Fire regimes, forest change, and self-organization in an old-growth mixed-conifer forest, Yosemite National Park, USA.

PubMed

Scholl, Andrew E; Taylor, Alan H

2010-03-01

Fire is recognized as a keystone process in dry mixed-conifer forests that have been altered by decades of fire suppression, Restoration of fire disturbance to these forests is a guiding principle of resource management in the U.S. National Park Service. Policy implementation is often hindered by a poor understanding of forest conditions before fire exclusion, the characteristics of forest changes since excluding fire, and the influence of topographic or self-organizing controls on forest structure. In this study the spatial and temporal characteristics of fire regimes and forest structure are reconstructed in a 2125-ha mixed-conifer forest. Forests were multi-aged, burned frequently at low severity and fire-return interval, and forest structure did not vary with slope aspect, elevation, or slope position. Fire exclusion has caused an increase in forest density and basal area and a compositional shift to shade-tolerant and fire-intolerant species. The median point fire-return interval and extent of a fire was 10 yr and 115 ha, respectively. The pre-Euro-American settlement fire rotation of 13 yr increased to 378 yr after 1905. The position of fire scars within tree rings indicates that 79% of fires burned in the midsummer to fall period. The spatial pattern of burns exhibited self-organizing behavior. Area burned was 10-fold greater when an area had not been burned by the previous fire. Fires were frequent and widespread, but patches of similar aged trees were < 0.2 ha, suggesting small fire-caused canopy openings. Managers need to apply multiple burns at short intervals for a sustained period to reduce surface fuels and create small canopy openings characteristic of the reference forest. By coupling explicit reference conditions with consideration of current conditions and projected climate change, management activities can balance restoration and risk management.

Decreases in Soil Moisture and Organic Matter Quality Suppress Microbial Decomposition Following a Boreal Forest Fire

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

Holden, Sandra R.; Berhe, Asmeret A.; Treseder, Kathleen K.

Climate warming is projected to increase the frequency and severity of wildfires in boreal forests, and increased wildfire activity may alter the large soil carbon (C) stocks in boreal forests. Changes in boreal soil C stocks that result from increased wildfire activity will be regulated in part by the response of microbial decomposition to fire, but post-fire changes in microbial decomposition are poorly understood. Here, we investigate the response of microbial decomposition to a boreal forest fire in interior Alaska and test the mechanisms that control post-fire changes in microbial decomposition. We used a reciprocal transplant between a recently burnedmore » boreal forest stand and a late successional boreal forest stand to test how post-fire changes in abiotic conditions, soil organic matter (SOM) composition, and soil microbial communities influence microbial decomposition. We found that SOM decomposing at the burned site lost 30.9% less mass over two years than SOM decomposing at the unburned site, indicating that post-fire changes in abiotic conditions suppress microbial decomposition. Our results suggest that moisture availability is one abiotic factor that constrains microbial decomposition in recently burned forests. In addition, we observed that burned SOM decomposed more slowly than unburned SOM, but the exact nature of SOM changes in the recently burned stand are unclear. Finally, we found no evidence that post-fire changes in soil microbial community composition significantly affect decomposition. Taken together, our study has demonstrated that boreal forest fires can suppress microbial decomposition due to post-fire changes in abiotic factors and the composition of SOM. Models that predict the consequences of increased wildfires for C storage in boreal forests may increase their predictive power by incorporating the observed negative response of microbial decomposition to boreal wildfires.« less

Synergy between land use and climate change increases future fire risk in Amazon forests

DOE PAGES

Le Page, Yannick; Morton, Douglas; Hartin, Corinne; ...

2017-12-20

Tropical forests have been a permanent feature of the Amazon basin for at least 55 million years, yet climate change and land use threaten the forest's future over the next century. Understory forest fires, which are common under the current climate in frontier forests, may accelerate Amazon forest losses from climate-driven dieback and deforestation. Far from land use frontiers, scarce fire ignitions and high moisture levels preclude significant burning, yet projected climate and land use changes may increase fire activity in these remote regions. Here, we used a fire model specifically parameterized for Amazon understory fires to examine the interactionsmore » between anthropogenic activities and climate under current and projected conditions. In a scenario of low mitigation efforts with substantial land use expansion and climate change – Representative Concentration Pathway (RCP) 8.5 – projected understory fires increase in frequency and duration, burning 4–28 times more forest in 2080–2100 than during 1990–2010. In contrast, active climate mitigation and land use contraction in RCP4.5 constrain the projected increase in fire activity to 0.9–5.4 times contemporary burned area. Importantly, if climate mitigation is not successful, land use contraction alone is very effective under low to moderate climate change, but does little to reduce fire activity under the most severe climate projections. These results underscore the potential for a fire-driven transformation of Amazon forests if recent regional policies for forest conservation are not paired with global efforts to mitigate climate change.« less

Synergy between land use and climate change increases future fire risk in Amazon forests

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

Le Page, Yannick; Morton, Douglas; Hartin, Corinne

Tropical forests have been a permanent feature of the Amazon basin for at least 55 million years, yet climate change and land use threaten the forest's future over the next century. Understory forest fires, which are common under the current climate in frontier forests, may accelerate Amazon forest losses from climate-driven dieback and deforestation. Far from land use frontiers, scarce fire ignitions and high moisture levels preclude significant burning, yet projected climate and land use changes may increase fire activity in these remote regions. Here, we used a fire model specifically parameterized for Amazon understory fires to examine the interactionsmore » between anthropogenic activities and climate under current and projected conditions. In a scenario of low mitigation efforts with substantial land use expansion and climate change – Representative Concentration Pathway (RCP) 8.5 – projected understory fires increase in frequency and duration, burning 4–28 times more forest in 2080–2100 than during 1990–2010. In contrast, active climate mitigation and land use contraction in RCP4.5 constrain the projected increase in fire activity to 0.9–5.4 times contemporary burned area. Importantly, if climate mitigation is not successful, land use contraction alone is very effective under low to moderate climate change, but does little to reduce fire activity under the most severe climate projections. These results underscore the potential for a fire-driven transformation of Amazon forests if recent regional policies for forest conservation are not paired with global efforts to mitigate climate change.« less

Modeling Forest Understory Fires in an Eastern Amazonian Landscape

NASA Technical Reports Server (NTRS)

Alencar, A. A. C.; Solorzano, L. A.; Nepstad, D. C.

2004-01-01

Forest understory fires are an increasingly important cause of forest impoverishment in Ammonia, but little is known of the landscape characteristics and climatic phenomena that determine their occurrence. We developed empirical functions relating the occurrence of understory fires to landscape features near Paragominas, a 35- yr-old ranching and logging center in eastern Ammonia. An historical sequence of maps of forest understory fire was created based on field interviews With local farmers and Landsat TM images. Several landscape features that might explain spatial variations in the occurrence of understory fires were also mapped and co-registered for each of the sample dates, including: forest fragment size and shape, forest impoverishment through logging and understory fires, source of ignition (settlements and charcoal pits), roads, forest edges, and others. The spatial relationship between forest understory fire and each landscape characteristic was tested by regression analyses. Fire probability models were then developed for various combinations of landscape characteristics. The analyses were conducted separately for years of the El Nino Southern Oscillation (ENSO), which are associated with severe drought in eastern Amazonia, and non-ENS0 years. Most (91 %) of the forest area that burned during the 10-yr sequence caught fire during ENSO years, when severe drought may have increased both forest flammability and the escape of agricultural management fires. Forest understory fires were associated with forest edges, as reported in previous studies from Ammonia. But the strongest predictor of forest fire was the percentage of the forest fragment that had been previously logged or burned. Forest fragment size, distance to charcoal pits, distance to agricultural settlement, proximity to forest edge, and distance to roads were also correlated with forest understory fire. Logistic regression models using information on fragment degradation and distance to ignition sources accurately predicted the location of lss than 80% of the forest fires observed during the ENSO event of 1997- 1998. In this Amazon landscape, forest understory fire is a complex function of several variables that influence both the flammability and ignition exposure of the forest.

Restoring surface fire stabilizes forest carbon under extreme fire weather in the Sierra Nevada

Treesearch

Daniel J. Krofcheck; Matthew D. Hurteau; Robert M. Scheller; E. Louise Loudermilk

2017-01-01

Climate change in the western United States has increased the frequency of extreme fire weather events and is projected to increase the area burned by wildfire in the coming decades. This changing fire regime, coupled with increased high-severity fire risk from a legacy of fire exclusion, could destabilize forest carbon (C), decrease net ecosystem exchange (...

Increasing elevation of fire in the Sierra Nevada and implications for forest change

USGS Publications Warehouse

Schwartz, Mark W.; Butt, Nathalie; Dolanc, Christopher R.; Holguin, Andrew; Moritz, Max A.; North, Malcolm P.; Safford, Hugh D.; Stephenson, Nathan L.; Thorne, James H.; van Mantgem, Phillip J.

2015-01-01

Fire in high-elevation forest ecosystems can have severe impacts on forest structure, function and biodiversity. Using a 105-year data set, we found increasing elevation extent of fires in the Sierra Nevada, and pose five hypotheses to explain this pattern. Beyond the recognized pattern of increasing fire frequency in the Sierra Nevada since the late 20th century, we find that the upper elevation extent of those fires has also been increasing. Factors such as fire season climate and fuel build up are recognized potential drivers of changes in fire regimes. Patterns of warming climate and increasing stand density are consistent with both the direction and magnitude of increasing elevation of wildfire. Reduction in high elevation wildfire suppression and increasing ignition frequencies may also contribute to the observed pattern. Historical biases in fire reporting are recognized, but not likely to explain the observed patterns. The four plausible mechanistic hypotheses (changes in fire management, climate, fuels, ignitions) are not mutually exclusive, and likely have synergistic interactions that may explain the observed changes. Irrespective of mechanism, the observed pattern of increasing occurrence of fire in these subalpine forests may have significant impacts on their resilience to changing climatic conditions.

Fire Impact on Surface Fuels and Carbon Emissions in Scots pine Logged Sites of Siberia

NASA Astrophysics Data System (ADS)

Ivanova, G. A.; Kukavskaya, E. A.; Bogorodskaya, A. V.; Ivanov, V. A.; Zhila, S. V.; Conard, S. G.

2012-04-01

Forest fire and large-scale forest harvesting are the two major disturbances in the Russian boreal forests. Non-recovered logged sites total about a million hectares. Logged sites are characterized by higher fire hazard than forest sites due great amounts of logging slash, which dries out much more rapidly compared to understory fuels. Moreover, most logging sites can be easily accessed by local population. Both legal and illegal logging are also increasing rapidly in many forest areas of Siberia. Fire effects on forest overstory, subcanopy woody layer, and ground vegetation biomass were estimated on logged vs. unlogged sites in the Central Siberia region in 2009-2012 as a part of the project "The Influence of Changing Forestry Practices on the Effects of Wildfire and on Interactions Between Fire and Changing Climate in Central Siberia" supported by NASA (NEESPI). Dead down woody fuels are significantly less at unburned/logged area of dry southern regions compared to more humid northern regions. Fuel consumption was typically less in spring fires than during summer fires. Fire-caused carbon emissions on logged sites appeared to be twice that on unlogged sites. Soil respiration is less at logged areas compared to undisturbed forest. After fire soil respiration decreases both at logged and unlogged areas. arbon emissions from fire and post-fire ecosystem damage on logged sites are expected to increase under changing climate conditions and as a result of anticipated increases in future forest harvesting in Siberia.

Effects of prescribed fire on wintering, bark-foraging birds in northern Arizona

Treesearch

Theresa L. Pope

2006-01-01

Forest management practices of the past century have led to an increase in unnatural and destructive crown fires in ponderosa pine (Pinus ponderosa) forests of the southwest. To combat large fires, forest managers are attempting to simulate past fire regimes of low-intensity surface fires using prescribed fire. While there have been many studies...

Simulating boreal forest carbon dynamics after stand-replacing fire disturbance: insights from a global process-based vegetation model

NASA Astrophysics Data System (ADS)

Yue, C.; Ciais, P.; Luyssaert, S.; Cadule, P.; Harden, J.; Randerson, J.; Bellassen, V.; Wang, T.; Piao, S. L.; Poulter, B.; Viovy, N.

2013-04-01

Stand-replacing fires are the dominant fire type in North American boreal forest and leave a historical legacy of a mosaic landscape of different aged forest cohorts. To accurately quantify the role of fire in historical and current regional forest carbon balance using models, one needs to explicitly simulate the new forest cohort that is established after fire. The present study adapted the global process-based vegetation model ORCHIDEE to simulate boreal forest fire CO2 emissions and follow-up recovery after a stand-replacing fire, with representation of postfire new cohort establishment, forest stand structure and the following self-thinning process. Simulation results are evaluated against three clusters of postfire forest chronosequence observations in Canada and Alaska. Evaluation variables for simulated postfire carbon dynamics include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index (LAI), and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). The model simulation results, when forced by local climate and the atmospheric CO2 history on each chronosequence site, generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with measurement accuracy (for CO2 flux ~100 g C m-2 yr-1, for biomass carbon ~1000 g C m-2 and for soil carbon ~2000 g C m-2). We find that current postfire forest carbon sink on evaluation sites observed by chronosequence methods is mainly driven by historical atmospheric CO2 increase when forests recover from fire disturbance. Historical climate generally exerts a negative effect, probably due to increasing water stress caused by significant temperature increase without sufficient increase in precipitation. Our simulation results demonstrate that a global vegetation model such as ORCHIDEE is able to capture the essential ecosystem processes in fire-disturbed boreal forests and produces satisfactory results in terms of both carbon fluxes and carbon stocks evolution after fire, making it suitable for regional simulations in boreal regions where fire regimes play a key role on ecosystem carbon balance.

Landscape-scale effects of fire severity on mixed-conifer and red fir forest structure in Yosemite National Park

USGS Publications Warehouse

Kane, Van R.; Lutz, James A.; Roberts, Susan L.; Smith, Douglas F.; McGaughey, Robert J.; Povak, Nicholas A.; Brooks, Matthew L.

2013-01-01

While fire shapes the structure of forests and acts as a keystone process, the details of how fire modifies forest structure have been difficult to evaluate because of the complexity of interactions between fires and forests. We studied this relationship across 69.2 km2 of Yosemite National Park, USA, that was subject to 32 fires ⩾40 ha between 1984 and 2010. Forests types included ponderosa pine (Pinus ponderosa), white fir-sugar pine (Abies concolor/Pinus lambertiana), and red fir (Abies magnifica). We estimated and stratified burned area by fire severity using the Landsat-derived Relativized differenced Normalized Burn Ratio (RdNBR). Airborne LiDAR data, acquired in July 2010, measured the vertical and horizontal structure of canopy material and landscape patterning of canopy patches and gaps. Increasing fire severity changed structure at the scale of fire severity patches, the arrangement of canopy patches and gaps within fire severity patches, and vertically within tree clumps. Each forest type showed an individual trajectory of structural change with increasing fire severity. As a result, the relationship between estimates of fire severity such as RdNBR and actual changes appears to vary among forest types. We found three arrangements of canopy patches and gaps associated with different fire severities: canopy-gap arrangements in which gaps were enclosed in otherwise continuous canopy (typically unburned and low fire severities); patch-gap arrangements in which tree clumps and gaps alternated and neither dominated (typically moderate fire severity); and open-patch arrangements in which trees were scattered across open areas (typically high fire severity). Compared to stands outside fire perimeters, increasing fire severity generally resulted first in loss of canopy cover in lower height strata and increased number and size of gaps, then in loss of canopy cover in higher height strata, and eventually the transition to open areas with few or no trees. However, the estimated fire severities at which these transitions occurred differed for each forest type. Our work suggests that low severity fire in red fir forests and moderate severity fire in ponderosa pine and white fir-sugar pine forests would restore vertical and horizontal canopy structures believed to have been common prior to the start of widespread fire suppression in the early 1900s. The fusion of LiDAR and Landsat data identified post-fire structural conditions that would not be identified by Landsat alone, suggesting a broad applicability of combining Landsat and LiDAR data for landscape-scale structural analysis for fire management.

Alaska's Changing Fire Regime - Implications for the Vulnerability of Its Boreal Forests

NASA Technical Reports Server (NTRS)

Kasischke, E. S.; Hoy, E. E.; Verbyla, D. L.; Rupp, T. S.; Duffy, P. A.; McGuire, A. D.; Murphy, K. A.; Jandt, R.; Barnes, J. L.; Calef, M.;

Alaska’s changing fire regime - Implications for the vulnerability of its boreal forests

USGS Publications Warehouse

Kasischke, Eric S.; Verbyla, David L.; Rupp, T. Scott; McGuire, A. David; Murphy, Karen A.; Jandt, R.; Barnes, Jennifer L.; Hoy, E.; Duffy, Paul A.; Calef, Monika; Turetsky, Merritt R.

2010-01-01

A synthesis was carried out to examine Alaska’s boreal forest fire regime. During the 2000s, an average of 767 000 ha·year–1 burned, 50% higher than in any previous decade since the 1940s. Over the past 60 years, there was a decrease in the number of lightning-ignited fires, an increase in extreme lightning-ignited fire events, an increase in human-ignited fires, and a decrease in the number of extreme human-ignited fire events. The fraction of area burned from human-ignited fires fell from 26% for the 1950s and 1960s to 5% for the 1990s and 2000s, a result from the change in fire policy that gave the highest suppression priorities to fire events that occurred near human settlements. The amount of area burned during late-season fires increased over the past two decades. Deeper burning of surface organic layers in black spruce (Picea mariana (Mill.) BSP) forests occurred during late-growing-season fires and on more well-drained sites. These trends all point to black spruce forests becoming increasingly vulnerable to the combined changes of key characteristics of Alaska’s fire regime, except on poorly drained sites, which are resistant to deep burning. The implications of these fire regime changes to the vulnerability and resilience of Alaska’s boreal forests and land and fire management are discussed.

[Responses of boreal forest landscape in northern Great Xing'an Mountains of Northeast China to climate change].

PubMed

Li, Xiao-Na; He, Hong-Shi; Wu, Zhi-Wei; Liang, Yu

2012-12-01

With the combination of forest landscape model (LANDIS) and forest gap model (LINKAGES), this paper simulated the effects of climate change on the boreal forest landscape in the Great Xing'an Mountains, and compared the direct effects of climate change and the effects of climate warming-induced fires on the forest landscape. The results showed that under the current climate conditions and fire disturbances, the forest landscape in the study area could maintain its dynamic balance, and Larix gmelinii was still the dominant tree species. Under the future climate and fire disturbances scenario, the distribution area of L. gmelinii and Pinus pumila would be decreased, while that of Betula platyphylla, Populus davidiana, Populus suaveolens, Chosenia arbutifolia, and Pinus sylvestris var. mongolica would be increased, and the forest fragmentation and forest diversity would have an increase. The changes of the forest landscape lagged behind climate change. Climate warming would increase the growth of most tree species except L. gmelinii, while the increased fires would increase the distribution area of P. davidiana, P. suaveolens, and C. arbutifolia and decrease the distribution area of L. gmelinii, P. sylvestris var. mongolica, and P. pumila. The effects of climate warming-induced fires on the forest landscape were almost equal to the direct effects of climate change, and aggravated the direct effects of climate change on forest composition, forest landscape fragmentation, and forest landscape diversity.

Analysing Forst Fores in China

NASA Astrophysics Data System (ADS)

Casanova, Jose-Luis; Sanz, Julia; Garcia, Miguel; Salvador, Pablo; Quin, Xianlin; Li, Zengyuan; Yin, Lingyu; Sun, Guifen; Goldammer, Johann

2016-08-01

Forest fires are a major concern in China because of the economical and biodiversity looses and because the emission of trace gases into the atmosphere. During 12 years LATUV has been working in the development of forest fires products, especially in North China. A catalogue of products has been generated like: forest fire detection, burnt area mapping, gas emissions, severity and burnt biomass.Forest fires can be detected by different platforms and sensor but the rate of false alarms is high because of industrial activity. The gas emissions are important, because of the forest fires inside China and because the forest fires between China and Russia that have a considerable impact in the atmosphere composition in China.The availability of new sensors on board sentinel 2 and sentinel 3 platforms will increase the product catalogue with new products more accurate and increasing the periodicity information.

Effectiveness of Prescribed Fire as a Fuel Treatment in Californian Coniferous Forests

Treesearch

Nicole M. Vaillant; JoAnn Fites-Kaufman; Scott L. Stephens

2006-01-01

Effective fire suppression for the past century has altered forest structure and increased fuel loads. Prescribed fire as a fuels treatment can reduce wildfire size and severity. This study investigates how prescribed fire affects fuel loads, forest structure, potential fire behavior, and modeled tree mortality at 80th, 90th, and 97.5th percentile fire weather...

A soil burn severity index for understanding soil-fire relations in tropical forests

Treesearch

Theresa B. Jain; William A. Gould; Russell T. Graham; David S. Pilliod; Leigh B. Lentile; Grizelle Gonzalez

2008-01-01

Methods for evaluating the impact of fires within tropical forests are needed as fires become more frequent and human populations and demands on forests increase. Short- and long-term fire effects on soils are determined by the prefire, fire, and postfire environments. We placed these components within a fire-disturbance continuum to guide our literature synthesis and...

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.

Effects of biotic feedback and harvest management on boreal forest fire activity under climate change.

PubMed

Krawchuk, Meg A; Cumming, Steve G

2011-01-01

Predictions of future fire activity over Canada's boreal forests have primarily been generated from climate data following assumptions that direct effects of weather will stand alone in contributing to changes in burning. However, this assumption needs explicit testing. First, areas recently burned can be less likely to burn again in the near term, and this endogenous regulation suggests the potential for self-limiting, negative biotic feedback to regional climate-driven increases in fire. Second, forest harvest is ongoing, and resulting changes in vegetation structure have been shown to affect fire activity. Consequently, we tested the assumption that fire activity will be driven by changes in fire weather without regulation by biotic feedback or regional harvest-driven changes in vegetation structure in the mixedwood boreal forest of Alberta, Canada, using a simulation experiment that includes the interaction of fire, stand dynamics, climate change, and clear cut harvest management. We found that climate change projected with fire weather indices calculated from the Canadian Regional Climate Model increased fire activity, as expected, and our simulations established evidence that the magnitude of regional increase in fire was sufficient to generate negative feedback to subsequent fire activity. We illustrate a 39% (1.39-fold) increase in fire initiation and 47% (1.47-fold) increase in area burned when climate and stand dynamics were included in simulations, yet 48% (1.48-fold) and 61% (1.61-fold) increases, respectively, when climate was considered alone. Thus, although biotic feedbacks reduced burned area estimates in important ways, they were secondary to the direct effect of climate on fire. We then show that ongoing harvest management in this region changed landscape composition in a way that led to reduced fire activity, even in the context of climate change. Although forest harvesting resulted in decreased regional fire activity when compared to unharvested conditions, forest composition and age structure was shifted substantially, illustrating a trade-off between management goals to minimize fire and conservation goals to emulate natural disturbance.

Changing patterns of fire occurrence in proximity to forest edges, roads and rivers between NW Amazonian countries

NASA Astrophysics Data System (ADS)

Armenteras, Dolors; Barreto, Joan Sebastian; Tabor, Karyn; Molowny-Horas, Roberto; Retana, Javier

2017-06-01

Tropical forests in NW Amazonia are highly threatened by the expansion of the agricultural frontier and subsequent deforestation. Fire is used, both directly and indirectly, in Brazilian Amazonia to propagate deforestation and increase forest accessibility. Forest fragmentation, a measure of forest degradation, is also attributed to fire occurrence in the tropics. However, outside the Brazilian Legal Amazonia the role of fire in increasing accessibility and forest fragmentation is less explored. In this study, we compared fire regimes in five countries that share this tropical biome in the most north-westerly part of the Amazon Basin (Venezuela, Colombia, Ecuador, Peru and Brazil). We analysed spatial differences in the timing of peak fire activity and in relation to proximity to roads and rivers using 12 years of MODIS active fire detections. We also distinguished patterns of fire in relation to forest fragmentation by analysing fire distance to the forest edge as a measure of fragmentation for each country. We found significant hemispheric differences in peak fire occurrence with the highest number of fires in the south in 2005 vs. 2007 in the north. Despite this, both hemispheres are equally affected by fire. We also found difference in peak fire occurrence by country. Fire peaked in February in Colombia and Venezuela, whereas it peaked in September in Brazil and Peru, and finally Ecuador presented two fire peaks in January and October. We confirmed the relationship between fires and forest fragmentation for all countries and also found significant differences in the distance between the fire and the forest edge for each country. Fires were associated with roads and rivers in most countries. These results can inform land use planning at the regional, national and subnational scales to minimize the contribution of road expansion and subsequent access to the Amazonian natural resources to fire occurrence and the associated deforestation and carbon emissions.

Long-term impacts of prescribed fire on stand structure, growth, mortality, and individual tree vigor in Pinus resinosa forests

Treesearch

Sawyer S. Scherer; Anthony W. D' Amato; Christel C. Kern; Brian J. Palik; Matthew B. Russell

2016-01-01

Prescribed fire is increasingly being viewed as a valuable tool for mitigating the ecological consequences of long-term fire suppression within fire-adapted forest ecosystems. While the use of burning treatments in northern temperate conifer forests has at times received considerable attention, the long-term (>10 years) effects on forest structure and...

Reintroducing fire in regenerated dry forests following stand-replacing wildfire.

Treesearch

David W. Peterson; Paul F. Hessburg; Brion Salter; Kevin M. James; Matthew C. Dahlgreen; John A. Barnes

2007-01-01

Prescribed fire use may be effective for increasing fire resilience in young coniferous forests by reducing surface fuels, modifying overstory stand structure, and promoting development of large trees of fire resistant species. Questions remain, however, about when and how to reintroduce fire in regenerated forests, and to what end. We studied the effects of spring...

Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed conifer forest

Treesearch

Dylan W. Schwilk; Eric E. Knapp; Scott M. Ferrenberg; Jon E. Keeley; Anthony. Caprio

2006-01-01

Over the last century, fire exclusion in the forests of the Sierra Nevada has allowed surface fuels to accumulate and has led to increased tree density. Stand composition has also been altered as shade tolerant tree species crowd out shade intolerant species. To restore forest structure and reduce the risk of large, intense fires, managers have increasingly used...

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.

A soil burn severity index for understanding soil-fire relations in tropical forests [Chinese version

Treesearch

Theresa B. Jain; William A. Gould; Russell T. Graham; David S. Pilliod; Leigh B. Lentile; Grizelle Gonzalez

2008-01-01

Methods for evaluating the impact of fires within tropical forests are needed as fires become more frequent and human populations and demands on forests increase. Short- and long-term fire effects on soils are determined by the prefire, fire, and postfire environments. We placed these components within a fire-disturbance continuum to guide our literature synthesis and...

Interactive effects of historical logging and fire exclusion on ponderosa pine forest structure in the northern Rockies.

PubMed

Naficy, Cameron; Sala, Anna; Keeling, Eric G; Graham, Jon; DeLuca, Thomas H

2010-10-01

Increased forest density resulting from decades of fire exclusion is often perceived as the leading cause of historically aberrant, severe, contemporary wildfires and insect outbreaks documented in some fire-prone forests of the western United States. Based on this notion, current U.S. forest policy directs managers to reduce stand density and restore historical conditions in fire-excluded forests to help minimize high-severity disturbances. Historical logging, however, has also caused widespread change in forest vegetation conditions, but its long-term effects on vegetation structure and composition have never been adequately quantified. We document that fire-excluded ponderosa pine forests of the northern Rocky Mountains logged prior to 1960 have much higher average stand density, greater homogeneity of stand structure, more standing dead trees and increased abundance of fire-intolerant trees than paired fire-excluded, unlogged counterparts. Notably, the magnitude of the interactive effect of fire exclusion and historical logging substantially exceeds the effects of fire exclusion alone. These differences suggest that historically logged sites are more prone to severe wildfires and insect outbreaks than unlogged, fire-excluded forests and should be considered a high priority for fuels reduction treatments. Furthermore, we propose that ponderosa pine forests with these distinct management histories likely require distinct restoration approaches. We also highlight potential long-term risks of mechanical stand manipulation in unlogged forests and emphasize the need for a long-term view of fuels management.

Fire risk and adaptation strategies in Northern Eurasian forests

NASA Astrophysics Data System (ADS)

Shvidenko, Anatoly; Schepaschenko, Dmitry

2013-04-01

On-going climatic changes substantially accelerate current fire regimes in Northern Eurasian ecosystems, particularly in forests. During 1998-2012, wildfires enveloped on average ~10.5 M ha year-1 in Russia with a large annual variation (between 3 and 30 M ha) and average direct carbon emissions at ~150 Tg C year-1. Catastrophic fires, which envelope large areas, spread in usually incombustible wetlands, escape from control and provide extraordinary negative impacts on ecosystems, biodiversity, economics, infrastructure, environment, and health of population, become a typical feature of the current fire regimes. There are new evidences of correlation between catastrophic fires and large-scale climatic anomalies at a continental scale. While current climatic predictions suggest the dramatic warming (at the average at 6-7 °C for the country and up to 10-12°C in some northern continental regions), any substantial increase of summer precipitation does not expected. Increase of dryness and instability of climate will impact fire risk and severity of consequences. Current models suggest a 2-3 fold increase of the number of fires by the end of this century in the boreal zone. They predict increases of the number of catastrophic fires; a significant increase in the intensity of fire and amount of consumed fuel; synergies between different types of disturbances (outbreaks of insects, unregulated anthropogenic impacts); acceleration of composition of the gas emissions due to enhanced soil burning. If boreal forests would become a typing element, the mass mortality of trees would increase fire risk and severity. Permafrost melting and subsequent change of hydrological regimes very likely will lead to the degradation and destruction of boreal forests, as well as to the widespread irreversible replacement of forests by other underproductive vegetation types. A significant feedback between warming and escalating fire regimes is very probable in Russia and particularly in the permafrost areas. Overall, Russia should expect a disproportionate escalation of fire regimes compared to increasing climatic fire danger. Thus, development and implementation of an efficient adaptation strategy is a pressing problem of current forest management of the country. An appropriate system of forest fire protection which would be able to meet challenges of future climates is a corner stone of such a strategy. We consider possible systems solutions of this complex problem including (1) integrated ecological and socio-economic analysis of current and future fire regimes; (2) regional requirements to and specific features of a new paradigm of forest fire protection in the boreal zone of Northern Eurasia; (3) anticipatory strategy of the prevention of large-scale disturbances in forests, including adaptation of forest landscapes to the future climates (regulation of tree composition; setup of relevant spatial structure of forest landscapes; etc.); (4) implementation of an effective system of forest monitoring as part of integrated observing systems; (5) transition to ecologically-friendly systems of industrial development of northern territories; (6) development of new/ improvement of existing legislation and institutional frameworks of forest management which would be satisfactory to react on challenges of climate change; and (6) international cooperation.

Prescribed fire in upland harwood forests

Treesearch

T.L. Keyser; C.H. Greenberg; H. McNab

2014-01-01

In upland hardwood forests of the Southeastern U.S.,prescribed fire is increasingly used by land managers citing objectives that include hazardous fuels reduction, wildlife habitat improvement, promoting oak regeneration, or restoring forest composition or structure to an historic condition. Research suggests that prescribed fire effects on hardwood forests and...

[Influence of fire disturbance on aboveground deadwood debris carbon storage in Huzhong forest region of Great Xing'an Mountains, Northeast China].

PubMed

Yang, Da; He, Hong-shi; Wu, Zhi-wei; Liang, Yu; Huang, Chao; Luo, Xu; Xiao, Jiang-tao; Zhang, Qing-long

2015-02-01

Based on the field inventory data, the aboveground deadwood debris carbon storage under different fire severities was analyzed in Huzhong forest region of Great Xing' an Mountains. The results showed that the fire severity had a significant effect on aboveground deadwood debris carbon storage. The deadwood debris carbon storage was in the order of high-severity > low-severity > unburned in Larix gmelinii stands, and mixed conifer-broadleaf stands ( L. gmelinii and Betula platyphylla), and in the order of high severity > unburned > low-severity in B. platyphylla stands. Fire disturbance significantly changed the component percentage of the deadwood debris carbon storage. The component percentage of snags increased and litter decreased with the increasing fire severity. Logs and stumps did not change significantly with the increasing fire severity. The spatial variation of deadwood debris carbon storage in forests burned with low-severity fire was higher than that in unburned forests. The spatial variation of deadwood debris carbon storage with high-severity fires was lowest. This spatial variation needed to be accounted when calculating forest deadwood debris carbon storage.

Non-supervised method for early forest fire detection and rapid mapping

NASA Astrophysics Data System (ADS)

Artés, Tomás; Boca, Roberto; Liberta, Giorgio; San-Miguel, Jesús

2017-09-01

Natural hazards are a challenge for the society. Scientific community efforts have been severely increased assessing tasks about prevention and damage mitigation. The most important points to minimize natural hazard damages are monitoring and prevention. This work focuses particularly on forest fires. This phenomenon depends on small-scale factors and fire behavior is strongly related to the local weather. Forest fire spread forecast is a complex task because of the scale of the phenomena, the input data uncertainty and time constraints in forest fire monitoring. Forest fire simulators have been improved, including some calibration techniques avoiding data uncertainty and taking into account complex factors as the atmosphere. Such techniques increase dramatically the computational cost in a context where the available time to provide a forecast is a hard constraint. Furthermore, an early mapping of the fire becomes crucial to assess it. In this work, a non-supervised method for forest fire early detection and mapping is proposed. As main sources, the method uses daily thermal anomalies from MODIS and VIIRS combined with land cover map to identify and monitor forest fires with very few resources. This method relies on a clustering technique (DBSCAN algorithm) and on filtering thermal anomalies to detect the forest fires. In addition, a concave hull (alpha shape algorithm) is applied to obtain rapid mapping of the fire area (very coarse accuracy mapping). Therefore, the method leads to a potential use for high-resolution forest fire rapid mapping based on satellite imagery using the extent of each early fire detection. It shows the way to an automatic rapid mapping of the fire at high resolution processing as few data as possible.

