin. Conclusion The physiological analyses clearly demonstrate the high biochemical versatility found in the C. violaceum genome and molecular methods allowed to detect the intra and inter-population diversity of isolates from three Brazilian ecosystems. PMID:17584942

Potential contribution of groundwater to dry-season ET in the Amazon

NASA Astrophysics Data System (ADS)

Miguez-Macho, Gonzalo; Fan, Ying

2010-05-01

Climate and land ecosystem models simulate vegetation stress in the Amazon forest in the dry season, but observations show enhanced growth in response to higher radiation under less cloudy skies indicating an adequate water supply. The question is: how does the vegetation obtain sufficient water, and what is missing in the models? Shallow model soil and rooting depth is a factor; the ability of roots to move water up and down (hydraulic redistribution) may be another, but another cause may lie in the buffering effect of the groundwater found in nature but absent in models. We present observational and modeling evidence that the vast groundwater store, consequence of high annual rainfall combined with poor drainage in the Amazon, may provide a stable source for dry-season photosynthesis. The water table beneath the Amazon is sufficiently shallow (38% area <5m and 63% area <10m deep) as to contribute >2mm/day to dry-season evapotranspiration, a non-negligible portion of tower-observed flux of 3-4mm/day, the latter including canopy-interception loss and open-water evaporation. This may have important implications to our understanding of Amazonia ecosystem response and feedback to climate change. Current models, lacking groundwater, predict a significant reduction in dry-season photosynthesis under current climate and large-scale dieback under projected future climate converting the Amazon from a net carbon sink to a net source and accelerating warming. If groundwater is considered in the models, the magnitude of the responses and feedbacks may be reduced.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubey, Manvendra Krishna

Forests soak up 25% of the carbon dioxide (CO 2) emitted by anthropogenic fossil energy use (10 Gt C y -1) moderating its atmospheric accumulation. How this terrestrial CO 2 uptake will evolve with climate change in the 21st century is largely unknown. Rainforests are the most active ecosystems with the Amazon basin storing 120 Gt C as biomass and exchanging 18 Gt C y -1 of CO 2 via photosynthesis and respiration and fixing carbon at 2-3 kg C m -2 y -1. Furthermore, the intense hydrologic and carbon cycles are tightly coupled in the Amazon where about halfmore » of the water is recycled by evapotranspiration and the other half imported from the ocean by Northeasterly trade winds. Climate models predict a drying in the Amazon with reduced carbon uptake while observationally guided assessments indicate sustained uptake. We will resolve this huge discrepancy in the size and sign of the future Amazon carbon cycle by performing the first simultaneous regional scale high frequency measurements of atmospheric CO 2, H 2O, HOD, CH 4, N 2O and CO at the T3 site in Manacupuru, Brazil as part of DOE's GoAmazon project. Our data will be used to inform and develop DOE's CLM on the tropical carbon-water couplings at the appropriate grid scale (10-50km). Our measurements will also validate the CO 2 data from Japan's GOSAT and NASA's imminent OCO-2 satellite (launch date July 2014).« less

Modeling biomass burning emissions for Amazon forest and pastures in Rondônia, Brazil.

Treesearch

Liane S. Guild; J. Boone Kauffman; Warren B. Cohen; Christine A. Hlavka; Darold E. Ward

2004-01-01

As a source of atmospheric carbon, biomass burning emissions associated with deforestation in the Amazon are globally significant. Once deforested, these lands continue to be sources of substantial burning emissions for many years due to frequent pasture burning. The objective of this research was to quantify biomass-burning emissions at a local scale. We estimated...

Quaternary ecological and geomorphic changes associated with rainfall events in presently semi-arid northeastern Brazil

NASA Astrophysics Data System (ADS)

Auler, Augusto S.; Wang, Xianfeng; Edwards, R. Lawrence; Cheng, Hai; Cristalli, Patrícia S.; Smart, Peter L.; Richards, David A.

2004-10-01

Several geomorphic features and palaeobiotic remains in now semi-arid northeastern Brazil indicate major palaeoenvironmental changes during past periods of increased rainfall. 230Th mass spectrometric ages of speleothems and travertines have allowed the determination of the timing and duration of wetter than present conditions. The data demonstrate that wet events have occurred throughout much of the Pleistocene, present dry conditions having been established at the end of the Younger Dryas. A markedly different fauna comprising megafaunal elements not adapted to the present low arboreal scrubland caatinga vegetation existed in the area. Palaeobotanical remains embedded in travertine indicate forested vegetation at these wetter intervals, suggesting that the caatinga was then replaced or mixed with a semi-deciduous forest. Due to the abundance of travertine sites containing fossil botanical remains in northeastern Brazil, it is believed that forest expansion occurred over large areas of the now semi-arid zone, showing that the long hypothesised forested links between biodiversity-rich Amazon and Atlantic rainforests may indeed have existed during these moister phases. Copyright

Net nitrogen mineralization and net nitrification rates in soils following deforestation for pasture across the southwestern Brazilian Amazon Basin landscape.

PubMed

Neill, Christopher; Piccolo, Marisa C; Cerri, Carlos C; Steudler, Paul A; Melillo, Jerry M; Brito, Marciano

1997-04-01

Previous studies of the effect of tropical forest conversion to cattle pasture on soil N dynamics showed that rates of net N mineralization and net nitrification were lower in pastures compared with the original forest. In this study, we sought to determine the generality of these patterns by examining soil inorganic N concentrations, net mineralization and nitrification rates in 6 forests and 11 pastures 3 years old or older on ultisols and oxisols that encompassed a wide variety of soil textures and spanned a 700-km geographical range in the southwestern Brazilian Amazon Basin state of Rondônia. We sampled each site during October-November and April-May. Forest soils had higher extractable NO 3 - -N and total inorganic N concentrations than pasture soils, but substantial NO 3 - -N occurred in both forest and pasture soils. Rates of net N mineralization and net nitrification were higher in forest soils. Greater concentrations of soil organic matter in finer textured soils were associated with greater rates of net N mineralization and net nitrification, but this relationship was true only under native forest vegetation; rates were uniformly low in pastures, regardless of soil type or texture. Net N mineralization and net nitrification rates per unit of total soil organic matter showed no pattern across the different forest sites, suggesting that controls of net N mineralization may be broadly similar across a wide range of soil types. Similar reductions in rates of net N transformations in pastures 3 years old or older across a range of textures on these soils suggest that changes to soil N cycling caused by deforestation for pasture may be Basin-wide in extent. Lower net N mineralization and net nitrification rates in established pastures suggest that annual N losses from largely deforested landscapes may be lower than losses from the original forest. Total ecosystem N losses since deforestation are likely to depend on the balance between lower N loss rates from established pastures and the magnitude and duration of N losses that occur in the years immediately following forest clearing.

Tropical Tree Trait Diversity Enhances Forest Biomass Resilience in a Dynamic Global Vegetation Model

NASA Astrophysics Data System (ADS)

Sakschewski, B.; Kirsten, T.; von Bloh, W.; Poorter, L.; Pena-Claros, M.; Boit, A.

2016-12-01

Functional diversity of ecosystems has been found to increase ecosystem functions and therefore enhance ecosystem resilience against environmental stressors. However, global carbon-cycle and biosphere models still classify the global vegetation into a relatively small number of distinct plant functional types (PFT) with constant features over space and time. Therefore, those models might underestimate the resilience and adaptive capacity of natural vegetation under climate change by ignoring positive effects that functional diversity might bring about. We diversified a set a of selected tree traits in a dynamic global vegetation model (LPJmL). In the new subversion, called LPJmL-FIT, Amazon region biomass stocks and forest structure appear significantly more resilient against climate change. Enhanced tree trait diversity enables the simulated rainforests to adjust to new environmental conditions via ecological sorting. These results may stimulate a new debate on the value of biodiversity for climate change mitigation.

Types and rates of forest disturbance in Brazilian Legal Amazon, 2000–2013

PubMed Central

Tyukavina, Alexandra; Hansen, Matthew C.; Potapov, Peter V.; Stehman, Stephen V.; Smith-Rodriguez, Kevin; Okpa, Chima; Aguilar, Ricardo

2017-01-01

Deforestation rates in primary humid tropical forests of the Brazilian Legal Amazon (BLA) have declined significantly since the early 2000s. Brazil’s national forest monitoring system provides extensive information for the BLA but lacks independent validation and systematic coverage outside of primary forests. We use a sample-based approach to consistently quantify 2000–2013 tree cover loss in all forest types of the region and characterize the types of forest disturbance. Our results provide unbiased forest loss area estimates, which confirm the reduction of primary forest clearing (deforestation) documented by official maps. By the end of the study period, nonprimary forest clearing, together with primary forest degradation within the BLA, became comparable in area to deforestation, accounting for an estimated 53% of gross tree cover loss area and 26 to 35% of gross aboveground carbon loss. The main type of tree cover loss in all forest types was agroindustrial clearing for pasture (63% of total loss area), followed by small-scale forest clearing (12%) and agroindustrial clearing for cropland (9%), with natural woodlands being directly converted into croplands more often than primary forests. Fire accounted for 9% of the 2000–2013 primary forest disturbance area, with peak disturbances corresponding to droughts in 2005, 2007, and 2010. The rate of selective logging exploitation remained constant throughout the study period, contributing to forest fire vulnerability and degradation pressures. As the forest land use transition advances within the BLA, comprehensive tracking of forest transitions beyond primary forest loss is required to achieve accurate carbon accounting and other monitoring objectives. PMID:28439536