Forest fire effects on mercury deposition in the boreal forest

Treesearch

Emma L. Witt; Randall K. Kolka; Edward A. Nater; Trent R. Wickman

2009-01-01

The objective of this study was to determine how forest fire effects Hg deposition to nearby landscapes impacted by smoke plumes. Hg concentrations and deposition were hypothesized to increase in throughfall and open precipitation after fire, and canopy type was hypothesized to influence the magnitude of the increase. Conifer canopies, which are better able to scavenge...

Working forests, forest health and management challenges in the redwood region

Treesearch

Ken Pimlott

2017-01-01

As California continues into a fifth year of drought, tree mortality enhanced by the unprecedented bark beetle epidemic contributes to wildfires that continue to increase in frequency and severity. Recent fires have posed increasing fire suppression challenges, life safety concerns, post fire watershed impacts and lasting damage to forested landscapes. The ability of...

Increasing resiliency in frequent fire forests: Lessons from the Sierra Nevada and western Australia

Treesearch

Scott L. Stephens

2014-01-01

This paper will primarily focus on the management and restoration of forests adapted to frequent, low-moderate intensity fire regimes. These are the forest types that are most at risk from large, high-severity wildfires and in many regions their fire regimes are changing. Fire as a landscape process can exhibit self-limiting characteristics in some forests which can...

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.

Larch Forests of Middle Siberia: Long-Term Trends in Fire Return Intervals

NASA Technical Reports Server (NTRS)

Kharuk, Viacheslav I.; Dvinskaya, Mariya L.; Petrov, Ilya A.; Im, Sergei T.; Ranson, Kenneth J.

2016-01-01

Fire history within the northern larch forests of Central Siberia was studied (65+degN). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRIs) were found to be 112 +/- 49 years (based on firescars) and 106 +/- 36 years (based on firescars and tree natality dates). FRIs were increased with latitude increase and observed to be about 80 years at 64N, about 200 years near the Arctic Circle and about 300 years nearby the northern range limit of larch stands (approx.71+degN). Northward FRIs increase correlated with incoming solar radiation (r = -0.95). Post- Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase. Keywords Fire ecology Fire history Fire frequency Siberian wildfires Larch forests Climate change

Examining fire-induced forest changes using novel remote sensing technique: a case study in a mixed pine-oak forest

NASA Astrophysics Data System (ADS)

Meng, R.; Wu, J.; Zhao, F. R.; Cook, B.; Hanavan, R. P.; Serbin, S.

2017-12-01

Fire-induced forest changes has long been a central focus for forest ecology and global carbon cycling studies, and is becoming a pressing issue for global change biologists particularly with the projected increases in the frequency and intensity of fire with a warmer and drier climate. Compared with time-consuming and labor intensive field-based approaches, remote sensing offers a promising way to efficiently assess fire effects and monitor post-fire forest responses across a range of spatial and temporal scales. However, traditional remote sensing studies relying on simple optical spectral indices or coarse resolution imagery still face a number of technical challenges, including confusion or contamination of the signal by understory dynamics and mixed pixels with moderate to coarse resolution data (>= 30 m). As such, traditional remote sensing may not meet the increasing demand for more ecologically-meaningful monitoring and quantitation of fire-induced forest changes. Here we examined the use of novel remote sensing technique (i.e. airborne imaging spectroscopy and LiDAR measurement, very high spatial resolution (VHR) space-borne multi-spectral measurement, and high temporal-spatial resolution UAS-based (Unmanned Aerial System) imagery), in combination with field and phenocam measurements to map forest burn severity across spatial scales, quantify crown-scale post-fire forest recovery rate, and track fire-induced phenology changes in the burned areas. We focused on a mixed pine-oak forest undergoing multiple fire disturbances for the past several years in Long Island, NY as a case study. We demonstrate that (1) forest burn severity mapping from VHR remote sensing measurement can capture crown-scale heterogeneous fire patterns over large-scale; (2) the combination of VHR optical and structural measurements provides an efficient means to remotely sense species-level post-fire forest responses; (3) the UAS-based remote sensing enables monitoring of fire-induced forest phenology changes at unprecedented temporal and spatial resolutions. This work provides the methodological approach monitor fire-induced forest changes in a spatially explicit manner across scales, with important implications for fire-related forest management and for constraining/benchmarking process models.

Surface Fire Influence on Carbon Balance Components in Scots Pine Forest of Siberia, Russia

NASA Astrophysics Data System (ADS)

Kukavskaya, E.; Ivanova, G. A.; Conard, S. G.; Soja, A. J.

2008-12-01

Wildfire is one of the most important disturbances in boreal forests, and it can have a profound effect on forest-atmosphere carbon exchange. Pinus sylvestris (Scots pine) stands of Siberia are strongly impacted by fires of low to high severity. Biomass distribution in mature lichen/feathermoss Scots pine stands indicates that they are carbon sinks before fire. Fires contribute significantly to the carbon budget resulting in a considerable carbon efflux, initially through direct consumption of forest fuels and later as a result of tree mortality and decomposition of dead material accumulated on the forest floor. In initial postfire years these processes dominate over photosynthetic carbon assimilation, and the ecosystems become a carbon source. Over several postfire years, above-ground carbon in dead biomass tends to increase, with the increase depending significantly on fire severity. High-severity fire enhances dead biomass carbon, while moderate- and low-severity fires have minimal effect on above-ground carbon distribution in Scots pine ecosystems. Dead stand biomass carbon increases, primarily during the first two years following fires, due to tree mortality. This increase can account for up to 12.4% of the total stand biomass after low- and moderate- intensity fires. We found tree dieback following a high-intensity fire is an order of magnitude higher, and thus the dead biomass increases up to 88.1% of total above-ground biomass. Photosynthetic CO2 uptake decreases with increasing tree mortality, and needle foliage and bark are incorporated into the upper layer of the forest floor in the course of years. Ground vegetation and duff carbon were >90, 71-83, and 82% of prefire levels after fires of low, moderate, and high severity, respectively for the first 4 to 5 years after fire. Fires of low and moderate severity caused down woody fuel carbon to increase by 2.1 and 3.6 t ha-1 respectively by four years after burning as compared to the pre-fire values. Climate change and increasing drought length observed in recent decades have increased the probability of high-intensity fire occurrence. Areas burned have increased in extent and severity across Siberia, resulting in increased carbon emissions to the atmosphere from fuel combustion and post fire decomposition.

Restoring forest structure and process stabilizes forest carbon in wildfire-prone southwestern ponderosa pine forests

Treesearch

Matthew D. Hurteau; Shuang Liang; Katherine L. Martin; Malcolm P. North; George W. Koch; Bruce A. Hungate

2016-01-01

Changing climate and a legacy of fire-exclusion have increased the probability of high-severity wildfire, leading to an increased risk of forest carbon loss in ponderosa pine forests in the southwestern USA. Efforts to reduce high-severity fire risk through forest thinning and prescribed burning require both the removal and emission of carbon from these forests, and...

A review of the relationships between drought and forest fire in the United States

Treesearch

Jeremy S. Littell; David L. Peterson; Karin L. Riley; Yongqiang Liu; Charlie H. Luce

2016-01-01

The historical and presettlement relationships between drought and wildfire are well documented in North America, with forest fire occurrence and area clearly increasing in response to drought. There is also evidence that drought interacts with other controls (forest productivity, topography, fire weather, management activities) to affect fire intensity,...

Refining the oak-fire hypothesis for management of oak-dominated forests of the eastern United States

Treesearch

Mary A. Arthur; Heather D. Alexander; Daniel C. Dey; Callie J. Schweitzer; David L. Loftis

2012-01-01

Prescribed fires are increasingly implemented throughout eastern deciduous forests to accomplish various management objectives, including maintenance of oak-dominated (Quercus spp.) forests. Despite a regional research-based understanding of prehistoric and historic fire regimes, a parallel understanding of contemporary fire use to preserve oak...

Increased heat resistance in mycelia from wood fungi prevalent in forests characterized by fire: a possible adaptation to forest fire.

PubMed

Carlsson, Fredrik; Edman, Mattias; Holm, Svante; Eriksson, Anna-Maria; Jonsson, Bengt Gunnar

2012-10-01

Forest fires have been the major stand-replacing/modifying disturbance in boreal forests. To adapt to fire disturbance, different strategies have evolved. This study focuses on wood fungi, and a specific adaptation to forest fire: increased heat resistance in their mycelia. Fifteen species of wood fungi were selected and a priori sorted in two groups according to their prevalence in fire-affected environments. The fungi were cultivated on fresh wood and exposed to 100, 140, 180, 220 °C for 5, 10, 15, 20 and 25 min. under laboratory conditions. A clear difference was found among the two groups. Species prevalent in fire-affected habitats had a much higher survival rate over all combinations of time and temperature compared to species associated with other environments. Thus, the results indicate that fire adaptation in terms of increased heat resistance in mycelia occurs in some species of wood fungi. Such adaptation will influence the ecology and population dynamics of wood fungi, as well as having implications for best practices during restoration fires. Copyright © 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Fire intensity impacts on post-fire temperate coniferous forest net primary productivity

NASA Astrophysics Data System (ADS)

Sparks, Aaron M.; Kolden, Crystal A.; Smith, Alistair M. S.; Boschetti, Luigi; Johnson, Daniel M.; Cochrane, Mark A.

2018-02-01

Fire is a dynamic ecological process in forests and impacts the carbon (C) cycle through direct combustion emissions, tree mortality, and by impairing the ability of surviving trees to sequester carbon. While studies on young trees have demonstrated that fire intensity is a determinant of post-fire net primary productivity, wildland fires on landscape to regional scales have largely been assumed to either cause tree mortality, or conversely, cause no physiological impact, ignoring the impacted but surviving trees. Our objective was to understand how fire intensity affects post-fire net primary productivity in conifer-dominated forested ecosystems on the spatial scale of large wildland fires. We examined the relationships between fire radiative power (FRP), its temporal integral (fire radiative energy - FRE), and net primary productivity (NPP) using 16 years of data from the MOderate Resolution Imaging Spectrometer (MODIS) for 15 large fires in western United States coniferous forests. The greatest NPP post-fire loss occurred 1 year post-fire and ranged from -67 to -312 g C m-2 yr-1 (-13 to -54 %) across all fires. Forests dominated by fire-resistant species (species that typically survive low-intensity fires) experienced the lowest relative NPP reductions compared to forests with less resistant species. Post-fire NPP in forests that were dominated by fire-susceptible species were not as sensitive to FRP or FRE, indicating that NPP in these forests may be reduced to similar levels regardless of fire intensity. Conversely, post-fire NPP in forests dominated by fire-resistant and mixed species decreased with increasing FRP or FRE. In some cases, this dose-response relationship persisted for more than a decade post-fire, highlighting a legacy effect of fire intensity on post-fire C dynamics in these forests.

Implications of the spatial dynamics of fire spread for the bistability of savanna and forest.

PubMed

Schertzer, E; Staver, A C; Levin, S A

2015-01-01

The role of fire in expanding the global distribution of savanna is well recognized. Empirical observations and modeling suggest that fire spread has a threshold response to fuel-layer continuity, which sets up a positive feedback that maintains savanna-forest bistability. However, modeling has so far failed to examine fire spread as a spatial process that interacts with vegetation. Here, we use simple, well-supported assumptions about fire spread as an infection process and its effects on trees to ask whether spatial dynamics qualitatively change the potential for savanna-forest bistability. We show that the spatial effects of fire spread are the fundamental reason that bistability is possible: because fire spread is an infection process, it exhibits a threshold response to fuel continuity followed by a rapid increase in fire size. Other ecological processes affecting fire spread may also contribute including temporal variability in demography or fire spread. Finally, including the potential for spatial aggregation increases the potential both for savanna-forest bistability and for savanna and forest to coexist in a landscape mosaic.

Warm Dry Weather Conditions Cause of 2016 Fort McMurray Wild Forest Fire and Associated Air Quality

NASA Astrophysics Data System (ADS)

de Azevedo, S. C.; Singh, R. P.; da Silva, E. A., Sr.

2016-12-01

The climate change is evident from the increasing temperature around the world, day to day life and increasing frequency of natural hazards. The warm and dry conditions are the cause of frequent forest fires around the globe. Forest fires severely affect the air quality and human health. Multi sensor satellites and dense network of ground stations provide information about vegetation health, meteorological, air quality and atmospheric parameters. We have carried out detailed analysis of satellite and ground data of wild forest fire that occurred in May 2016 in Fort McMurray, Alberta, Canada. This wild forest fire destroyed 10 per cent of Fort McMurray's housing and forced more than 90,000 people to evacuate the surrounding areas. Our results show that the warm and dry conditions with low rainfall were the cause of Fort McMurray wild fire. The air quality parameters (particulate matter, CO, ozone, NO2, methane) and greenhouse gases measured from Atmospheric Infrared Sounder (AIRS) satellite show enhanced levels soon after the forest fire. The emissions from the forest fire affected health of population living in surrounding areas up to 300 km radius.

Using fire to increase the scale, benefits and future maintenance of fuels treatments

Treesearch

Malcolm P. North; Brandon M. Collins; Scott L Stephens

2012-01-01

The Forest Service is implementing a new planning rule and starting to revise forest plans for many of the 155 National Forests. In forests that historically had frequent fire regimes, the scale of current fuels reduction treatments has often been too limited to affect fire severity and the Forest Service has predominantly focused on suppression. In addition to...

Presettlement fire regime and vegetation mapping in Southeastern Coastal Plain forest ecosystems

Treesearch

Andrew D. Bailey; Robert Mickler; Cecil Frost

2007-01-01

Fire-adapted forest ecosystems make up 95 percent of the historic Coastal Plain vegetation types in the Southeastern United States. Fire suppression over the last century has altered the species composition of these ecosystems, increased fuel loads, and increased wildfire risk. Prescribed fire is one management tool used to reduce fuel loading and restore fire-adapted...

Defining fire environment zones in the boreal forests of northeastern China.

PubMed

Wu, Zhiwei; He, Hong S; Yang, Jian; Liang, Yu

2015-06-15

Fire activity in boreal forests will substantially increase with prolonged growing seasons under a warming climate. This trend poses challenges to managing fires in boreal forest landscapes. A fire environment zone map offers a basis for evaluating these fire-related problems and designing more effective fire management plans to improve the allocation of management resources across a landscape. Toward that goal, we identified three fire environment zones across boreal forest landscapes in northeastern China using analytical methods to identify spatial clustering of the environmental variables of climate, vegetation, topography, and human activity. The three fire environment zones were found to be in strong agreement with the spatial distributions of the historical fire data (occurrence, size, and frequency) for 1966-2005. This paper discusses how the resulting fire environment zone map can be used to guide forest fire management and fire regime prediction. Copyright © 2015 Elsevier B.V. All rights reserved.

Short- and long-term effects of fire on carbon in US dry temperate forest systems

USGS Publications Warehouse

Hurteau, Matthew D.; Brooks, Matthew L.

2011-01-01

Forests sequester carbon from the atmosphere, and in so doing can mitigate the effects of climate change. Fire is a natural disturbance process in many forest systems that releases carbon back to the atmosphere. In dry temperate forests, fires historically burned with greater frequency and lower severity than they do today. Frequent fires consumed fuels on the forest floor and maintained open stand structures. Fire suppression has resulted in increased understory fuel loads and tree density; a change in structure that has caused a shift from low- to high-severity fires. More severe fires, resulting in greater tree mortality, have caused a decrease in forest carbon stability. Fire management actions can mitigate the risk of high-severity fires, but these actions often require a trade-off between maximizing carbon stocks and carbon stability. We discuss the effects of fire on forest carbon stocks and recommend that managing forests on the basis of their specific ecologies should be the foremost goal, with carbon sequestration being an ancillary benefit. ?? 2011 by American Institute of Biological Sciences. All rights reserved.

Prioritizing forest fuels treatments based on the probability of high-severity fire restores adaptive capacity in Sierran forests

Treesearch

Daniel J. Krofcheck; Matthew D. Hurteau; Robert M. Scheller; E. Louise Loudermilk

2017-01-01

In frequent fire forests of the western United States, a legacy of fire suppression coupled with increases in fire weather severity have altered fire regimes and vegetation dynamics. When coupled with projected climate change, these conditions have the potential to lead to vegetation type change and altered carbon (C) dynamics. In the Sierra Nevada, fuels...

Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

PubMed

Baker, William L

2015-01-01

Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984-2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984-2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046-2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in dry forests.

Climate change, forests, fire, water, and fish: Building resilient landscapes, streams, and managers

Treesearch

Charles Luce; Penny Morgan; Kathleen Dwire; Daniel Isaak; Zachary Holden; Bruce Rieman

2012-01-01

Fire will play an important role in shaping forest and stream ecosystems as the climate changes. Historic observations show increased dryness accompanying more widespread fire and forest die-off. These events punctuate gradual changes to ecosystems and sometimes generate stepwise changes in ecosystems. Climate vulnerability assessments need to account for fire in their...

Broadleaf deciduous forest counterbalanced the direct effect of climate on Holocene fire regime in hemiboreal/boreal region (NE Europe)

NASA Astrophysics Data System (ADS)

Feurdean, Angelica; Veski, Siim; Florescu, Gabriela; Vannière, Boris; Pfeiffer, Mirjam; O'Hara, Robert B.; Stivrins, Normunds; Amon, Leeli; Heinsalu, Atko; Vassiljev, Jüri; Hickler, Thomas

2017-08-01

Disturbances by fire are essential for the functioning of boreal/hemiboreal forests, but knowledge of long-term fire regime dynamics is limited. We analysed macrocharcoal morphologies and pollen of a sediment record from Lake Lielais Svētiņu (eastern Latvia), and in conjunction with fire traits analysis present the first record of Holocene variability in fire regime, fuel sources and fire types in boreal forests of the Baltic region. We found a phase of moderate to high fire activity during the cool and moist early (mean fire return interval; mFRI of ∼280 years; 11,700-7500 cal yr BP) and the late (mFRI of ∼190 years; 4500-0 cal yr BP) Holocene and low fire activity (mFRI of ∼630 years) during the Holocene Thermal Optimum (7500-4500 cal yr BP). Charcoal morphotypes and the pollen record show the predominance of frequent surface fires, occasionally transitioning to the crown during Pinus sylvestris-Betula boreal forests and less frequent surface fires during the dominance of temperate deciduous forests. In contrast to the prevailing opinion that fires in boreal forests are mostly low to moderate severity surface fires, we found evidence for common occurrence of stand-replacing crown fires in Picea abies canopy. Our results highlight that charcoal morphotypes analysis allows for distinguishing the fuel types and surface from crown fires, therefore significantly advancing our interpretation of fire regime. Future warmer temperatures and increase in the frequency of dry spells and abundant biomass accumulation can enhance the fire risk on the one hand, but will probably promote the expansion of broadleaf deciduous forests to higher latitudes, on the other hand. By highlighting the capability of broadleaf deciduous forests to act as fire-suppressing landscape elements, our results suggest that fire activity may not increase in the Baltic area under future climate change.

Disturbance and productivity interactions mediate stability of forest composition and structure.

PubMed

O'Connor, Christopher D; Falk, Donald A; Lynch, Ann M; Swetnam, Thomas W; Wilcox, Craig P

2017-04-01

Fire is returning to many conifer-dominated forests where species composition and structure have been altered by fire exclusion. Ecological effects of these fires are influenced strongly by the degree of forest change during the fire-free period. Response of fire-adapted species assemblages to extended fire-free intervals is highly variable, even in communities with similar historical fire regimes. This variability in plant community response to fire exclusion is not well understood; however, ecological mechanisms such as individual species' adaptations to disturbance or competition and underlying site characteristics that facilitate or impede establishment and growth have been proposed as potential drivers of assemblage response. We used spatially explicit dendrochronological reconstruction of tree population dynamics and fire regimes to examine the influence of historical disturbance frequency (a proxy for adaptation to disturbance or competition), and potential site productivity (a proxy for underlying site characteristics) on the stability of forest composition and structure along a continuous ecological gradient of pine, dry mixed-conifer, mesic mixed-conifer, and spruce-fir forests following fire exclusion. While average structural density increased in all forests, species composition was relatively stable in the lowest productivity pine-dominated and highest productivity spruce-fir-dominated sites immediately following fire exclusion and for the next 100 years, suggesting site productivity as a primary control on species composition and structure in forests with very different historical fire regimes. Species composition was least stable on intermediate productivity sites dominated by mixed-conifer forests, shifting from primarily fire-adapted species to competition-adapted, fire-sensitive species within 20 years of fire exclusion. Rapid changes to species composition and stand densities have been interpreted by some as evidence of high-severity fire. We demonstrate that the very different ecological process of fire exclusion can produce similar changes by shifting selective pressures from disturbance-mediated to productivity-mediated controls. Restoring disturbance-adapted species composition and structure to intermediate productivity forests may help to buffer them against projected increasing temperatures, lengthening fire seasons, and more frequent and prolonged moisture stress. Fewer management options are available to promote adaptation in forest assemblages historically constrained by underlying site productivity. © 2016 by the Ecological Society of America.

Roost selection by male Indiana Myotis following forest fires in central Appalachian hardwoods forests

Treesearch

Joshua B. Johnson; W. Mark Ford; Jane L. Rodrigue; John W. Edwards; Catherine Johnson

2010-01-01

Despite the potential for prescribed fire and natural wildfire to increase snag abundance in hardwood forests, few studies have investigated effects of fire on bat roosting habitat, particularly that of the endangered Indiana myotis Myotis sodalis. From 2001 to 2009, we examined roost selection of Indiana myotis in burned and unburned forests in...

Fire and vegetation dynamics in the Cross Timbers forests of south-central North America

Treesearch

Steve W. Hallgren; Ryan D. DeSantis; Jesse A. Burton

2012-01-01

The vegetation of the Cross Timbers forests was maintained for thousands of years by fire; the historic fire return interval was likely 1 to 10 years. Fire suppression over the past century led to a doubling of stand basal area, increased diversity of tree species, reduced dominance of oak, and increased mesic species intolerant of fire. Dendrochronological studies...

[Simulating the effects of climate change and fire disturbance on aboveground biomass of boreal forests in the Great Xing'an Mountains, Northeast China].

PubMed

Luo, Xu; Wang, Yu Li; Zhang, Jin Quan

2018-03-01

Predicting the effects of climate warming and fire disturbance on forest aboveground biomass is a central task of studies in terrestrial ecosystem carbon cycle. The alteration of temperature, precipitation, and disturbance regimes induced by climate warming will affect the carbon dynamics of forest ecosystem. Boreal forest is an important forest type in China, the responses of which to climate warming and fire disturbance are increasingly obvious. In this study, we used a forest landscape model LANDIS PRO to simulate the effects of climate change on aboveground biomass of boreal forests in the Great Xing'an Mountains, and compared direct effects of climate warming and the effects of climate warming-induced fires on forest aboveground biomass. The results showed that the aboveground biomass in this area increased under climate warming scenarios and fire disturbance scenarios with increased intensity. Under the current climate and fire regime scenario, the aboveground biomass in this area was (97.14±5.78) t·hm -2 , and the value would increase up to (97.93±5.83) t·hm -2 under the B1F2 scenario. Under the A2F3 scenario, aboveground biomass at landscape scale was relatively higher at the simulated periods of year 100-150 and year 150-200, and the value were (100.02±3.76) t·hm -2 and (110.56±4.08) t·hm -2 , respectively. Compared to the current fire regime scenario, the predicted biomass at landscape scale was increased by (0.56±1.45) t·hm -2 under the CF2 scenario (fire intensity increased by 30%) at some simulated periods, and the aboveground biomass was reduced by (7.39±1.79) t·hm -2 in CF3 scenario (fire intensity increased by 230%) at the entire simulation period. There were significantly different responses between coniferous and broadleaved species under future climate warming scenarios, in that the simulated biomass for both Larix gmelinii and Betula platyphylla showed decreasing trend with climate change, whereas the simulated biomass for Pinus sylvestris var. mongolica, Picea koraiensis and Populus davidiana showed increasing trend at different degrees during the entire simulation period. There was a time lag for the direct effect of climate warming on biomass for coniferous and broadleaved species. The response time of coniferous species to climate warming was 25-30 years, which was longer than that for broadleaf species. The forest landscape in the Great Xing'an Mountains was sensitive to the interactive effect of climate warming (high CO 2 emissions) and high intensity fire disturbance. Future climate warming and high intensity forest fire disturbance would significantly change the composition and structure of forest ecosystem.

Lagged cumulative spruce budworm defoliation affects the risk of fire ignition in Ontario, Canada.

PubMed

James, Patrick M A; Robert, Louis-Etienne; Wotton, B Mike; Martell, David L; Fleming, Richard A

2017-03-01

Detailed understanding of forest disturbance interactions is needed for effective forecasting, modelling, and management. Insect outbreaks are a significant forest disturbance that alters forest structure as well as the distribution and connectivity of combustible fuels at broad spatial scales. The effect of insect outbreaks on fire activity is an important but contentious issue with significant policy consequences. The eastern spruce budworm (Choristoneura fumiferana) is a native defoliating insect in eastern North America whose periodic outbreaks create large patches of dead fir and spruce trees. Of particular concern to fire and forest managers is whether these patches represent an increased fire risk, if so, for how long, and how the relationship between defoliation and fire risk varies through space and time. Previous work suggests a temporary increase in flammability in budworm-killed forests, but regional and seasonal variability in these relationships has not been examined. Using an extensive database on historical lightning-caused fire ignitions and spruce budworm defoliation between 1963 and 2000, we assess the relative importance of cumulative defoliation and fire weather on the probability of ignition in Ontario, Canada. We modeled fire ignition using a generalized additive logistic regression model that accounts for temporal autocorrelation in fire weather. We compared two ecoregions in eastern Ontario (Abitibi Plains) and western Ontario (Lake of the Woods) that differ in terms of climate, geomorphology, and forest composition. We found that defoliation has the potential to both increase and decrease the probability of ignition depending on the time scale, ecoregion, and season examined. Most importantly, we found that lagged spruce budworm defoliation (8-10 yr) increases the risk of fire ignition whereas recent defoliation (1 yr) can decrease this risk. We also found that historical defoliation has a greater influence on ignition risk during the spring than during the summer fire season. Given predicted increases in forest insect activity due to global change, these results represent important information for fire management agencies that can be used to refine existing models of fire risk. © 2016 by the Ecological Society of America.

Carbon Emission from Forest Fires on Scots Pine Logging Sites in the Angara Region of Central Siberia

NASA Astrophysics Data System (ADS)

Ivanova, G. A.; Conard, S. G.; McRae, D. J.; Kukavskaya, E. A.; Bogorodskaya, A. V.; Kovaleva, N. M.

2010-12-01

Wildfire and large-scale forest harvesting are the two major disturbances in the Russian boreal forests. Non-recovered logged sites total about a million hectares in Siberia. Logged sites are characterized by higher fire hazard than forest sites due to the presence of generally untreated logging slash (i.e., available fuel) which dries out much more rapidly compared to understory fuels. Moreover, most logging sites can be easily accessed by local population; this increases the risk for fire ignition. Fire impacts on the overstory trees, subcanopy woody layer, and ground vegetation biomass were estimated on 14 logged and unlogged comparison sites in the Lower Angara Region in 2009-2010 as part of the NASA-funded NEESPI project, The Influence of Changing Forestry Practices on the Effects of Wildfire and on Interactions Between Fire and Changing Climate in Central Siberia. Based on calculated fuel consumption, we estimated carbon emission from fires on both logged and unlogged burned sites. Carbon emission from fires on logged sites appeared to be twice that on unlogged sites. Soil respiration decreased on both site types after fires. This reduction may partially offset fire-produced carbon emissions. Carbon emissions from fire and post-fire ecosystem damage on logged sites are expected to increase under changing climate conditions and as a result of anticipated increases in future forest harvesting in Siberia.

Fire and drought [Chapter 7

Treesearch

Jeremy S. Littell; David L. Peterson; Karin L. Riley; Yongqiang Liu; Charles H. Luce

2016-01-01

Historical and presettlement relationships between drought and wildfire have been well documented in much of North America, with forest fire occurrence and area burned clearly increasing in response to drought. Drought interacts with other controls (forest productivity, topography, and fire weather) to affect fire intensity and severity. Fire regime characteristics (...

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).

Simulating boreal forest carbon dynamics after stand-replacing fire disturbance: insights from a global process-based vegetation model

USGS Publications Warehouse

Yue, C.; Ciais, P.; Luyssaert, S.; Cadule, P.; Harden, J.; Randerson, J.; Bellassen, V.; Wang, T.; Piao, S.L.; Poulter, B.; Viovy, N.

2013-01-01

Stand-replacing fires are the dominant fire type in North American boreal forests. They leave a historical legacy of a mosaic landscape of different aged forest cohorts. This forest age dynamics must be included in vegetation models to accurately quantify the role of fire in the historical and current regional forest carbon balance. The present study adapted the global process-based vegetation model ORCHIDEE to simulate the CO2 emissions from boreal forest fire and the subsequent recovery after a stand-replacing fire; the model represents postfire new cohort establishment, forest stand structure and the self-thinning process. Simulation results are evaluated against observations of three clusters of postfire forest chronosequences in Canada and Alaska. The variables evaluated include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index, and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). When forced by local climate and the atmospheric CO2 history at each chronosequence site, the model simulations generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with the measurement accuracy (for CO2 flux ~100 g C m−2 yr−1, for biomass carbon ~1000 g C m−2 and for soil carbon ~2000 g C m−2). We find that the current postfire forest carbon sink at the evaluation sites, as observed by chronosequence methods, is mainly due to a combination of historical CO2 increase and forest succession. Climate change and variability during this period offsets some of these expected carbon gains. The negative impacts of climate were a likely consequence of increasing water stress caused by significant temperature increases that were not matched by concurrent increases in precipitation. Our simulation results demonstrate that a global vegetation model such as ORCHIDEE is able to capture the essential ecosystem processes in fire-disturbed boreal forests and produces satisfactory results in terms of both carbon fluxes and carbon-stock evolution after fire. This makes the model suitable for regional simulations in boreal regions where fire regimes play a key role in the ecosystem carbon balance.

Simulating boreal forest carbon dynamics after stand-replacing fire disturbance: insights from a global process-based vegetation model

NASA Astrophysics Data System (ADS)

Yue, C.; Ciais, P.; Luyssaert, S.; Cadule, P.; Harden, J.; Randerson, J.; Bellassen, V.; Wang, T.; Piao, S. L.; Poulter, B.; Viovy, N.

2013-12-01

Stand-replacing fires are the dominant fire type in North American boreal forests. They leave a historical legacy of a mosaic landscape of different aged forest cohorts. This forest age dynamics must be included in vegetation models to accurately quantify the role of fire in the historical and current regional forest carbon balance. The present study adapted the global process-based vegetation model ORCHIDEE to simulate the CO2 emissions from boreal forest fire and the subsequent recovery after a stand-replacing fire; the model represents postfire new cohort establishment, forest stand structure and the self-thinning process. Simulation results are evaluated against observations of three clusters of postfire forest chronosequences in Canada and Alaska. The variables evaluated include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index, and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). When forced by local climate and the atmospheric CO2 history at each chronosequence site, the model simulations generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with the measurement accuracy (for CO2 flux ~100 g C m-2 yr-1, for biomass carbon ~1000 g C m-2 and for soil carbon ~2000 g C m-2). We find that the current postfire forest carbon sink at the evaluation sites, as observed by chronosequence methods, is mainly due to a combination of historical CO2 increase and forest succession. Climate change and variability during this period offsets some of these expected carbon gains. The negative impacts of climate were a likely consequence of increasing water stress caused by significant temperature increases that were not matched by concurrent increases in precipitation. Our simulation results demonstrate that a global vegetation model such as ORCHIDEE is able to capture the essential ecosystem processes in fire-disturbed boreal forests and produces satisfactory results in terms of both carbon fluxes and carbon-stock evolution after fire. This makes the model suitable for regional simulations in boreal regions where fire regimes play a key role in the ecosystem carbon balance.

Carbon dynamics of forest in Washington, USA: 21st century projections based on climate-driven changes in fire regimes

Treesearch

Crystal L. Raymond; Donald McKenzie

2012-01-01

During the 21st century, climate-driven changes in fire regimes will be a key agent of change in forests of the U.S. Pacific Northwest (PNW). Understanding the response of forest carbon (C) dynamics to increases in fire will help quantify limits on the contribution of forest C storage to climate change mitigation and prioritize forest types for...

Efficacy of variable density thinning and prescribed fire for restoring forest heterogeneity to mixed-conifer forest in the central Sierra Nevada, CA

Treesearch

Eric E. Knapp; Jamie M. Lydersen; Malcolm P. North; Brandon M. Collins

2017-01-01

Frequent-fire forests were historically characterized by lower tree density, a higher proportion of pine species, and greater within-stand spatial variability, compared to many contemporary forests where fire has been excluded. As a result, such forests are now increasingly unstable, prone to uncharacteristically severe wildfire or high levels of tree mortality in...

Shifts in functional traits elevate risk of fire-driven tree dieback in tropical savanna and forest biomes.

PubMed

Pellegrini, Adam F A; Franco, Augusto C; Hoffmann, William A

2016-03-01

Numerous predictions indicate rising CO2 will accelerate the expansion of forests into savannas. Although encroaching forests can sequester carbon over the short term, increased fires and drought-fire interactions could offset carbon gains, which may be amplified by the shift toward forest plant communities more susceptible to fire-driven dieback. We quantify how bark thickness determines the ability of individual tree species to tolerate fire and subsequently determine the fire sensitivity of ecosystem carbon across 180 plots in savannas and forests throughout the 2.2-million km(2) Cerrado region in Brazil. We find that not accounting for variation in bark thickness across tree species underestimated carbon losses in forests by ~50%, totaling 0.22 PgC across the Cerrado region. The lower bark thicknesses of plant species in forests decreased fire tolerance to such an extent that a third of carbon gains during forest encroachment may be at risk of dieback if burned. These results illustrate that consideration of trait-based differences in fire tolerance is critical for determining the climate-carbon-fire feedback in tropical savanna and forest biomes. © 2015 John Wiley & Sons Ltd.

Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

PubMed Central

Odion, Dennis C.; Hanson, Chad T.; Arsenault, André; Baker, William L.; DellaSala, Dominick A.; Hutto, Richard L.; Klenner, Walt; Moritz, Max A.; Sherriff, Rosemary L.; Veblen, Thomas T.; Williams, Mark A.

2014-01-01

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to “restore” forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America. PMID:24498383

Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America.

PubMed

Odion, Dennis C; Hanson, Chad T; Arsenault, André; Baker, William L; Dellasala, Dominick A; Hutto, Richard L; Klenner, Walt; Moritz, Max A; Sherriff, Rosemary L; Veblen, Thomas T; Williams, Mark A

2014-01-01

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.

Climate change, fire management, and ecological services in the southwestern US

USGS Publications Warehouse

Hurteau, Matthew D.; Bradford, John B.; Fulé, Peter Z.; Taylor, Alan H.; Martin, Katherine L.

2014-01-01

The diverse forest types of the southwestern US are inseparable from fire. Across climate zones in California, Nevada, Arizona, and New Mexico, fire suppression has left many forest types out of sync with their historic fire regimes. As a result, high fuel loads place them at risk of severe fire, particularly as fire activity increases due to climate change. A legacy of fire exclusion coupled with a warming climate has led to increasingly large and severe wildfires in many southwest forest types. Climate change projections include an extended fire season length due to earlier snowmelt and a general drying trend due to rising temperatures. This suggests the future will be warmer and drier regardless of changes in precipitation. Hotter, drier conditions are likely to increase forest flammability, at least initially. Changes in climate alone have the potential to alter the distribution of vegetation types within the region, and climate-driven shifts in vegetation distribution are likely to be accelerated when coupled with stand-replacing fire. Regardless of the rate of change, the interaction of climate and fire and their effects on Southwest ecosystems will alter the provisioning of ecosystem services, including carbon storage and biodiversity. Interactions between climate, fire, and vegetation growth provide a source of great uncertainty in projecting future fire activity in the region, as post-fire forest recovery is strongly influenced by climate and subsequent fire frequency. Severe fire can be mitigated with fuels management including prescribed fire, thinning, and wildfire management, but new strategies are needed to ensure the effectiveness of treatments across landscapes. We review the current understanding of the relationship between fire and climate in the Southwest, both historical and projected. We then discuss the potential implications of climate change for fire management and examine the potential effects of climate change and fire on ecosystem services. We conclude with an assessment of the role of fire management in an increasingly flammable Southwest.

Impact of prescribed fire and other factors on cheatgrass persistence in a Sierra Nevada ponderosa pine forest

USGS Publications Warehouse

Keeley, J.E.; McGinnis, T.W.

2007-01-01

Following the reintroduction of fire Bromus tectorum has invaded the low elevation ponderosa pine forests in parts of Kings Canyon National Park, California. We used prescribed burns, other field manipulations, germination studies, and structural equation modelling, to investigate how fire and other factors affect the persistence of cheatgrass in these forests. Our studies show that altering burning season to coincide with seed maturation is not likely to control cheatgrass because sparse fuel loads generate low fire intensity. Increasing time between prescribed fires may inhibit cheatgrass by increasing surface fuels (both herbaceous and litter), which directly inhibit cheatgrass establishment, and by creating higher intensity fires capable of killing a much greater fraction of the seed bank. Using structural equation modelling, postfire cheatgrass dominance was shown to be most strongly controlled by the prefire cheatgrass seedbank; other factors include soil moisture, fire intensity, soil N, and duration of direct sunlight. Current fire management goals in western conifer forests are focused on restoring historical fire regimes; however, these frequent fire regimes may enhance alien plant invasion in some forest types. Where feasible, fire managers should consider the option of an appropriate compromise between reducing serious fire hazards and exacerbating alien plant invasions. ?? IAWF 2007.

Opportunities for making wood products from small diameter trees in Colorado

Treesearch

Dennis L. Lynch; Kurt H. Mackes

2002-01-01

Colorado's forests are at risk to forest health problems and catastrophic fire. Forest areas at high risk to catastrophic fire, commonly referred to as Red Zones, contain 2.4 million acres in the Colorado Front Range and 6.3 million acres Statewide. The increasing frequency, size, and intensity of recent forest fires have prompted large appropriations of Federal...

Carbon tradeoffs of restoration and provision of endangered species habitat in a fire-maintained forest

Treesearch

Katherine L. Martin; Matthew D. Hurteau; Bruce A. Hungate; George W. Koch; Malcolm P. North

2015-01-01

Forests are a significant part of the global carbon cycle and are increasingly viewed as tools for mitigating climate change. Natural disturbances, such as fire, can reduce carbon storage. However, many forests and dependent species evolved with frequent fire as an integral ecosystem process. We used a landscape forest simulation model to evaluate the effects of...

Bird Responses to burns and clear cuts in the boreal forest of Canada

Treesearch

Susan J. Hannon; Pierre Drapeau

2005-01-01

Unlike many other ecosystems in North America, the boreal forest in Canada still retains a natural fire regime. However, increasing industrial forestry, primarily clear cutting, could alter natural fire dynamics and adversely affect some species. A possible solution to this, promoted by many forest managers, is to cut the forest in a way that emulates natural fire...

Direct and indirect effects of fires on the carbon balance of tropical forest ecosystems (Invited)

NASA Astrophysics Data System (ADS)

Randerson, J. T.; Tosca, M. G.; Ward, D. S.; Kasibhatla, P. S.; Mahowald, N. M.; Hess, P. G.

2013-12-01

Fires influence the carbon budget of tropical forests directly because they account for a significant component of net emissions from deforestation and forest degradation. They also have indirect effects on nearby intact forests by modifying regional climate, atmospheric composition, and patterns of nutrient deposition. These latter pathways are not well understood and are often ignored in climate mitigation efforts such as the United Nations Program on Reducing Emissions from Deforestation and forest Degradation (REDD+). Here we used the Community Atmosphere Model (CAM5) and the Global Fire Emissions Database (GFED3) to quantify the impacts of fire-emitted aerosols on the productivity of tropical forests. Across the tropical forest biome, fire-emitted aerosols reduced surface temperatures and increased the diffuse solar insolation fraction. These changes in surface meteorology increased gross primary production (GPP) in the Community Land Model. However, these drivers were more than offset in many regions by reductions in soil moisture and total solar radiation. The net effect of fire aerosols caused GPP to decrease by approximately 8% in equatorial Asia and 6% in the central Africa. In the Amazon, decreases in photosynthesis in the western part of the basin were nearly balanced by increases in the south and east. Using additional CAM5 and GEOS-Chem model simulations, we estimated fire contributions to surface concentrations of ozone. Using empirical relationships between ozone exposure and GPP from field studies and models, we estimated how tropical forest GPP was further modified by fire-induced ozone. Our results suggest that efforts to reduce the fire component of tropical land use fluxes may have sustainability benefits that extend beyond the balance sheet for greenhouse gases.

Management options for mitigating Nitrogen (N) losses from N-saturated mixed-conifer forests in California

Treesearch

Benjamin S. Gimeno; Fengming Yuan; Mark E. Fenn; Thomas Meixner

2009-01-01

Mixed-conifer forests of southern California are exposed to nitrogen (N) deposition levels that impair carbon (C) and N cycling, enhance forest flammability, increase the risk of fire occurrence and air pollution emissions in fire, and increase nitrate...

Wildfire and forest disease interaction lead to greater loss of soil nutrients and carbon.

PubMed

Cobb, Richard C; Meentemeyer, Ross K; Rizzo, David M

2016-09-01

Fire and forest disease have significant ecological impacts, but the interactions of these two disturbances are rarely studied. We measured soil C, N, Ca, P, and pH in forests of the Big Sur region of California impacted by the exotic pathogen Phytophthora ramorum, cause of sudden oak death, and the 2008 Basin wildfire complex. In Big Sur, overstory tree mortality following P. ramorum invasion has been extensive in redwood and mixed evergreen forests, where the pathogen kills true oaks and tanoak (Notholithocarpus densiflorus). Sampling was conducted across a full-factorial combination of disease/no disease and burned/unburned conditions in both forest types. Forest floor organic matter and associated nutrients were greater in unburned redwood compared to unburned mixed evergreen forests. Post-fire element pools were similar between forest types, but lower in burned-invaded compared to burned-uninvaded plots. We found evidence disease-generated fuels led to increased loss of forest floor C, N, Ca, and P. The same effects were associated with lower %C and higher PO4-P in the mineral soil. Fire-disease interactions were linear functions of pre-fire host mortality which was similar between the forest types. Our analysis suggests that these effects increased forest floor C loss by as much as 24.4 and 21.3 % in redwood and mixed evergreen forests, respectively, with similar maximum losses for the other forest floor elements. Accumulation of sudden oak death generated fuels has potential to increase fire-related loss of soil nutrients at the region-scale of this disease and similar patterns are likely in other forests, where fire and disease overlap.

Different fire-climate relationships on forested and non-forested landscapes in the Sierra Nevada ecoregion

USGS Publications Warehouse

Keeley, Jon E.; Syphard, Alexandra D.

2015-01-01

In the California Sierra Nevada region, increased fire activity over the last 50 years has only occurred in the higher-elevation forests on US Forest Service (USFS) lands, and is not characteristic of the lower-elevation grasslands, woodlands and shrublands on state responsibility lands (Cal Fire). Increased fire activity on USFS lands was correlated with warmer and drier springs. Although this is consistent with recent global warming, we found an equally strong relationship between fire activity and climate in the first half of the 20th century. At lower elevations, warmer and drier conditions were not strongly tied to fire activity over the last 90 years, although prior-year precipitation was significant. It is hypothesised that the fire–climate relationship in forests is determined by climatic effects on spring and summer fuel moisture, with hotter and drier springs leading to a longer fire season and more extensive burning. In contrast, future fire activity in the foothills may be more dependent on rainfall patterns and their effect on the herbaceous fuel load. We predict spring and summer warming will have a significant impact on future fire regimes, primarily in higher-elevation forests. Lower elevation ecosystems are likely to be affected as much by global changes that directly involve land-use patterns as by climate change.

Fire-induced Carbon Emissions and Regrowth Uptake in Western U.S. Forests: Documenting Variation Across Forest Types, Fire Severity, and Climate Regions

NASA Technical Reports Server (NTRS)

Ghimire, Bardan; Williams, Christopher A.; Collatz, George James; Vanderhoof, Melanie

2012-01-01

The forest area in the western United States that burns annually is increasing with warmer temperatures, more frequent droughts, and higher fuel densities. Studies that examine fire effects for regional carbon balances have tended to either focus on individual fires as examples or adopt generalizations without considering how forest type, fire severity, and regional climate influence carbon legacies. This study provides a more detailed characterization of fire effects and quantifies the full carbon impacts in relation to direct emissions, slow release of fire-killed biomass, and net carbon uptake from forest regrowth. We find important variations in fire-induced mortality and combustion across carbon pools (leaf, live wood, dead wood, litter, and duff) and across low- to high-severity classes. This corresponds to fire-induced direct emissions from 1984 to 2008 averaging 4 TgC/yr and biomass killed averaging 10.5 TgC/yr, with average burn area of 2723 sq km/yr across the western United States. These direct emission and biomass killed rates were 1.4 and 3.7 times higher, respectively, for high-severity fires than those for low-severity fires. The results show that forest regrowth varies greatly by forest type and with severity and that these factors impose a sustained carbon uptake legacy. The western U.S. fires between 1984 and 2008 imposed a net source of 12.3 TgC/yr in 2008, accounting for both direct fire emissions (9.5 TgC/yr) and heterotrophic decomposition of fire-killed biomass (6.1 TgC yr1) as well as contemporary regrowth sinks (3.3 TgC/yr). A sizeable trend exists toward increasing emissions as a larger area burns annually.

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.

Implementation of the fire and fire surrogate study— a national research effort to evaluate the consequences of fuel reduction treatments

Treesearch

Andrew Youngblood; Kerry L. Metlen; Eric E. Knapp; Kenneth W. Outcalt; Scott L. Stephens; Thomas A. Waldrop; Daniel Yaussy

2005-01-01

Many fire-dependent forests today are denser, contain fewer large trees, have higher fuel loads, and greater fuel continuity than occurred under historical fire regimes. These conditions increase the probability of unnaturally severe wildfires. Silviculturists are increasingly being asked to design fuel reduction treatments to help protect existing and future forest...

Effects of post-fire logging on forest surface air temperatures in the Siskiyou Mountains, Oregon, USA

Treesearch

Joseph B. Fontaine; Daniel C. Donato; John L. Campbell; Jonathan G. Martin; Beverley E. Law

2010-01-01

Following stand-replacing wildfire, post-fire (salvage) logging of fire-killed trees is a widely implemented management practice in many forest types. A common hypothesis is that removal of fire-killed trees increases surface temperatures due to loss of shade and increased solar radiation, thereby influencing vegetation establishment and possibly stand development. Six...

Post Wildfire Changes in Plant Functioning and Vegetation Dynamics: Implications for Water Fluxes in Re-sprouting Forests

NASA Astrophysics Data System (ADS)

Nolan, R. H.; Lane, P. N.; Mitchell, P. J.; Bradstock, R. A.

2011-12-01

Fire induced changes to the vegetation dynamics in temperate forests have been demonstrated to affect evapotranspiration (Et) rates through increases in plant size and density and stand-level transpiration and interception. In many cases these transient changes in forest structure result in substantial declines in stream flow for protracted periods after the disturbance. However to date research has focused on the wetter 'ash' forests of south-eastern Australia which solely regenerate via seedlings, it is unknown what changes in Et may occur in those forests which re-sprout post-fire. We hypothesize that Et fluxes track post-fire changes in sapwood area and leaf area index (L) in re-sprouting temperate forests, increasing as the forest regenerates. Following the 2009 Black Saturday wildfires in Victoria, we monitored Et rates for over a year in both damp and dry re-sprouting forest, incorporating a range of fire severity classes. Components of Et including overstorey transpiration, rainfall interception loss and forest floor Et were measured in conjunction with changes in L, sapwood area and leaf physiology. The monitoring period began one year post-fire with a typical hot, dry summer, at which stage Et rates in burnt forest were similar or less than those in unburnt forest. During the following summer, which was one of the wettest on record, Et increased across all monitoring plots but particularly so in the burnt forest where seedling regeneration resulted in an understorey L nearly twice that of unburnt forest. Forest floor Et was up to 46% higher in burnt forest, and rainfall interception values accounted for approximately 25% of rainfall compared to 15% in unburnt forest. The greatest increase in canopy transpiration rates over this period occurred in those trees subject to a low intensity fire where most of the canopy remained intact but there was also fire-triggered sprouting of new leaves along the trunk and main branches. In these trees rates of sapflow, standardized by sapwood area, were up to 50% greater than in unburnt trees. Measurements of leaf physiology in mature leaves, regenerating canopy leaves and in seedlings indicate higher rates of stomatal conductance in seedlings, and in the early regeneration phase of canopy leaves, which may be driving higher rates of water use per unit leaf area in the early stages of post-fire regeneration. This research indicates that disturbance-induced changes in vegetation dynamics are dependent on fire severity and can alter forest energy and water balances through changes in stand structure (i.e. L) and adjustments in plant functioning via leaf level increases in water use.

Boreal ditched forest and peatland are more vulnerable to forest fire than unditched areas

NASA Astrophysics Data System (ADS)

Köhler, Stephan J.; Granath, Gustav; Landahl, Anna; Fölster, Jens

2016-04-01

During summer of 2014 the largest wildfire in Swedish modern history occurred. The fire was ignited in a forest close to the Swedish town Sala and incinerated a total of 14 000 ha. The frequency of wildfires is expected to increase, due to effects of climate change such as increased temperature and decreased precipitation during the summer months. Wildfires can have a considerable impact on aquatic ecosystems and previous studies of wildfires have shown elevated concentrations of nutrients, cat- and anions. The area of the fire mainly consists of forestland, peatland and lakes and has been affected by acidification and intensive forestry. To assess the fire severity and the effects on the water chemistry, the fire severity were analyzed and classified using aerial phtographs and high resolution LIDAR data. The analysis indicated that increased fire intensity caused increased fire severity and that drained forested areas were more vulnerable to fire than undrained peatland. Measurements of water chemistry were conducted at nine streams and ten lakes inside the affected area. At two sites sensors for multiple parameters were deployed. During the initial three months of the post-fire period large peaks of ammonia-N and sulphate were observed in the streams and in a majority of the lakes while DOC was suppressed. In one stream Gärsjöbäcken the median concentrations of ammonia-N were 79 times higher after the fire. Due to nitrification the elevated concentrations of ammonia-N-nitrogen caused elevated concentrations of nitrate-nitrogen. The initial peak of sulphate caused a drop in ANC but after the peak had past ANC increased due to elevated concentrations of base cations. Correlation analysis of fire severity and water chemistry indicated that the maximum concentrations of ammonia-N increased with severely burned canopies in drained forested peatlands and in scorched open peatland. In a future climate with increased dry spells extensive ditching operations in forested peatlands might be counterproductive as it promotes fire vulnerability even in cold boreal regions.

The way to a healthy future for National Forest ecosystems in the West : what role can silviculture and prescribed fire play?

Treesearch

Douglas W. MacCleery

1995-01-01

The 1994 wildfires in the U.S. West have highlighted a problem of forest health and fuel buildups that has been increasing for decades. In many Western forest ecosystems, forest biomass per acre has risen substantially since the 1940s and many forests have dense, fire-prone understories. If current trends continue, there will be: 1) increasing risks to National Forest...

Evaluating and monitoring forest fuel treatments using remote sensing applications in Arizona, U.S.A.

USGS Publications Warehouse

Petrakis, Roy; Villarreal, Miguel; Wu, Zhuoting; Hetzler, Robert; Middleton, Barry R.; Norman, Laura M.

2018-01-01

The practice of fire suppression across the western United States over the past century has led to dense forests, and when coupled with drought has contributed to an increase in large and destructive wildfires. Forest management efforts aimed at reducing flammable fuels through various fuel treatments can help to restore frequent fire regimes and increase forest resilience. Our research examines how different fuel treatments influenced burn severity and post-fire vegetative stand dynamics on the San Carlos Apache Reservation, in east-central Arizona, U.S.A. Our methods included the use of multitemporal remote sensing data and cloud computing to evaluate burn severity and post-fire vegetation conditions as well as statistical analyses. We investigated how forest thinning, commercial harvesting, prescribed burning, and resource benefit burning (managed wildfire) related to satellite measured burn severity (the difference Normalized Burn Ratio – dNBR) following the 2013 Creek Fire and used spectral measures of post-fire stand dynamics to track changes in land surface characteristics (i.e., brightness, greenness and wetness). We found strong negative relationships between dNBR and post-fire greenness and wetness, and a positive non-linear relationship between dNBR and brightness, with greater variability at higher severities. Fire severity and post-fire surface changes also differed by treatment type. Our results showed harvested and thinned sites that were not treated with prescribed fire had the highest severity fire. When harvesting was followed by a prescribed burn, the sites experienced lower burn severity and reduced post-fire changes in vegetation greenness and wetness. Areas that had previously experienced resource benefit burns had the lowest burn severities and the highest post-fire greenness measurements compared to all other treatments, except for where the prescribed burn had occurred. These results suggest that fire treatments may be most effective at reducing the probability of hazardous fire and increasing post-fire recovery. This research demonstrates the utility of remote sensing and spatial data to inform forest management, and how various fuel treatments can influence burn severity and post-fire vegetation response within ponderosa pine forests across the southwestern U.S.

Fuel and fire behavior in high-elevation five-needle pines affected by mountain pine beetle

Treesearch

Michael J. Jenkins

2011-01-01

Bark beetle-caused tree mortality in conifer forests affects the quantity and quality of forest fuels and has long been assumed to increase fire hazard and potential fire behavior. In reality, bark beetles and their effects on fuel accumulation and subsequent fire hazard have only recently been described. We have extensively sampled fuels in three conifer forest types...

Potential climate change impacts on fire intensity and key wildfire suppression thresholds in Canada

NASA Astrophysics Data System (ADS)

Wotton, B. M.; Flannigan, M. D.; Marshall, G. A.

2017-09-01

Much research has been carried out on the potential impacts of climate change on forest fire activity in the boreal forest. Indeed, there is a general consensus that, while change will vary regionally across the vast extent of the boreal, in general the fire environment will become more conducive to fire. Land management agencies must consider ways to adapt to these new conditions. This paper examines the impact of that changed fire environment on overall wildfire suppression capability. We use multiple General Circulation Models and carbon emission pathways to generate future fire environment scenarios for Canada’s forested region. We then use these scenarios with the Canadian Forest Fire Behaviour Prediction System and spatial coverages of the current forest fuel composition across the landscape to examine potential variation in key fire behaviour outputs that influence whether fire management resources can effectively suppress fire. Specifically, we evaluate how the potential for crown fire occurrence and active growth of fires changes with the changing climate. We also examine future fire behaviour through the lens of operational fire intensity thresholds used to guide decisions about resources effectiveness. Results indicate that the proportion of days in fire seasons with the potential for unmanageable fire will increase across Canada’s forest, more than doubling in some regions in northern and eastern boreal forest.

Fortifying the forest: thinning and burning increase resistance to a bark beetle outbreak and promote forest resilience.

PubMed

Hood, Sharon M; Baker, Stephen; Sala, Anna

2016-10-01

Fire frequency in low-elevation coniferous forests in western North America has greatly declined since the late 1800s. In many areas, this has increased tree density and the proportion of shade-tolerant species, reduced resource availability, and increased forest susceptibility to forest insect pests and high-severity wildfire. In response, treatments are often implemented with the goal of increasing ecosystem resilience by increasing resistance to disturbance. We capitalized on an existing replicated study of fire and stand density treatments in a ponderosa pine (Pinus ponderosa)-Douglas-fir (Pseudotsuga menziesii) forest in western Montana, USA, that experienced a naturally occurring mountain pine beetle (MPB; Dendroctonus ponderosae) outbreak 5 yr after implementation of fuels treatments. We explored whether treatment effects on tree-level defense and stand structure affected resistance to MPB. Mortality from MPB was highest in the denser, untreated control and burn-only treatments, with approximately 50% and 39%, respectively, of ponderosa pine killed during the outbreak, compared to almost no mortality in the thin-only and thin-burn treatments. Thinning treatments, with or without fire, dramatically increased tree growth and resin ducts relative to control and burn-only treatments. Prescribed burning did not increase resin ducts but did cause changes in resin chemistry that may have affected MPB communication and lowered attack success. While ponderosa pine remained dominant in the thin and thin-burn treatments after the outbreak, the high pine mortality in the control and burn-only treatment caused a shift in species dominance to Douglas-fir. The high Douglas-fir component in the control and burn-only treatments due to 20th century fire exclusion, coupled with high pine mortality from MPB, has likely reduced resilience of this forest beyond the ability to return to a ponderosa pine-dominated system in the absence of further fire or mechanical treatment. Our results show treatments designed to increase resistance to high-severity fire in ponderosa pine-dominated forests in the Northern Rockies can also increase resistance to MPB, even during an outbreak. This study suggests that fuel and restoration treatments in fire-dependent ponderosa pine forests that reduce tree density increase ecosystem resilience in the short term, while the reintroduction of fire is important for long-term resilience. © 2016 by the Ecological Society of America.

A vicious circle of fire, deforestation and climate change: an integrative study for the Amazon region

NASA Astrophysics Data System (ADS)

Thonicke, K.; Rammig, A.; Gumpenberger, M.; Vohland, K.; Poulter, B.; Cramer, W.

2009-04-01

The Amazon rainforest is threatened by deforestation due to wood extraction and agricultural production leading to increasing forest fragmentation and forest degradation. These changes in land surface characteristics and water fluxes are expected to further reduce convective precipitation. Under future climate change the stability of the Amazon rainforest is likely to decrease thus leading to forest dieback (savannization) or forest degradation (secondarization). This puts the Amazon rainforest at risk to reduce the generation of precipitation, to act as a carbon sink and biodiversity hotspot. Fires increased in the past during drought years and in open vegetation thereby further accelerating forest degradation. Deforestation as a result of socioeconomic development in the Amazon basin is projected to further increase in the 21st century and brings climate-induced changes forward. Combined effects of deforestation vs. climate change on the stability of the Amazon rainforest and the role of fire in this system need to be quantified in an integrated study. We present simulation results from future climate (AR4) and deforestation (SimAmazon) experiments using the LPJmL-SPITFIRE vegetation model. Land use change is the main driving factor of forest degradation before 2050, whereas extreme climate change scenarios lead to forest degradation by the end of 2100. Forest fires increase with increasing drought conditions during the 21st century. The resulting effects on vegetation secondarization and savannization and their feedbacks on fire spread and emissions will be presented. The effect of wildfires and intentional burning on forest degradation under future climate and socioeconomic change will be discussed, and recommendations for an integrated land use and fire management are given.

Long-term overstory and understory change following logging and fire exclusion in a Sierra Nevada mixed-conifer forest

Treesearch

Eric E. Knapp; Carl N. Skinner; Malcolm P. North; Becky L. Estes

2013-01-01

In many forests of the western US, increased potential for fires of uncharacteristic intensity and severity is frequently attributed to structural changes brought about by fire exclusion, past land management practices, and climate. Extent of forest change and effect on understory vegetation over time are not well understood, but such information is useful to forest...

FUEL CONDITIONS ASSOCIATED WITH NATIVE AND EXOTIC GRASSES IN A SUBTROPICAL DRY FOREST IN PUERTO RICO

Treesearch

Jarrod M. Thaxton; Skip J. Van Bloem; Stefanie Whitmire

2012-01-01

Exotic grasses capable of increasing frequency and intensity of anthropogenic fire have invaded subtropical and tropical dry forests worldwide. Since many dry forest trees are susceptible to fire, this can result in decline of native species and loss of forest cover. While the contribution of exotic grasses to altered fire regimes has been well documented, the role of...

Benefits of hindsight: reestablishing fire on the landscape.

Treesearch

Sally Duncan

2001-01-01

Well-intentioned fire suppression efforts during the last 80 to 100 years have altered the structure of low-elevation forests in the interior Northwest. Historically, nondestructive, frequent, low-intensity fires have given way to larger, infrequent, severe, high-intensity fires. Because of altered fire behavior, forests now have increased fuel, and consequently, are...

Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

PubMed Central

Baker, William L.

2015-01-01

Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984–2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984–2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046–2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in dry forests. PMID:26351850

Simulating the interactions of forest structure, fire regime, and plant invasion in the southern Appalachians using LANDIS

Treesearch

Weimin Xi; Szu-Hung Chen; Andrew G. Birt; John D. Waldron; Charles W. Lafon; David M. Cairns; Maria D. Tchakerian; Kier D. Klepzig; Robert N. Coulson

2011-01-01

Southern Appalachian forests face multiple environmental threats, including periodic fires, insect outbreaks, and more recently, exotic invasive plants. Past studies suggest these multiple disturbances interact to shape species-rich forest landscape, and they hypothesize that changes in fire regimes and increasing landscape fragmentation may influence invasive...

Fire and forest history at Mount Rushmore.

PubMed

Brown, Peter M; Wienk, Cody L; Symstad, Amy J

2008-12-01

Mount Rushmore National Memorial in the Black Hills of South Dakota is known worldwide for its massive sculpture of four of the United States' most respected presidents. The Memorial landscape also is covered by extensive ponderosa pine (Pinus ponderosa) forest that has not burned in over a century. We compiled dendroecological and forest structural data from 29 plots across the 517-ha Memorial and used fire behavior modeling to reconstruct the historical fire regime and forest structure and compare them to current conditions. The historical fire regime is best characterized as one of low-severity surface fires with occasional (> 100 years) patches (< 100 ha) of passive crown fire. We estimate that only approximately 3.3% of the landscape burned as crown fire during 22 landscape fire years (recorded at > or = 25% of plots) between 1529 and 1893. The last landscape fire was in 1893. Mean fire intervals before 1893 varied depending on spatial scale, from 34 years based on scar-to-scar intervals on individual trees to 16 years between landscape fire years. Modal fire intervals were 11-15 years and did not vary with scale. Fire rotation (the time to burn an area the size of the study area) was estimated to be 30 years for surface fire and 800+ years for crown fire. The current forest is denser and contains more small trees, fewer large trees, lower canopy base heights, and greater canopy bulk density than a reconstructed historical (1870) forest. Fire behavior modeling using the NEXUS program suggests that surface fires would have dominated fire behavior in the 1870 forest during both moderate and severe weather conditions, while crown fire would dominate in the current forest especially under severe weather. Changes in the fire regime and forest structure at Mount Rushmore parallel those seen in ponderosa pine forests from the southwestern United States. Shifts from historical to current forest structure and the increased likelihood of crown fire justify the need for forest restoration before a catastrophic wildfire occurs and adversely impacts the ecological and aesthetic setting of the Mount Rushmore sculpture.

Effectiveness of Fire and Fire Surrogate Treatments For Controlling Wildfire Behavior in Piedmont Forests: A Simulation Study

Treesearch

Helen H. Mohr; Thomas A. Waldrop; Sandra Rideout; Ross J. Phillips; Charles T. Flint

2004-01-01

The need for fuel reduction has increased in United States forests due to decades of fire exclusion. Excessive fuel buildup has led to uncharacteristically severe fires in areas with historically short-interval, low-to-moderate-intensity fire regimes. The National Fire and Fire Surrogate (NFFS) Study compared the impacts of three fuel-reduction treatments on numerous...

Impacts of the Canadian forest fires on atmospheric mercury and carbonaceous particles in Northern New York.

PubMed

Wang, Yungang; Huang, Jiaoyan; Zananski, Tiffany J; Hopke, Philip K; Holsen, Thomas M

2010-11-15

The impact of Canadian forest fires in Quebec on May 31, 2010 on PM(2.5), carbonaceous species, and atmospheric mercury species was observed at three rural sites in northern New York. The results were compared with previous studies during a 2002 Quebec forest fire episode. MODIS satellite images showed transport of forest fire smoke from southern Quebec, Canada to northern New York on May 31, 2010. Back-trajectories were consistent with this regional transport. During the forest fire event, as much as an 18-fold increase in PM(2.5) concentration was observed. The concentrations of episode-related OC, EC, BC, UVBC, and their difference (Delta-C), reactive gaseous mercury (RGM), and particle-bound mercury (PBM) were also significantly higher than those under normal conditions, suggesting a high impact of Canadian forest fire emissions on air quality in northern New York. PBM, RGM, and Delta-C are all emitted from forest fires. The correlation coefficient between Delta-C and other carbonaceous species may serve as an indicator of forest fire smoke. Given the marked changes in PBM, it may serve as a more useful tracer of forest fires over distances of several hundred kilometers relative to GEM. However, the Delta-C concentration changes are more readily measured.

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

Fire treatment effects on vegetation structure, fuels, and potential fire severity in western U.S. forests

USGS Publications Warehouse

Stephens, S.L.; Moghaddas, J.J.; Edminster, C.; Fiedler, C.E.; Haase, S.; Harrington, M.; Keeley, J.E.; Knapp, E.E.; Mciver, J.D.; Metlen, K.; Skinner, C.N.; Youngblood, A.

2009-01-01

Abstract. Forest structure and species composition in many western U.S. coniferous forests have been altered through fire exclusion, past and ongoing harvesting practices, and livestock grazing over the 20th century. The effects of these activities have been most pronounced in seasonally dry, low and mid-elevation coniferous forests that once experienced frequent, low to moderate intensity, fire regimes. In this paper, we report the effects of Fire and Fire Surrogate (FFS) forest stand treatments on fuel load profiles, potential fire behavior, and fire severity under three weather scenarios from six western U.S. FFS sites. This replicated, multisite experiment provides a framework for drawing broad generalizations about the effectiveness of prescribed fire and mechanical treatments on surface fuel loads, forest structure, and potential fire severity. Mechanical treatments without fire resulted in combined 1-, 10-, and 100-hour surface fuel loads that were significantly greater than controls at three of five FFS sites. Canopy cover was significantly lower than controls at three of five FFS sites with mechanical-only treatments and at all five FFS sites with the mechanical plus burning treatment; fire-only treatments reduced canopy cover at only one site. For the combined treatment of mechanical plus fire, all five FFS sites with this treatment had a substantially lower likelihood of passive crown fire as indicated by the very high torching indices. FFS sites that experienced significant increases in 1-, 10-, and 100-hour combined surface fuel loads utilized harvest systems that left all activity fuels within experimental units. When mechanical treatments were followed by prescribed burning or pile burning, they were the most effective treatment for reducing crown fire potential and predicted tree mortality because of low surface fuel loads and increased vertical and horizontal canopy separation. Results indicate that mechanical plus fire, fire-only, and mechanical-only treatments using whole-tree harvest systems were all effective at reducing potential fire severity under severe fire weather conditions. Retaining the largest trees within stands also increased fire resistance. ?? 2009 by the Ecological Society of America.

Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region

NASA Astrophysics Data System (ADS)

Miesel, Jessica R.; Hockaday, William C.; Kolka, Randall K.; Townsend, Philip A.