Stormflow influence on nutrient dynamics in micro-catchments under contrasting land use in the Cerrado and Amazon Biomes, Brazil

NASA Astrophysics Data System (ADS)

Edelmann, Katharina; Nóbrega, Rodolfo L. B.; Gerold, Gerhard

2017-04-01

The Amazon and Cerrado biomes in Brazil have been under intense land-use change during the past few decades. The conversion of native vegetation to pastures and croplands has caused impacts on hydrological processes in these biomes, resulting in increased streamflow and nutrient fluxes. Our aim was to compare the nutrient dynamics during stormflow events in two pairs of adjacent micro-catchments with similar physical characteristics under contrasting land use, i.e. native vegetation (rainforest or cerrado) and pasture. One pair of catchments was located in the Amazon and the other in the Cerrado, both on the Amazon Agricultural Frontier in the Brazilian states of Mato Grosso and Pará. We collected hydrological and hydrochemical data on 50 stormflow events on a sub-hourly resolution during the wet seasons of 2013 and 2014. We compared the dynamics of total inorganic carbon (TIC), total organic carbon (TOC), dissolved organic carbon (DOC), nitrate (NO3), calcium (Ca), potassium (K), and magnesium (Mg) in different hydrograph parts, i.e. rising limb, peak and recession limb, between the catchments within the same biome. For the Cerrado biome, our findings show that the nutrient concentrations in the stormflows were higher in the pasture catchment than in the cerrado catchment. In the Amazon biome, we found an inverse relationship with higher concentrations in the forest catchment than in the pasture catchment, except for TIC and K. Most nutrients in the cerrado catchment had the highest concentrations in the rising limb. Mg, however, reached highest concentrations during peak discharge, and lowest in the recession limb. In the adjacent pasture catchment, in contrast, the highest nutrient concentrations were observed during the peak discharge (TIC, TOC, Ca) or the recession limb (DOC, NO3, K, Mg) with lowest in the rising limb, except for NO3, which showed the lowest concentrations during peak discharge. In the Amazon forest catchment, the peak discharge showed the highest nutrient concentrations, while concentrations in the recession limb were higher than in the rising limb. We also found that in this catchment K concentrations were lower in the recession limb than in the rising limb. In the Amazonian pasture catchment, the peak discharge showed the greatest concentrations for TIC, TOC, and Ca, and the rising limb the lowest. DOC and NO3 concentrations in this catchment were the highest in the rising and were lowest in peak discharge, while K increased over time. Based on that, we conclude that stormflow is an important driver of nutrients fluxes due to land-use change on the Amazon Agricultural Frontier, with significant increases and distinguished dynamics during the storm events, and higher nutrient concentrations in the catchments with pastures than in the ones with native vegetation, especially for TIC and K.

Performance of the Enhanced Vegetation Index to Detect Inner-annual Dry Season and Drought Impacts on Amazon Forest Canopies

NASA Astrophysics Data System (ADS)

Brede, B.; Verbesselt, J.; Dutrieux, L.; Herold, M.

2015-04-01

The Amazon rainforests represent the largest connected forested area in the tropics and play an integral role in the global carbon cycle. In the last years the discussion about their phenology and response to drought has intensified. A recent study argued that seasonality in greenness expressed as Enhanced Vegetation Index (EVI) is an artifact of variations in sun-sensor geometry throughout the year. We aimed to reproduce these results with the Moderate-Resolution Imaging Spectroradiometer (MODIS) MCD43 product suite, which allows modeling the Bidirectional Reflectance Distribution Function (BRDF) and keeping sun-sensor geometry constant. The derived BRDF-adjusted EVI was spatially aggregated over large areas of central Amazon forests. The resulting time series of EVI spanning the 2000-2013 period contained distinct seasonal patterns with peak values at the onset of the dry season, but also followed the same pattern of sun geometry expressed as Solar Zenith Angle (SZA). Additionally, we assessed EVI's sensitivity to precipitation anomalies. For that we compared BRDF-adjusted EVI dry season anomalies to two drought indices (Maximum Cumulative Water Deficit, Standardized Precipitation Index). This analysis covered the whole of Amazonia and data from the years 2000 to 2013. The results showed no meaningful connection between EVI anomalies and drought. This is in contrast to other studies that investigate the drought impact on EVI and forest photosynthetic capacity. The results from both sub-analyses question the predictive power of EVI for large scale assessments of forest ecosystem functioning in Amazonia. Based on the presented results, we recommend a careful evaluation of the EVI for applications in tropical forests, including rigorous validation supported by ground plots.

Markedly divergent estimates of Amazon forest carbon density from ground plots and satellites.

PubMed

Mitchard, Edward T A; Feldpausch, Ted R; Brienen, Roel J W; Lopez-Gonzalez, Gabriela; Monteagudo, Abel; Baker, Timothy R; Lewis, Simon L; Lloyd, Jon; Quesada, Carlos A; Gloor, Manuel; Ter Steege, Hans; Meir, Patrick; Alvarez, Esteban; Araujo-Murakami, Alejandro; Aragão, Luiz E O C; Arroyo, Luzmila; Aymard, Gerardo; Banki, Olaf; Bonal, Damien; Brown, Sandra; Brown, Foster I; Cerón, Carlos E; Chama Moscoso, Victor; Chave, Jerome; Comiskey, James A; Cornejo, Fernando; Corrales Medina, Massiel; Da Costa, Lola; Costa, Flavia R C; Di Fiore, Anthony; Domingues, Tomas F; Erwin, Terry L; Frederickson, Todd; Higuchi, Niro; Honorio Coronado, Euridice N; Killeen, Tim J; Laurance, William F; Levis, Carolina; Magnusson, William E; Marimon, Beatriz S; Marimon Junior, Ben Hur; Mendoza Polo, Irina; Mishra, Piyush; Nascimento, Marcelo T; Neill, David; Núñez Vargas, Mario P; Palacios, Walter A; Parada, Alexander; Pardo Molina, Guido; Peña-Claros, Marielos; Pitman, Nigel; Peres, Carlos A; Poorter, Lourens; Prieto, Adriana; Ramirez-Angulo, Hirma; Restrepo Correa, Zorayda; Roopsind, Anand; Roucoux, Katherine H; Rudas, Agustin; Salomão, Rafael P; Schietti, Juliana; Silveira, Marcos; de Souza, Priscila F; Steininger, Marc K; Stropp, Juliana; Terborgh, John; Thomas, Raquel; Toledo, Marisol; Torres-Lezama, Armando; van Andel, Tinde R; van der Heijden, Geertje M F; Vieira, Ima C G; Vieira, Simone; Vilanova-Torre, Emilio; Vos, Vincent A; Wang, Ophelia; Zartman, Charles E; Malhi, Yadvinder; Phillips, Oliver L

2014-08-01

The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset. Tropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: http://dx.doi.org/10.5521/FORESTPLOTS.NET/2014_1. Two recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons. The two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by > 25%, whereas regional uncertainties for the maps were reported to be < 5%. Pantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space.

Markedly divergent estimates of Amazon forest carbon density from ground plots and satellites

PubMed Central

Mitchard, Edward T A; Feldpausch, Ted R; Brienen, Roel J W; Lopez-Gonzalez, Gabriela; Monteagudo, Abel; Baker, Timothy R; Lewis, Simon L; Lloyd, Jon; Quesada, Carlos A; Gloor, Manuel; ter Steege, Hans; Meir, Patrick; Alvarez, Esteban; Araujo-Murakami, Alejandro; Aragão, Luiz E O C; Arroyo, Luzmila; Aymard, Gerardo; Banki, Olaf; Bonal, Damien; Brown, Sandra; Brown, Foster I; Cerón, Carlos E; Chama Moscoso, Victor; Chave, Jerome; Comiskey, James A; Cornejo, Fernando; Corrales Medina, Massiel; Da Costa, Lola; Costa, Flavia R C; Di Fiore, Anthony; Domingues, Tomas F; Erwin, Terry L; Frederickson, Todd; Higuchi, Niro; Honorio Coronado, Euridice N; Killeen, Tim J; Laurance, William F; Levis, Carolina; Magnusson, William E; Marimon, Beatriz S; Marimon Junior, Ben Hur; Mendoza Polo, Irina; Mishra, Piyush; Nascimento, Marcelo T; Neill, David; Núñez Vargas, Mario P; Palacios, Walter A; Parada, Alexander; Pardo Molina, Guido; Peña-Claros, Marielos; Pitman, Nigel; Peres, Carlos A; Poorter, Lourens; Prieto, Adriana; Ramirez-Angulo, Hirma; Restrepo Correa, Zorayda; Roopsind, Anand; Roucoux, Katherine H; Rudas, Agustin; Salomão, Rafael P; Schietti, Juliana; Silveira, Marcos; de Souza, Priscila F; Steininger, Marc K; Stropp, Juliana; Terborgh, John; Thomas, Raquel; Toledo, Marisol; Torres-Lezama, Armando; van Andel, Tinde R; van der Heijden, Geertje M F; Vieira, Ima C G; Vieira, Simone; Vilanova-Torre, Emilio; Vos, Vincent A; Wang, Ophelia; Zartman, Charles E; Malhi, Yadvinder; Phillips, Oliver L

2014-01-01

Aim The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset. Location Tropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: http://dx.doi.org/10.5521/FORESTPLOTS.NET/2014_1 Methods Two recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons. Results The two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by > 25%, whereas regional uncertainties for the maps were reported to be < 5%. Main conclusions Pantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space. PMID:26430387

Global Physiographic and Climatic Maps to Support Revision of Environmental Testing Guidelines

DTIC Science & Technology

2009-07-06

precipitation and boarded by High and Low Relief Mountains or Interior Plains and Plateaus, such as the Amazon River Basin in South America and the Congo...taxonomy system. These form in hot climates with continual moisture availability, typically thought to occur only beneath tropical rainforests , though...Montane Tropical Forest Tropical Degraded Forest Seasonal Tropical Forest Rain Green Tropical Forest Tropical Rainforest FIGURE 6-1 DATE: 6-02

Climatic and biotic controls on annual carbon storage in Amazonian ecosystems

USGS Publications Warehouse

Tian, H.; Melillo, J.M.; Kicklighter, D.W.; McGuire, A.D.; Helfrich, J.; Moore, B.; Vorosmarty, C.J.