2015-06-01

Recent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildfire may become increasingly severe. Losses of forest soil organic matter (SOM) during fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition of postfire SOM. We sampled the forest floor layer (i.e., full organic horizon) and 0-10 cm mineral soil from stands dominated by coniferous (Pinus banksiana Lamb.) or deciduous (Populus tremuloides Michx.) species 1-2 months after the 2011 Pagami Creek wildfire in northern Minnesota. We used solid-state 13C NMR to characterize SOM composition across a gradient of fire severity in both forest cover types. SOM composition was affected by fire, even when no statistically significant losses of total C stocks were evident. The most pronounced differences in SOM composition between burned and unburned reference areas occurred in the forest floor for both cover types. Carbohydrate stocks in forest floor and mineral horizons decreased with severity level in both cover types, whereas pyrogenic C stocks increased with severity in the coniferous forest floor and decreased in only the highest severity level in the deciduous forest floor. Loss of carbohydrate and lignin pools contributed to a decreased SOM stability index and increased decomposition index. Our results suggest that increases in fire severity expected to occur under future climate scenarios may lead to changes in SOM composition and dynamics with consequences for postfire forest recovery and C uptake.

Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

NASA Astrophysics Data System (ADS)

Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

2010-12-01

Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how contemporary changes in fire activity and land use are changing the global carbon cycle.

Effects of fire on Sonoran desert plant communities

Treesearch

Eddie J. Alford; John H. Brock; Gerald J. Gottfried

2005-01-01

The number of fires has increased during the past 45 years in the Sonoran Desert within the Tonto National Forest of central Arizona. The positive trend in the number of fires was consistent with an increase in the population of Maricopa County and an increase in traffic along major Sonoran Desert highways in the Tonto National Forest. The number of hectares burned did...

Assessing fire effects on forest spatial structure using a fusion of Landsat and airborne LiDAR data in Yosemite National Park

Treesearch

Van R. Kane; Malcolm P. North; James A. Lutz; Derek J. Churchill; Susan L. Roberts; Douglas F. Smith; Robert J. McGaughey; Jonathan T. Kane; Matthew L. Brooks

2014-01-01

Mosaics of tree clumps and openings are characteristic of forests dominated by frequent, low-and moderate-severity fires. When restoring these fire-suppressed forests, managers often try to reproduce these structures to increase ecosystem resilience. We examined unburned and burned forest structures for 1937 0.81 ha sample areas in Yosemite National Park, USA. We...

Effects of experimental fuel additions on fire intensity and severity: unexpected carbon resilience of a neotropical forest.

PubMed

Brando, Paulo M; Oliveria-Santos, Claudinei; Rocha, Wanderley; Cury, Roberta; Coe, Michael T

2016-07-01

Global changes and associated droughts, heat waves, logging activities, and forest fragmentation may intensify fires in Amazonia by altering forest microclimate and fuel dynamics. To isolate the effects of fuel loads on fire behavior and fire-induced changes in forest carbon cycling, we manipulated fine fuel loads in a fire experiment located in southeast Amazonia. We predicted that a 50% increase in fine fuel loads would disproportionally increase fire intensity and severity (i.e., tree mortality and losses in carbon stocks) due to multiplicative effects of fine fuel loads on the rate of fire spread, fuel consumption, and burned area. The experiment followed a fully replicated randomized block design (N = 6) comprised of unburned control plots and burned plots that were treated with and without fine fuel additions. The fuel addition treatment significantly increased burned area (+22%) and consequently canopy openness (+10%), fine fuel combustion (+5%), and mortality of individuals ≥5 cm in diameter at breast height (dbh; +37%). Surprisingly, we observed nonsignificant effects of the fuel addition treatment on fireline intensity, and no significant differences among the three treatments for (i) mortality of large trees (≥30 cm dbh), (ii) aboveground forest carbon stocks, and (iii) soil respiration. It was also surprising that postfire tree growth and wood increment were higher in the burned plots treated with fuels than in the unburned control. These results suggest that (i) fine fuel load accumulation increases the likelihood of larger understory fires and (ii) single, low-intensity fires weakly influence carbon cycling of this primary neotropical forest, although delayed postfire mortality of large trees may lower carbon stocks over the long term. Overall, our findings indicate that increased fine fuel loads alone are unlikely to create threshold conditions for high-intensity, catastrophic fires during nondrought years. © 2016 John Wiley & Sons Ltd.

A simulation of wildfire behavior in piedmont forests

Treesearch

Helen H. Mohr; Thomas A. Waldrop

2006-01-01

Decades of fire exclusion have increased the need for fuel reduction in U.S. forests. The buildup of excessive fuels has led to uncharacteristically severe fires in areas with historically short-interval, low to moderate intensity fire regimes. The National Fire and Fire Surrogate Study compares the impacts of three fuel reduction treatments on numerous response...

Detecting post-fire salvage logging with Landsat change maps and national fire survey data

Treesearch

Todd A. Schroeder; Michael A. Wulder; Sean P. Healey; Gretchen G. Moisen

2012-01-01

In Canadian boreal forests, wildfire is the predominant agent of natural disturbance often with millions of hectares burning annually. In addition to fire, nearly one quarter of Canada's boreal forest is also managed for industrial wood production. Post-fire logging (or salvage harvesting) is increasingly used to minimize economic losses from fire, notwithstanding...

The largest forest fires in Portugal: the constraints of burned area size on the comprehension of fire severity.

PubMed

Tedim, Fantina; Remelgado, Ruben; Martins, João; Carvalho, Salete

2015-01-01

Portugal is a European country with highest forest fires density and burned area. Since beginning of official forest fires database in 1980, an increase in number of fires and burned area as well as appearance of large and catastrophic fires have characterized fire activity in Portugal. In 1980s, the largest fires were just a little bit over 10,000 ha. However, in the beginning of 21st century several fires occurred with a burned area over 20,000 ha. Some of these events can be classified as mega-fires due to their ecological and socioeconomic severity. The present study aimed to discuss the characterization of large forest fires trend, in order to understand if the largest fires that occurred in Portugal were exceptional events or evidences of a new trend, and the constraints of fire size to characterize fire effects because, usually, it is assumed that larger the fire higher the damages. Using Portuguese forest fire database and satellite imagery, the present study showed that the largest fires could be seen at the same time as exceptional events and as evidence of a new fire regime. It highlighted the importance of size and patterns of unburned patches within fire perimeter as well as heterogeneity of fire ecological severity, usually not included in fire regime description, which are critical to fire management and research. The findings of this research can be used in forest risk reduction and suppression planning.

Historical dominance of low-severity fire in dry and wet mixed-conifer forest habitats of the endangered terrestrial Jemez Mountains salamander (Plethodon neomexicanus)

USGS Publications Warehouse

Margolis, Ellis; Malevich, Steven B.

2016-01-01

Anthropogenic alteration of ecosystem processes confounds forest management and conservation of rare, declining species. Restoration of forest structure and fire hazard reduction are central goals of forest management policy in the western United States, but restoration priorities and treatments have become increasingly contentious. Numerous studies have documented changes in fire regimes, forest stand structure and species composition following a century of fire exclusion in dry, frequent-fire forests of the western U.S. (e.g., ponderosa pine and dry mixed-conifer). In contrast, wet mixed-conifer forests are thought to have historically burned infrequently with mixed- or high-severity fire—resulting in reduced impacts from fire exclusion and low restoration need—but data are limited. In this study we quantified the current forest habitat of the federally endangered, terrestrial Jemez Mountains salamander (Plethodon neomexicanus) and compared it to dendroecological reconstructions of historical habitat (e.g., stand structure and composition), and fire regime parameters along a gradient from upper ponderosa pine to wet mixed-conifer forests. We found that current fire-free intervals in Jemez Mountains salamander habitat (116–165 years) are significantly longer than historical intervals, even in wet mixed-conifer forests. Historical mean fire intervals ranged from 10 to 42 years along the forest gradient. Low-severity fires were historically dominant across all forest types (92 of 102 fires). Although some mixed- or highseverity fire historically occurred at 67% of the plots over the last four centuries, complete mortality within 1.0 ha plots was rare, and asynchronous within and among sites. Climate was an important driver of temporal variability in fire severity, such that mixed- and high-severity fires were associated with more extreme drought than low-severity fires. Tree density in dry conifer forests historically ranged from open (90 trees/ha) to moderately dense (400 trees/ha), but has doubled on average since fire exclusion. Infill of fire-sensitive tree species has contributed to the conversion of historically dry mixedconifer to wet mixed-conifer forest. We conclude that low-severity fire, which has been absent for over a century, was a critical ecosystem process across the forest gradient in Jemez Mountains salamander habitat, and thus is an important element of ecosystem restoration, resilience, and rare species recovery.

Basic principles of forest fuel reduction treatments

Treesearch

James K. Agee; Carl N. Skinner

2005-01-01

Successful fire exclusion in the 20th century has created severe fire problems across the West. Not every forest is at risk of uncharacteristically severe wildfire, but drier forests are in need of active management to mitigate fire hazard. We summarize a set of simple principles important to address in fuel reduction treatments: reduction of surface fuels, increasing...

The influence of fires on the properties of forest soils in the Amur River basin (the Norskii Reserve)

NASA Astrophysics Data System (ADS)

Tsibart, A. S.; Gennadiev, A. N.

2008-07-01

The influence of forest fires on the properties of taiga brown, gley taiga brown, and alluvial bog soils widespread in the area of the Norskii Reserve (the Amur River basin) was studied. During several years after the fire, the humus content increased, especially in the soils subjected to fires of high intensity. In the soils of steep slopes, the humus content decreased due to damage to the forest vegetation and activation of lateral runoff after the fire. As a rule, in the soils subjected to fire, the C ha-to-C fa ratio increased and correlated with the fire intensity. Some relationships between the forest fires and the acid-base properties of the soils were revealed. After the fires, the pH values often became higher. The stronger the fire, the higher the pH values. The stony soils differed from the other ones, since the reaction of their upper horizons turned out to be more acid after the fires. The analysis of the authors’ and literature data showed that the pyrogenic changes of some soil properties have been poorly studied and need further investigation, including their geographical aspects.

Vegetation cover and species richness after recurrent forest fires in the Eastern Mediterranean ecosystem of Mount Carmel, Israel.

PubMed

Tessler, Naama; Wittenberg, Lea; Greenbaum, Noam

2016-12-01

Fire is a common disturbance in Mediterranean ecosystems, and can have a destructive, influential, and even essential, effect on vegetation and wildlife. In recent decades there has been a general increase in the number of fires in the Mediterranean Basin, including in Mount Carmel, Israel. The effects of recurrent forest fires on vegetation cover and species richness were determined in the spring of 2009 and 2010 by field surveys. The results of this study showed that the vegetation cover changes after recurrent forest fires, and can serve as a good indicator of the influence of fire and the resulting ecosystem rehabilitation. The dominant cover in most fire-damaged areas was composed of shrubs and dwarf-shrubs, especially Cistus salviifolius and Calicotome villosa. Tree cover was severely damaged after recurrent fires, and in those areas there was a drastic decrease of the total plant cover. Species richness increased mainly in the first decade after the recurrent fires, and decreased when the forest canopy began to close. Fire recurrence with short intervals (4-6years) between fires may lower the rehabilitated processes of the ecosystem and change its equilibrium. Copyright © 2016 Elsevier B.V. All rights reserved.

Forest fire increases mercury accumulation by fishes via food web restructuring and increased mercury inputs.

PubMed

Kelly, Erin N; Schindler, David W; St Louis, Vincent L; Donald, David B; Vladicka, Katherine E

2006-12-19

Recent findings indicate that fishes from lakes in partially burned catchments contain greater mercury (Hg) concentrations than fishes from reference catchments. Increased methyl Hg (MeHg) concentrations in fishes can result in serious health problems for consumers. Here we show that a forest fire caused a 5-fold increase in whole-body Hg accumulation by rainbow trout (Oncorhynchus mykiss) and smaller Hg increases in muscle of several fish species in a mountain lake. The enhanced Hg accumulation was caused primarily by increased nutrient concentrations in the lake, which enhanced productivity and restructured the food web through increased piscivory and consumption of Mysis. This restructuring resulted in increases to the trophic positions and Hg concentrations of fishes. Forest fire also caused a large short-term release of total Hg (THg) and MeHg to streams and the lake. This release initiated a small pulse of MeHg in invertebrates that contributed to enhanced Hg accumulation by fishes. Climate change and prescribed burning to compensate for past fire suppression are predicted to increase future forest fire occurrence in North America, and increased Hg accumulation by fishes may be an unexpected consequence.

Forest fire increases mercury accumulation by fishes via food web restructuring and increased mercury inputs

PubMed Central

Kelly, Erin N.; Schindler, David W.; St. Louis, Vincent L.; Donald, David B.; Vladicka, Katherine E.

2006-01-01

Recent findings indicate that fishes from lakes in partially burned catchments contain greater mercury (Hg) concentrations than fishes from reference catchments. Increased methyl Hg (MeHg) concentrations in fishes can result in serious health problems for consumers. Here we show that a forest fire caused a 5-fold increase in whole-body Hg accumulation by rainbow trout (Oncorhynchus mykiss) and smaller Hg increases in muscle of several fish species in a mountain lake. The enhanced Hg accumulation was caused primarily by increased nutrient concentrations in the lake, which enhanced productivity and restructured the food web through increased piscivory and consumption of Mysis. This restructuring resulted in increases to the trophic positions and Hg concentrations of fishes. Forest fire also caused a large short-term release of total Hg (THg) and MeHg to streams and the lake. This release initiated a small pulse of MeHg in invertebrates that contributed to enhanced Hg accumulation by fishes. Climate change and prescribed burning to compensate for past fire suppression are predicted to increase future forest fire occurrence in North America, and increased Hg accumulation by fishes may be an unexpected consequence. PMID:17158215

Alaska's changing fire regime--implications for the vulnerability of its boreal forests

Treesearch

Eric S. Kasischke; David L. Verbyla; T. Scott Rupp; A. David McGuire; Karen A. Murphy; Randi Jandt; Jennifer L. Barnes; Elizabeth E. Hoy; Paul A. Duffy; Monika Calef; Merritt R. Turetsky

2010-01-01

A synthesis was carried out to examine Alaska's boreal forest fire regime. During the 2000s, an average of 767 000 ha×year-1 burned, 50% higher than in any previous decade since the 1940s. Over the past 60 years, there was a decrease in the number of lightning-ignited fires, an increase in extreme lightning-ignited fire events, an increase...

Assessing fire effects on forest spatial structure using a fusion of Landsat and airborne LiDAR data in Yosemite National Park

USGS Publications Warehouse

Kane, Van R.; North, Malcolm P.; Lutz, James A.; Churchill, Derek J.; Roberts, Susan L.; Smith, Douglas F.; McGaughey, Robert J.; Kane, Jonathan T.; Brooks, Matthew L.

2014-01-01

Mosaics of tree clumps and openings are characteristic of forests dominated by frequent, low- and moderate-severity fires. When restoring these fire-suppressed forests, managers often try to reproduce these structures to increase ecosystem resilience. We examined unburned and burned forest structures for 1937 0.81 ha sample areas in Yosemite National Park, USA. We estimated severity for fires from 1984 to 2010 using the Landsat-derived Relativized differenced Normalized Burn Ratio (RdNBR) and measured openings and canopy clumps in five height strata using airborne LiDAR data. Because our study area lacked concurrent field data, we identified methods to allow structural analysis using LiDAR data alone. We found three spatial structures, canopy-gap, clump-open, and open, that differed in spatial arrangement and proportion of canopy and openings. As fire severity increased, the total area in canopy decreased while the number of clumps increased, creating a patchwork of openings and multistory tree clumps. The presence of openings > 0.3 ha, an approximate minimum gap size needed to favor shade-intolerant pine regeneration, increased rapidly with loss of canopy area. The range and variation of structures for a given fire severity were specific to each forest type. Low- to moderate-severity fires best replicated the historic clump-opening patterns that were common in forests with frequent fire regimes. Our results suggest that managers consider the following goals for their forest restoration: 1) reduce total canopy cover by breaking up large contiguous areas into variable-sized tree clumps and scattered large individual trees; 2) create a range of opening sizes and shapes, including ~ 50% of the open area in gaps > 0.3 ha; 3) create multistory clumps in addition to single story clumps; 4) retain historic densities of large trees; and 5) vary treatments to include canopy-gap, clump-open, and open mosaics across project areas to mimic the range of patterns found for each forest type in our study.

Climate changes and wildfire alter vegetation of Yellowstone National Park, but forest cover persists

USGS Publications Warehouse

Clark, Jason A.; Loehman, Rachel A.; Keane, Robert E.

2017-01-01

We present landscape simulation results contrasting effects of changing climates on forest vegetation and fire regimes in Yellowstone National Park, USA, by mid-21st century. We simulated potential changes to fire dynamics and forest characteristics under three future climate projections representing a range of potential future conditions using the FireBGCv2 model. Under the future climate scenarios with moderate warming (>2°C) and moderate increases in precipitation (3–5%), model simulations resulted in 1.2–4.2 times more burned area, decreases in forest cover (10–44%), and reductions in basal area (14–60%). In these same scenarios, lodgepole pine (Pinus contorta) decreased in basal area (18–41%), while Douglas-fir (Pseudotsuga menziesii) basal area increased (21–58%). Conversely, mild warming (<2°C) coupled with greater increases in precipitation (12–13%) suggested an increase in forest cover and basal area by mid-century, with spruce and subalpine fir increasing in abundance. Overall, we found changes in forest tree species compositions were caused by the climate-mediated changes in fire regime (56–315% increase in annual area burned). Simulated changes in forest composition and fire regime under warming climates portray a landscape that shifts from lodgepole pine to Douglas-fir caused by the interaction between the magnitude and seasonality of future climate changes, by climate-induced changes in the frequency and intensity of wildfires, and by tree species response.

Protection against fire in the mountainous forests of Greece case study: forest complex of W. Nestos

NASA Astrophysics Data System (ADS)

Drosos, Vasileios C.; Giannoulas, Vasileios J.; Stergiadou, Anastasia; Karagiannis, Evaggelos; Doukas, Aristotelis-Kosmas G.

2014-08-01

Forest fires are an ancient phenomenon. Appear, however, with devastating frequency and intensity over the last 30 years. In our country, the climatic conditions in combination with the intense relief, favor their rapid spread. Considering the fact that environmental conditions provided for decades even worse (increased temperature, drought and vegetation), then the problem of forest fires in our country, is expected to become more intense. The work focuses on the optimization model of the opening up of the forest mountain areas taking into account the prevention and suppression of forest fires. Research area is the mountain forest complex of W. Nestos of Drama Prefecture. The percentage of forest protection area is examined under the light whether the total hose length corresponds to the actual operational capacity to reach a fire source. For this reason are decided to present a three case study concerning area of the forest being protected by fire extinguishing vehicles. The first one corresponds to a fire suppression bandwidth (buffer zone) with a capacity radius of 150m uphill and 250m downhill from the origin point where the fire extinguishing vehicle stands. The second one corresponds to a fire suppression capacity of 200m uphill and 400m downhill and the third one corresponds to a fire suppression capacity of 300m uphill and 500m downhill. The most important forest technical infrastructures to prevent fire are roads network (opening up) for fire protection and buffer zones. Patrols of small and agile 4 × 4 appropriately equipped (pipe length of 500 meters and putting pressure on uphill to 300 meters) for the first attack of the fire in the summer months coupled with early warning of fire observatories adequately cover the forest protection of W. Nestos complex. But spatial distribution needed improvements to a road density of the optimum economic Dec, both forest protection and for better management (skidding) of woody capital.

The influence of fire on the radiocarbon signature and character of soil organic matter in the Siskiyou national forest, Oregon, USA

Treesearch

Katherine Heckman; John L. Campbell; Heath Powers; Beverly E. Law; Chris Swanston

2013-01-01

Forest fires contribute a significant amount of CO2 to the atmosphere each year, and CO2 emissions from fires are likely to increase under projected conditions of global climate change. In addition to volatilizing aboveground biomass and litter layers, forest fires have a profound effect on belowground carbon (C) pools and the cycling of soil organic matter as a whole...

Estimation of Wild Fire Risk Area based on Climate and Maximum Entropy in Korean Peninsular

NASA Astrophysics Data System (ADS)

Kim, T.; Lim, C. H.; Song, C.; Lee, W. K.

2015-12-01

The number of forest fires and accompanying human injuries and physical damages has been increased by frequent drought. In this study, forest fire danger zone of Korea is estimated to predict and prepare for future forest fire hazard regions. The MaxEnt (Maximum Entropy) model is used to estimate the forest fire hazard region which estimates the probability distribution of the status. The MaxEnt model is primarily for the analysis of species distribution, but its applicability for various natural disasters is getting recognition. The detailed forest fire occurrence data collected by the MODIS for past 5 years (2010-2014) is used as occurrence data for the model. Also meteorology, topography, vegetation data are used as environmental variable. In particular, various meteorological variables are used to check impact of climate such as annual average temperature, annual precipitation, precipitation of dry season, annual effective humidity, effective humidity of dry season, aridity index. Consequently, the result was valid based on the AUC(Area Under the Curve) value (= 0.805) which is used to predict accuracy in the MaxEnt model. Also predicted forest fire locations were practically corresponded with the actual forest fire distribution map. Meteorological variables such as effective humidity showed the greatest contribution, and topography variables such as TWI (Topographic Wetness Index) and slope also contributed on the forest fire. As a result, the east coast and the south part of Korea peninsula were predicted to have high risk on the forest fire. In contrast, high-altitude mountain area and the west coast appeared to be safe with the forest fire. The result of this study is similar with former studies, which indicates high risks of forest fire in accessible area and reflects climatic characteristics of east and south part in dry season. To sum up, we estimated the forest fire hazard zone with existing forest fire locations and environment variables and had meaningful result with artificial and natural effect. It is expected to predict future forest fire risk with future climate variables as the climate changes.

Risk of large-scale fires in boreal forests of Finland under changing climate

NASA Astrophysics Data System (ADS)

Lehtonen, I.; Venäläinen, A.; Kämäräinen, M.; Peltola, H.; Gregow, H.

2016-01-01

The target of this work was to assess the impact of projected climate change on forest-fire activity in Finland with special emphasis on large-scale fires. In addition, we were particularly interested to examine the inter-model variability of the projected change of fire danger. For this purpose, we utilized fire statistics covering the period 1996-2014 and consisting of almost 20 000 forest fires, as well as daily meteorological data from five global climate models under representative concentration pathway RCP4.5 and RCP8.5 scenarios. The model data were statistically downscaled onto a high-resolution grid using the quantile-mapping method before performing the analysis. In examining the relationship between weather and fire danger, we applied the Canadian fire weather index (FWI) system. Our results suggest that the number of large forest fires may double or even triple during the present century. This would increase the risk that some of the fires could develop into real conflagrations which have become almost extinct in Finland due to active and efficient fire suppression. However, the results reveal substantial inter-model variability in the rate of the projected increase of forest-fire danger, emphasizing the large uncertainty related to the climate change signal in fire activity. We moreover showed that the majority of large fires in Finland occur within a relatively short period in May and June due to human activities and that FWI correlates poorer with the fire activity during this time of year than later in summer when lightning is a more important cause of fires.

Forest fires are associated with elevated mortality in a dense urban setting.

PubMed

Analitis, Antonis; Georgiadis, Ioannis; Katsouyanni, Klea

2012-03-01

The climate and vegetation of the greater Athens area (population over three million) make forest fires a real threat to the environment during the summer. A few studies have reported the adverse health effects of forest fires, mainly using morbidity outcomes. The authors investigated the short-term effects of forest fires on non-accidental mortality in the population of Athens, Greece, during 1998-2004. The authors used generalised additive models to investigate the effect of forest fires on daily mortality, adjusting for time trend and meteorological variables, taking into account air pollution as measured from fixed monitors. Forest fires were classified by size according to the area burnt. Small fires do not have an effect on mortality. Medium sized fires are associated with an increase of 4.9% (95% CI 0.3% to 9.6%) in the daily total number of deaths, 6.0% (95% CI -0.3% to 12.6%) in the number of cardiovascular deaths and 16.2% (95% CI 1.3% to 33.4%) in the number of respiratory deaths. Cardiovascular effects are larger in those aged <75 years, while respiratory effects are larger in older people. The corresponding effects of the one large fire are: 49.7% (95% CI 37.2% to 63.4%), 60.6% (95% CI 43.1% to 80.3%) and 92.0% (95% CI 47.5% to 150.0%). These effects cannot be completely explained by an increase in ambient particle concentrations. Forest fires have an immediate effect on mortality, not associated with accidental deaths, which is a significant public health problem, especially if the fire occurs near a densely populated area.

Decreases in net primary production and net ecosystem production along a repeated-fires induced forest/grassland gradient

NASA Astrophysics Data System (ADS)

Cheng, C. H.; Huang, Y. H.; Chung-Yu, L.; Menyailo, O.

2016-12-01

Fire is one of the most important disturbances in ecosystems. Fire rapidly releases stored carbon into atmosphere and also plays critical roles on soil properties, light and moisture regimes, and plant structures and communities. With the interventions of climate change and human activities, fire regimes become more severe and frequent. In many parts of world, forest fire regimes can be further altered by grass invasion because the invasive grasses create a positive feedback cycle through their rapid recovery after fires and their high flammability during dry periods and allow forests to be burned repeatedly in a relatively short time. For such invasive grass-fire cycle, a great change of native vegetation community can occur. In this study, we examined a C4 invasive grass () fire-induced forest/grassland gradient to quantify the changes of net primary production (NPP) and net ecosystem production (NEP) from an unburned forest to repeated fire grassland. Our results demonstrated negative effects of repeated fires on NPP and NEP. Within 4 years of the onset of repeated fires on the unburned forest, NPP declined by 14%, mainly due to the reduction in aboveground NPP but offset by increase of belowground NPP. Subsequent fires cumulatively caused reductions in both aboveground and belowground NPP. A total of 40% reduction in the long-term repeated fire induced grassland was found. Soil respiration rate were not significantly different along the forest/grassland gradient. Thus, a great reduction in NEP were shown in grassland, which shifted from 4.6 Mg C ha-1 yr-1 in unburnt forest to -2.6 Mg C ha-1 yr-1. Such great losses are critical within the context of forest carbon cycling and long-term sustainability. Forest management practices that can effectively reduce the likelihood of repeated fires and consequent likelihood of establishment of the grass fire cycle are essential for protecting the forest.

Abrupt fire regime change may cause landscape-wide loss of mature obligate seeder forests.

PubMed

Bowman, David M J S; Murphy, Brett P; Neyland, Dominic L J; Williamson, Grant J; Prior, Lynda D

2014-03-01

Obligate seeder trees requiring high-severity fires to regenerate may be vulnerable to population collapse if fire frequency increases abruptly. We tested this proposition using a long-lived obligate seeding forest tree, alpine ash (Eucalyptus delegatensis), in the Australian Alps. Since 2002, 85% of the Alps bioregion has been burnt by several very large fires, tracking the regional trend of more frequent extreme fire weather. High-severity fires removed 25% of aboveground tree biomass, and switched fuel arrays from low loads of herbaceous and litter fuels to high loads of flammable shrubs and juvenile trees, priming regenerating stands for subsequent fires. Single high-severity fires caused adult mortality and triggered mass regeneration, but a second fire in quick succession killed 97% of the regenerating alpine ash. Our results indicate that without interventions to reduce fire severity, interactions between flammability of regenerating stands and increased extreme fire weather will eliminate much of the remaining mature alpine ash forest. © 2013 John Wiley & Sons Ltd.

Fire in Siberian boreal forests -- implications for global climate and air quality

Treesearch

Eduard P. Davidenko

1998-01-01

Boreal forests and woodlands comprise about 29 percent of the world's forest cover. About 70 percent of this forest is in Eurasia, mostly in the Russian Federation. Boreal forests contain about 45 percent of the world's growing stock and are an increasingly important part of global timber production. Fire impacts large areas of boreal forest annually in...

Ecological responses to el Niño-induced surface fires in central Brazilian Amazonia: management implications for flammable tropical forests.

PubMed Central

Barlow, Jos; Peres, Carlos A

2004-01-01

Over the past 20 years the combined effects of El Niño-induced droughts and land-use change have dramatically increased the frequency of fire in humid tropical forests. Despite the potential for rapid ecosystem alteration and the current prevalence of wildfire disturbance, the consequences of such fires for tropical forest biodiversity remain poorly understood. We provide a pan-tropical review of the current state of knowledge of these fires, and include data from a study in a seasonally dry terra firme forest of central Brazilian Amazonia. Overall, this study supports predictions that rates of tree mortality and changes in forest structure are strongly linked to burn severity. The potential consequences for biomass loss and carbon emissions are explored. Despite the paucity of data on faunal responses to tropical forest fires, some trends are becoming apparent; for example, large canopy frugivores and understorey insectivorous birds appear to be highly sensitive to changes in forest structure and composition during the first 3 years after fires. Finally, we appraise the management implications of fires and evaluate the viability of techniques and legislation that can be used to reduce forest flammability, prevent anthropogenic ignition sources from coming into contact with flammable forests and aid the post-fire recovery process. PMID:15212091

Fire suppression has led to greater drought-sensitivity in dry conifer forests: tree-ring carbon isotope evidence from Central Oregon

NASA Astrophysics Data System (ADS)

Voelker, S.; Merschel, A. G.; Meinzer, F. C.; Spies, T. A.; Still, C. J.

2016-12-01

Mortality events of economically and ecologically important conifers have been widespread across Western North America over recent decades. Many of these events have been linked to "global change-type droughts" characterized by greater temperatures and evaporative demand. In parallel, since the early to mid- 20th century, increasing atmospheric [CO2] has been shown to increase the water use efficiency (WUE) of trees worldwide while conifer forests in western North America have become denser after the advent of modern fire suppression efforts. Therefore, competing hypotheses include that conifer forests have experienced 1) less drought stress due to water savings from increased WUE, 2) more drought stress due to increased demand for water in dense forests with greater leaf area index, or 3) unchanging stress because these two factors have cancelled each other out. To provide a test of these hypotheses we used inter-annual latewood carbon isotope discrimination, Δ13C, across a dry mixed-conifer forest landscape of central Oregon in the rain shadow of the Cascade Mountains. The forests are dominated by old-growth ponderosa pines (Pinus ponderosa) and younger and fire-intolerant grand firs (Abies grandis). Dendrochronological dating of tree establishment and fires scars established sharp declines in fire frequency and associated increases in the densities of grand fir since the early 1900s. Δ13C data for ponderosa pine and grand fir spanned 1830-2013 and 1900-2013, respectively. For our analyses these years were split into periods of high fire frequency (1830-1900), moderate fire frequency (1901-1956) and fire-exclusion (1957-2013). Comparisons of Δ13C to reconstructed Palmer Drought Severity Index values for the same years revealed that leaf gas exchange of both species has been more sensitive to drought during the recent fire-exclusion period compared to previous periods when surface fires kept tree densities much lower. Similar research is needed elsewhere to provide additional tests. However, this initial evidence suggests that despite CO2-driven increases in WUE, conifer forests in western North America have experienced greater drought stress and been made more susceptible to mortality events due to progressive increases in tree densities and competition for water over the past century.

Fuel Treatment Effects on Water Use Efficiency in Western Pine Forests Under Fire Suppression Evaluated Using Tree Ring Carbon Isotopes

NASA Astrophysics Data System (ADS)

Taylor, A. H.; Belmecheri, S.; Harris, L. B.

2016-12-01

We identified variation on water use efficiency interpreted from carbon 13 in tree ring cellulose in dense ponderosa pines forests in Washington and Arizona. Historically, these forests burned every decade until fires were suppressed beginning in the early twentieth century. The reduction in fire caused large increases in forest density and forest biomass and potential for intense fire. Forests with hazardous fuels are common in the western United States and these types of forests are treated with mechanical thinning and mechanical thinning and burning to reduce hazardous fuels and fire intensity. At each site we extracted tree ring samples from five trees in each treatment type and a control to identify the effects of fuel treatment of concentration of carbon 13 in tree ring cellulose. Water use efficiency as measured by carbon 13 increased after fuel treatments. Treatment effects were larger for the mechanical plus burn treatment than for the mechanical treatment in each study area compared to the control stands Our results suggest that fuel treatments reduce sensitivity of tree growth to climate and increase water use efficiency. Since tree ring carbon 13 is related to plant productivity, carbon 13 in tree rings can be used as a metric of change in ecosystem function for evaluating fuel treatments.

Estimating canopy fuels in conifer forests

Treesearch

Joe H. Scott; Elizabeth D. Reinhardt

2002-01-01

Crown fires occur in a variety of coniferous forest types (Agee 1993), including some that are not historically prone to crown fire, such as ponderosa pine (Mutch and others 1993). The head fire spread rate of a crown fire is usually several times faster than that of a surface fire burning under the same conditions, which leads to a significant increase in the number...

Holocene Fire, Climate, and Geomorphic Response: Perspectives From the Past and Indications for the Future

NASA Astrophysics Data System (ADS)

Meyer, G. A.; Pierce, J. L.; Frechette, J. D.; New, J.; Jull, A.