2000-01-01

1 The role of undisturbed tropical land ecosystems in the global carbon budget is not well understood. It has been suggested that inter-annual climate variability can affect the capacity of these ecosystems to store carbon in the short term. In this paper, we use a transient version of the Terrestrial Ecosystem Model (TEM) to estimate annual carbon storage in undisturbed Amazonian ecosystems during the period 1980-94, and to understand the underlying causes of the year-to-year variations in net carbon storage for this region. 2 We estimate that the total carbon storage in the undisturbed ecosystems of the Amazon Basin in 1980 was 127.6 Pg C, with about 94.3 Pg C in vegetation and 33.3 Pg C in the reactive pool of soil organic carbon. About 83% of the total carbon storage occurred in tropical evergreen forests. Based on our model's results, we estimate that, over the past 15 years, the total carbon storage has increased by 3.1 Pg C (+ 2%), with a 1.9-Pg C (+2%) increase in vegetation carbon and a 1.2-Pg C (+4%) increase in reactive soil organic carbon. The modelled results indicate that the largest relative changes in net carbon storage have occurred in tropical deciduous forests, but that the largest absolute changes in net carbon storage have occurred in the moist and wet forests of the Basin. 3 Our results show that the strength of interannual variations in net carbon storage of undisturbed ecosystems in the Amazon Basin varies from a carbon source of 0.2 Pg C/year to a carbon sink of 0.7 Pg C/year. Precipitation, especially the amount received during the drier months, appears to be a major controller of annual net carbon storage in the Amazon Basin. Our analysis indicates further that changes in precipitation combine with changes in temperature to affect net carbon storage through influencing soil moisture and nutrient availability. 4 On average, our results suggest that the undisturbed Amazonian ecosystems accumulated 0.2 Pg C/year as a result of climate variability and increasing atmospheric CO2 over the study period. This amount is large enough to have compensated for most of the carbon losses associated with tropical deforestation in the Amazon during the same period. 5 Comparisons with empirical data indicate that climate variability and CO2 fertilization explain most of the variation in net carbon storage for the undisturbed ecosystems. Our analyses suggest that assessment of the regional carbon budget in the tropics should be made over at least one cycle of El Nino-Southern Oscillation because of inter-annual climate variability. Our analyses also suggest that proper scaling of the site-specific and sub-annual measurements of carbon fluxes to produce Basin-wide flux estimates must take into account seasonal and spatial variations in net carbon storage.

Airborne and spaceborne radar images for geologic and environmental mapping in the Amazon rain forest, Brazil

NASA Technical Reports Server (NTRS)

Hurtak, James J.; Ford, John P.

1986-01-01

Spaceborne and airborne radar image of portions of the Middle and Upper Amazon basin in the state of Amazonas and the Territory of Roraima are compared for purposes of geological and environmental mapping. The contrasted illumination geometries and imaging parameters are related to terrain slope and surface roughness characteristics for corresponding areas that were covered by each of the radar imaging systems. Landforms range from deeply dissected mountain and plateau with relief up to 500 m in Roraima, revealing ancient layered rocks through folded residual mountains to deeply beveled pediplain in Amazonas. Geomorphic features provide distinct textural signatures that are characteristic of different rock associations. The principle drainages in the areas covered are the Rio Negro, Rio Branco, and the Rio Japura. Shadowing effects and low radar sensitivity to subtle linear fractures that are aligned parallel or nearly parallel to the direction of radar illumination illustrate the need to obtain multiple coverage with viewing directions about 90 degrees. Perception of standing water and alluvial forest in floodplains varies with incident angle and with season. Multitemporal data sets acquired over periods of years provide an ideal method of monitoring environmental changes.

Protected Areas’ Impacts on Brazilian Amazon Deforestation: Examining Conservation – Development Interactions to Inform Planning

PubMed Central

Pfaff, Alexander; Robalino, Juan; Herrera, Diego; Sandoval, Catalina

2015-01-01

Protected areas are the leading forest conservation policy for species and ecoservices goals and they may feature in climate policy if countries with tropical forest rely on familiar tools. For Brazil's Legal Amazon, we estimate the average impact of protection upon deforestation and show how protected areas’ forest impacts vary significantly with development pressure. We use matching, i.e., comparisons that are apples-to-apples in observed land characteristics, to address the fact that protected areas (PAs) tend to be located on lands facing less pressure. Correcting for that location bias lowers our estimates of PAs’ forest impacts by roughly half. Further, it reveals significant variation in PA impacts along development-related dimensions: for example, the PAs that are closer to roads and the PAs closer to cities have higher impact. Planners have multiple conservation and development goals, and are constrained by cost, yet still conservation planning should reflect what our results imply about future impacts of PAs. PMID:26225922

Protected Areas' Impacts on Brazilian Amazon Deforestation: Examining Conservation-Development Interactions to Inform Planning.

PubMed

Pfaff, Alexander; Robalino, Juan; Herrera, Diego; Sandoval, Catalina

2015-01-01

Protected areas are the leading forest conservation policy for species and ecoservices goals and they may feature in climate policy if countries with tropical forest rely on familiar tools. For Brazil's Legal Amazon, we estimate the average impact of protection upon deforestation and show how protected areas' forest impacts vary significantly with development pressure. We use matching, i.e., comparisons that are apples-to-apples in observed land characteristics, to address the fact that protected areas (PAs) tend to be located on lands facing less pressure. Correcting for that location bias lowers our estimates of PAs' forest impacts by roughly half. Further, it reveals significant variation in PA impacts along development-related dimensions: for example, the PAs that are closer to roads and the PAs closer to cities have higher impact. Planners have multiple conservation and development goals, and are constrained by cost, yet still conservation planning should reflect what our results imply about future impacts of PAs.

Impact of Climate Variability on Forest Dynamics in Eastern Amazon: the Role of Large-Scale Droughts, Local Droughts, and Other Disturbances

NASA Astrophysics Data System (ADS)

Longo, M.; Hayek, M.; Alves, L. F.; Bonal, D.; Camargo, P. B.; Restrepo-Coupe, N.; Fitzjarrald, D. R.; Knox, R. G.; Saleska, S. R.; da Silva, R.; Stark, S.; Tapajos, R.; Wiedemann, K. T.; Moorcroft, P. R.; Wofsy, S. C.

2012-12-01

Droughts in the Amazon - especially in the southern and eastern regions - are likely to become more frequent and severe with climate change, potentially resulting in significant losses of biomass. Therefore, understanding the ecosystem response to past events, such as the major Amazonian drought of 2005, is fundamental to forecast the ecosystem resilience to extreme droughts in case they become more frequent. In this study we evaluate whether and how large-scale droughts affected the forest dynamics both in terms of productivity and in mortality, and what is the relative contribution of other factors, such as windthrow and smaller local droughts, to explain the observed dynamics. We focus on two sites in Eastern Amazon: Tapajos National Forest near Santarem, Brazil (S67), and Guyaflux tower at Paracou Field Station in French Guiana (GYF). We analyzed site-level observations from eddy flux towers, biometric measurements, and simulated the environment with the Ecosystem Demography Model, version 2 (ED2). This model has the advantage to represent the forest structure in size and functional type, and also biophysical processes within and above canopy, making comparisons with observations more direct. Preliminary results indicate that while the large-scale 2005 drought influenced productivity at both sites, local droughts and windthrow had also a significant contribution to the variation in productivity and mortality rates. Mortality in S67 increased significantly between 2005 and 2007, and was slightly higher in GYF between 2006 and 2008. In both cases, however, higher incidence of uprooted and broken trees suggests a significant contribution from windthrow to mortality. In S67, preliminary simulations using ED2 indicate that water stress reduced productivity during a local but severe drought at the end of 2006, followed by an increase in mortality particularly among trees with diameter at breast height less than 35 cm and early successional trees. In GYF, both ED2 and observations show decline in productivity late in the 2008 dry season, which was longer and drier than average, although the impact on mortality was negligible.

Bamboo-Dominated Forests of the Southwest Amazon: Detection, Spatial Extent, Life Cycle Length and Flowering Waves

PubMed Central

de Carvalho, Anelena L.; Nelson, Bruce W.; Bianchini, Milton C.; Plagnol, Daniela; Kuplich, Tatiana M.; Daly, Douglas C.

2013-01-01

We map the extent, infer the life-cycle length and describe spatial and temporal patterns of flowering of sarmentose bamboos (Guadua spp) in upland forests of the southwest Amazon. We first examine the spectra and the spectral separation of forests with different bamboo life stages. False-color composites from orbital sensors going back to 1975 are capable of distinguishing life stages. These woody bamboos flower produce massive quantities of seeds and then die. Life stage is synchronized, forming a single cohort within each population. Bamboo dominates at least 161,500 km2 of forest, coincident with an area of recent or ongoing tectonic uplift, rapid mechanical erosion and poorly drained soils rich in exchangeable cations. Each bamboo population is confined to a single spatially continuous patch or to a core patch with small outliers. Using spatial congruence between pairs of mature-stage maps from different years, we estimate an average life cycle of 27–28 y. It is now possible to predict exactly where and approximately when new bamboo mortality events will occur. We also map 74 bamboo populations that flowered between 2001 and 2008 over the entire domain of bamboo-dominated forest. Population size averaged 330 km2. Flowering events of these populations are temporally and/or spatially separated, restricting or preventing gene exchange. Nonetheless, adjacent populations flower closer in time than expected by chance, forming flowering waves. This may be a consequence of allochronic divergence from fewer ancestral populations and suggests a long history of widespread bamboo in the southwest Amazon. PMID:23359438

Decoupling of Deforestation and Soy Production in the Southern Amazon During the Late 2000s

NASA Technical Reports Server (NTRS)

Macedo, Marcia N.; DeFries, Ruth S.; Morton, Douglas C.; Stickler, Claudia M.; Galford, Gillian L.; Shimabukuro, Yosio E.

2011-01-01

From 2006-2010 deforestation in the Amazon frontier state of Mato Grosso decreased to 30% of its historical average (1996-2005) while agricultural production reached an all time high, achieving the oft-cited objective of increasing production while maintaining forest cover. This study combines satellite data with government deforestation and production statistics to assess land-use transitions and potential market and policy drivers associated with these trends. In the forested region of the state, increased soy production from 2001-2005 was entirely due to cropland expansion into previously cleared areas (74%) or forests (26%). From 2006-2010, 78% of production increases were due to expansion (22% to yield increases), with 91% on previously cleared land. Cropland expansion fell from 10% to 2% of deforestation between the two periods, with pasture expansion accounting for most remaining deforestation. Declining deforestation coincided with a collapse of commodity markets and implementation of policy measures to reduce deforestation. Soybean profitability has since increased to pre-2006 levels while deforestation continued to decline, suggesting that anti-deforestation measures may have influenced the agricultural sector. We found little evidence of leakage of soy expansion into cerrado in Mato Grosso or forests in neighboring Amazon states during the late 2000s, although leakage to more distant regions is possible. This study provides empirical evidence that reduced deforestation and increased agricultural production can occur simultaneously in tropical forest frontiers through productive use of already cleared lands. It remains uncertain whether government and industry-led policies can contain deforestation when market conditions again favor a boom in agricultural expansion.

Financial returns under uncertainty for conventional and reduced-impact logging in permanent production forests of the Brazilian Amazon

Treesearch

Frederick Boltz; Douglas R. Carter; Thomas P. Holmes; Rodrigo Pereira

2001-01-01

Reduced-impact logging (RIL) techniques are designed to improve the efficiency of timber harvesting while mitigating its adverse effects on the forest ecosystem. Research on RIL in select tropical forest regions has demonstrated clear ecological benefits relative to conventional logging (CL) practices while the financial competitiveness of RIL is less conclusive. We...

Seeing the forest beyond the trees

Treesearch

Sassan Saatchi; Joseph Mascaro; Liang Xu; Michael Keller; Yan Yang; Paul Duffy; Fernando Espirito-Santo; Alessandro Baccini; Jeffery Chambers; David Schimel

2014-01-01

In a recent paper (Mitchard et al. 2014, Global Ecology and Biogeography, 23,935-946) a new map of forest biomass based on a geostatistical model of field data for the Amazon (and surrounding forests) was presented and contrasted with two earlier maps based on remote sensing data Saatchi et al. (2011; RS1) and Baccini et al. (2012; RS2). Mitchard et al....

Detecting leaf phenology of seasonally moist tropical forests in South America with multi-temporal MODIS images.

Treesearch

Xiangming Xiao; Stephen Hagen; Qingyuan Zhang; Michael Keller; Berrien Moore III

2006-01-01

Leaf phenology of tropical evergreen forests affects carbon and water fluxes. In an earlier study of a seasonally moist evergreen tropical forest site in the Amazon basin, time series data of Enhanced Vegetation Index (EVI) from the VEGETATION and Moderate Resolution Imaging Spectroradiometer (MODIS) sensors showed an unexpected seasonal pattern, with higher EVI in the...

Mosquito (Diptera: Culicidae) diversity of a forest-fragment mosaic in the Amazon rain forest.

PubMed

Hutchings, Rosa Sá Gomes; Sallum, Maria Anice Mureb; Hutchings, Roger William

2011-03-01

To study the impact of Amazonian forest fragmentation on the mosquito fauna, an inventory of Culicidae was conducted in the upland forest research areas of the Biological Dynamics of Forest Fragments Project located 60 km north of Manaus, Amazonas, Brazil. The culicid community was sampled monthly between February 2002 and May 2003. CDC light traps, flight interception traps, manual aspiration, and net sweeping were used to capture adult specimens along the edges and within forest fragments of different sizes (1, 10, and 100 ha), in second-growth areas surrounding the fragments and around camps. We collected 5,204 specimens, distributed in 18 genera and 160 species level taxa. A list of mosquito taxa is presented with 145 species found in the survey, including seven new records for Brazil, 16 new records for the state of Amazonas, along with the 15 morphotypes that probably represent undescribed species. No exotic species [Aedes aegypti (L.) and Aedes albopictus (Skuse)] were found within the sampled areas. Several species collected are potential vectors of Plasmodium causing human malaria and of various arboviruses. The epidemiological and ecological implications of mosquito species found are discussed, and the results are compared with other mosquito inventories from the Amazon region.

Leaf Pressure Volume Data in Caxiuana and Tapajos National Forest, Para, Brazil (2011)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Thomas; Moorcroft, Paul

Pressure volume curve measurements on leaves of canopy trees from the from the Caxiuana and Tapajos National Forests, Para, Brazil. Tapajos samples were harvested from the km 67 forested area, which is adjacent to the decommissioned throughfall exclusion drought experimental plot. Caxiuana samples were harvested from trees growing in the throughfall exclusion plots. Data were collected in 2011. Dataset includes: date of measurement, site ID, plot ID, tree ID (species, tree tag #), leaf area, fresh weight, relative weight, leaf water potential, and leaf water loss. P-V curve parameters (turgor loss point, osmotic potential, and bulk modulus of elasticity) canmore » be found in Powell et al. (2017) Differences in xylem cavitation resistance and leaf hydraulic traits explain differences in drought tolerance among mature Amazon rainforest trees. Global Change Biology.« less

Individual tree detection in intact forest and degraded forest areas in the north region of Mato Grosso State, Brazilian Amazon

NASA Astrophysics Data System (ADS)

Santos, E. G.; Jorge, A.; Shimabukuro, Y. E.; Gasparini, K.

2017-12-01

The State of Mato Grosso - MT has the second largest area with degraded forest among the states of the Brazilian Legal Amazon. Land use and land cover change processes that occur in this region cause the loss of forest biomass, releasing greenhouse gases that contribute to the increase of temperature on earth. These degraded forest areas lose biomass according to the intensity and magnitude of the degradation type. The estimate of forest biomass, commonly performed by forest inventory through sample plots, shows high variance in degraded forest areas. Due to this variance and complexity of tropical forests, the aim of this work was to estimate forest biomass using LiDAR point clouds in three distinct forest areas: one degraded by fire, another by selective logging and one area of intact forest. The approach applied in these areas was the Individual Tree Detection (ITD). To isolate the trees, we generated Canopy Height Models (CHM) images, which are obtained by subtracting the Digital Elevation Model (MDE) and the Digital Terrain Model (MDT), created by the cloud of LiDAR points. The trees in the CHM images are isolated by an algorithm provided by the Quantitative Ecology research group at the School of Forestry at Northern Arizona University (SILVA, 2015). With these points, metrics were calculated for some areas, which were used in the model of biomass estimation. The methodology used in this work was expected to reduce the error in biomass estimate in the study area. The cloud points of the most representative trees were analyzed, and thus field data was correlated with the individual trees found by the proposed algorithm. In a pilot study, the proposed methodology was applied generating the individual tree metrics: total height and area of the crown. When correlating 339 isolated trees, an unsatisfactory R² was obtained, as heights found by the algorithm were lower than those obtained in the field, with an average difference of 2.43 m. This shows that the algorithm used to isolate trees in temperate areas did not obtained satisfactory results in the tropical forest of Mato Grosso State. Due to this, in future works two algorithms, one developed by Dalponte et al. (2015) and another by Li et al. (2012) will be used.

Biomass burning emissions of reactive gases estimated from satellite data analysis and ecosystem modeling for the Brazilian Amazon region

NASA Astrophysics Data System (ADS)

Potter, Christopher; Brooks-Genovese, Vanessa; Klooster, Steven; Torregrosa, Alicia

2002-10-01

To produce a new daily record of trace gas emissions from biomass burning events for the Brazilian Legal Amazon, we have combined satellite advanced very high resolution radiometer (AVHRR) data on fire counts together for the first time with vegetation greenness imagery as inputs to an ecosystem biomass model at 8 km spatial resolution. This analysis goes beyond previous estimates for reactive gas emissions from Amazon fires, owing to a more detailed geographic distribution estimate of vegetation biomass, coupled with daily fire activity for the region (original 1 km resolution), and inclusion of fire effects in extensive areas of the Legal Amazon (defined as the Brazilian states of Acre, Amapá, Amazonas, Maranhao, Mato Grosso, Pará, Rondônia, Roraima, and Tocantins) covered by open woodland, secondary forests, savanna, and pasture vegetation. Results from our emissions model indicate that annual emissions from Amazon deforestation and biomass burning in the early 1990s total to 102 Tg yr-1 carbon monoxide (CO) and 3.5 Tg yr-1 nitrogen oxides (NOx). Peak daily burning emissions, which occurred in early September 1992, were estimated at slightly more than 3 Tg d-1for CO and 0.1 Tg d-1for NOx flux to the atmosphere. Other burning source fluxes of gases with relatively high emission factors are reported, including methane (CH4), nonmethane hydrocarbons (NMHC), and sulfur dioxide (SO2), in addition to total particulate matter (TPM). We estimate the Brazilian Amazon region to be a source of between one fifth and one third for each of these global emission fluxes to the atmosphere. The regional distribution of burning emissions appears to be highest in the Brazilian states of Maranhao and Tocantins, mainly from burning outside of moist forest areas, and in Pará and Mato Grosso, where we identify important contributions from primary forest cutting and burning. These new daily emission estimates of reactive gases from biomass burning fluxes are designed to be used as detailed spatial and temporal inputs to computer models and data analysis of tropospheric chemistry over the tropical region.

Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest

PubMed Central

Malhi, Yadvinder; Aragão, Luiz E. O. C.; Galbraith, David; Huntingford, Chris; Fisher, Rosie; Zelazowski, Przemyslaw; Sitch, Stephen; McSweeney, Carol; Meir, Patrick

2009-01-01

We examine the evidence for the possibility that 21st-century climate change may cause a large-scale “dieback” or degradation of Amazonian rainforest. We employ a new framework for evaluating the rainfall regime of tropical forests and from this deduce precipitation-based boundaries for current forest viability. We then examine climate simulations by 19 global climate models (GCMs) in this context and find that most tend to underestimate current rainfall. GCMs also vary greatly in their projections of future climate change in Amazonia. We attempt to take into account the differences between GCM-simulated and observed rainfall regimes in the 20th century. Our analysis suggests that dry-season water stress is likely to increase in E. Amazonia over the 21st century, but the region tends toward a climate more appropriate to seasonal forest than to savanna. These seasonal forests may be resilient to seasonal drought but are likely to face intensified water stress caused by higher temperatures and to be vulnerable to fires, which are at present naturally rare in much of Amazonia. The spread of fire ignition associated with advancing deforestation, logging, and fragmentation may act as nucleation points that trigger the transition of these seasonal forests into fire-dominated, low biomass forests. Conversely, deliberate limitation of deforestation and fire may be an effective intervention to maintain Amazonian forest resilience in the face of imposed 21st-century climate change. Such intervention may be enough to navigate E. Amazonia away from a possible “tipping point,” beyond which extensive rainforest would become unsustainable. PMID:19218454

Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest.

PubMed

Malhi, Yadvinder; Aragão, Luiz E O C; Galbraith, David; Huntingford, Chris; Fisher, Rosie; Zelazowski, Przemyslaw; Sitch, Stephen; McSweeney, Carol; Meir, Patrick

2009-12-08

We examine the evidence for the possibility that 21st-century climate change may cause a large-scale "dieback" or degradation of Amazonian rainforest. We employ a new framework for evaluating the rainfall regime of tropical forests and from this deduce precipitation-based boundaries for current forest viability. We then examine climate simulations by 19 global climate models (GCMs) in this context and find that most tend to underestimate current rainfall. GCMs also vary greatly in their projections of future climate change in Amazonia. We attempt to take into account the differences between GCM-simulated and observed rainfall regimes in the 20th century. Our analysis suggests that dry-season water stress is likely to increase in E. Amazonia over the 21st century, but the region tends toward a climate more appropriate to seasonal forest than to savanna. These seasonal forests may be resilient to seasonal drought but are likely to face intensified water stress caused by higher temperatures and to be vulnerable to fires, which are at present naturally rare in much of Amazonia. The spread of fire ignition associated with advancing deforestation, logging, and fragmentation may act as nucleation points that trigger the transition of these seasonal forests into fire-dominated, low biomass forests. Conversely, deliberate limitation of deforestation and fire may be an effective intervention to maintain Amazonian forest resilience in the face of imposed 21st-century climate change. Such intervention may be enough to navigate E. Amazonia away from a possible "tipping point," beyond which extensive rainforest would become unsustainable.

Impacts of future deforestation and climate change on the hydrology of the Amazon Basin: a multi-model analysis with a new set of land-cover change scenarios

NASA Astrophysics Data System (ADS)

Guimberteau, Matthieu; Ciais, Philippe; Ducharne, Agnès; Boisier, Juan Pablo; Dutra Aguiar, Ana Paula; Biemans, Hester; De Deurwaerder, Hannes; Galbraith, David; Kruijt, Bart; Langerwisch, Fanny; Poveda, German; Rammig, Anja; Andres Rodriguez, Daniel; Tejada, Graciela; Thonicke, Kirsten; Von Randow, Celso; Von Randow, Rita C. S.; Zhang, Ke; Verbeeck, Hans

2017-03-01

Deforestation in Amazon is expected to decrease evapotranspiration (ET) and to increase soil moisture and river discharge under prevailing energy-limited conditions. The magnitude and sign of the response of ET to deforestation depend both on the magnitude and regional patterns of land-cover change (LCC), as well as on climate change and CO2 levels. On the one hand, elevated CO2 decreases leaf-scale transpiration, but this effect could be offset by increased foliar area density. Using three regional LCC scenarios specifically established for the Brazilian and Bolivian Amazon, we investigate the impacts of climate change and deforestation on the surface hydrology of the Amazon Basin for this century, taking 2009 as a reference. For each LCC scenario, three land surface models (LSMs), LPJmL-DGVM, INLAND-DGVM and ORCHIDEE, are forced by bias-corrected climate simulated by three general circulation models (GCMs) of the IPCC 4th Assessment Report (AR4). On average, over the Amazon Basin with no deforestation, the GCM results indicate a temperature increase of 3.3 °C by 2100 which drives up the evaporative demand, whereby precipitation increases by 8.5 %, with a large uncertainty across GCMs. In the case of no deforestation, we found that ET and runoff increase by 5.0 and 14 %, respectively. However, in south-east Amazonia, precipitation decreases by 10 % at the end of the dry season and the three LSMs produce a 6 % decrease of ET, which is less than precipitation, so that runoff decreases by 22 %. For instance, the minimum river discharge of the Rio Tapajós is reduced by 31 % in 2100. To study the additional effect of deforestation, we prescribed to the LSMs three contrasted LCC scenarios, with a forest decline going from 7 to 34 % over this century. All three scenarios partly offset the climate-induced increase of ET, and runoff increases over the entire Amazon. In the south-east, however, deforestation amplifies the decrease of ET at the end of dry season, leading to a large increase of runoff (up to +27 % in the extreme deforestation case), offsetting the negative effect of climate change, thus balancing the decrease of low flows in the Rio Tapajós. These projections are associated with large uncertainties, which we attribute separately to the differences in LSMs, GCMs and to the uncertain range of deforestation. At the subcatchment scale, the uncertainty range on ET changes is shown to first depend on GCMs, while the uncertainty of runoff projections is predominantly induced by LSM structural differences. By contrast, we found that the uncertainty in both ET and runoff changes attributable to uncertain future deforestation is low.

Where have all the flowers gone: deforestation in the Third World

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-01-01

The papers in this issue (and in its companion issue) describe tropical forest destruction and analyze implications at several levels. The contributions are representative of the major regions of the tropical moist forests (TMFs) - Amazonia, Africa, and Indo-Malaysia - and reveal a process whose ramifications will affect all parts and components of the biosphere. The authors and titles of the 13 paprs are: Norman Myers, Deforestation in the Tropics: Who Gains, Who Loses; William M. Denevan, Swiddens and Cattle Versus Forest: The Imminent Demise of the Amazon Rain Forest Reexamined; Stephen G. Bunker, Impact of Deforestation on Peasant Communitiesmore » in the Medio Amazonas of Brazil; Susanna B. Hecht, Deforestation in the Amazon Basin: Magnitude, Dynamics and Soil-Resource Effects; K. Twum-Barima, Forests of Ghana - A Diminishing Asset; J. Leroy Deval (English abstract), Man and Development in the Forests of Gabon; J. Leroy Deval, L'Homme et Le Developpement de La Foret du Gabon Dans Le Passe; Faustin Legault (English Translation), Reforestation in the Republic of Gabon; Faustin Legault, Le Reboisement en Republique Gabonaise; Peter S. Ashton, Forest Conditions in the Tropics of Asia and the Far East; Gurmit Singh K.S., Destroying Malaysian Forests; Kuswata Kartawinata, Environmental Consequences of Tree Removal from the Forest in Indonesia; and Robert Goodland, Indonesia's Environmental Progress in Economic Development.« less

Anthropogenic Landscape in Southeastern Amazonia: Contemporary Impacts of Low-Intensity Harvesting and Dispersal of Brazil Nuts by the Kayapó Indigenous People

PubMed Central

Ribeiro, Maria Beatriz N.; Jerozolimski, Adriano; de Robert, Pascale; Salles, Nilson V.; Kayapó, Biribiri; Pimentel, Tania P.; Magnusson, William E.