2006-12-01

Increased wildfire activity has accompanied late 20th-century to present warming across the diverse conifer forests of western North America. In ponderosa pine forests in particular, large, severe wildfires and ensuing erosion and debris flows appear unprecedented in light of tree-ring fire-scar records, and are often attributed to increased stand density following Euro-American settlement and fire suppression starting in the late 1800s. Yet, presettlement periods in fire-scar records correspond to mostly cooler Little Ice Age climates, when we expect that severe fires may be less probable. AMS 14C dating of fire-related alluvial-fan deposits provides a longer-term context for assessing links between fire, climate, erosion, and anthropogenic change. Infrequent high-severity fire is typical of cool, high-elevation Yellowstone National Park (YNP). Fire-related debris flows were common in YNP 2350-2000 cal yr BP and in Medieval time 1050-650 BP, both relatively warm periods at many sites across the Northern Hemisphere. Drier, low-elevation ponderosa forests in central Idaho also experienced severe fires and debris flows at these times, and ~25% of fan aggradation in the last 4000 yr occurred via postfire debris flows within the 400-yr Medieval period containing widespread, multidecadal droughts (Cook et al. 2004). Few fire-related deposits in YNP date to the Little Ice Age and prior cold episodes ca. 1400 and 2800 BP. At these same times, thin charcoal-bearing deposits indicate frequent low-severity fires in Idaho, where cooler, effectively wetter climates promoted growth of grass and fine fuels that promoted surface fires in the typically dry summers of this region. Initial data from varied forest types in the monsoonal (dry spring, wet summer) climate of the Sacramento Mountains, New Mexico, indicate voluminous fire-related sedimentation 6000-4500 BP, consistent with a warm middle Holocene. Fire-induced debris flows were less frequent in the late Holocene, but indicate that some severe fires affected ponderosa pine-dominated forests. Therefore, modern postfire debris flows are not without precedent in any of these areas, where fire has been an important catalyst for episodic erosion. Each record indicates an increased probability of severe fire with warmer climates. As greenhouse gas increases are virtually assured over the next century, impacts on fire and erosion have likely just begun. Earlier snowmelt accompanying warming lengthens the fire season in much of the Rocky Mountains, including YNP and central Idaho (Westerling et al. 2006). In ponderosa and similar forests where surface fires were suppressed by humans, increased stand density compounds the effect of warming. Increasing temperatures may also heighten precipitation intensity, producing greater postfire erosion. Although Holocene history provides imperfect analogs for a uniquely anthropogenic future, the sensitivity of fire regimes to past warming portends future increases in severe fires and geomorphic change.

Fire and the herbaceous layer of eastern oak forests

Treesearch

Todd Hutchinson

2006-01-01

Across oak forest landscapes, the herbaceous layer supports the great majority of plant diversity. As the use of prescribed fire increases, it is important to better understand its effects on biodiversity. This paper reviews the current ?state of the knowledge? regarding fire effects on herbaceous layer vegetation. In typical dormant-season fires, direct heating...

Understanding the long-term fire risks in forests affected by sudden oak death

Treesearch

Yana Valachovic; Chris Lee; Radoslaw Glebocki; Hugh Scanlon; J. Morgan Varner; David Rizzo

2010-01-01

It is assumed that large numbers of dead and down tanoak in forests infested by Phytophthora ramorum contribute to increased fire hazard risk and fuel loading. We studied the impact of P. ramorum infestation on surface fuel loading, potential fire hazard, and potential fire behavior in Douglas-fir- (Pseudotsuga...

Carbon dioxide, methane and nitrous oxide fluxes from a fire chronosequence in subarctic boreal forests of Canada.

PubMed

Köster, Egle; Köster, Kajar; Berninger, Frank; Aaltonen, Heidi; Zhou, Xuan; Pumpanen, Jukka

2017-12-01

Forest fires are one of the most important natural disturbances in boreal forests, and their occurrence and severity are expected to increase as a result of climate warming. A combination of factors induced by fire leads to a thawing of the near-surface permafrost layer in subarctic boreal forest. Earlier studies reported that an increase in the active layer thickness results in higher carbon dioxide (CO 2 ) and methane (CH 4 ) emissions. We studied changes in CO 2 , CH 4 and nitrous oxide (N 2 O) fluxes in this study, and the significance of several environmental factors that influence the greenhouse gas (GHG) fluxes at three forest sites that last had fires in 2012, 1990 and 1969, and we compared these to a control area that had no fire for at least 100years. The soils in our study acted as sources of CO 2 and N 2 O and sinks for CH 4 . The elapsed time since the last forest fire was the only factor that significantly influenced all studied GHG fluxes. Soil temperature affected the uptake of CH 4 , and the N 2 O fluxes were significantly influenced by nitrogen and carbon content of the soil, and by the active layer depth. Results of our study confirm that the impacts of a forest fire on GHGs last for a rather long period of time in boreal forests, and are influenced by the fire induced changes in the ecosystem. Copyright © 2017 Elsevier B.V. All rights reserved.

Shrub removal in reforested post-fire areas increases native plant species richness

Treesearch

Gabrielle N. Bohlman; Malcolm North; Hugh D. Safford

2016-01-01

Large, high severity fires are becoming more prevalent in Sierra Nevada mixed-conifer forests, largely due to heavy fuel loading and forest densification caused by past and current management practices. In post-fire areas distant from seed trees, conifers are often planted to re-establish a forest and to prevent a potential type-conversion to shrub fields. Typical...

Kanawha State Forest, WV: Wildland fire fuel load assessment and geospatial distribution

Treesearch

Adele Fenwick; Jamie L. Schuler; Shawn Grushecky; Thomas M. Schuler; Melissa Thomas-Van Gundy

2014-01-01

Fire has become a major concern along the wildland-urban interface (WUI), and there is increased awareness that fires could result in serious damage to people and property in residential areas occurring in forested landscapes. Part of the long-term strategy the West Virginia Division of Forestry outlined in the 2010 West Virginia Statewide Forest Resource Assessment...

Fighting forest fires in Brazil

Treesearch

José Carlos Mendes de Morais

2013-01-01

Fire has been used in Brazil for many years, but the increased use of this tool, combined with natural events and the presence of large forest and agricultural areas, has led to a significant jump in the number of forest fires, most of them caused by accident. To optimize existing resources and to cope with growing demand, action levels were adopted according to the...

Human ecological intervention and the role of forest fires in human ecology.

PubMed

Caldararo, N

2002-06-26

The present text is a summary of research on the relationship between forest fires and human activities. Numerous theories have been created to explain changes in forests during the late Pleistocene and early Holocene, and a general understanding has developed in the past 50 years regarding natural fire regimes. The present summary is directed to assess the validity of these theories. A re-analysis of the literature argues that the intense forest fires we experience today are an artifact of human intervention in forest ecology, especially by the reduction of herbivores and are relatively recent, approximately 100,000-250,000 BP. The history of fire, especially in the context of the increased dominance of humans, has produced a progressively fire-adapted ecology, which argues for human-free wildlife areas and against prescribed burns under many circumstances.

Risk for large-scale fires in boreal forests of Finland under changing climate

NASA Astrophysics Data System (ADS)

Lehtonen, I.; Venäläinen, A.; Kämäräinen, M.; Peltola, H.; Gregow, H.

2015-08-01

The target of this work was to assess the impact of projected climate change on the number of large forest fires (over 10 ha fires) and burned area in Finland. For this purpose, we utilized a strong relationship between fire occurrence and the Canadian fire weather index (FWI) during 1996-2014. We used daily data from five global climate models under representative concentration pathway RCP4.5 and RCP8.5 scenarios. The model data were statistically downscaled onto a high-resolution grid using the quantile-mapping method before performing the analysis. Our results suggest that the number of large forest fires may double or even triple during the present century. This would increase the risk that some of the fires could develop into real conflagrations which have become almost extinct in Finland due to active and efficient fire suppression. Our results also reveal substantial inter-model variability in the rate of the projected increase in forest-fire danger. We moreover showed that the majority of large fires occur within a relatively short period in May and June due to human activities and that FWI correlates poorer with the fire activity during this time of year than later in summer when lightning is more important cause of fires.

The effects of prescribed fire and silvicultural thinning on the aboveground carbon stocks and net primary production of overstory trees in an oak-hickory ecosystem in southern Ohio

Treesearch

Jyh-Min Chiang; Ryan W. McEwan; Daniel A. Yaussy; Kim J. Brown

2008-01-01

More than 70 years of fire suppression has influenced forest dynamics and led to the accumulation of fuels in many forests of the United States. To address these changes, forest managers increasingly seek to restore historical ecosystem structure and function through the reintroduction of fire and disturbance processes that mimic fire such as silvicultural thinning. In...

Postfire Forest Recovery in California's National Forests

NASA Astrophysics Data System (ADS)

Welch, K.; Young, T.; Safford, H.

2012-12-01

Due to fire suppression policies and other management practices over the last century, many low- to mid-elevation forest types in the Sierra Nevada have accumulated high fuel loads that promote stand-replacing high-intensity fires. Current and future projected trends in climate are predicted to increase the occurrence of such fires. We established over 1,000 plots in a range of elevations, environments, forest types, climate zones and fire severity classes to provide insight into the factors that promote natural tree regeneration after wildfires, the limiting factors in species establishment, and the differences in post-fire responses of conifers and hardwoods. We employed a standardized protocol that measured site characteristics, seedling densities, and woody plant growth. Preliminary results reveal that fire severity generally has a unimodal relationship with rates of natural regeneration, although effects of site and local environment act to modulate the shape of the relationship. Above low to moderate severities, natural regeneration rates of all tree species decrease with increasing severity, possibly due to a combination of factors including seed mortality, increasing distance to the nearest living seed tree, and more severe microclimatic conditions. Though hardwoods (oaks) are able to both seed and resprout from top-killed root crowns in a postfire environment, conifers still have the numerical advantage over hardwoods through seeding alone. We did not find evidence that shrubs have a strong either facilitative or competitive effect on conifer seedling establishment or growth in the first five years of forest recovery. Understanding forest recovery and regeneration processes after high severity fires is critical to appropriately applying management strategies on National Forest lands.

Afforestation, subsequent forest fires and provision of hydrological services: a model-based analysis for a Mediterranean mountainous catchment

NASA Astrophysics Data System (ADS)

Nunes, João Pedro; Naranjo Quintanilla, Paula; Santos, Juliana; Serpa, Dalila; Carvalho-Santos, Cláudia; Rocha, João; Keizer, Jan Jacob; Keesstra, Saskia

2017-04-01

Mediterranean landscapes have experienced extensive abandonment and reforestation in recent decades, which should have improved the provision of hydrological services, such as flood mitigation, soil erosion protection and water quality regulation. However, these forests are fire-prone, and the post-fire increase in runoff, erosion and sediment exports could negatively affect service provision. This issue was assessed using the SWAT model for a small mountain agroforestry catchment, which was monitored between 2010 and 2014 and where some eucalypt stands burned in 2011 and were subsequently plowed for replanting. The model was calibrated and validated for streamflow, sediment yield and erosion in agricultural fields and the burnt hillslopes, showing that it can be adapted for post-fire simulation. It was then used to perform a decadal assessment of surface runoff, erosion, and sediment exports between 2004 and 2014. Results show that the fire did not noticeably affect flood mitigation but that it increased erosion by 3 orders of magnitude, which subsequently increased sediment yield. Erosion in the burnt forest during this decade was one order of magnitude above that in agricultural fields. SWAT was also used to assess different fire and land-use scenarios during the same period. Results indicate that the impacts of fire were lower without post-fire soil management, and when the fire occurred in pine forests (i.e. before the 1990s) or in shrublands (i.e. before afforestation in the 1930s). These impacts were robust to changes in post-fire weather conditions and to a lower fire frequency (20-year intervals). The results suggest that, in the long term, fire-prone forests might not provide the anticipated soil protection and water quality regulation services in wet Mediterranean regions.

Western forest, fire risk, and climate change

Treesearch

Valerie Rapp

2004-01-01

Climate warming may first show up in forests as increased growth, which occurs as warmer temperatures, increased carbon dioxide, and more precipitation encourage higher rates of photosynthesis. The second way that climate change may show up in forests is through changes in disturbance regimes—the long-term patterns of fire, drought, insects, and diseases that are basic...

Western forests, fire risk, and climate change.

Treesearch

Valerie Rapp

2004-01-01

Climate warming may first show up in forests as increased growth, which occurs as warmer temperatures, increased carbon dioxide, and more precipitation encourage higher rates of photosynthesis. The second way that climate change may show up in forests is through changes in disturbance regimes—the long-term patterns of fire, drought, insects, and diseases that are basic...

[Forest fire risk assessment for China under different climate scenarios.

PubMed

Tian, Xiao Rui; Dai, Xuan; Wang, Ming Yu; Zhao, Feng Jun; Shu, Li Fu

2016-03-01

Forest fire risk depends on the hazard factors, affected body, and hazard prevention and reduction ability. The integrated risk assessment is the foundation for developing scientific fire mana-gement policies and carrying out the forest fire prevention measures. A forest fire risk assessment model and index system were established based on the classic natural disaster risk model and available data, and the model was used to assess the forest fire risks in past and future. The future climate scenario data included outputs from five global climate models (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM and NorESM1-M) for RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5, respectively. Each component index of Fire Weather Index (FWI) system was calculated daily for each grid in 1987-2050 for the historical observations and future climate scenarios according to the maximum temperature, minimum relative humidity, wind speed and daily precipitation. The results showed that areas with high and very high fire danger ratings in 1987-2010 accounted for 21.2% and 6.2%, respectively, which were distributed in Greater Xing'an Mountains and the Changbai Mountain area, most parts of Yunnan, and many fragment areas in southern China. The areas with high and very high burn possibilities were mainly distributed in the northeast and southwest region, accounting for 13.1% and 4.0%, respectively. Compared with the observation period, the areas with high and very high fire danger ratings in 2021-2050 would increase by 0.6%, 5.5%, 2.3%, and 3.5% under RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5 respectively, and North China would show significant increase. The regions with high-risk forest fires would also increase due to climate change, with the most significant increase under RCP 8.5 scenario (+1.6%).

The Impact of Increasing Fire Frequency on Forest Transformations in the Zabaikal Region, Southern Siberia

NASA Astrophysics Data System (ADS)

Conard, S. G.; Kukavskaya, E. A.; Buryak, L. V.; Shvetsov, E.; Kalenskaya, O. P.; Zhila, S.

2017-12-01

The Zabaikal region of southern Siberia is characterized by some of the highest fire activity in Russia. There has been a significant increase of fire frequency and burned area in the region over the last two decades due to a combination of high anthropogenic pressure, decreased funding to the forestry sector, and increased fire danger, which was associated with higher frequency and intensity of extreme weather events. Central and southern parts of the Zabaikal region where population density is higher and road network is relatively more developed are the most disturbed by fires. Larch stands cover the largest proportion of fire-disturbed lands in the region, while the less common pine and birch stands are characterized by higher fire frequency. About 13% (3.9 M ha) of the total forest area in the Zabaikal region was burned more than once in the 20 years from 1996 to 2015, with many sites burned multiple times. Repeat disturbances led to inadequate tree regeneration on all but the moistest sites. Pine stands on dry soils, which are common in the forest-steppe zone, were the most vulnerable. After repeat burns and over large burned sites we observed transformation of the forests to steppe ecosystems. The most likely causes of insufficient forest regeneration are soil overheating, dominance of tall grasses, and lack of nearby seed sources. Extensive tree plantations have potential to mitigate negative fire impacts; however, due to high fire hazard in the recent decade about half of the plantation area has been burned. Changes in the SWVI index were used to assess postfire reforestation based on a combination of satellite and field data. In the southwestern part of the Zabaikal region, we estimated that reforestation had been hampered over 11% of the forest land area. Regional climate models project increasing temperatures and decreasing precipitation across Siberia by the end of the 21st century, with changes in the Zabaikal region projected to be more than twice the average rate in Siberia. This would likely lead to higher fire activity in the region. Implementation of sustainable forest management strategies has the potential to mitigate effects of changing climate and fire regimes on forest ecosystems in the Zabaikal region. This research was supported by the RFBR grant (# 15-04-06567) and the NASA LCLUC Program.

Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring.

PubMed

Westerling, Anthony LeRoy

2016-06-05

Prior work shows western US forest wildfire activity increased abruptly in the mid-1980s. Large forest wildfires and areas burned in them have continued to increase over recent decades, with most of the increase in lightning-ignited fires. Northern US Rockies forests dominated early increases in wildfire activity, and still contributed 50% of the increase in large fires over the last decade. However, the percentage growth in wildfire activity in Pacific northwestern and southwestern US forests has rapidly increased over the last two decades. Wildfire numbers and burned area are also increasing in non-forest vegetation types. Wildfire activity appears strongly associated with warming and earlier spring snowmelt. Analysis of the drivers of forest wildfire sensitivity to changes in the timing of spring demonstrates that forests at elevations where the historical mean snow-free season ranged between two and four months, with relatively high cumulative warm-season actual evapotranspiration, have been most affected. Increases in large wildfires associated with earlier spring snowmelt scale exponentially with changes in moisture deficit, and moisture deficit changes can explain most of the spatial variability in forest wildfire regime response to the timing of spring.This article is part of the themed issue 'The interaction of fire and mankind'. © 2016 The Author(s).

Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring

PubMed Central

2016-01-01

Prior work shows western US forest wildfire activity increased abruptly in the mid-1980s. Large forest wildfires and areas burned in them have continued to increase over recent decades, with most of the increase in lightning-ignited fires. Northern US Rockies forests dominated early increases in wildfire activity, and still contributed 50% of the increase in large fires over the last decade. However, the percentage growth in wildfire activity in Pacific northwestern and southwestern US forests has rapidly increased over the last two decades. Wildfire numbers and burned area are also increasing in non-forest vegetation types. Wildfire activity appears strongly associated with warming and earlier spring snowmelt. Analysis of the drivers of forest wildfire sensitivity to changes in the timing of spring demonstrates that forests at elevations where the historical mean snow-free season ranged between two and four months, with relatively high cumulative warm-season actual evapotranspiration, have been most affected. Increases in large wildfires associated with earlier spring snowmelt scale exponentially with changes in moisture deficit, and moisture deficit changes can explain most of the spatial variability in forest wildfire regime response to the timing of spring. This article is part of the themed issue ‘The interaction of fire and mankind’. PMID:27216510

Past and future changes in Canadian boreal wildfire activity.

PubMed

Girardin, Martin P; Mudelsee, Manfred

2008-03-01

Climate change in Canadian boreal forests is usually associated with increased drought severity and fire activity. However, future fire activity could well be within the range of values experienced during the preindustrial period. In this study, we contrast 21st century forecasts of fire occurrence (FireOcc, number of large forest fires per year) in the southern part of the Boreal Shield, Canada, with the historical range of the past 240 years statistically reconstructed from tree-ring width data. First, a historical relationship between drought indices and FireOcc is developed over the calibration period 1959-1998. Next, together with seven tree-ring based drought reconstructions covering the last 240 years and simulations from the CGCM3 and ECHAM4 global climate models, the calibration model is used to estimate past (prior to 1959) and future (post 1999) FireOcc. Last, time-dependent changes in mean FireOcc and in the occurrence rate of extreme fire years are evaluated with the aid of advanced methods of statistical time series analysis. Results suggest that the increase in precipitation projected toward the end of the 21st century will be insufficient to compensate for increasing temperatures and will be insufficient to maintain potential evapotranspiration at current levels. Limited moisture availability would cause FireOcc to increase as well. But will future FireOcc exceed its historical range? The results obtained from our approach suggest high probabilities of seeing future FireOcc reach the upper limit of the historical range. Predictions, which are essentially weighed on northwestern Ontario and eastern boreal Manitoba, indicate that, by 2061-2100, typical FireOcc could increase by more than 34% when compared with the past two centuries. Increases in fire activity as projected by this study could negatively affect the implementation in the next century of forest management inspired by historical or natural disturbance dynamics. This approach is indeed feasible only if current and future fire activities are sufficiently low compared with the preindustrial fire activity, so a substitution of fire by forest management could occur without elevating the overall frequency of disturbance. Conceivable management options will likely have to be directed toward minimizing the adverse impacts of the increasing fire activity.

Fire as the dominant driver of central Canadian boreal forest carbon balance.

PubMed

Bond-Lamberty, Ben; Peckham, Scott D; Ahl, Douglas E; Gower, Stith T

2007-11-01

Changes in climate, atmospheric carbon dioxide concentration and fire regimes have been occurring for decades in the global boreal forest, with future climate change likely to increase fire frequency--the primary disturbance agent in most boreal forests. Previous attempts to assess quantitatively the effect of changing environmental conditions on the net boreal forest carbon balance have not taken into account the competition between different vegetation types on a large scale. Here we use a process model with three competing vascular and non-vascular vegetation types to examine the effects of climate, carbon dioxide concentrations and fire disturbance on net biome production, net primary production and vegetation dominance in 100 Mha of Canadian boreal forest. We find that the carbon balance of this region was driven by changes in fire disturbance from 1948 to 2005. Climate changes affected the variability, but not the mean, of the landscape carbon balance, with precipitation exerting a more significant effect than temperature. We show that more frequent and larger fires in the late twentieth century resulted in deciduous trees and mosses increasing production at the expense of coniferous trees. Our model did not however exhibit the increases in total forest net primary production that have been inferred from satellite data. We find that poor soil drainage decreased the variability of the landscape carbon balance, which suggests that increased climate and hydrological changes have the potential to affect disproportionately the carbon dynamics of these areas. Overall, we conclude that direct ecophysiological changes resulting from global climate change have not yet been felt in this large boreal region. Variations in the landscape carbon balance and vegetation dominance have so far been driven largely by increases in fire frequency.

Resilience Through Disturbance: Effects of Wildfire on Vegetation and Water Balance in the Sierra Nevadas

NASA Astrophysics Data System (ADS)

Boisrame, G. F. S.; Thompson, S. E.; Stephens, S.; Collins, B.; Tague, N.

2015-12-01

A century of fire suppression in the Western United States has drastically altered the historically fire-adapated ecology in California's Sierra Nevada Mountains. Fire suppression is understood to have increased the forest cover, as well as the stem density, canopy cover and water demand of montane forests, reducing resilience of the forests to drought, and increasing the risk of catastrophic fire by drying the landscape and increasing fuel loads. The potential to reverse these trends by re-introducing fire into the Sierra Nevada is highly promising, but the likely effects on vegetation structure and water balance are poorly quantified. The Illilouette Creek Basin in Yosemite National Park represents a unique experiment in the Sierra Nevada, in which managers have moved from fire suppression to allowing a near-natural fire regime to prevail since 1972. Changes in vegetation structure in the Illilouette since the restoration of natural burning provides a unique opportunity to examine how frequent, mixed severity fires can reshape the Sierra Nevada landscape. We characterize these changes from 1969 to the present using a combination of Landsat products and high-resolution aerial imagery. We describe how the landscape structure has changed in terms of vegetation composition and its spatial organization, and explore the drivers of different post-fire vegetation type transitions (e.g. forest to shrubland vs. forest to meadow). By upscaling field data using vegetation maps and Landsat wetness indices, we explore how these vegetation transitions have impacted the water balance of the Illilouette Creek Basin, potentially increasing its resilience in the face of drought, climate change, and catastrophic fire. In a region that is adapted to frequent disturbance from fire, this work helps us understand how allowing such natural disturbances to take place can increase the sustainability of diverse landscapes in the long term.

Climate- and disturbance-driven changes in vegetation composition and structure limit future potential carbon storage in the Greater Yellowstone Ecosystem, USA

NASA Astrophysics Data System (ADS)

Henne, Paul D.; Hawbaker, Todd J.; Zhao, Feng; Huang, Chengquan; Berryman, Erin M.; Zhu, Zhiliang

2016-04-01

The Greater Yellowstone Ecosystem (GYE) provides unique opportunities to understand how changing climate, land use, and disturbance affect ecosystem carbon balance. The GYE is one of the largest, most intact ecosystems in the United States. However, distinct management histories on National Park, National Forest, and private lands, elevational climate gradients, and variable fire activity, have created a mosaic of stand ages and forest types. It is uncertain how greenhouse forcing may alter the carbon balance of the GYE. Whereas increasing temperatures may enhance productivity and perpetuate the GYE as a carbon sink, climate-driven increases in fire frequency may offset productivity gains by limiting biomass accumulation. We investigated how changes in fire frequency and size may affect vegetation dynamics and carbon sequestration potential in the GYE using the LANDIS-II dynamic landscape vegetation model. LANDIS-II provides sufficient spatial resolution to capture landscape-level variation in forest biomass and forest types (i.e. 90 × 90 m grid cells), but can integrate disturbance regimes and vegetation dynamics across the entire GYE (92,000 km2). We initiated our simulations with biomass and stand conditions that preceded the exceptional 1988 fire, when 16% of the GYE burned. We inferred the biomass, species abundances, and stand demographics of each model cell by combining satellite imagery with forest inventory data, and developed two fire regime scenarios from historical fire records. We developed a historic wildfire scenario with infrequent fires by excluding 1988 from our calibration of fire sizes and frequencies, and a future scenario with more frequent and larger fires by including 1988 in our calibrations. Fire frequency increased in all forest types in our future scenario, with a 152% increase in the annual forest area burned relative to observed area burned during recent decades. However, the changes in fire frequency varied among forest types, with the largest increases in lodgepole pine (Pinus contorta; 332% increase) and spruce/fir (Picea engelmannii, Abies lasiocarpa; 243% increase) stands. In model runs with the historic fire regime, average stand age and live biomass remained consistent with pre-1988 values during the 200-year simulation period; biomass increased significantly only in recently-logged areas. In contrast, a marked shift to younger stands with lower biomass occurred in the future fire scenario. Average stand age declined from 112 years to 31 years in lodgepole pine stands, and from 191 years to 65 years in spruce/fir stands, with consequent reductions in living biomass. A smaller shift in stand age was simulated for douglas-fir (Pseudotsuga menziesii) stands (i.e. 121 to 92 years). These fire-driven changes in stand age and biomass coincided with important shifts in species abundances. Specifically, lodgepole pine stands replaced large areas previously dominated by spruce and fir. Our results suggest that the potential for increasing the amount of fossil fuel emissions offset by carbon sequestration on public lands in the American West is limited by ongoing changes in disturbance regimes. Instead, land managers may need to consider strategies to adapt to climate change impacts.

Severe fire weather and intensive forest management increase fire severity in a multi-ownership landscape.

PubMed

Zald, Harold S J; Dunn, Christopher J

2018-04-26

Many studies have examined how fuels, topography, climate, and fire weather influence fire severity. Less is known about how different forest management practices influence fire severity in multi-owner landscapes, despite costly and controversial suppression of wildfires that do not acknowledge ownership boundaries. In 2013, the Douglas Complex burned over 19,000 ha of Oregon & California Railroad (O&C) lands in Southwestern Oregon, USA. O&C lands are composed of a checkerboard of private industrial and federal forestland (Bureau of Land Management, BLM) with contrasting management objectives, providing a unique experimental landscape to understand how different management practices influence wildfire severity. Leveraging Landsat based estimates of fire severity (Relative differenced Normalized Burn Ratio, RdNBR) and geospatial data on fire progression, weather, topography, pre-fire forest conditions, and land ownership, we asked (1) what is the relative importance of different variables driving fire severity, and (2) is intensive plantation forestry associated with higher fire severity? Using Random Forest ensemble machine learning, we found daily fire weather was the most important predictor of fire severity, followed by stand age and ownership, followed by topographic features. Estimates of pre-fire forest biomass were not an important predictor of fire severity. Adjusting for all other predictor variables in a general least squares model incorporating spatial autocorrelation, mean predicted RdNBR was higher on private industrial forests (RdNBR 521.85 ± 18.67 [mean ± SE]) vs. BLM forests (398.87 ± 18.23) with a much greater proportion of older forests. Our findings suggest intensive plantation forestry characterized by young forests and spatially homogenized fuels, rather than pre-fire biomass, were significant drivers of wildfire severity. This has implications for perceptions of wildfire risk, shared fire management responsibilities, and developing fire resilience for multiple objectives in multi-owner landscapes. © 2018 by the Ecological Society of America.

Persistent effects of fire severity on early successional forests in interior Alaska

Treesearch

Aditi Shenoy; Jill F. Johnstone; Eric S. Kasischke; Knut Kielland

2011-01-01

There has been a recent increase in the frequency and extent of wildfires in interior Alaska, and this trend is predicted to continue under a warming climate. Although less well documented, corresponding increases in fire severity are expected. Previous research from boreal forests in Alaska and western Canada indicate that severe fire promotes the recruitment of...

Impact air quality by wildfire and agricultural fire in Mexico city 2015

NASA Astrophysics Data System (ADS)

Mendoza Campos, Alejandra; Agustín García Reynoso, José; Castro Romero, Telma Gloria; Carbajal Pérez, José Noel; Mar Morales, Bertha Eugenia; Gerardo Ruiz Suárez, Luis

2016-04-01

A forest fire is a large-scale process natural combustion where different types of flora and fauna of different sizes and ages are consumed. Consequently, forest fires are a potential source of large amounts of air pollutants that must be considered when trying to relate emissions to the air quality in neighboring cities of forest areas as in the Valley of Mexico. The size, intensity and occurrence of a forest fire directly dependent variables such as weather conditions, topography, vegetation type and its moisture content and the mass of fuel per hectare. An agricultural fire is a controlled combustion, which occurred a negligence can get out of control and increase the burned area or the possibly become a wildfire. Once a fire starts, the dry combustible material is consumed first. If the energy release is large and of sufficient duration, drying green material occurs live, with subsequent burning it. Under proper fuel and environmental conditions, this process can start a chain reaction. These events occur mainly in the dry season. Forest fires and agriculture fires contribute directly in the increase of carbon dioxide (CO2) into the atmosphere; The main pollutants emitted to the atmosphere by a wildfire are the PM10, PM2.5, NOx and VOC's, the consequences have by fire are deforestation, soil erosion or change of structure and composition of forests (Villers, 2006), also it affects ecosystems and the health of the population. In this study the impact of air quality for the emissions of particulate matter less than ten microns PM10, by wildfire and agricultural fire occurred on the same day and same place, the study was evaluated in Mexico City the Delegation Milpa Alta in the community of San Lorenzo Tlacoyucan, the fire occurred on 3rd March, 2015, the wildfire duration 12 hours consuming 32 hectares of oak forest and the agricultural fire duration 6 hours consumed 16 hectares of corn. To evaluate the impact of air quality the WRF-Chem, WRF-Fire and METv3 models were used, four scenarios were made, in the first forest fire emissions were included, in the second agricultural fire emissions were included, the third was the difference between agricultural burning and forest fire and the last stage model without fire emissions. In making the interpolation of the modeled scenarios forest and agricultural fires the impact of air quality in the Valley of Mexico was obtained by increasing the concentration of particles smaller than ten micrometers PM10, with the results of the modeling are obtained that the PM10 concentration is ten times higher in the wildfire regarding agricultural fire. By making interpolation between this difference and considering the fire scenario without emissions by that date, a maximum PM10 concentration was 170μg /m3 during the hours of the fires, which exceeds the Mexican standard NOM-025-SSA1-2014 that provides that the maximum allowable limit of exposure to particulate matter less than ten microns is 75μg/m3 on average 24 hours, forest and agricultural fires have an impact of 226% in the PM10 air quality affecting ecosystems and human health

Effects of wild fires on the emissions of reactive gases from boreal and subarctic soils

NASA Astrophysics Data System (ADS)

Zhang-Turpeinen, Huizhong; Pumpanen, Jukka; Kivimäenpää, Minna

2017-04-01

Wild fire has long-term effects on the ecosystem and biological processes of boreal forest, and the frequency of wild fires is increasing as a consequence of climate change. Boreal forests lie largely on permafrost area, and the increase in fire frequency or intensity will affect the depth of the active layer on top of permafrost. The thawing of permafrost soils and increase in the active layer depth could induce significant reactive trace gas emissions. Biogenic volatile organic compounds (BVOCs) and nitrous acid (HONO) are closely associated with air chemistry in the troposphere. They react easily with ozone, hydroxyl radicals, and the reaction products may condense into aerosol particles or affect the growth of atmospheric aerosols which act as cloud condensation nuclei. Forests, and in particular permafrost soils, could be potentially large sources of BVOCs and HONO, because of the large amount of decomposing litter and soil organic matter. However, the forest soil BVOC emissions are poorly known, in contrast to BVOCs emitted from branch and canopy levels in boreal forests. The production rates of HONO in various soils are also poorly known. We studied BVOC and HONO fluxes from boreal forest soils and the effects of wild fires and the time since the last fire on them. We measured BVOCs emissions in west Siberia larch forest stands on permafrost soil in a fire chronosequence where the last forest fires had occurred 2, 24, and more than 100 years ago. HONO emissions in northern boreal subarctic Scots pine forest stands in Eastern Lapland in Finland in a fire chronosequence where the last fires had occurred 7, 47, 72 and 157 years ago. BVOC flux measurements were carried out by drawing air samples from chamber headspace into a steel adsorbent tube containing Tenax TA and carbopack B. The sampling tubes were analyzed on gas chromatography-mass spectrometry (GC-MS). Soil samples were measured for HONO flux in laboratory with LOPAP (Long path absorption photometer). According to our preliminary results the influence and the duration of the impact of forest fires were not observed in HONO emissions. However, the HONO emissions were sensitive to soil moisture. The unexpectedly high rate of release of isoprene measured in the middle age forest sites with warm scenario. Environmental parameters were correlated with the presence of BVOCs. We compared the BVOC fluxes with environmental parameters such as temperature, humidity and PAR, and with ground vegetation coverage and with litter input. The BVOC data is under processing still and more detail results is coming later.

Temporal and Spatial Wildfire Dynamics of Northern Siberia: Larch Forests and Insect Outbreak Areas

NASA Astrophysics Data System (ADS)

Kharuk, Viacheslav; Antamoshkina, Olga; Ponomarev, Eugene

2017-04-01

Wildfire number and burned area temporal dynamics within all of Siberia and along a south-north transect in central Siberia (45 - 73°N) were studied based on NOAA/AVHRR and Terra/MODIS data and field measurements for the period since 1996. In addition, fire return interval along the south-north transect was analyzed. Third, pest outbreak (Siberian silkmoth) impact on the wildfires was studied. Both, number of forest fires and burned area in Siberia increased during recent decades. Significant correlations were found between forest fires, burned areas and air temperature (r = 0.5) and drought index (SPEI) (r = -0.43). Within larch stands along the transect wildfire frequency was strongly correlated with incoming solar radiation (r = 0.91). Fire danger period length decreased linearly from south to north along the transect. Fire return interval increased from 80 years at 62°N to 200 years at the Arctic Circle (66°33'N), and to about 300 years near the northern limit of closed forest stands ( 71+°N). That increase was negatively correlated with incoming solar radiation (r = -0.95). Siberian silkmoth outbreaks leads to an order of magnitude increase in burned area and fire frequency. Multiple fires turns former "dark needle conifer" taiga into grass and bush communities for decades.