2014-01-01

Brazil nut, the Bertholletia excelsa seed, is one of the most important non-timber forest products in the Amazon Forest and the livelihoods of thousands of traditional Amazonian families depend on its commercialization. B. excelsa has been frequently cited as an indicator of anthropogenic forests and there is strong evidence that past human management has significantly contributed to its present distribution across the Amazon, suggesting that low levels of harvesting may play a positive role in B. excelsa recruitment. Here, we evaluate the effects of Brazil nut harvesting by the Kayapó Indigenous people of southeastern Amazonia on seedling recruitment in 20 B. excelsa groves subjected to different harvesting intensities, and investigated if management by harvesters influences patterns of B. excelsa distribution. The number of years of low-intensity Brazil nut harvesting by the Kayapó over the past two decades was positively related to B. excelsa seedling density in groves. One of the mechanisms behind the higher seedling density in harvested sites seems to be seed dispersal by harvesters along trails. The Kayapó also intentionally plant B. excelsa seeds and seedlings across their territories. Our results show not only that low-intensity Brazil nut harvesting by the Kayapó people does not reduce recruitment of seedlings, but that harvesting and/or associated activities conducted by traditional harvesters may benefit B. excelsa beyond grove borders. Our study supports the hypothesis that B. excelsa dispersal throughout the Amazon was, at least in part, influenced by indigenous groups, and strongly suggests that current human management contributes to the maintenance and formation of B. excelsa groves. We suggest that changes in Brazil nut management practices by traditional people to prevent harvesting impacts may be unnecessary and even counterproductive in many areas, and should be carefully evaluated before implementation. PMID:25029191

Tiger-Moths in Savannas in Eastern Amazon: First Assessment of Diversity and Seasonal Aspects.

PubMed

Valente, D M P; Zenker, M M; Teston, J A

2018-01-06

Biodiversity knowledge on insects is urgently needed due to the ever growing demand for food and the consequent deforestation process and loss of natural habitats in many understudied tropical regions. In this paper, we describe the outcome of a biodiversity research on tiger moths performed for the first time in a poorly studied Amazonian landscape-the savanna. We sampled tiger moths monthly with UV automatic light traps for 12 consecutive months in two sampling points in an area of savanna in eastern Amazon, and we compared our results to previously available data for eastern Amazon. We found a total of 91 species of which 80 were identified to species level. The most species-rich subtribes were Phaegopterina and Euchromiina with 32 species each. Species richness and abundance did not differ among sampling sites, but in general the species richness was higher during the dry season while abundance was higher during the wet season. This seasonal diversity pattern differs from the most common patterns recorded for savannas in other parts of the world. The species composition also changed in wet and dry seasons and correlated significantly with temperature and relative humidity. Our results suggest that the alpha diversity of the Amazonian savannas in our sampling area is lower than that in nearby rain forests and similar to that in agriculturally disturbed areas surrounded by rain forests. However, the species composition differed considerably from natural and disturbed areas. These results highlight the need of basic biodiversity surveys of insects in Amazonian savannas.

Dust Transport and Deposition Observed from the Terra-Moderate Image Spectrometer (MODIS) Space Observations

NASA Technical Reports Server (NTRS)

Kaufman, Y.

2004-01-01

Meteorological observations, in situ data and satellite images of dust episodes were used already in the 1970s to estimate that 100 tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but deteriorates air quality and caries pathogens as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport and deposition. The Terra spacecraft launched at the dawn of the last millennium provides first systematic well calibrated multispectral measurements from the MODIS instrument, for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and evaluate the African dust column concentration, transport and deposition. We found that 230 plus or minus 80 tg of dust are transported annually from Africa to the Atlantic Ocean, 30 tg return to Africa and Europe, 70 tg reach the Caribbean, 45 tg fertilize the Amazon Basin, 4 times as previous estimates thus explaining a paradox regarding the source of nutrition to the Amazon forest, and 120 plus or minus 40 tg are deposited in the Atlantic Ocean. The results are compared favorably with dust transport models for particle radius less than or equal to 12 microns. This study is a first example of quantitative use of MODIS aerosol for a geophysical study.

Dust Transport and Deposition Observed from the Terra-MODIS Space Observations

NASA Technical Reports Server (NTRS)

Kaufman, Y. J.; Koren, I.; Remer, L. A.; Tanre, D.; Fan, Ginoux; Fan, S.

2004-01-01

Meteorological observations, in situ data and satellite images of dust episodes were used already in the 1970s to estimate that 100 tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but deteriorates air quality and caries pathogens as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport and deposition. The Terra spacecraft launched at the dawn of the last millennium provides first systematic well calibrated multispectral measurements from the MODIS instrument, for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and evaluate the African dust column concentration, transport and deposition. We found that 230+/-80 tg of dust are transported annually from Africa to the Atlantic Ocean, 30 tg return to Africa and Europe, 70 tg reach the Caribbean, 45 tg fertilize the Amazon Basin, 4 times as previous estimates thus explaining a paradox regarding the source of nutrition to the Amazon forest, and 120+/-40 tg are deposited in the Atlantic Ocean. The results are compared favorably with dust transport models for particle radius less than or equal to 12 microns. This study is a first example of quantitative use of MODIS aerosol for a geophysical study.

Partitioning controls on Amazon forest photosynthesis between environmental and biotic factors at hourly to interannual timescales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jin; Guan, Kaiyu; Hayek, Matthew

Gross ecosystem productivity (GEP) in tropical forests varies both with the environment and with biotic changes in photosynthetic infrastructure, but our understanding of the relative effects of these factors across timescales is limited. Here, we used a statistical model to partition the variability of seven years of eddy covariance-derived GEP in a central Amazon evergreen forest into two main causes: variation in environmental drivers (solar radiation, diffuse light fraction, and vapor pressure deficit) that interact with model parameters that govern photosynthesis and biotic variation in canopy photosynthetic light-use efficiency associated with changes in the parameters themselves. Our fitted model wasmore » able to explain most of the variability in GEP at hourly (R 2 = 0.77) to interannual (R 2 = 0.80) timescales. At hourly timescales, we found that 75% of observed GEP variability could be attributed to environmental variability. When aggregating GEP to the longer timescales (daily, monthly, and yearly), however, environmental variation explained progressively less GEP variability: At monthly timescales, it explained only 3%, much less than biotic variation in canopy photosynthetic light-use efficiency, which accounted for 63%. These results challenge modeling approaches that assume GEP is primarily controlled by the environment at both short and long timescales. Our approach distinguishing biotic from environmental variability can help to resolve debates about environmental limitations to tropical forest photosynthesis. For example, we found that biotically regulated canopy photosynthetic light-use efficiency (associated with leaf phenology) increased with sunlight during dry seasons (consistent with light but not water limitation of canopy development) but that realized GEP was nonetheless lower relative to its potential efficiency during dry than wet seasons (consistent with water limitation of photosynthesis in given assemblages of leaves). Lastly, this work highlights the importance of accounting for differential regulation of GEP at different timescales and of identifying the underlying feedbacks and adaptive mechanisms.« less

Partitioning controls on Amazon forest photosynthesis between environmental and biotic factors at hourly to interannual timescales

DOE PAGES

Wu, Jin; Guan, Kaiyu; Hayek, Matthew; ...

2016-09-19

Gross ecosystem productivity (GEP) in tropical forests varies both with the environment and with biotic changes in photosynthetic infrastructure, but our understanding of the relative effects of these factors across timescales is limited. Here, we used a statistical model to partition the variability of seven years of eddy covariance-derived GEP in a central Amazon evergreen forest into two main causes: variation in environmental drivers (solar radiation, diffuse light fraction, and vapor pressure deficit) that interact with model parameters that govern photosynthesis and biotic variation in canopy photosynthetic light-use efficiency associated with changes in the parameters themselves. Our fitted model wasmore » able to explain most of the variability in GEP at hourly (R 2 = 0.77) to interannual (R 2 = 0.80) timescales. At hourly timescales, we found that 75% of observed GEP variability could be attributed to environmental variability. When aggregating GEP to the longer timescales (daily, monthly, and yearly), however, environmental variation explained progressively less GEP variability: At monthly timescales, it explained only 3%, much less than biotic variation in canopy photosynthetic light-use efficiency, which accounted for 63%. These results challenge modeling approaches that assume GEP is primarily controlled by the environment at both short and long timescales. Our approach distinguishing biotic from environmental variability can help to resolve debates about environmental limitations to tropical forest photosynthesis. For example, we found that biotically regulated canopy photosynthetic light-use efficiency (associated with leaf phenology) increased with sunlight during dry seasons (consistent with light but not water limitation of canopy development) but that realized GEP was nonetheless lower relative to its potential efficiency during dry than wet seasons (consistent with water limitation of photosynthesis in given assemblages of leaves). Lastly, this work highlights the importance of accounting for differential regulation of GEP at different timescales and of identifying the underlying feedbacks and adaptive mechanisms.« less

Partitioning controls on Amazon forest photosynthesis between environmental and biotic factors at hourly to interannual timescales.