Mega-fire Recovery in Dry Conifer Forests of the Interior West

NASA Astrophysics Data System (ADS)

Malone, S. L.; Fornwalt, P.; Chambers, M. E.; Battaglia, M.

2015-12-01

Wildfire is a complex landscape process with great uncertainty in whether trends in size and severity are shifting trajectories for ecosystem recovery that are outside of the historical range of variability. Considering that wildfire size and severity is likely to increase into the future with a drier climate, it is important that we understand wildfire effects and ecosystem recovery. To evaluate how ecosystems recover from wildfire we measured spatial patterns in regeneration and mapped tree refugia within mega-fire perimeters (Hayman, Jasper, Bobcat, and Grizzly Gulch) in ponderosa pine (Pinus ponderosa) dominated forest. On average, high severity fire effects accounted for > 15% of burned area and increased with fire size. Areas with high severity fire effects contained 1 - 15% tree refugia cover, compared to 37 - 70% observed in low severity areas . Large high severity patches with low coverage of tree refugia, were more frequent in larger fires and regeneration distances required to initiate forest recovery far exceeded 1.5 canopy height or 200 m, distances where the vast majority of regeneration is likely to arise. Using a recovery model driven by distance, we estimate recovery times between 300 to > 1000 years for these mega-fires. In Western dry conifer forests, large patches of stand replacing fire are likely to lead to uneven aged forest and very long recovery times.

Climate, soil organic layer, and nitrogen jointly drive forest development after fire in the North American boreal zone

NASA Astrophysics Data System (ADS)

Trugman, A. T.; Fenton, N. J.; Bergeron, Y.; Xu, X.; Welp, L. R.; Medvigy, D.

2016-09-01

Previous empirical work has shown that feedbacks between fire severity, soil organic layer thickness, tree recruitment, and forest growth are important factors controlling carbon accumulation after fire disturbance. However, current boreal forest models inadequately simulate this feedback. We address this deficiency by updating the ED2 model to include a dynamic feedback between soil organic layer thickness, tree recruitment, and forest growth. The model is validated against observations spanning monthly to centennial time scales and ranging from Alaska to Quebec. We then quantify differences in forest development after fire disturbance resulting from changes in soil organic layer accumulation, temperature, nitrogen availability, and atmospheric CO2. First, we find that ED2 accurately reproduces observations when a dynamic soil organic layer is included. Second, simulations indicate that the presence of a thick soil organic layer after a mild fire disturbance decreases decomposition and productivity. The combination of the biological and physical effects increases or decreases total ecosystem carbon depending on local conditions. Third, with a 4°C temperature increase, some forests transition from undergoing succession to needleleaf forests to recruiting multiple cohorts of broadleaf trees, decreasing total ecosystem carbon by ˜40% after 300 years. However, the presence of a thick soil organic layer due to a persistently mild fire regime can prevent this transition and mediate carbon losses even under warmer temperatures. Fourth, nitrogen availability regulates successional dynamics; broadleaf species are less competitive with needleleaf trees under low nitrogen regimes. Fifth, the boreal forest shows additional short-term capacity for carbon sequestration as atmospheric CO2 increases.

Atlantic SSTs control regime shifts in forest fire activity of Northern Scandinavia

PubMed Central

Drobyshev, Igor; Bergeron, Yves; Vernal, Anne de; Moberg, Anders; Ali, Adam A.; Niklasson, Mats

2016-01-01

Understanding the drivers of the boreal forest fire activity is challenging due to the complexity of the interactions driving fire regimes. We analyzed drivers of forest fire activity in Northern Scandinavia (above 60 N) by combining modern and proxy data over the Holocene. The results suggest that the cold climate in northern Scandinavia was generally characterized by dry conditions favourable to periods of regionally increased fire activity. We propose that the cold conditions over the northern North Atlantic, associated with low SSTs, expansion of sea ice cover, and the southward shift in the position of the subpolar gyre, redirect southward the precipitation over Scandinavia, associated with the westerlies. This dynamics strengthens high pressure systems over Scandinavia and results in increased regional fire activity. Our study reveals a previously undocumented teleconnection between large scale climate and ocean dynamics over the North Atlantic and regional boreal forest fire activity in Northern Scandinavia. Consistency of the pattern observed annually through millennium scales suggests that a strong link between Atlantic SST and fire activity on multiple temporal scales over the entire Holocene is relevant for understanding future fire activity across the European boreal zone. PMID:26940995

Atlantic SSTs control regime shifts in forest fire activity of Northern Scandinavia

NASA Astrophysics Data System (ADS)

Drobyshev, Igor; Bergeron, Yves; Vernal, Anne De; Moberg, Anders; Ali, Adam A.; Niklasson, Mats

2016-03-01

Understanding the drivers of the boreal forest fire activity is challenging due to the complexity of the interactions driving fire regimes. We analyzed drivers of forest fire activity in Northern Scandinavia (above 60 N) by combining modern and proxy data over the Holocene. The results suggest that the cold climate in northern Scandinavia was generally characterized by dry conditions favourable to periods of regionally increased fire activity. We propose that the cold conditions over the northern North Atlantic, associated with low SSTs, expansion of sea ice cover, and the southward shift in the position of the subpolar gyre, redirect southward the precipitation over Scandinavia, associated with the westerlies. This dynamics strengthens high pressure systems over Scandinavia and results in increased regional fire activity. Our study reveals a previously undocumented teleconnection between large scale climate and ocean dynamics over the North Atlantic and regional boreal forest fire activity in Northern Scandinavia. Consistency of the pattern observed annually through millennium scales suggests that a strong link between Atlantic SST and fire activity on multiple temporal scales over the entire Holocene is relevant for understanding future fire activity across the European boreal zone.

Atlantic SSTs control regime shifts in forest fire activity of Northern Scandinavia.

PubMed

Drobyshev, Igor; Bergeron, Yves; Vernal, Anne de; Moberg, Anders; Ali, Adam A; Niklasson, Mats

2016-03-04

Understanding the drivers of the boreal forest fire activity is challenging due to the complexity of the interactions driving fire regimes. We analyzed drivers of forest fire activity in Northern Scandinavia (above 60 N) by combining modern and proxy data over the Holocene. The results suggest that the cold climate in northern Scandinavia was generally characterized by dry conditions favourable to periods of regionally increased fire activity. We propose that the cold conditions over the northern North Atlantic, associated with low SSTs, expansion of sea ice cover, and the southward shift in the position of the subpolar gyre, redirect southward the precipitation over Scandinavia, associated with the westerlies. This dynamics strengthens high pressure systems over Scandinavia and results in increased regional fire activity. Our study reveals a previously undocumented teleconnection between large scale climate and ocean dynamics over the North Atlantic and regional boreal forest fire activity in Northern Scandinavia. Consistency of the pattern observed annually through millennium scales suggests that a strong link between Atlantic SST and fire activity on multiple temporal scales over the entire Holocene is relevant for understanding future fire activity across the European boreal zone.

Sensitivity of woody carbon stocks to bark investment strategy in Neotropical savannas and forests

NASA Astrophysics Data System (ADS)

Trugman, Anna T.; Medvigy, David; Hoffmann, William A.; Pellegrini, Adam F. A.

2018-01-01

Fire frequencies are changing in Neotropical savannas and forests as a result of forest fragmentation and increasing drought. Such changes in fire regime and climate are hypothesized to destabilize tropical carbon storage, but there has been little consideration of the widespread variability in tree fire tolerance strategies. To test how aboveground carbon stocks change with fire frequency and composition of plants with different fire tolerance strategies, we update the Ecosystem Demography model 2 (ED2) with (i) a fire survivorship module based on tree bark thickness (a key fire-tolerance trait across woody plants in savannas and forests), and (ii) plant functional types representative of trees in the region. With these updates, the model is better able to predict how fire frequency affects population demography and aboveground woody carbon. Simulations illustrate that the high survival rate of thick-barked, large trees reduces carbon losses with increasing fire frequency, with high investment in bark being particularly important in reducing losses in the wettest sites. Additionally, in landscapes that frequently burn, bark investment can broaden the range of climate and fire conditions under which savannas occur by reducing the range of conditions leading to either complete tree loss or complete grass loss. These results highlight that tropical vegetation dynamics depend not only on rainfall and changing fire frequencies but also on tree fire survival strategy. Further, our results indicate that fire survival strategy is fundamentally important in regulating tree size demography in ecosystems exposed to fire, which increases the preservation of aboveground carbon stocks and the coexistence of different plant functional groups.

Fire-induced erosion and millennial-scale climate change in northern ponderosa pine forests.

PubMed

Pierce, Jennifer L; Meyer, Grant A; Jull, A J Timothy

2004-11-04

Western US ponderosa pine forests have recently suffered extensive stand-replacing fires followed by hillslope erosion and sedimentation. These fires are usually attributed to increased stand density as a result of fire suppression, grazing and other land use, and are often considered uncharacteristic or unprecedented. Tree-ring records from the past 500 years indicate that before Euro-American settlement, frequent, low-severity fires maintained open stands. However, the pre-settlement period between about ad 1500 and ad 1900 was also generally colder than present, raising the possibility that rapid twentieth-century warming promoted recent catastrophic fires. Here we date fire-related sediment deposits in alluvial fans in central Idaho to reconstruct Holocene fire history in xeric ponderosa pine forests and examine links to climate. We find that colder periods experienced frequent low-severity fires, probably fuelled by increased understory growth. Warmer periods experienced severe droughts, stand-replacing fires and large debris-flow events that comprise a large component of long-term erosion and coincide with similar events in sub-alpine forests of Yellowstone National Park. Our results suggest that given the powerful influence of climate, restoration of processes typical of pre-settlement times may be difficult in a warmer future that promotes severe fires.

Fire Return Interval Within the Northern Boundary of the Larch Forest

NASA Technical Reports Server (NTRS)

Kharuk, V. I.; Dvinskaya, M. L.; Ranson, K. J.

2011-01-01

Larch (Larix spp.) dominant forests compose a large proportion of the forests of Russia (i.e., about 40% of forested areas). These forests range from the Yenisei ridge on the west to the Pacific Ocean on the east, and from Lake Baikal on the south to the 73rd parallel in the north. Larch stands comprise the world s northern most forest at Ary-Mas (72 deg 28' N, 102 deg 15' E). Larch dominated forests occupy about 70% of the permafrost areas in Siberia. Larch forms high closure stands as well as open forests, and is found mainly over permafrost, where other tree species barely survive. Wildfires are typical for this territory with the majority occurring as ground fires due to low crown closure. Due to the thin active layer in permafrost soils and a dense lichen-moss cover, ground fires may cause stand mortality. The vast areas of larch-dominant forests is generally considered as a "carbon sink"; however, positive long-term temperature trends at higher latitudes are expected to result in an increase of fire frequency, and thus may convert this area to a source for greenhouse gases. There are recent observations regarding the increase of fire frequency within non-protected territories. Surprisingly, there are few publications on fire chronoseqences for the huge forested territory between the Ural Mountains and the Pacific Ocean. Also there is a general understanding that bimodal (late spring -- early summer and late summer-beginning of fall) fire seasonal distribution in the south becomes uni-modal (late spring -- early summer) in the north. The purpose of this study is to investigate the wildfire history at the northern edge of the zone of larch dominance.

Climate-Soil-Vegetation Interactions: A Case-Study from the Forest Fire Phenomenon in Southern Switzerland

NASA Astrophysics Data System (ADS)

Reinhard, M.; Alexakis, E.; Rebetez, M.; Schlaepfer, R.

2003-04-01

In Southern Switzerland, we have observed increasing trends in extreme drought and precipitation events, probably linked to global climatic change. These modifications are more important than changes in annual precipitation sums. On the one hand, an increase in extreme drought implies a higher risk for forest fires, impeding the fulfilment of the various forest functions, on the other hand, extreme precipitation events, developing over a short time span, could simultaneously damage the forest ecosystems or destabilise the soil of burned areas, triggering debris flows. Climatic changes might additionally lead to modifications of the current species composition in the forests. Changes are currently observed at lower elevations (laurophiliation), but are still largely unknown at higher elevations. For the time being, forest fires cannot be regarded as natural phenomena in the South of Switzerland because they are mostly anthropogenically triggered. However, the changing climatic patterns, which set new conditions for the forests, may become a new ecological regulator for the forests as well as the forest fires. The social and environmental consequences are important for these issues. The implications for forest planning and management must be further studied and taken into account. Despite uncertainty about the response of forest ecosystems to climate change, planning and management can no longer rely on decadal to century climatic patterns. The increasing importance of changing environmental conditions within the framework of prevention will have to be reconsidered.

Modeling long-term effects of altered fire regimes following Southern Pine Beetle outbreaks (North Carolina).

Treesearch

Weiman Xi; John Waldron; Charles Lafon; David Cairns; Andrew Birt; Maria Tchakerian; Robert Coulson; Kier Klepzig

2009-01-01

Periodic fires are an important factor shaping the species-rich southern Appalachian forest landscape, and fire regimes in this region have changed significantly over time. The role of fire in maintaining Appalachian forests has been debated and increasingly studied (Delcourt and Delcourt 1998). Experimental studies have shown that pine...

National Fire Plan Research and Development 2002 Business Summary

Treesearch

USDA Forest Service

2003-01-01

This report summarizes the progress made by Forest Service NFP R&D in FY2002, the second year of NFP funding. Fire research conducted by Forest Service R&D is working to provide the scientific foundation necessary to increase firefighting safety and effectiveness, enhance restoration of fire-scarred landscapes, reduce fire risk through improved management of...

Impacts of fire and fire surrogate treatments on ecosystem nitrogen storage patterns: similarities and differences between forests of eastern and western North America

Treesearch

R.E.J. Boerner; J. Huang; S.C. Hart

2009-01-01

The Fire and Fire Surrogates (FFS) network is composed of 12 forest sites that span the continental United States, all of which historically had frequent low-severity fire. The goal of the FFS study was to assess the efficacy of three management treatments (prescribed fire, mechanical thinning, and their combination) in reducing wildfire hazard and increasing ecosystem...

Late Holocene vegetation and fire dynamics from a savanna-forest ecotone in Roraima state, northern Brazilian Amazon

NASA Astrophysics Data System (ADS)

da Silva Meneses, Maria Ecilene Nunes; da Costa, Marcondes Lima; Behling, Hermann

2013-03-01

Two sediment cores from Mauritia flexuosa palm swamps have been studied by pollen and charcoal analysis. The cores Fazenda Cigana (FC) and Terra Indígena Aningal (TIA) were taken from a savanna-forest ecotone area in the Roraima State, northern Brazilian Amazon. Based on 5 radiocarbon dates, these records allow the reconstruction of the vegetation fire and climate dynamics during the past 1550 years. At the FC site was recorded a higher proportion of forest cover, suggesting local wetter climatic conditions favorable for forest expansion, especially by gallery forests, between 1550 and 1400 cal yr BP. Stands of M. flexuosa started to establish on the site indicating sufficient soil moisture. From 1400 to 1050 cal yr BP, forest cover retreated while savanna, and the Mauritia palm swamp expanded considerably. The FC site was marked by savanna and Mauritia cover with a slight increase of forest between ca. 1050 and 900 cal yr BP. From 900 to 300 cal yr BP the savanna and palm swamp taxa became dominant and the forest area decreased. At the TIA site the savanna cover was dominant between 1200 and 1000 cal yr BP. From 1000 to 700 forest expanded while savanna and Mauritia palm swamp reduced. Between 700 and 300 cal yr BP savanna and Mauritia palm swamp increased and forest area decreased. The high amount of charred particles found in the sediments, indicate fires with a marked increase between 1400 to 1000 cal yr BP (FC site) and 700 to 300 cal yr BP (TIA site), and probably caused the retreat of forest cover during these two time intervals. The relatively lower fire activity after 300 cal yr BP until present-day favored the increase of forested area at both TIA and FC sites. The arrival of the European settler and the subsequent introduction of cattle, is suggested as the main reason for the decrease of fire in the study region. The results point the fire caused by indigenous people as the principal controlling factor for forest and savanna dynamics during the past 1550 years.

Vulnerability to forest loss through altered postfire recovery dynamics in a warming climate in the Klamath Mountains.

PubMed

Tepley, Alan J; Thompson, Jonathan R; Epstein, Howard E; Anderson-Teixeira, Kristina J

2017-10-01

In the context of ongoing climatic warming, certain landscapes could be near a tipping point where relatively small changes to their fire regimes or their postfire forest recovery dynamics could bring about extensive forest loss, with associated effects on biodiversity and carbon-cycle feedbacks to climate change. Such concerns are particularly valid in the Klamath Region of northern California and southwestern Oregon, where severe fire initially converts montane conifer forests to systems dominated by broadleaf trees and shrubs. Conifers eventually overtop the competing vegetation, but until they do, these systems could be perpetuated by a cycle of reburning. To assess the vulnerability of conifer forests to increased fire activity and altered forest recovery dynamics in a warmer, drier climate, we characterized vegetation dynamics following severe fire in nine fire years over the last three decades across the climatic aridity gradient of montane conifer forests. Postfire conifer recruitment was limited to a narrow window, with 89% of recruitment in the first 4 years, and height growth tended to decrease as the lag between the fire year and the recruitment year increased. Growth reductions at longer lags were more pronounced at drier sites, where conifers comprised a smaller portion of live woody biomass. An interaction between seed-source availability and climatic aridity drove substantial variation in the density of regenerating conifers. With increasing climatic water deficit, higher propagule pressure (i.e., smaller patch sizes for high-severity fire) was needed to support a given conifer seedling density, which implies that projected future increases in aridity could limit postfire regeneration across a growing portion of the landscape. Under a more severe prospective warming scenario, by the end of the century more than half of the area currently capable of supporting montane conifer forest could become subject to minimal conifer regeneration in even moderate-sized (10s of ha) high-severity patches. © 2017 John Wiley & Sons Ltd.

Forest Fire Smoke Exposures and Out-of-Hospital Cardiac Arrests in Melbourne, Australia: A Case-Crossover Study.

PubMed

Dennekamp, Martine; Straney, Lahn D; Erbas, Bircan; Abramson, Michael J; Keywood, Melita; Smith, Karen; Sim, Malcolm R; Glass, Deborah C; Del Monaco, Anthony; Haikerwal, Anjali; Tonkin, Andrew M

2015-10-01

Millions of people can potentially be exposed to smoke from forest fires, making this an important public health problem in many countries. In this study we aimed to measure the association between out-of-hospital cardiac arrest (OHCA) and forest fire smoke exposures in a large city during a severe forest fire season, and estimate the number of excess OHCAs due to the fire smoke. We investigated the association between particulate matter (PM) and other air pollutants and OHCA using a case-crossover study of adults (≥ 35 years of age) in Melbourne, Australia. Conditional logistic regression models were used to derive estimates of the percent change in the rate of OHCA associated with an interquartile range (IQR) increase in exposure. From July 2006 through June 2007, OHCA data were collected from the Victorian Ambulance Cardiac Arrest Registry. Hourly air pollution concentrations and meteorological data were obtained from a central monitoring site. There were 2,046 OHCAs with presumed cardiac etiology during our study period. Among men during the fire season, greater increases in OHCA were observed with IQR increases in the 48-hr lagged PM with diameter ≤ 2.5 μm (PM2.5) (8.05%; 95% CI: 2.30, 14.13%; IQR = 6.1 μg/m(3)) or ≤ 10 μm (PM10) (11.1%; 95% CI: 1.55, 21.48%; IQR = 13.7 μg/m(3)) and carbon monoxide (35.7%; 95% CI: 8.98, 68.92%; IQR = 0.3 ppm). There was no significant association between the rate of OHCA and air pollutants among women. One hundred seventy-four "fire-hours" (i.e., hours in which Melbourne's air quality was affected by forest fire smoke) were identified during 12 days of the 2006/2007 fire season, and 23.9 (95% CI: 3.1, 40.2) excess OHCAs were estimated to occur due to elevations in PM2.5 during these fire-hours. This study found an association between exposure to forest fire smoke and an increase in the rate of OHCA. These findings have implications for public health messages to raise community awareness and for planning of emergency services during forest fire seasons.

Is Managed Wildfire Protecting Yosemite National Park from Drought?

NASA Astrophysics Data System (ADS)

Boisrame, G. F. S.; Thompson, S. E.; Stephens, S.; Collins, B.; Kelly, M.; Tague, N.

2016-12-01

Fire suppression in many dry forest types has left a legacy of dense, homogeneous forests. Such landscapes have high water demands and fuel loads, and when burned can result in catastrophically large fires. These characteristics are undesirable in the face of projected warming and drying in the Western US. This project explores the potential of managed wildfire - a forest management strategy in which fires caused by lightning are allowed to burn naturally as long as certain safety parameters are met - to reverse the effects of fire suppression. The Illilouette Creek Basin in Yosemite National Park has experienced 40 years of managed wildfire, reducing forest cover and increasing meadow and shrubland areas. We have collected evidence from field measurements and remote sensing which suggest that managed wildfire increases landscape and hydrologic heterogeneity, and likely improves resilience to disturbances such as fire and drought. Vegetation maps created from aerial photos show an increase in landscape heterogeneity following the introduction of managed wildfire. Soil moisture observations during the drought years of 2013-2016 suggest that transitions from dense forest to shrublands or meadows can increase summer soil moisture. In the winter of 2015-2016, snow depth measurements showed deeper spring snowpacks in burned areas compared to dense forests. Our study provides a unique view of relatively long-term effects of managed wildfire on vegetation change, ecohydrology, and drought resistance. Understanding these effects is increasingly important as the use of managed wildfire becomes more widely accepted, and as the likelihood of both drought and wildfire increases.

One year monitoring of fire-induced effects on dissolved organic matter and nutrient dynamics under different land-use

NASA Astrophysics Data System (ADS)

Potthast, Karin; Meyer, Stefanie; Crecelius, Anna; Schubert, Ulrich; Michalzik, Beate

2016-04-01

It is supposed that the changing climate will promote extreme weather events that in turn will increase drought periods and the abundance of fire events in temperate climate regions such as Central Europe. The impact of fires on the nutrient budgets of ecosystems is highly diverse and seems to depend on the ecosystem type. For example, little is known about fire effects on water-bound organic matter (OM) and nutrient fluxes in temperate managed forest ecosystems. Fires can strongly alter the distribution (forest floor vs. mineral soil), binding forms (organic vs. inorganic) and availability (solubility by water) of OM and associated nutrients. To elucidate the effects and seasonality of low intensity fires on the mobilization of dissolved organic carbon and nutrients, an experimental ground fire was conducted in November 2014 in the Hainich region, Central Germany. In addition, differences in response patterns between two land-use types (pasture and beech forest) were investigated. Lysimeters (n=5 controls/ 5 fire-manipulated) with topsoil monoliths (0-4 cm), rainfall/throughfall samplers, littertraps as well as temperature and moisture sensors were installed on three sites of each land-use type. During the one year of monitoring (Sep14-Dec15) soil solution, rainfall, and throughfall samples were taken biweekly and analyzed for pH, dissolved and particulate organic carbon (DOC, POC) and nitrogen (DN, PN) as well as for nutrients (e.g. K, Ca, Mg, P, S). Compared to the control sites, the ground fire immediately induced a short-run release peak of DOC in both land-use types. Within two weeks these differences were muted in the post-fire period. The effect of fire was land-use specific with annual DOC fluxes of 82 and 45 kg/(ha*a) for forest and pasture sites, respectively. In contrast, nitrogen fluxes responded differently to the fire event. In the forest, a significant increase in DN concentrations was notable five months after the fire, at the beginning of the vegetation period and lasted until November with DN concentrations in June being 4 times higher compared to the control (82 vs. 18 mg DN/L) and being negatively correlated with pH-values (r=-0.51 p<0.001). Annual DN fluxes from fire manipulated forest plots were two times higher compared to control ones (62 vs. 29 kg DN/(ha*a)) whereas only low impact was found at the pasture with 45 and 38 kg DN/(ha*a) for fire-manipulated plots and control, respectively. In general, the results exhibit highly differing response patterns of elements to fire between the two land-use types and with season. Starting in spring higher DN fluxes following fire event at the forest site could be associated with accelerated activity of soil microbes mineralizing released organic substances from burned forest floor and/or from dead roots. This mineralization process resulted in a significant increase in acidity of the soil solution that may affect important ecosystem functions like nutrient cycling and primary production. Hence, high resolution monitoring following a low intensive fire indicated nutrient losses from the forest ecosystem that could be a hazard for managed forests on nutrient poor soils if fire frequency increases with climate change.

Temporal scaling behavior of forest and urban fires

NASA Astrophysics Data System (ADS)

Wang, J.; Song, W.; Zheng, H.; Telesca, L.

2009-04-01

It has been found that many natural systems are characterized by scaling behavior. In such systems natural factors dominate the event dynamics. Forest fires in different countries have been found to exhibit frequency-size power law over many orders of magnitude and with similar value of parameters. But in countries with high population density such as China and Japan, more than 95% of the forest fire disasters are caused by human activities. Furthermore, with the development of society, the wildland-urban interface (WUI) area is becoming more and more populated, and the forest fire is much connected with urban fire. Therefore exploring the scaling behavior of fires dominated by human-related factors is very challenging. The present paper explores the temporal scaling behavior of forest fires and urban fires in Japan with mathematical methods. Two factors, Allan factor (AF) and Fano factor (FF) are used to investigate time-scaling of fire systems. It is found that the FF for both forest fires and urban fires increases linearly in log-log scales, and this indicates that it behaves as a power-law for all the investigated timescales. From the AF plot a 7 days cycle is found, which indicates a weekly cycle. This may be caused by human activities which has a weekly periodicity because on weekends people usually have more outdoor activities, which may cause more hidden trouble of fire disasters. Our findings point out that although the human factors are the main cause, both the forest fires and urban fires exhibit time-scaling behavior. At the same time, the scaling exponents for urban fires are larger than forest fires, signifying a more intense clustering. The reason may be that fires are affected not only by weather condition, but also by human activities, which play a more important role for urban fires than forest fires and have a power law distribution and scaling behavior. Then some work is done to the relative humidity. Similar distribution law characterizes the relative humidity. The AF plot and FF plot of relative humidity validate the existence of a strong link between weather and fires, and it is very likely that the daily humidity cycle determines the daily fire periodicity.

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

Climate and wildfires in the North American boreal forest.

PubMed

Macias Fauria, Marc; Johnson, E A

2008-07-12

The area burned in the North American boreal forest is controlled by the frequency of mid-tropospheric blocking highs that cause rapid fuel drying. Climate controls the area burned through changing the dynamics of large-scale teleconnection patterns (Pacific Decadal Oscillation/El Niño Southern Oscillation and Arctic Oscillation, PDO/ENSO and AO) that control the frequency of blocking highs over the continent at different time scales. Changes in these teleconnections may be caused by the current global warming. Thus, an increase in temperature alone need not be associated with an increase in area burned in the North American boreal forest. Since the end of the Little Ice Age, the climate has been unusually moist and variable: large fire years have occurred in unusual years, fire frequency has decreased and fire-climate relationships have occurred at interannual to decadal time scales. Prolonged and severe droughts were common in the past and were partly associated with changes in the PDO/ENSO system. Under these conditions, large fire years become common, fire frequency increases and fire-climate relationships occur at decadal to centennial time scales. A suggested return to the drier climate regimes of the past would imply major changes in the temporal dynamics of fire-climate relationships and in area burned, a reduction in the mean age of the forest, and changes in species composition of the North American boreal forest.

Chapter 17: Forecasting wildfire suppression expenditures for the United States Forest Service

Treesearch

Karen L. Abt; Jeffrey P. Prestemon; Krista Gebert

2008-01-01

The wildland fire management organization of the United States Forest Service (USFS) operates under policy and budget legacies that began nearly 100 years ago and a forest fuel situation that is all too current. The confluence of these three factors contributes to increased burning and fire fighting costs for the agency, and increased concern from both the U.S....

Nitrogen balance along a northern boreal forest fire chronosequence.

PubMed

Palviainen, Marjo; Pumpanen, Jukka; Berninger, Frank; Ritala, Kaisa; Duan, Baoli; Heinonsalo, Jussi; Sun, Hui; Köster, Egle; Köster, Kajar

2017-01-01

Fire is a major natural disturbance factor in boreal forests, and the frequency of forest fires is predicted to increase due to climate change. Nitrogen (N) is a key determinant of carbon sequestration in boreal forests because the shortage of N limits tree growth. We studied changes in N pools and fluxes, and the overall N balance across a 155-year non stand-replacing fire chronosequence in sub-arctic Pinus sylvestris forests in Finland. Two years after the fire, total ecosystem N pool was 622 kg ha-1 of which 16% was in the vegetation, 8% in the dead biomass and 76% in the soil. 155 years after the fire, total N pool was 960 kg ha-1, with 27% in the vegetation, 3% in the dead biomass and 69% in the soil. This implies an annual accumulation rate of 2.28 kg ha-1 which was distributed equally between soil and biomass. The observed changes in N pools were consistent with the computed N balance +2.11 kg ha-1 yr-1 over the 155-year post-fire period. Nitrogen deposition was an important component of the N balance. The biological N fixation increased with succession and constituted 9% of the total N input during the 155 post-fire years. N2O fluxes were negligible (≤ 0.01 kg ha-1 yr-1) and did not differ among post-fire age classes. The number and intensity of microbial genes involved in N cycling were lower at the site 60 years after fire compared to the youngest and the oldest sites indicating potential differences in soil N cycling processes. The results suggest that in sub-arctic pine forests, the non-stand-replacing, intermediate-severity fires decrease considerably N pools in biomass but changes in soil and total ecosystem N pools are slight. Current fire-return interval does not seem to pose a great threat to ecosystem productivity and N status in these sub-arctic forests.

Nitrogen balance along a northern boreal forest fire chronosequence

PubMed Central

Pumpanen, Jukka; Berninger, Frank; Ritala, Kaisa; Duan, Baoli; Heinonsalo, Jussi; Sun, Hui; Köster, Egle; Köster, Kajar

2017-01-01

Fire is a major natural disturbance factor in boreal forests, and the frequency of forest fires is predicted to increase due to climate change. Nitrogen (N) is a key determinant of carbon sequestration in boreal forests because the shortage of N limits tree growth. We studied changes in N pools and fluxes, and the overall N balance across a 155-year non stand-replacing fire chronosequence in sub-arctic Pinus sylvestris forests in Finland. Two years after the fire, total ecosystem N pool was 622 kg ha-1 of which 16% was in the vegetation, 8% in the dead biomass and 76% in the soil. 155 years after the fire, total N pool was 960 kg ha-1, with 27% in the vegetation, 3% in the dead biomass and 69% in the soil. This implies an annual accumulation rate of 2.28 kg ha-1 which was distributed equally between soil and biomass. The observed changes in N pools were consistent with the computed N balance +2.11 kg ha-1 yr-1 over the 155-year post-fire period. Nitrogen deposition was an important component of the N balance. The biological N fixation increased with succession and constituted 9% of the total N input during the 155 post-fire years. N2O fluxes were negligible (≤ 0.01 kg ha-1 yr-1) and did not differ among post-fire age classes. The number and intensity of microbial genes involved in N cycling were lower at the site 60 years after fire compared to the youngest and the oldest sites indicating potential differences in soil N cycling processes. The results suggest that in sub-arctic pine forests, the non-stand-replacing, intermediate-severity fires decrease considerably N pools in biomass but changes in soil and total ecosystem N pools are slight. Current fire-return interval does not seem to pose a great threat to ecosystem productivity and N status in these sub-arctic forests. PMID:28358884

Fire decreases arthropod abundance but increases diversity: early and late season prescribed fire effects in a Sierra Nevada mixed-conifer forest

Treesearch

Scott M. Ferrenberg; Dylan W. Schwilk; Eric E. Knapp; Eric Groth; Jon E. Keeley

2006-01-01

Prior to fire suppression in the 20th century, the mixed-conifer forests of the Sierra Nevada, California, U.S.A., historically burned in frequent fires that typically occurred during the late summer and early fall. Fire managers have been attempting to restore natural ecosystem processes through prescription burning, and have often favored burning during the fall in...

Using simulated historical time series to prioritize fuel treatments on landscapes across the United States: The LANDFIRE prototype project

Treesearch

Robert E. Keane; Matthew Rollins; Zhi-Liang Zhu

2007-01-01

Canopy and surface fuels in many fire-prone forests of the United States have increased over the last 70 years as a result of modern fire exclusion policies, grazing, and other land management activities. The Healthy Forest Restoration Act and National Fire Plan establish a national commitment to reduce fire hazard and restore fire-adapted ecosystems across the USA....

Forest construction infrastructures for the prevision, suppression, and protection before and after forest fires

NASA Astrophysics Data System (ADS)

Drosos, Vasileios C.; Giannoulas, Vasileios J.; Daoutis, Christodoulos

2014-08-01

Climatic changes cause temperature rise and thus increase the risk of forest fires. In Greece the forests with the greatest risk to fire are usually those located near residential and tourist areas where there are major pressures on land use changes, while there are no currently guaranteed cadastral maps and defined title deeds because of the lack of National and Forest Cadastre. In these areas the deliberate causes of forest fires are at a percentage more than 50%. This study focuses on the forest opening up model concerning both the prevention and suppression of forest fires. The most urgent interventions that can be done after the fire destructions is also studied in relation to soil protection constructions, in order to minimize the erosion and the torrential conditions. Digital orthophotos were used in order to produce and analyze spatial data using Geographical Information Systems (GIS). Initially, Digital Elevation Models were generated, based on photogrammetry and forest areas as well as the forest road network were mapped. Road density, road distance, skidding distance and the opening up percentage were accurately measured for a forest complex. Finally, conclusions and suggestions have been drawn about the environmental compatibility of forest protection and wood harvesting works. In particular the contribution of modern technologies such as digital photogrammetry, remote sensing and Geographical Information Systems is very important, allowing reliable, effective and fast process of spatial analysis contributing to a successful planning of opening up works and fire protection.

Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years

PubMed Central

Kelly, Ryan; Chipman, Melissa L.; Higuera, Philip E.; Stefanova, Ivanka; Brubaker, Linda B.; Hu, Feng Sheng

2013-01-01

Wildfire activity in boreal forests is anticipated to increase dramatically, with far-reaching ecological and socioeconomic consequences. Paleorecords are indispensible for elucidating boreal fire regime dynamics under changing climate, because fire return intervals and successional cycles in these ecosystems occur over decadal to centennial timescales. We present charcoal records from 14 lakes in the Yukon Flats of interior Alaska, one of the most flammable ecoregions of the boreal forest biome, to infer causes and consequences of fire regime change over the past 10,000 y. Strong correspondence between charcoal-inferred and observational fire records shows the fidelity of sedimentary charcoal records as archives of past fire regimes. Fire frequency and area burned increased ∼6,000–3,000 y ago, probably as a result of elevated landscape flammability associated with increased Picea mariana in the regional vegetation. During the Medieval Climate Anomaly (MCA; ∼1,000–500 cal B.P.), the period most similar to recent decades, warm and dry climatic conditions resulted in peak biomass burning, but severe fires favored less-flammable deciduous vegetation, such that fire frequency remained relatively stationary. These results suggest that boreal forests can sustain high-severity fire regimes for centuries under warm and dry conditions, with vegetation feedbacks modulating climate–fire linkages. The apparent limit to MCA burning has been surpassed by the regional fire regime of recent decades, which is characterized by exceptionally high fire frequency and biomass burning. This extreme combination suggests a transition to a unique regime of unprecedented fire activity. However, vegetation dynamics similar to feedbacks that occurred during the MCA may stabilize the fire regime, despite additional warming. PMID:23878258

Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years.

PubMed

Kelly, Ryan; Chipman, Melissa L; Higuera, Philip E; Stefanova, Ivanka; Brubaker, Linda B; Hu, Feng Sheng

2013-08-06

Wildfire activity in boreal forests is anticipated to increase dramatically, with far-reaching ecological and socioeconomic consequences. Paleorecords are indispensible for elucidating boreal fire regime dynamics under changing climate, because fire return intervals and successional cycles in these ecosystems occur over decadal to centennial timescales. We present charcoal records from 14 lakes in the Yukon Flats of interior Alaska, one of the most flammable ecoregions of the boreal forest biome, to infer causes and consequences of fire regime change over the past 10,000 y. Strong correspondence between charcoal-inferred and observational fire records shows the fidelity of sedimentary charcoal records as archives of past fire regimes. Fire frequency and area burned increased ∼6,000-3,000 y ago, probably as a result of elevated landscape flammability associated with increased Picea mariana in the regional vegetation. During the Medieval Climate Anomaly (MCA; ∼1,000-500 cal B.P.), the period most similar to recent decades, warm and dry climatic conditions resulted in peak biomass burning, but severe fires favored less-flammable deciduous vegetation, such that fire frequency remained relatively stationary. These results suggest that boreal forests can sustain high-severity fire regimes for centuries under warm and dry conditions, with vegetation feedbacks modulating climate-fire linkages. The apparent limit to MCA burning has been surpassed by the regional fire regime of recent decades, which is characterized by exceptionally high fire frequency and biomass burning. This extreme combination suggests a transition to a unique regime of unprecedented fire activity. However, vegetation dynamics similar to feedbacks that occurred during the MCA may stabilize the fire regime, despite additional warming.

Using topography to meet wildlife and fuels treatment objectives in fire-suppressed landscapes

Treesearch

Emma C. Underwood; Joshua H. Viers; James F. Quinn; Malcolm North

2010-01-01

Past forest management practices, fire suppression, and climate change are increasing the need to actively manage California Sierra Nevada forests for multiple environmental amenities. Here we present a relatively low-cost, repeatable method for spatially parsing the landscape to help the U.S. Forest Service manage for different forest and fuel conditions to meet...

Interacting disturbances: Wildfire severity affected by stage of forest disease invasion

Treesearch

Margaret Metz; Kerri Frangioso; Ross Meentemeyer; David Rizzo

2010-01-01

Sudden oak death (SOD) is an emerging forest disease causing extensive tree mortality in coastal California forests. Recent California wildfires provided an opportunity to test a major assumption underlying discussions of SOD and land management: SOD mortality will increase fire severity. We examined pre-fire fuels from host species in a forest monitoring plot network...

Hydrologic Impacts Associated with the Increased Role of Wildland Fire Across the Rangeland-Xeric Forest Continuum of the Great Basin and Intermountain West, USA

NASA Astrophysics Data System (ADS)

Williams, C. J.; Pierson, F. B.; Robichaud, P. R.; Boll, J.; Al-Hamdan, O. Z.

2011-12-01

The increased role of wildland fire across the rangeland-xeric forest continuum in the western United States (US) presents landscape-scale consequences relative runoff and erosion. Concomitant climate conditions and altered plant community transitions in recent decades along grassland-shrubland-woodland-xeric forest transitions have promoted frequent and large wildland fires, and the continuance of the trend appears likely if current or warming climate conditions prevail. Much of the Great Basin and Intermountain West in the US now exists in a state in which rangeland and woodland wildfires stimulated by invasive cheatgrass and dense, horizontal and vertical fuel layers have a greater likelihood of progressing upslope into xeric forests. Drier moisture conditions and warmer seasonal air temperatures, along with dense fuel loads, have lengthened fire seasons and facilitated an increase in the frequency, severity and area burned in mid-elevation western US forests. These changes potentially increase the overall hydrologic vulnerability across the rangeland-xeric forest continuum by spatially and temporally increasing soil surface exposure to runoff and erosion processes. Plot-to-hillslope scale studies demonstrate burning may increase event runoff and/or erosion by factors of 2-40 over small-plots scales and more than 100-fold over large-plot to hillslope scales. Anecdotal reports of large-scale flooding and debris-flow events from rangelands and xeric forests following burning document the potential risk to resources (soil loss, water quality, degraded aquatic habitat, etc.), property and infrastructure, and human life. Such risks are particularly concerning for urban centers near the urban-wildland interface. We do not yet know the long-term ramifications of frequent soil loss associated with commonly occurring runoff events on repeatedly burned sites. However, plot to landscape-scale post-fire erosion rate estimates suggest potential losses of biologically important surface soils may be critically damaging for rangelands given inherent slow soil formation rates. This study presents a summary of fire effects on runoff and erosion across the rangeland-xeric forest continuum of the western US and highlights how that knowledge addresses post-fire hydrologic modeling needs. Further, we present a conceptual framework for advancing post-fire hydrologic vulnerability assessment and identify key areas for future research.

Effects of fire and post-fire salvage logging on avian communities in conifer-dominated forests of the western United States

USGS Publications Warehouse

Kotliar, N.B.; Hejl, S.J.; Hutto, R.L.; Saab, V.; Melcher, Cynthia; McFadzen, M.E.; George, T.L.; Dobkin, D.S.

2002-01-01

Historically, fire was one of the most widespread natural disturbances in the western United States. More recently, however, significant anthropogenic activities, especially fire suppression and silvicultural practices, have altered fire regimes; as a result, landscapes and associated communities have changed as well. Herein, we review current knowledge of how fire and postfire salvaging practices affect avian communities in conifer-dominated forests of the western United States. Specifically, we contrast avian communities in (1) burned vs. unburned forest, and (2) unsalvaged vs. salvage-logged burns. We also examine how variation in burn characteristics (e.g., severity, age, size) and salvage logging can alter avian communities in burns.Of the 41 avian species observed in three or more studies comparing early postfire and adjacent unburned forests, 22% are consistently more abundant in burned forests, 34% are usually more abundant in unburned forests, and 44% are equally abundant in burned and unburned forests or have varied responses. In general, woodpeckers and aerial foragers are more abundant in burned forest, whereas most foliage-gleaning species are more abundant in unburned forests. Bird species that are frequently observed in stand-replacement burns are less common in understory burns; similarly, species commonly observed in unburned forests often decrease in abundance with increasing burn severity. Granivores and species common in open-canopy forests exhibit less consistency among studies. For all species, responses to tire may be influenced by a number of factors including burn severity, fire size and shape, proximity to unburned forests, pre-and post-fire cover types, and time since fire. In addition, postfire management can alter species’ responses to burns. Most cavity-nesting species do not use severely salvaged burns, whereas some cavity-nesters persist in partially salvaged burns. Early post fire specialists, in particular, appear to prefer unsalvaged burns. We discuss several alternatives to severe salvage-logging that will help provide habitat for cavity nesters.We provide an overview of critical research questions and design considerations crucial for evaluating the effects of prescribed fire and other anthropogenic disturbances, such as forest fragmentation. Management of native avifaunas may be most successful if natural disturbance regimes, including fire, are permitted to occur when possible. Natural fires could be augmented with practices, such as prescribed fire (including high-severity fire), that mimic inherent disturbance regimes.

Long-term effects of fire and harvest on carbon stocks of boreal forests in northeastern China

NASA Astrophysics Data System (ADS)

Huang, C.; He, H. S.; Hawbaker, T. J.; Zhu, Z.; Liang, Y.; Gong, P.

2017-12-01

Fire, harvest and their interactions have strong effects on boreal forests carbon stocks. Repeated disturbances associated with relatively short fire return intervals and harvest rotations, and their interactions caused their effects to increase over simulation time.Boreal forests in the northeastern of China cover 8.46×105 km2, store about 350 Tg aboveground carbon, and play an important role in maintaining China's carbon balance. Boreal forests in this region are facing pressures from repeated fires and timber harvesting activities.The objectives of our study were to evaluate the effects of fire, harvest and their interactions on boreal forest carbon stocks of northeastern China.We used the LANDIS PRO-LINKAGES model-coupling framework to simulate the landscape-level effects of fire and harvest and their interactions over 150 years. Our simulation results suggested that aboveground and soil organic carbon are significantly reduced by fire and harvest over 150 years. The long-term effects of fire and harvest on carbon stocks were greater than the short-term effects in the Great Xing' an Mountains. The total effects of fire-harvest interactions on boreal forests are less than the sum of separate effects of fire and harvest. The response of carbon stocks among ecoregions diverged and was due to the spatial variability of fire and harvest regimes.These results emphasize that fire, harvest, and their interactions play an important role in regulating boreal forest carbon stocks, the extent of fire and harvest effects depended on the intensity of these disturbances.

The impact of boreal forest fire on climate warming

USGS Publications Warehouse

Randerson, J.T.; Liu, H.; Flanner, M.G.; Chambers, S.D.; Jin, Y.; Hess, P.G.; Pfister, G.; Mack, M.C.; Treseder, K.K.; Welp, L.R.; Chapin, F.S.; Harden, J.W.; Goulden, M.L.; Lyons, E.; Neff, J.C.; Schuur, E.A.G.; Zender, C.S.

2006-01-01

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 ?? 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 ?? 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.

The impact of boreal forest fire on climate warming.

PubMed

Randerson, J T; Liu, H; Flanner, M G; Chambers, S D; Jin, Y; Hess, P G; Pfister, G; Mack, M C; Treseder, K K; Welp, L R; Chapin, F S; Harden, J W; Goulden, M L; Lyons, E; Neff, J C; Schuur, E A G; Zender, C S

2006-11-17

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 +/- 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 +/- 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.

VISUAL-SEVEIF, a tool for integrating fire behavior simulation and economic evaluation of the impact of Wildfires

Treesearch

Francisco Rodríguez y Silva; Juan Ramón Molina Martínez; Miguel Ángel Herrera Machuca; Jesús Mª Rodríguez Leal

2013-01-01

Progress made in recent years in fire science, particularly as applied to forest fire protection, coupled with the increased power offered by mathematical processors integrated into computers, has led to important developments in the field of dynamic and static simulation of forest fires. Furthermore, and similarly, econometric models applied to economic...

Burn me twice, shame on who? Interactions between successive forest fires across a temperate mountain region.

PubMed

Harvey, Brian J; Donato, Daniel C; Turner, Monica G

2016-09-01

Increasing rates of natural disturbances under a warming climate raise important questions about how multiple disturbances interact. Escalating wildfire activity in recent decades has resulted in some forests re-burning in short succession, but how the severity of one wildfire affects that of a subsequent wildfire is not fully understood. We used a field-validated, satellite-derived, burn-severity atlas to assess interactions between successive wildfires across the US Northern Rocky Mountains a 300,000-km 2 region dominated by fire-prone forests. In areas that experienced two wildfires between 1984 and 2010, we asked: (1) How do overall frequency distributions of burn-severity classes compare between first and second fires? (2) In a given location, how does burn severity of the second fire relate to that of the first? (3) Do interactions between successive fires vary by forest zone or the interval between fires? (4) What factors increase the probability of burning twice as stand-replacing fire? Within the study area, 138,061 ha burned twice between 1984 and 2010. Overall, frequency distributions of burn severity classes (low, moderate, high; quantified using relativized remote sensing indices) were similar between the first and second fires; however burn severity was 5-13% lower in second fires on average. Negative interactions between fires were most pronounced in lower-elevation forests and woodlands, when fire intervals were <10 yr, and when burn severity was low in the first fire. When the first fire burned as high severity and fire intervals exceeded 10-12 yr, burn-severity interactions switched from negative to positive, with high-severity fire begetting subsequent high-severity fire. Locations most likely to experience successive stand-replacing fires were high-elevation forests, which are adapted to high-severity fire, and areas conducive to abundant post-fire tree regeneration. Broadly similar severities among short-interval "re-burns" and other wildfires indicate that positive severity feedbacks, an oft-posited agent of ecosystem decline or state shift, are not an inevitable outcome of re-burning. Nonetheless, context-dependent shifts in both the magnitude and direction of wildfire interactions (associated with forest zone, initial burn-severity, and disturbance interval) illustrate complexities in disturbance interactions and can inform management and predictions of future system dynamics. © 2016 by the Ecological Society of America.

Wildfires in bamboo-dominated Amazonian forest: impacts on above-ground biomass and biodiversity.

PubMed

Barlow, Jos; Silveira, Juliana M; Mestre, Luiz A M; Andrade, Rafael B; Camacho D'Andrea, Gabriela; Louzada, Julio; Vaz-de-Mello, Fernando Z; Numata, Izaya; Lacau, Sébastien; Cochrane, Mark A

2012-01-01

Fire has become an increasingly important disturbance event in south-western Amazonia. We conducted the first assessment of the ecological impacts of these wildfires in 2008, sampling forest structure and biodiversity along twelve 500 m transects in the Chico Mendes Extractive Reserve, Acre, Brazil. Six transects were placed in unburned forests and six were in forests that burned during a series of forest fires that occurred from August to October 2005. Normalized Burn Ratio (NBR) calculations, based on Landsat reflectance data, indicate that all transects were similar prior to the fires. We sampled understorey and canopy vegetation, birds using both mist nets and point counts, coprophagous dung beetles and the leaf-litter ant fauna. Fire had limited influence upon either faunal or floral species richness or community structure responses, and stems <10 cm DBH were the only group to show highly significant (p = 0.001) community turnover in burned forests. Mean aboveground live biomass was statistically indistinguishable in the unburned and burned plots, although there was a significant increase in the total abundance of dead stems in burned plots. Comparisons with previous studies suggest that wildfires had much less effect upon forest structure and biodiversity in these south-western Amazonian forests than in central and eastern Amazonia, where most fire research has been undertaken to date. We discuss potential reasons for the apparent greater resilience of our study plots to wildfire, examining the role of fire intensity, bamboo dominance, background rates of disturbance, landscape and soil conditions.

Wildfires in Bamboo-Dominated Amazonian Forest: Impacts on Above-Ground Biomass and Biodiversity

PubMed Central

Barlow, Jos; Silveira, Juliana M.; Mestre, Luiz A. M.; Andrade, Rafael B.; Camacho D'Andrea, Gabriela; Louzada, Julio; Vaz-de-Mello, Fernando Z.; Numata, Izaya; Lacau, Sébastien; Cochrane, Mark A.

2012-01-01

Fire has become an increasingly important disturbance event in south-western Amazonia. We conducted the first assessment of the ecological impacts of these wildfires in 2008, sampling forest structure and biodiversity along twelve 500 m transects in the Chico Mendes Extractive Reserve, Acre, Brazil. Six transects were placed in unburned forests and six were in forests that burned during a series of forest fires that occurred from August to October 2005. Normalized Burn Ratio (NBR) calculations, based on Landsat reflectance data, indicate that all transects were similar prior to the fires. We sampled understorey and canopy vegetation, birds using both mist nets and point counts, coprophagous dung beetles and the leaf-litter ant fauna. Fire had limited influence upon either faunal or floral species richness or community structure responses, and stems <10 cm DBH were the only group to show highly significant (p = 0.001) community turnover in burned forests. Mean aboveground live biomass was statistically indistinguishable in the unburned and burned plots, although there was a significant increase in the total abundance of dead stems in burned plots. Comparisons with previous studies suggest that wildfires had much less effect upon forest structure and biodiversity in these south-western Amazonian forests than in central and eastern Amazonia, where most fire research has been undertaken to date. We discuss potential reasons for the apparent greater resilience of our study plots to wildfire, examining the role of fire intensity, bamboo dominance, background rates of disturbance, landscape and soil conditions. PMID:22428035

Effects of forest fires and post-fire rehabilitation: a Colorado, USA case study

Treesearch

Lee H. MacDonald; Isaac J. Larsen

2009-01-01

Anthropogenic activities have increased the number of large, high-burn severity wildfires in the lower and mid-elevation coniferous forests in Colorado as well as much of the western US. Forests provide most of the water for cities and agriculture, and the increased runoff and erosion after wildfires is a major concern because of the potential adverse effects on...

A comparison of the costs of forest service and contract fire crews in the Pacific Northwest.

Treesearch

Geoffrey H. Donovan

2005-01-01

Rising wildfire suppression expenditures on public land in the United States have led to increased scrutiny of wildfire management practices. One area that has received particular attention is the Forest Service's increasing reliance on contract fire crews. Because a contract crew rate includes several costs that are not included in the wage costs of a Forest...

High-resolution records detect human-caused changes to the boreal forest wildfire regime in interior Alaska

USGS Publications Warehouse

Gaglioti, Benjamin V.; Mann, Daniel H.; Jones, Benjamin M.; Wooller, Matthew J.; Finney, Bruce P.

2016-01-01

Stand-replacing wildfires are a keystone disturbance in the boreal forest, and they are becoming more common as the climate warms. Paleo-fire archives from the wildland–urban interface can quantify the prehistoric fire regime and assess how both human land-use and climate change impact ecosystem dynamics. Here, we use a combination of a sedimentary charcoal record preserved in varved lake sediments (annually layered) and fire scars in living trees to document changes in local fire return intervals (FRIs) and regional fire activity over the last 500 years. Ace Lake is within the boreal forest, located near the town of Fairbanks in interior Alaska, which was settled by gold miners in AD 1902. In the 400 years before settlement, fires occurred near the lake on average every 58 years. After settlement, fires became much more frequent (average every 18  years), and background charcoal flux rates rose to four times their preindustrial levels, indicating a region-wide increase in burning. Despite this surge in burning, the preindustrial boreal forest ecosystem and permafrost in the watershed have remained intact. Although fire suppression has reduced charcoal influx since the 1950s, an aging fuel load experiencing increasingly warm summers may pose management problems for this and other boreal sites that have similar land-use and fire histories. The large human-caused fire events that we identify can be used to test how increasingly common megafires may alter ecosystem dynamics in the future.

Forest Fires Darken Snow for Years following Disturbance: Magnitude, Duration, and Composition of Light Absorbing Impurities in Seasonal Snow across a Chronosequence of Burned Forests in the Colorado River Headwaters

NASA Astrophysics Data System (ADS)

Gleason, K. E.; Arienzo, M. M.; Chellman, N.; McConnell, J.

2017-12-01

Charred forests shed black carbon and burned debris, which accumulates and concentrates on winter snowpack, reducing snow surface albedo, and subsequently increasing snowmelt rates, and advancing the date of snow disappearance. Forest fires have occurred across vast areas of the seasonal snow zone in recent decades, however we do not understand the long-term implications of burned forests in montane headwaters to snow hydrology and downstream water resources. Across a chronosequence of nine burned forests in the Colorado River Headwaters, we sampled snow throughout the complete snowpack profile to conserve the composition, properties, and vertical stratigraphy of impurities in the snowpack during maximum snow accumulation. Using state-of-the-art geochemical analyses, we determined the magnitude, composition, and particle size distribution of black carbon, dust, and other impurities in the snowpack relative to years-since fire. Forest fires continue to darken snow for many years following fire, however the magnitude, composition, and particle size distribution of impurities change through time, altering the post-fire radiative forcing on snow as a burned forest ages.

Fire Effects on Microbial Enzyme Activities in Larch Forests of the Siberian Arctic

NASA Astrophysics Data System (ADS)

Ludwig, S.; Alexander, H. D.; Bulygina, E. B.; Mann, P. J.; Natali, S.

2012-12-01

Arctic forest ecosystems are warming at an accelerated rate relative to lower latitudes, with global implications for C cycling within these regions. As climate continues to warm and dry, wildfire frequency and severity are predicted to increase, creating a positive feedback to climate warming. Increased fire activity will also influence the microenvironment experienced by soil microbes in disturbed soils. Because soil microbes regulate carbon (C) and nitrogen (N) cycling between terrestrial ecosystems and the atmosphere, it is important to understand microbial response to fires, particularly in the understudied larch forests in the Siberian Arctic. In this project, we created experimental burn plots in a mature larch forest in the Kolyma River watershed of Northeastern Siberia. Plots were burned at several treatments: control (no burn), low, moderate, and severe. After, 1 and 8 d post-fire, we measured soil organic layer depth, soil organic matter (SOM) content, soil moisture, and CO2 flux from the plots. Additionally, we leached soils and measured dissolved organic carbon (DOC), total dissolved nitrogen (TDN), NH4, NO3, soluble reactive phosphorus (SRP), and chromophoric dissolved organic matter (CDOM). Furthermore, we measured extracellular activity of four enzymes involved in soil C and nutrient cycling (leucine aminopeptidase (LAP), β-glucosidase, phosphatase, and phenol oxidase). One day post-fire, LAP activity was similarly low in all treatments, but by 8 d post-fire, LAP activity was lower in burned plots compared to control plots, likely due to increased nitrogen content with increasing burn severity. Phosphatase activity decreased with burn severity 1 d post-fire, but after 8 d, moderate and severe burn plots exhibited increased phosphatase activity. Coupled with trends in LAP activity, this suggests a switch in nutrient limitation from N to phosphorus that is more pronounced with burn severity. β-glucosidase activity similarly decreased with burn severity 1 d post-fire, but by 8 d post-fire activity was the same in all treatments, indicating complete recovery of the microbial population. Phenol oxidase activity was low in all treatments 1 d post-fire, but by 8 d post-fire, severe plots had substantially increased phenol oxidase activity, likely due to microbial efforts to mitigate phenolic compound toxicity following severe fires. Both DOC and the slope ratio of CDOM absorbance increased with burn severity 1 d post-fire, indicating higher extractability of lighter molecular weight C from severe burns. These results imply that black C created from fires remains as a stable C pool while more labile C is mobilized with increasing burn severity. Our results suggest that the immediate effects of fire severity on microbial communities have the potential to change both nutrient use and the form and concentration of C being processed and mobilized from larch forest ecosystems. These findings highlight the importance of changing fire regimes on soil dynamics with implications for forest re-growth, soil-atmospheric feedbacks, and terrestrial inputs to aquatic ecosystems.

Fire patterns in the Amazonian biome

NASA Astrophysics Data System (ADS)

Aragao, Luiz E. O. C.; Shimabukuro, Yosio E.; Lima, Andre; Anderson, Liana O.; Barbier, Nicolas; Saatchi, Sassan

2010-05-01

This paper aims to provide an overview of our recent findings on the interplay between climate and land use dynamics in defining fire patterns in Amazonia. Understanding these relationships is currently a fundamental concern for assessing the vulnerability of Amazonia to climate change and its potential for mitigating current increases in atmospheric greenhouse gases. Reducing carbon emissions from tropical deforestation and forest degradation (REDD), for instance, could contribute to a cumulative emission reduction of 13-50 billion tons of carbon (GtC) by 2100. In Amazonia, though, forest fires can release similar quantities of carbon to the atmosphere (~0.2 GtC yr-1) as deforestation alone. Therefore, to achieve carbon savings through REDD mechanism there is an urgent need of understanding and subsequently restraining related Amazonian fire drivers. In this study, we analyze satellite-derived monthly and annual time-series of fires, rainfall and deforestation in Amazonia to: (1) quantify the seasonal patterns and relationships between these variables; (2) quantify fire and rainfall anomalies to evaluate the impact of recent drought on fire patterns; (3) quantify recent trends in fire and deforestation to understand how land use affects fire patterns in Amazonia. Our results demonstrate a marked seasonality of fires. The majority of fires occurs along the Arc of Deforestation, the expanding agricultural frontier in southern and eastern Amazonia, indicating humans are the major ignition sources determining fire seasonality, spatial distribution and long-term patterns. There is a marked seasonality of fires, which is highly correlated (p<0.05) with monthly rainfall and deforestation rates. Deforestation and fires reach their highest values three and six months, respectively, after the peak of the rainy season. This result clearly describes the impact of major human activities on fire incidence, which is generally characterized by the slash-and-burn of Amazonian vegetation for implementation of pastures and agricultural fields. The cumulative number of hot pixels is exponentially related to the monthly rainfall, which ultimately defines where and when fire can potentially strike. During the 2005 Amazonian drought, the number of hot pixels increased 33% in relation to mean 1998-2005. However, even with a large fraction of the basin experiencing considerable water deficits, fires have only affect areas with extensive human activity. Our spatially explicit trend analysis on deforestation and fire data revealed that more than half of the area experiencing increased fire occurrence have reduced deforestation rates. This reverse pattern is likely to be associated with the slash-and-burn of secondary forests and the increase of fragmentation and forest edges, favouring the leakage of fires from deforested lands into forests. Finally, our analysis points towards a reduction of fire incidence due to land use intensification in this region. In this study, we demonstrated that anthropogenic forcing, such as deforestation rates, is decisive in determining the seasonality and annual patterns of fire occurrence. Moreover, droughts can significantly increase the number of fires in the region exacerbating human impacts in Amazonia. Due to ongoing deforestation and the predicted intensification of climate change induced droughts, it is anticipated that a large area of forest edge will be under increased risk of fires and carbon savings from REDD may be partially offset by increased emissions following fire events. Improved fire-free land management practices may provide a sustainable solution for reducing emissions from the world's largest rainforest. Acknowledges The first author would like to thank the financial support of the Natural Environment Research Council (NERC-UK/grant NE/F015356/1).

Larch Forests of Middle Siberia: Long-Term Trends in Fire Return Intervals

NASA Technical Reports Server (NTRS)

Kharuk, Viacheslav I.; Dvinskaya, Mariya L.; Petrov, Ilya A.; Im, Sergei T.; Ranson, Kenneth J.

2016-01-01

Fire history within the northern larch forests of Central Siberia was studied (65 + deg N). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRIs) were found to be 112 ± 49 years (based on fire scars) and 106 ± 36 years (based on fire scars and tree natality dates). FRI were increased with latitude increase and observed to be about 80 years at 64 deg N, about 200 years near the Arctic Circle and about 300 years nearby the northern range limit of larch stands (approximately 71 deg + N). Northward FRI increase correlated with incoming solar radiation (r = -0.95). Post Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase.

Larch Forests of Middle Siberia: Long-Term Trends in Fire Return Intervals

PubMed Central

Kharuk, Viacheslav I.; Dvinskaya, Mariya L.; Petrov, Ilya A.; Im, Sergei T.; Ranson, Kenneth J.

2017-01-01

Fire history within the northern larch forests of Central Siberia was studied (65+°N). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRI) were found to be 112 ± 49 years (based on fire scars) and 106 ± 36 years (based on fire scars and tree natality dates). FRI were increased with latitude increase, and observed to be about 80 years at 64°N, about 200 years near the Arctic Circle, and about 300 years nearby the northern range limit of larch stands (~71°+N). Northward FRI increase correlated with incoming solar radiation (r = − 0.95). Post Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase. PMID:28966554

Spatial distribution of ozone over Indonesia (Study case: Forest fire event 2015)

NASA Astrophysics Data System (ADS)

Muslimah, Sri; Buce Saleh, Muhamad; Hidayat, Rahmat

2018-05-01

Tropospheric ozone is known as surface ozone and caused several health impact. The objective of this study was to analysis spatial distribution of tropospheric ozone over Indonesia case study forest fire event in 2015. Monthly observation measured by Ozone Monitoring Instrument (OMI) have been analysed from January – December 2015 to study spatial distribution of tropospheric ozone related to forest fire event 2015. The study discovered high level of tropospheric column ozone (TCO) from October to November 2015. The result shows increasing average of TCO from September to October almost 6 DU. Meanwhile, monthly number of hotspot is higher in September 2015 with total number 257 hotspot which is acquired by Moderate Resolution Imaging Spectrometer (MODIS) Terra version 6.1 with confidence level same or more than 90%. The hotspot distribution compared with spatial TCO distribution and shows interesting time lag with respect to hotspot distribution, one month. Further study for daily comparison of TCO and forest fire event needed. This result suggested that the tropospheric ozone over the Indonesian region increases in 2015 were remarkable and corresponded to forest fire event.

Wildfires Dynamics in Siberian Larch Forests

NASA Technical Reports Server (NTRS)

Ponomarev, Evgenii I.; Kharuk, Viacheslav I.; Ranson, Kenneth J.

2016-01-01

Wildfire number and burned area temporal dynamics within all of Siberia and along a south-north transect in central Siberia (45deg-73degN) were studied based on NOAA/AVHRR (National Oceanic and Atmospheric Administration/ Advanced Very High Resolution Radiometer) and Terra/MODIS (Moderate Resolution Imaging Spectroradiometer) data and field measurements for the period 1996-2015. In addition, fire return interval (FRI) along the south-north transect was analyzed. Both the number of forest fires and the size of the burned area increased during recent decades (p < 0.05). Significant correlations were found between forest fires, burned areas and air temperature (r = 0.5) and drought index (The Standardized Precipitation Evapotranspiration Index, SPEI) (r = 0.43). Within larch stands along the transect, wildfire frequency was strongly correlated with incoming solar radiation (r = 0.91). Fire danger period length decreased linearly from south to north along the transect. Fire return interval increased from 80 years at 62 N to 200 years at the Arctic Circle (6633' N), and to about 300 years near the northern limit of closed forest stands (about 71+ N). That increase was negatively correlated with incoming solar radiation (r = 0.95). Keywords: wildfires; drought index; larch stands; fire return interval; fire frequency; burned area; climate-induced trends in Siberian wildfires

Post-fire vegetation and fuel development influences fire severity patterns in reburns.

PubMed

Coppoletta, Michelle; Merriam, Kyle E; Collins, Brandon M

2016-04-01

In areas where fire regimes and forest structure have been dramatically altered, there is increasing concern that contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire. Our study utilized an extensive set of field plots established following four fires that occurred between 2000 and 2010 in the northern Sierra Nevada, California, USA that were subsequently reburned in 2012. The information obtained from these field plots allowed for a unique set of analyses investigating the effect of vegetation, fuels, topography, fire weather, and forest management on reburn severity. We also examined the influence of initial fire severity and time since initial fire on influential predictors of reburn severity. Our results suggest that high- to moderate-severity fire in the initial fires led to an increase in standing snags and shrub vegetation, which in combination with severe fire weather promoted high-severity fire effects in the subsequent reburn. Although fire behavior is largely driven by weather, our study demonstrates that post-fire vegetation composition and structure are also important drivers of reburn severity. In the face of changing climatic regimes and increases in extreme fire weather, these results may provide managers with options to create more fire-resilient ecosystems. In areas where frequent high-severity fire is undesirable, management activities such as thinning, prescribed fire, or managed wildland fire can be used to moderate fire behavior not only prior to initial fires, but also before subsequent reburns.

A review of the relationships between drought and forest fire in the United States

USGS Publications Warehouse

Littell, Jeremy; Peterson, David L.; Riley, Karin L.; Yongquiang Liu,; Luce, Charles H.

2016-01-01

The historical and pre-settlement relationships between drought and wildfire are well documented in North America, with forest fire occurrence and area clearly increasing in response to drought. There is also evidence that drought interacts with other controls (forest productivity, topography, fire weather, management activities) to affect fire intensity, severity, extent, and frequency. Fire regime characteristics arise across many individual fires at a variety of spatial and temporal scales, so both weather and climate—including short- and long-term droughts—are important and influence several, but not all, aspects of fire regimes. We review relationships between drought and fire regimes in United States forests, fire-related drought metrics and expected changes in fire risk, and implications for fire management under climate change. Collectively, this points to a conceptual model of fire on real landscapes: fire regimes, and how they change through time, are products of fuels and how other factors affect their availability (abundance, arrangement, continuity) and flammability (moisture, chemical composition). Climate, management, and land use all affect availability, flammability, and probability of ignition differently in different parts of North America. From a fire ecology perspective, the concept of drought varies with scale, application, scientific or management objective, and ecosystem.

A synthesis of post-fire Burned Area Reports from 1972 to 2009 for western US Forest Service lands: Trends in wildfire characteristics and post-fire stabilisation treatments and expenditures

Treesearch

Peter R. Robichaud; Hakjun Rhee; Sarah A. Lewis

2014-01-01

Over 1200 post-fire assessment and treatment implementation reports from four decades (1970s-2000s) of western US forest fires have been examined to identify decadal patterns in fire characteristics and the justifications and expenditures for the post-fire treatments. The main trends found were: (1) the area burned by wildfire increased over time and the rate of...