PubMed

Wu, Jin; Guan, Kaiyu; Hayek, Matthew; Restrepo-Coupe, Natalia; Wiedemann, Kenia T; Xu, Xiangtao; Wehr, Richard; Christoffersen, Bradley O; Miao, Guofang; da Silva, Rodrigo; de Araujo, Alessandro C; Oliviera, Raimundo C; Camargo, Plinio B; Monson, Russell K; Huete, Alfredo R; Saleska, Scott R

2017-03-01

Gross ecosystem productivity (GEP) in tropical forests varies both with the environment and with biotic changes in photosynthetic infrastructure, but our understanding of the relative effects of these factors across timescales is limited. Here, we used a statistical model to partition the variability of seven years of eddy covariance-derived GEP in a central Amazon evergreen forest into two main causes: variation in environmental drivers (solar radiation, diffuse light fraction, and vapor pressure deficit) that interact with model parameters that govern photosynthesis and biotic variation in canopy photosynthetic light-use efficiency associated with changes in the parameters themselves. Our fitted model was able to explain most of the variability in GEP at hourly (R 2  = 0.77) to interannual (R 2  = 0.80) timescales. At hourly timescales, we found that 75% of observed GEP variability could be attributed to environmental variability. When aggregating GEP to the longer timescales (daily, monthly, and yearly), however, environmental variation explained progressively less GEP variability: At monthly timescales, it explained only 3%, much less than biotic variation in canopy photosynthetic light-use efficiency, which accounted for 63%. These results challenge modeling approaches that assume GEP is primarily controlled by the environment at both short and long timescales. Our approach distinguishing biotic from environmental variability can help to resolve debates about environmental limitations to tropical forest photosynthesis. For example, we found that biotically regulated canopy photosynthetic light-use efficiency (associated with leaf phenology) increased with sunlight during dry seasons (consistent with light but not water limitation of canopy development) but that realized GEP was nonetheless lower relative to its potential efficiency during dry than wet seasons (consistent with water limitation of photosynthesis in given assemblages of leaves). This work highlights the importance of accounting for differential regulation of GEP at different timescales and of identifying the underlying feedbacks and adaptive mechanisms. © 2016 John Wiley & Sons Ltd.

Trace gas and aerosol transports into and out of the Amazon Basin

NASA Technical Reports Server (NTRS)

Garstang, Michael; Greco, Steven

1991-01-01

Overviews of the wet season Amazon Boundary Layer Experiment (ABLE IIB) are presented which give the context of the wet season experiment and some of the results. Copies of all reprints and manuscripts published or accepted for publication are attached. A complete list of all papers published in the reviewed literature, papers presented as well as published as part of conference preceedings, and articles published in the news media are listed in the appendices. Two scales of interaction of the rain forest were pursued in this work: (1) global interactions; and (2) local and regional interactions. Under the first scale, the role of the rain forest in the global system was the central thrust of the work. Under the second scale, the role of the rain forest on the basin and smaller scales was emphasized. The appendices also provide a summary of future work and a listing of degrees awarded during this report period.

Tropical forest response to elevated CO2: Model-experiment integration at the AmazonFACE site.

NASA Astrophysics Data System (ADS)

Frankenberg, C.; Berry, J. A.; Guanter, L.; Joiner, J.

2014-12-01

The terrestrial biosphere's response to current and future elevated atmospheric carbon dioxide (eCO2) is a large source of uncertainty in future projections of the C cycle, climate and ecosystem functioning. In particular, the sensitivity of tropical rainforest ecosystems to eCO­2 is largely unknown even though the importance of tropical forests for biodiversity, carbon storage and regional and global climate feedbacks is unambiguously recognized. The AmazonFACE (Free-Air Carbon Enrichment) project will be the first ecosystem scale eCO2 experiment undertaken in the tropics, as well as the first to be undertaken in a mature forest. AmazonFACE provides the opportunity to integrate ecosystem modeling with experimental observations right from the beginning of the experiment, harboring a two-way exchange, i.e. models provide hypotheses to be tested, and observations deliver the crucial data to test and improve ecosystem models. We present preliminary exploration of observed and expected process responses to eCO2 at the AmazonFACE site from the dynamic global vegetation model LPJ-GUESS, highlighting opportunities and pitfalls for model integration of tropical FACE experiments. The preliminary analysis provides baseline hypotheses, which are to be further developed with a follow-up multiple model inter-comparison. The analysis builds on the recently undertaken FACE-MDS (Model-Data Synthesis) project, which was applied to two temperate FACE experiments and exceeds the traditional focus on comparing modeled end-target output. The approach has proven successful in identifying well (and less well) represented processes in models, which are separated for six clusters also here; (1) Carbon fluxes, (2) Carbon pools, (3) Energy balance, (4) Hydrology, (5) Nutrient cycling, and (6) Population dynamics. Simulation performance of observed conditions at the AmazonFACE site (a.o. from Manaus K34 eddy flux tower) will highlight process-based model deficiencies, and aid the separation of uncertainties arising from general ecosystem responses and those responses related to eCO2.

OH radical "life expectancy" within and above the Amazon rainforest: vertical, diel and seasonal variations

NASA Astrophysics Data System (ADS)

Nölscher, A.; Yanez-Serrano, A. M.; Kesselmeier, J.; Artaxo, P. P.; Wolff, S.; Trebs, I.; Williams, J.

2013-12-01

The Amazon rainforest forest is the world's largest contiguous ecosystem. Being about 6 million km2 it is around two thirds the area of the United States. The Amazon forest plays an important part of the Earth's hydrological, energy and carbon cycles. Photosynthetic uptake of CO2 by the rainforest affects the global radiative budget and concomitant release of reactive biogenic volatile organic compounds (BVOCs) can directly impact the atmosphere's primary oxidant, the hydroxyl (OH) radical as well as aerosol production and growth. Direct measurement of the total atmospheric OH reactivity (or inverse OH lifetime), in parallel with the individual BVOC can reveal insights into the coupling between biogenic emissions, atmospheric oxidation processes, canopy transport, and the OH budget. In this study we present for the first time, vertical profiles of total OH reactivity and biogenic VOCs that were monitored simultaneously throughout dry season, wet season and transition periods, from a remote tropical rainforest site in the Amazon (Amazonian Tall Tower Observatory (ATTO), S 02°08'38.8'', W 58°59'59.5'', 120 m above sea level, 150 km NE of the city of Manaus, Brazil). The profiles consisted of sequential measurements at 0.05m, 0.5m, 4 m, 12m, 24m, 38m, 53m and 79m, a single profile taking 16 minutes to complete. The measurements were made using Proton Transfer Reaction Mass Spectrometry (PTR-MS), directly in the case of BVOC and using the Comparative Reactivity Method pre-reactor for total OH reactivity. The vertical, diel and seasonal variations in total OH reactivity will be discussed. Total OH reactivity and isoprene profiles were observed to vary strongly between the seasons. Biogenic emissions from the canopy impacted the measurements as well as photo-oxidation, turbulent mixing, and deposition. Tower in the Amazon rainforest for measurements of vertical profiles of BVOCs and total OH reactivity from the forest floor, through the canopy, up to 80m.

Tropical forest response to elevated CO2: Model-experiment integration at the AmazonFACE site.

NASA Astrophysics Data System (ADS)

Fleischer, K.

2015-12-01

The terrestrial biosphere's response to current and future elevated atmospheric carbon dioxide (eCO2) is a large source of uncertainty in future projections of the C cycle, climate and ecosystem functioning. In particular, the sensitivity of tropical rainforest ecosystems to eCO­2 is largely unknown even though the importance of tropical forests for biodiversity, carbon storage and regional and global climate feedbacks is unambiguously recognized. The AmazonFACE (Free-Air Carbon Enrichment) project will be the first ecosystem scale eCO2 experiment undertaken in the tropics, as well as the first to be undertaken in a mature forest. AmazonFACE provides the opportunity to integrate ecosystem modeling with experimental observations right from the beginning of the experiment, harboring a two-way exchange, i.e. models provide hypotheses to be tested, and observations deliver the crucial data to test and improve ecosystem models. We present preliminary exploration of observed and expected process responses to eCO2 at the AmazonFACE site from the dynamic global vegetation model LPJ-GUESS, highlighting opportunities and pitfalls for model integration of tropical FACE experiments. The preliminary analysis provides baseline hypotheses, which are to be further developed with a follow-up multiple model inter-comparison. The analysis builds on the recently undertaken FACE-MDS (Model-Data Synthesis) project, which was applied to two temperate FACE experiments and exceeds the traditional focus on comparing modeled end-target output. The approach has proven successful in identifying well (and less well) represented processes in models, which are separated for six clusters also here; (1) Carbon fluxes, (2) Carbon pools, (3) Energy balance, (4) Hydrology, (5) Nutrient cycling, and (6) Population dynamics. Simulation performance of observed conditions at the AmazonFACE site (a.o. from Manaus K34 eddy flux tower) will highlight process-based model deficiencies, and aid the separation of uncertainties arising from general ecosystem responses and those responses related to eCO2.

Slow growth rates of Amazonian trees: Consequences for carbon cycling

PubMed Central

Vieira, Simone; Trumbore, Susan; Camargo, Plinio B.; Selhorst, Diogo; Chambers, Jeffrey Q.; Higuchi, Niro; Martinelli, Luiz Antonio

2005-01-01

Quantifying age structure and tree growth rate of Amazonian forests is essential for understanding their role in the carbon cycle. Here, we use radiocarbon dating and direct measurement of diameter increment to document unexpectedly slow growth rates for trees from three locations spanning the Brazilian Amazon basin. Central Amazon trees, averaging only ≈1mm/year diameter increment, grow half as fast as those from areas with more seasonal rainfall to the east and west. Slow growth rates mean that trees can attain great ages; across our sites we estimate 17-50% of trees with diameter >10 cm have ages exceeding 300 years. Whereas a few emergent trees that make up a large portion of the biomass grow faster, small trees that are more abundant grow slowly and attain ages of hundreds of years. The mean age of carbon in living trees (60-110 years) is within the range of or slightly longer than the mean residence time calculated from C inventory divided by annual C allocation to wood growth (40-100 years). Faster C turnover is observed in stands with overall higher rates of diameter increment and a larger fraction of the biomass in large, fast-growing trees. As a consequence, forests can recover biomass relatively quickly after disturbance, whereas recovering species composition may take many centuries. Carbon cycle models that apply a single turnover time for carbon in forest biomass do not account for variations in life strategy and therefore may overestimate the carbon sequestration potential of Amazon forests. PMID:16339903

Restoring tropical forests on bauxite mined lands: lessons from the Brazilian Amazon

Treesearch

John A. Parrotta; Oliver H. Knowles

2001-01-01

Restoring self-sustaining tropical forest ecosystems on surface mined sites is a formidable challenge that requires the integration of proven reclamation techniques and reforestation strategies appropriate to specific site conditions, including landscape biodiversity patterns. Restorationists working in most tropical settings are usually hampered by lack of basic...

JPRS Report Environmental Issues.

DTIC Science & Technology

1990-11-02

Program Views Environmental Effects [0 GLOBO 30 Sep] ............................. 31 Environmental Affairs Institute Fines Illegal Amazon Lumber...ERICA 12 Oct] .................................................................................................. 33 PERU Court Nullifies Soviet Fishing...34. He said loss of forests in Burma remains at only 0.3 He disputed reports that logs are being cut down ran- percent of forest cover per year, or

How rare is too rare to harvest? Management challenges posed by timber species occurring at low densities in the Brazilian Amazon

Treesearch

Mark Schulze; James Grogan; R. Matthew Landis; Edson Vidal

2008-01-01

Tropical forests are characterized by diverse assemblages of plant and animal species compared to temperate forests. Corollary to this general rule is that most tree species, whether valued for timber or not, occur at low densities (

Deforestation and rainfall recycling in Brazil: Is decreased forest cover connectivity associated with decreased rainfall connectivity?

NASA Astrophysics Data System (ADS)

Adera, S.; Larsen, L.; Levy, M. C.; Thompson, S. E.

2017-12-01

In the Brazilian rainforest-savanna transition zone, deforestation has the potential to significantly affect rainfall by disrupting rainfall recycling, the process by which regional evapotranspiration contributes to regional rainfall. Understanding rainfall recycling in this region is important not only for sustaining Amazon and Cerrado ecosystems, but also for cattle ranching, agriculture, hydropower generation, and drinking water management. Simulations in previous studies suggest complex, scale-dependent interactions between forest cover connectivity and rainfall. For example, the size and distribution of deforested patches has been found to affect rainfall quantity and spatial distribution. Here we take an empirical approach, using the spatial connectivity of rainfall as an indicator of rainfall recycling, to ask: as forest cover connectivity decreased from 1981 - 2015, how did the spatial connectivity of rainfall change in the Brazilian rainforest-savanna transition zone? We use satellite forest cover and rainfall data covering this period of intensive forest cover loss in the region (forest cover from the Hansen Global Forest Change dataset; rainfall from the Climate Hazards Infrared Precipitation with Stations dataset). Rainfall spatial connectivity is quantified using transfer entropy, a metric from information theory, and summarized using network statistics. Networks of connectivity are quantified for paired deforested and non-deforested regions before deforestation (1981-1995) and during/after deforestation (2001-2015). Analyses reveal a decline in spatial connectivity networks of rainfall following deforestation.

Theorizing Land Cover and Land Use Change: The Peasant Economy of Colonization in the Amazon Basin

NASA Technical Reports Server (NTRS)

Caldas, Marcellus; Walker, Robert; Arima, Eugenio; Perz, Stephen; Aldrich, Stephen; Simmons, Cynthia

2007-01-01

This paper addresses deforestation processes in the Amazon basin. It deploys a methodology combining remote sensing and survey-based fieldwork to examine, with regression analysis, the impact household structure and economic circumstances on deforestation decisions made by colonist farmers in the forest frontiers of Brazil. Unlike most previous regression-based studies, the methodology implemented analyzes behavior at the level of the individual property. The regressions correct for endogenous relationships between key variables, and spatial autocorrelation, as necessary. Variables used in the analysis are specified, in part, by a theoretical development integrating the Chayanovian concept of the peasant household with spatial considerations stemming from von Thuenen. The results from the empirical model indicate that demographic characteristics of households, as well as market factors, affect deforestation in the Amazon. Thus, statistical results from studies that do not include household-scale information may be subject to error. From a policy perspective, the results suggest that environmental policies in the Amazon based on market incentives to small farmers may not be as effective as hoped, given the importance of household factors in catalyzing the demand for land. The paper concludes by noting that household decisions regarding land use and deforestation are not independent of broader social circumstances, and that a full understanding of Amazonian deforestation will require insight into why poor families find it necessary to settle the frontier in the first place.

Sustainable settlement in the Brazilian Amazon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almeida, A.L.O.; Campari, J.S.

1996-02-01

Presents and analyzes the largest and most complete data set ever produced on the economic variables that influence deforestation by small farmers in the Amazon. This landmark study presents the largest and most analytically complete data set ever produced on the economic variables that influence deforestation by small farmers in the Amazon. The authors examine the changing character of the Amazon frontier based on field surveys conducted during twenty years of settlement experience. By observing the economic behavior of small farmers from colonization during the 1970s until the chaotic aftermath of the early 1990s, the authors are able to pinpointmore » a central paradox: unsuccessful farmers tend to be unstable, moving on to new frontiers where they will again destroy forests. Successful farmers tend to increase deforestation in the places where they remain. The findings reveal that much of the Amazonian frontier land cleared by pioneers in the 1970s is becoming agriculturally unproductive. Small farmers should be rewarded for staying where they are and for pursuing sustainable farming. Good farming methods must be promoted, and deforestation must be penalized. The authors recommend the implementation of innovative economic policies and new forms of cooperation between environmental and economic agencies, including the World Bank, at both local and international levels. The aim of these policies should be to raise agricultural incomes and reduce environmental aggression.« less

Water availability not fruitfall modulates the dry season distribution of frugivorous terrestrial vertebrates in a lowland Amazon forest

PubMed Central

Paredes, Omar Stalin Landázuri; Norris, Darren; de Oliveira, Tadeu Gomes

2017-01-01

Terrestrial vertebrate frugivores constitute one of the major guilds in tropical forests. Previous studies show that the meso-scale distribution of this group is only weakly explained by variables such as altitude and tree basal area in lowland Amazon forests. For the first time we test whether seasonally limiting resources (water and fallen fruit) affect the dry season distribution in 25 species of terrestrial vertebrates. To examine the effects of the spatial availability of fruit and water on terrestrial vertebrates we used a standardized, regularly spaced arrangement of camera-traps within 25km2 of lowland Amazon forest. Generalized linear models (GLMs) were then used to examine the influence of four variables (altitude, distance to large rivers, distance to nearest water, and presence vs absence of fruits) on the number of photos on five functional groups (all frugivores, small, medium, large and very large frugivores) and on seven of the most abundant frugivore species (Cuniculus paca, Dasyprocta leporina, Mazama americana, Mazama nemorivaga, Myoprocta acouchy, Pecari tajacu and Psophia crepitans). A total of 279 independent photos of 25 species were obtained from 900 camera-trap days. For most species and three functional groups, the variation in the number of photos per camera was significantly but weakly explained by the GLMs (deviance explained ranging from 6.2 to 48.8%). Generally, we found that the presence of water availability was more important than the presence of fallen fruit for the groups and species studied. Medium frugivores, large-bodied frugivores, and two of the more abundant species (C. paca and P. crepitans) were recorded more frequently closer to water bodies; while none of the functional groups nor the most abundant species showed any significant relationship with the presence of fallen fruit. Two functional groups and two of the seven most common frugivore species assessed in the GLMs showed significant results with species-specific responses to altitude. Our findings provide a more detailed understanding of how frugivorous vertebrates cope with periods of water and fruit scarcity in lowland Amazon forests. PMID:28301589

Water availability not fruitfall modulates the dry season distribution of frugivorous terrestrial vertebrates in a lowland Amazon forest.

PubMed

Paredes, Omar Stalin Landázuri; Norris, Darren; Oliveira, Tadeu Gomes de; Michalski, Fernanda

2017-01-01

Terrestrial vertebrate frugivores constitute one of the major guilds in tropical forests. Previous studies show that the meso-scale distribution of this group is only weakly explained by variables such as altitude and tree basal area in lowland Amazon forests. For the first time we test whether seasonally limiting resources (water and fallen fruit) affect the dry season distribution in 25 species of terrestrial vertebrates. To examine the effects of the spatial availability of fruit and water on terrestrial vertebrates we used a standardized, regularly spaced arrangement of camera-traps within 25km2 of lowland Amazon forest. Generalized linear models (GLMs) were then used to examine the influence of four variables (altitude, distance to large rivers, distance to nearest water, and presence vs absence of fruits) on the number of photos on five functional groups (all frugivores, small, medium, large and very large frugivores) and on seven of the most abundant frugivore species (Cuniculus paca, Dasyprocta leporina, Mazama americana, Mazama nemorivaga, Myoprocta acouchy, Pecari tajacu and Psophia crepitans). A total of 279 independent photos of 25 species were obtained from 900 camera-trap days. For most species and three functional groups, the variation in the number of photos per camera was significantly but weakly explained by the GLMs (deviance explained ranging from 6.2 to 48.8%). Generally, we found that the presence of water availability was more important than the presence of fallen fruit for the groups and species studied. Medium frugivores, large-bodied frugivores, and two of the more abundant species (C. paca and P. crepitans) were recorded more frequently closer to water bodies; while none of the functional groups nor the most abundant species showed any significant relationship with the presence of fallen fruit. Two functional groups and two of the seven most common frugivore species assessed in the GLMs showed significant results with species-specific responses to altitude. Our findings provide a more detailed understanding of how frugivorous vertebrates cope with periods of water and fruit scarcity in lowland Amazon forests.