Range expansion of invasive shrubs: implication for crown fire risk in forestlands of the southern USA.

PubMed

Wang, Hsiao-Hsuan; Wonkka, Carissa L; Grant, William E; Rogers, William E

2016-01-01

Non-native plant invasions and changing management activities have dramatically altered the structure and composition of forests worldwide. Invasive shrubs and fire suppression have led to increased densification and biomass accumulation in forest ecosystems of the southeastern USA. Notably, Chinese and European privets are rapid growing, shade-tolerant shrubs which number among the most aggressive invasive species in these forests. Privet encroachment has caused losses of native diversity, alteration of ecosystem processes and changes in community structure. The latter has become manifest through decreases in fine herbaceous fuels concurrent with increases in coarse woody fuels in forest understoreys. These alterations in fuel structure will potentially lead to less frequent, but more severe forest fires, which threaten important forest resources during extreme weather conditions. Drawing on extensive data sets compiled by the US Forest Service, we integrated statistical forecasting and analytical techniques within a spatially explicit, agent-based, simulation framework to predict potential range expansion of Chinese and European privet (Ligustrum sinenseandL. vulgare) and the associated increase in crown fire risk over the next two decades in forestlands of Mississippi and Alabama. Our results indicate that probability of invasion is positively associated with elevation, adjacency (within 300 m) to water bodies, mean daily maximum temperature, site productivity and private land ownership, and is negatively associated with slope, stand age, artificial regeneration, distance to the nearest road and fire disturbance. Our projections suggest the total area invaded will increase from 1.36 to ≈31.39% of all forestlands in Mississippi and Alabama (≈7 million hectares) and the annual frequency of crown fires in these forestlands will approximately double within the next two decades. Such time series projections of annual range expansions and crown fire frequency should provide land managers and restoration practitioners with an invasion chronology upon which to base proactive management plans. Published by Oxford University Press on behalf of the Annals of Botany Company.

Range expansion of invasive shrubs: implication for crown fire risk in forestlands of the southern USA

PubMed Central

Wang, Hsiao-Hsuan; Wonkka, Carissa L.; Grant, William E.; Rogers, William E.

2016-01-01

Non-native plant invasions and changing management activities have dramatically altered the structure and composition of forests worldwide. Invasive shrubs and fire suppression have led to increased densification and biomass accumulation in forest ecosystems of the southeastern USA. Notably, Chinese and European privets are rapid growing, shade-tolerant shrubs which number among the most aggressive invasive species in these forests. Privet encroachment has caused losses of native diversity, alteration of ecosystem processes and changes in community structure. The latter has become manifest through decreases in fine herbaceous fuels concurrent with increases in coarse woody fuels in forest understoreys. These alterations in fuel structure will potentially lead to less frequent, but more severe forest fires, which threaten important forest resources during extreme weather conditions. Drawing on extensive data sets compiled by the US Forest Service, we integrated statistical forecasting and analytical techniques within a spatially explicit, agent-based, simulation framework to predict potential range expansion of Chinese and European privet (Ligustrum sinense and L. vulgare) and the associated increase in crown fire risk over the next two decades in forestlands of Mississippi and Alabama. Our results indicate that probability of invasion is positively associated with elevation, adjacency (within 300 m) to water bodies, mean daily maximum temperature, site productivity and private land ownership, and is negatively associated with slope, stand age, artificial regeneration, distance to the nearest road and fire disturbance. Our projections suggest the total area invaded will increase from 1.36 to ≈31.39% of all forestlands in Mississippi and Alabama (≈7 million hectares) and the annual frequency of crown fires in these forestlands will approximately double within the next two decades. Such time series projections of annual range expansions and crown fire frequency should provide land managers and restoration practitioners with an invasion chronology upon which to base proactive management plans. PMID:26903488

Modeling soil erosion and sediment transport from fires in forested watersheds of the South Carolina Piedmont

Treesearch

Tyler Crumbley; Ge Sun; Steve McNulty

2008-01-01

Forested watersheds in the Southeastern U.S. provide high quality water vital to ecosystem integrity and downstream aquatic resources. Excessive sedimentation from human activities in forest streams is of concern to responsible land managers. Prescribed fire is a common treatment applied to Southeastern piedmont forests and the risk of wildfire is becoming increasingly...

The effect of fire intensity on soil respiration in Siberia boreal forest

Treesearch

S. Baker; A. V. Bogorodskaya

2010-01-01

Russian boreal forests have an annual wildfire activity averaging 10 to 20 million ha, which has increased in recent years. This wildfire activity, in response to changing climate has the potential to significantly affect the carbon storage capacity of Siberian forests. A better understanding of the effect of fire on soil respiration rates in the boreal forest of...

Modeling soil erosion and sediment transport from fires in forested watersheds of the South Carolina Piedmont

Treesearch

Tyler Crumbley; Ge Sun; Steve McNulty

2007-01-01

Forested watersheds in the Southeastern U.S. provide high quality water vital to ecosystem integrity and downstream aquatic resources. Excessive sedimentation from human activities in forest streams is of concern to responsible land managers. Prescribed fire is a common treatment applied to Southeastern Piedmont forests and the risk of wildfire is becoming increasingly...

Management of forest fires to maximize carbon sequestration in temperate and boreal forests

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

Guggenheim, D.E.

1996-12-31

This study examines opportunities for applying prescribed burning strategies to forest stands to enhance net carbon sequestration and compared prescribed burning strategies with more conventional forestry-based climate change mitigation alternatives, including fire suppression and afforestation. Biomass burning is a major contributor to greenhouse gas accumulation in the atmosphere. Biomass burning has increased by 50% since 1850. Since 1977, the annual extent of burning in the northern temperate and boreal forests has increased dramatically, from six- to nine-fold. Long-term suppression of fires in North America, Russia, and other parts of the world has led to accumulated fuel load and an increasemore » in the destructive power of wildfires. Prescribed burning has been used successfully to reduce the destructiveness of wildfires. However, across vast areas of Russia and other regions, prescribed burning is not a component of forest management practices. Given these factors and the sheer size of the temperate-boreal carbon sink, increasing attention is being focused on the role of these forests in mitigating climate change, and the role of fire management strategies, such as prescribed burning, which could work alongside more conventional forestry-based greenhouse gas offset strategies, such as afforestation.« less

Compounding nonlinearities in the climate and wildfire system contribute to high uncertainty in estimates of future burned area in the western United State

NASA Astrophysics Data System (ADS)

Williams, P.

2015-12-01

Ecological studies are increasingly recognizing the importance of atmospheric vapor-pressure deficit (VPD) as a driver of forest drought stress and disturbance processes such as wildfire. Because of the nonlinear Clausius-Clapeyron relationship between temperature and saturation vapor pressure, small variations in temperature can have large impacts on VPD, and therefore drought, particularly in warm, dry areas and particularly during the warm season. It is also clear that VPD and drought affect forest fire nonlinearly, as incremental drying leads to increasingly large burned areas. Forest fire is also affected by fuel amount and connectivity, which are promoted by vegetation growth in previous years, which is in turn promoted by lack of drought, highlighting the importance of nuances in the sequencing of natural interannual climate variations in modulating the impacts of drought on wildfire. The many factors affecting forest fire, and the nonlinearities embedded within the climate and wildfire systems, cause interannual variability in forest-fire area and frequency to be wildly variable and strongly affected by internal climate variability. In addition, warming over the past century has produced a background increase in forest fire frequency and area in many regions. In this talk I focus on the western United States and will explore whether the relationships between internal climate variability on forest fire area have been amplified by the effects of warming as a result of the compounding nonlinearities described above. I will then explore what this means for future burned area in the western United States and make the case that uncertainties in the future global greenhouse gas emissions trajectory, model projections of mean temperatures, model projections of precipitation, and model projections of natural climate variability translate to very large uncertainties in the effects of future climate variability on forest fire area in the United States and globally.

[Prediction on the changes of forest fire danger rating in Great Xing'an Mountain region of Northeast China in the 21st century under effects of climate change].

PubMed

Yang, Guang; Shu, Li-Fu; Di, Xue-Ying

2012-12-01

Based on the A2a and B2a climatic scenarios for both the baseline period (1961-1990) and the future scenario periods (2010-2039, 2040-2069, and 2070-2099) from the Hadley Centre's General Circulation, and by using Delta method, WGEN downscaling methods, and Canadian Forest Fire Danger Rating System, this paper classified the forest fire dangers in Great Xing' an Mountains region of Heilongjiang Province, Northeast China, predicted the changes of the forest fire danger rating in the period 2010-2099 relative to baseline period (1961-1990), and analyzed the uncertainty of the long-term prediction of forest fire danger rating. It was predicted that under the background of climate warming, the mean annual days of extremely high, very high, and medium forest dangers in study region in the 21st century all showed an increasing trend, while the mean annual days of high and low forest dangers were in adverse. Relative to the baseline period of 1961-1990, the mean annual days of extremely high and very high forest dangers in the 2040-2069 and 2070-2099 under the scenarios of SRES A2a and B2a would be increased by 43 and 36, and 62 and 61, respectively.

78 FR 2947 - Manti-La Sal National Forest, Utah; Maverick Point Forest Health Project

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-15

... class structure via use of timber harvesting and prescribed fire. Project activities also seek to.... Over the last 20 years drought conditions have increased; fire size, severity, and total acres burned... fire regimes have been significantly altered from their historical range. The risk of losing key...

Quantifying changes in total and pyrogenic carbon stocks across fire severity gradients using active wildfire incidents

NASA Astrophysics Data System (ADS)

Miesel, Jessica; Reiner, Alicia; Ewell, Carol; Maestrini, Bernardo; Dickinson, Matthew

2018-05-01

Positive feedbacks between wildfire emissions and climate are expected to increase in strength in the future; however, fires not only release carbon (C) from terrestrial to atmospheric pools, they also produce pyrogenic C (PyC) which contributes to longer-term C stability. Our objective was to quantify wildfire impacts on total C and PyC stocks in California mixed-conifer forest, and to investigate relationships between C and PyC stocks and changes across gradients of fire severity, using metrics derived from remote sensing and field observations. Our unique study accessed active wildfires to establish and measure plots within days before and after fire, prior to substantial erosion. We measured pre- and post-fire aboveground forest structure and woody fuels to calculate aboveground biomass, C and PyC, and collected forest floor and 0-5 cm mineral soil samples. Tree mortality increased with severity, but overstory C loss was minimal and limited primarily to foliage. Fire released 85% of understory and herbaceous C (comprising <1.0% of total ecosystem C). The greatest C losses occurred from downed wood and forest floor pools (19.3±5.1 Mg ha-1 and 25.9±3.2 Mg ha-1, respectively). Tree bark and downed wood contributed the greatest PyC gains (1.5±0.3 Mg ha-1 and 1.9±0.8 Mg ha-1, respectively), and PyC in tree bark showed non-significant positive trends with increasing severity. Overall PyC losses of 1.9±0.3 Mg ha-1 and 0.5±0.1 Mg ha-1 occurred from forest floor and 0-5 cm mineral soil, with no clear patterns across severity. Fire resulted in a net ecosystem PyC gain (0.96±0.98 Mg ha-1) across aboveground and belowground components of these forests, and there were no differences among severity levels. Carbon emissions represented only 21.6% of total forest C; however, extensive conversion of C from live to dead pools will contribute to large downed wood C pools susceptible to release in a subsequent fire, indicating that there may be a delayed relationship between fire severity and C emissions. This research advances understanding of forest C loss and stabilization as PyC in wildfires; however, poor relationships between C and PyC gains or losses and fire severity highlight the complexity of fire impacts on forest C.

Efficacy of landscape scale woodland and savanna restoration at multiple spatial and temporal scales

USGS Publications Warehouse

Pittman, H. Tyler; Krementz, David G.

2016-01-01

The loss of historic ecosystem conditions has led forest managers to implement woodland and savanna ecosystem restoration on a landscape scale (≥10,000 ha) in the Ozark Plateau of Arkansas. Managers are attempting to restore and conserve these ecosystems through the reintroduction of disturbance, mainly short-rotation early-growing-season prescribed fire. Short-rotation early-growing season prescribed fire in the Ozarks typically occurs immediately before bud-break, through bud-break, and before leaf-out, and fire events occur on a three-to five-year interval. We examined short-rotation early-growing season prescribed fire as a restoration tool on vegetation characteristics. We collected vegetation measurements at 70 locations annually from 2011 to 2012 in and around the White Rock Ecosystem Restoration Area (WRERA), Ozark-St. Francis National Forest, Arkansas, and used generalized linear models to investigate the impact and efficacy of prescribed fire on vegetation structure. We found the number of large shrubs (>5 cm base diameter) decreased and small shrubs (<5 cm ground diameter) increased with prescribed fire severity. We found that horizontal understory cover from ground level to 1 m in height increased with time-since-prescribed-fire and woody ground cover decreased with the number of prescribed fire treatments. Using LANDFIRE datasets at the landscape scale, we found that since the initiation of a short-rotation early-growing season prescribed fire management regime, forest canopy cover has not reverted to levels characteristic of woodlands and savannas or reached restoration objectives over large areas. Without greater reductions in forest canopy cover and increases in forest-canopy cover heterogeneity, advanced regeneration will be limited in success, and woodland and savanna conditions will not return soon or to the extent desired.

The effect of remnant forest on insect successional response in tropical fire-impacted peatland: A bi-taxa comparison.

PubMed

Neoh, Kok-Boon; Bong, Lee-Jin; Muhammad, Ahmad; Itoh, Masayuki; Kozan, Osamu; Takematsu, Yoko; Yoshimura, Tsuyoshi

2017-01-01

Fire has become a common feature in tropical drained peatlands, and it may have detrimental impacts on the overall biodiversity of the forest ecosystem. We investigated the effect of fire on termite and ant assemblages and the importance of remnant forest in restoring species diversity in fire-impacted tropical peat swamp forests. The species loss of both termites and ants was as high as 50% in some fire-impacted peats compared to remnant forests, but in most cases the species richness for termites and ants was statistically equal along the land uses surveyed. However, a pronounced difference in functional group composition of termites was detected. In particular, sites close to remnant forests contained two additional termite feeding groups so that they shared a similar composition structure with remnant forests but were significantly different from sites distant from remnant forests. In general, ants were resilient to fire, and the similarity index showed a high degree of similarity among ant communities in all land uses surveyed. The Shannon diversity index for termites and ants decreased with increasing distance from the remnant forests and level of ecological degradation. Peat vegetation variables and ecological degradation were important in shaping termite and ant communities in the tropical peatlands, but their relative importance was not significant in fire-impacted peats regardless of distance from the remnant forests. This study highlights the importance of remnant forests as a biodiversity repository and natural buffer that can enhance species diversity and recolonization of forest-adapted species.

The effect of remnant forest on insect successional response in tropical fire-impacted peatland: A bi-taxa comparison

PubMed Central

Neoh, Kok-Boon; Bong, Lee-Jin; Muhammad, Ahmad; Itoh, Masayuki; Kozan, Osamu; Takematsu, Yoko; Yoshimura, Tsuyoshi

2017-01-01

Fire has become a common feature in tropical drained peatlands, and it may have detrimental impacts on the overall biodiversity of the forest ecosystem. We investigated the effect of fire on termite and ant assemblages and the importance of remnant forest in restoring species diversity in fire-impacted tropical peat swamp forests. The species loss of both termites and ants was as high as 50% in some fire-impacted peats compared to remnant forests, but in most cases the species richness for termites and ants was statistically equal along the land uses surveyed. However, a pronounced difference in functional group composition of termites was detected. In particular, sites close to remnant forests contained two additional termite feeding groups so that they shared a similar composition structure with remnant forests but were significantly different from sites distant from remnant forests. In general, ants were resilient to fire, and the similarity index showed a high degree of similarity among ant communities in all land uses surveyed. The Shannon diversity index for termites and ants decreased with increasing distance from the remnant forests and level of ecological degradation. Peat vegetation variables and ecological degradation were important in shaping termite and ant communities in the tropical peatlands, but their relative importance was not significant in fire-impacted peats regardless of distance from the remnant forests. This study highlights the importance of remnant forests as a biodiversity repository and natural buffer that can enhance species diversity and recolonization of forest-adapted species. PMID:28334021

Simulating the effect of ignition source type on forest fire statistics

NASA Astrophysics Data System (ADS)

Krenn, Roland; Hergarten, Stefan

2010-05-01

Forest fires belong to the most frightening natural hazards, and have long-term ecological and economic effects on the regions involved. It was found that their frequency-area distributions show power-law behaviour under a wide variety of conditions, interpreting them as a self-organised critical phenomenon. Using computer simulations, self-organised critical behaviour manifests in simple cellular automaton models. With respect to ignition source, forest fires can be categorised as lightning-induced or as a result of human activity. Lightning fires are considered to be natural, whereas ``man made'' fires are frequently caused by some sort of technological disaster, such as sparks from wheels of trains, the rupture of overhead electrical lines, the misuse of electrical or mechanical devices and so on. Taking into account that such events rarely occur deep in the woods, man made fires should start preferably on the edge of a forest or where the forest is not very dense. We present a modification in the self-organised critical Drossel-Schwabl forest fire model that takes these two different triggering mechanisms into account and increases the scaling exponent of the frequency-area distribution by ca. 1/3. Combined simulations further predict a dependence of the overall event-size distribution on the ratio of lightning-induced and man made fires as well as a splitting of their partial distributions. Lightning is identified as the dominant mechanism in the regime of the largest fires. The results are confirmed by the analysis of the Canadian Large Fire Database and suggest that lightning-induced and man made forest fires cannot be treated separately in wildfire modelling, hazard assessment and forest management.

Synergistic effects of drought and fire on the carbon carrying capacity of tropical forests and woodlands

NASA Astrophysics Data System (ADS)

Boer, Matthias; Bradstock, Ross

2014-05-01

More than half of the global forest carbon stock is held in tropical forests. A relatively large proportion of the tropical forest carbon is stored in plant biomass rather than in the soil, making these stocks particularly vulnerable to disturbances such as droughts, fires and cyclones. The frequencies, duration and intensities of such disturbances may change under future climates with poorly resolved but potentially significant (synergistic) effects on the carbon carrying capacity of tropical forests and thereby on global geochemical cycles. In this study we analyse high-resolution global data sets for tropical forest biomass (Saatchi et al., 2011. PNAS) and fire affected areas (GFED4, Giglio et al.,2013. JGR 118), together with climate data (WorldClim, Hijmans et al., 2005. Int. J. Clim. 25), to quantify the sensitivity of tropical forest carbon stocks in South America, Africa and Asia/Australia to seasonal water deficits and fire. Here, the climatic water deficit (D), calculated as the difference between mean annual potential evapotranspiration and actual evapotranspiration, is used as a measure of seasonal water stress (i.e., evaporative demand not met by available water), while the mean annual burned area fraction (1995-2013) of grid cells is used as a measure of average fire activity. Tropical forest carbon stocks are maximal, as expected, where water deficits are negligible. In those densely forested environments fire tends to be extremely rare as fuels are too wet to burn for most of the time. In all three continents, potential tropical forest carbon stocks are well predicted by a non-linear decreasing function of the mean annual climatic water deficit, with a steep drop in carbon stocks at D of 700-800 mm per year. At this threshold in the climatic water deficit we observe a strong increase in fire activity that is indicative of a critical change in vegetation structure (i.e., tree/grass ratio) and associated shift in the dominant climatic constraint on fire activity from fuel dryness to fuel productivity. By comparing predictions of potential forest carbon stocks (i.e., as a function of D only) with actual carbon stocks, we quantify the sensitivity of those stocks to increasing fire activity. Finally, we map the risk of losses in carbon carrying capacity of tropical forests under scenarios of future climate.

From open to closed canopy: A century of change in Douglas-fir forest, Orcas Island, Washington

USGS Publications Warehouse

Peterson, D.L.; Hammer, R.D.

2001-01-01

During the past century, forest structure on south-facing slopes of Mount Constitution, Orcas Island, Washington, has changed from open-grown Douglas-fir (Pseudotsuga menziesii) mixed with prairie to primarily closed canopy forest. Density of open-grown Douglas-fir was approximately 7 stems/ha in the 19th century, while current density of trees in closed-canopy mature forest is 426 stems/ha. Trees occur at intermediate densities in areas of transition from savanna-like stands to closed canopy. Analysis of fire scars indicates that at least seven fires have occurred on Mount Constitution since 1736, but only one fire has occurred since 1893, which suggests that the recent increase in stem density has been caused primarily by fire exclusion. The high stem densities currently found in this landscape put the relict (120-350+ years old) Douglas-fir at risk from contemporary fires, which would likely be high-intensity crown fires. Given the transition of forests on Orcas Island during the 20th century to closed canopy structure, undisturbed open-grown coniferous forest is now extremely rare in the San Juan Islands.

[Forest lighting fire forecasting for Daxing'anling Mountains based on MAXENT model].

PubMed

Sun, Yu; Shi, Ming-Chang; Peng, Huan; Zhu, Pei-Lin; Liu, Si-Lin; Wu, Shi-Lei; He, Cheng; Chen, Feng

2014-04-01

Daxing'anling Mountains is one of the areas with the highest occurrence of forest lighting fire in Heilongjiang Province, and developing a lightning fire forecast model to accurately predict the forest fires in this area is of importance. Based on the data of forest lightning fires and environment variables, the MAXENT model was used to predict the lightning fire in Daxing' anling region. Firstly, we studied the collinear diagnostic of each environment variable, evaluated the importance of the environmental variables using training gain and the Jackknife method, and then evaluated the prediction accuracy of the MAXENT model using the max Kappa value and the AUC value. The results showed that the variance inflation factor (VIF) values of lightning energy and neutralized charge were 5.012 and 6.230, respectively. They were collinear with the other variables, so the model could not be used for training. Daily rainfall, the number of cloud-to-ground lightning, and current intensity of cloud-to-ground lightning were the three most important factors affecting the lightning fires in the forest, while the daily average wind speed and the slope was of less importance. With the increase of the proportion of test data, the max Kappa and AUC values were increased. The max Kappa values were above 0.75 and the average value was 0.772, while all of the AUC values were above 0.5 and the average value was 0. 859. With a moderate level of prediction accuracy being achieved, the MAXENT model could be used to predict forest lightning fire in Daxing'anling Mountains.

Contribution of Earth Observation and meteorological datasets for the design and development of a national fire risk assessment system (NFOFRAS)

NASA Astrophysics Data System (ADS)

Katagis, Thomas; Bliziotis, Dimitris; Liantinioti, Chrysa; Gitas, Ioannis Z.; Charalampopoulou, Betty

2016-08-01

During the past decades, forest fires have increased both in frequency and severity thus, increasing the life threats for people and environment and leading countries to spend vast amounts of resources in fighting forest fires. Besides anthropogenic activities, climatic and environmental changes are considered as driving factors affecting fire occurrence and vegetation succession. Especially in the Mediterranean region, the development and existence of effective tools and services is crucial for assisting pre-fire planning and preparedness. The collaborative project NFOFRAS aims at introducing an innovative and effective system for rating forest fire risk, and is based on existing technology and standards that have been developed by countries with a long and a very successful involvement in this field. During the first phase of the project a detailed documentation of the proposed methodology was composed. In addition, Earth Observation (EO) and meteorological datasets were utilized for producing accurate pre-fire measurements over a selected study area in Greece.

A GIS-based decision support system for determining the shortest and safest route to forest fires: a case study in Mediterranean Region of Turkey.

PubMed

Akay, Abdullah E; Wing, Michael G; Sivrikaya, Fatih; Sakar, Dursun

2012-03-01

The ability of firefighting vehicles and staff to reach a fire area as quickly as possible is critical in fighting against forest fires. In this study, a Geographical Information System-based decision support system was developed to assist fire managers in determining the fastest and the safest or more reliable access routes from firefighting headquarters to fire areas. The decision support system was tested in the Kahramanmaras Forestry Regional Directoratein the Mediterranean region of Turkey. The study area consisted of forested lands which had been classified according to fire sensitivity. The fire response routing simulations considered firefighting teams located in 20 firefighting headquarter locations. The road network, the locations of the firefighting headquarters, and possible fire locations were mapped for simulation analysis. In alternative application simulations, inaccessible roads which might be closed due to fire or other reasons were indicated in the network analysis so that the optimum route was not only the fastest but also the safest and most reliable path. The selection of which firefighting headquarters to use was evaluated by considering critical response time to potential fire areas based on fire sensitivity levels. Results indicated that new firefighting headquarters should be established in the region in order to provide sufficient firefighting response to all forested lands. In addition, building new fire access roads and increasing the design speed on current roads could also increase firefighting response capabilities within the study area.

Emissions of Selected Semivolatile Organic Chemicals from Forest and Savannah Fires.

PubMed

Wang, Xianyu; Thai, Phong K; Mallet, Marc; Desservettaz, Maximilien; Hawker, Darryl W; Keywood, Melita; Miljevic, Branka; Paton-Walsh, Clare; Gallen, Michael; Mueller, Jochen F

2017-02-07

The emission factors (EFs) for a broad range of semivolatile organic chemicals (SVOCs) from subtropical eucalypt forest and tropical savannah fires were determined for the first time from in situ investigations. Significantly higher (t test, P < 0.01) EFs (μg kg -1 dry fuel, gas + particle-associated) for polycyclic aromatic hydrocarbons (∑ 13 PAHs) were determined from the subtropical forest fire (7,000 ± 170) compared to the tropical savannah fires (1,600 ± 110), due to the approximately 60-fold higher EFs for 3-ring PAHs from the former. EF data for many PAHs from the eucalypt forest fire were comparable with those previously reported from pine and fir forest combustion events. EFs for other SVOCs including polychlorinated biphenyl (PCB), polychlorinated naphthalene (PCN), and polybrominated diphenyl ether (PBDE) congeners as well as some pesticides (e.g., permethrin) were determined from the subtropical eucalypt forest fire. The highest concentrations of total suspended particles, PAHs, PCBs, PCNs, and PBDEs, were typically observed in the flaming phase of combustion. However, concentrations of levoglucosan and some pesticides such as permethrin peaked during the smoldering phase. Along a transect (10-150-350 m) from the forest fire, concentration decrease for PCBs during flaming was faster compared to PAHs, while levoglucosan concentrations increased.

Fire severity, size, and climate associations diverge from historical precedent along an ecological gradient in the Pinaleno Mountains, Arizona, USA

Treesearch

Christopher D. O' Connor; Donald A. Falk; Ann M. Lynch; Thomas W. Swetnam

2014-01-01

In recent decades fire size and severity have been increasing in high elevation forests of the American Southwest. Ecological outcomes of these increases are difficult to gauge without an historical context for the role of fire in these systems prior to interruption by Euro-American land uses. Across the gradient of forest types in the Pinaleño Mountains, a Sky Island...

Introduction, study area description, and experimental design

Treesearch

Elaine Kennedy Sutherland; Todd F. Hutchinson; Daniel A. Yaussy

2003-01-01

Throughout much of the Eastern Deciduous Forest, the sustainability of oak-dominated forests is threatened by poor oak regeneration as other tree species increase in abundance. Historically, fire was a frequent process in oak-dominated ecosystems (savannas, woodlands, open-structured forests) as Native Americans and then Euro-American settlers used fire for a variety...

Disequilibrium of fire-prone forests sets the stage for a rapid decline in conifer dominance during the 21st century.

PubMed

Serra-Diaz, Josep M; Maxwell, Charles; Lucash, Melissa S; Scheller, Robert M; Laflower, Danelle M; Miller, Adam D; Tepley, Alan J; Epstein, Howard E; Anderson-Teixeira, Kristina J; Thompson, Jonathan R

2018-04-30

The impacts of climatic changes on forests may appear gradually on time scales of years to centuries due to the long generation times of trees. Consequently, current forest extent may not reflect current climatic patterns. In contrast with these lagged responses, abrupt transitions in forests under climate change may occur in environments where alternative vegetation states are influenced by disturbances, such as fire. The Klamath forest landscape (northern California and southwest Oregon, USA) is currently dominated by high biomass, biodiverse temperate coniferous forests, but climate change could disrupt the mechanisms promoting forest stability (e.g. growth, regeneration and fire tolerance). Using a landscape simulation model, we estimate that about one-third of the Klamath forest landscape (500,000 ha) could transition from conifer-dominated forest to shrub/hardwood chaparral, triggered by increased fire activity coupled with lower post-fire conifer establishment. Such shifts were widespread under the warmer climate change scenarios (RCP 8.5) but were surprisingly prevalent under the climate of 1949-2010, reflecting the joint influences of recent warming trends and the legacy of fire suppression that may have enhanced conifer dominance. Our results demonstrate that major forest ecosystem shifts should be expected when climate change disrupts key stabilizing feedbacks that maintain the dominance of long-lived, slowly regenerating trees.

Modeling the Effects of Drought, Fire, Beetles, and Management on Future Carbon Cycling in the Western US

NASA Astrophysics Data System (ADS)

Buotte, P.; Law, B. E.; Hicke, J. A.; Hudiburg, T. W.; Levis, S.; Kent, J.

2017-12-01

Fire and beetle outbreaks can have substantial impacts on forest structure, composition, and function and these types of disturbances are expected to increase in the future. Therefore understanding the ecological impacts of these disturbances into the future is important. We used ecosystem process modeling to estimate the future occurrence of fire and beetle outbreaks and their impacts on forest resilience and carbon sequestration. We modified the Community Land Model (CLM4.5) to better represent forest growth and mortality in the western US through multiple avenues: 1) we increased the ecological resolution to recognize 14 forest types common to the region; 2) we improved CLM4.5's ability to handle drought stress by adding forest type-specific controls on stomatal conductance and increased rates of leaf shed during periods of low soil moisture; 3) we developed and implemented a mechanistic model of beetle population growth and subsequent tree mortality; 4) we modified the current fire module to account for more refined forest types; and 5) we developed multiple scenarios of harvest based on past harvest rates and proposed changes in land management policies. We ran CLM4.5 in offline mode with climate forcing data. We compare future forest growth rates and carbon sequestration with historical metrics to estimate the combined influence of future disturbances on forest composition and carbon sequestration in the western US.

Impacts of fire and climate change on long-term nitrogen availability and forest productivity in the New Jersey Pine Barrens

Treesearch

Melissa S. Lucash; Robert M. Scheller; Alec M. Kretchun; Kenneth L. Clark; John Hom

2014-01-01

Increased wildfires and temperatures due to climate change are expected to have profound effects on forest productivity and nitrogen (N) cycling. Forecasts about how wildfire and climate change will affect forests seldom consider N availability, which may limit forest response to climate change, particularly in fire-prone landscapes. The overall objective of this study...

Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region

Treesearch

Jessica R. Miesel; William C. Hockaday; Randy Kolka; Philip A. Townsend

2015-01-01

Recent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildfire may become increasingly severe. Losses of forest soil organic matter (SOM) during fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition...

Fungal Community Shifts in Structure and Function across a Boreal Forest Fire Chronosequence

PubMed Central

Santalahti, Minna; Pumpanen, Jukka; Köster, Kajar; Berninger, Frank; Raffaello, Tommaso; Jumpponen, Ari; Asiegbu, Fred O.; Heinonsalo, Jussi

2015-01-01

Forest fires are a common natural disturbance in forested ecosystems and have a large impact on the microbial communities in forest soils. The response of soil fungal communities to forest fire is poorly documented. Here, we investigated fungal community structure and function across a 152-year boreal forest fire chronosequence using high-throughput sequencing of the internal transcribed spacer 2 (ITS2) region and a functional gene array (GeoChip). Our results demonstrate that the boreal forest soil fungal community was most diverse soon after a fire disturbance and declined over time. The differences in the fungal communities were explained by changes in the abundance of basidiomycetes and ascomycetes. Ectomycorrhizal (ECM) fungi contributed to the increase in basidiomycete abundance over time, with the operational taxonomic units (OTUs) representing the genera Cortinarius and Piloderma dominating in abundance. Hierarchical cluster analysis by using gene signal intensity revealed that the sites with different fire histories formed separate clusters, suggesting differences in the potential to maintain essential biogeochemical soil processes. The site with the greatest biological diversity had also the most diverse genes. The genes involved in organic matter degradation in the mature forest, in which ECM fungi were the most abundant, were as common in the youngest site, in which saprotrophic fungi had a relatively higher abundance. This study provides insight into the impact of fire disturbance on soil fungal community dynamics. PMID:26341215

Understanding fire drivers and relative impacts in different Chinese forest ecosystems.

PubMed

Guo, Futao; Su, Zhangwen; Wang, Guangyu; Sun, Long; Tigabu, Mulualem; Yang, Xiajie; Hu, Haiqing

2017-12-15

In this study, spatial patterns and driving factors of fires were identified from 2000 to 2010 using Ripley's K (d) function and logistic regression (LR) model in two different forest ecosystems of China: the boreal forest (Daxing'an Mountains) and sub-tropical forest (Fujian province). Relative effects of each driving factor on fire occurrence were identified based on standardized coefficients in the LR model. Results revealed that fires were spatially clustered and that fire drivers vary amongst differing forest ecosystems in China. Fires in the Daxing'an Mountains respond primarily to human factors, of which infrastructure is recognized as the most influential. In contrast, climate factors played a critical role in fire occurrence in Fujian, of which the temperature of fire season was found to be of greater importance than other climate factors. Selected factors can predict nearly 80% of the total fire occurrence in the Daxing'an Mountains and 66% in Fujian, wherein human and climate factors contributed the greatest impact in the two study areas, respectively. This study suggests that different fire prevention and management strategies are required in the areas of study, as significant variations of the main fire-driving exist. Rapid socio-economic development has produced similar effects in different forest ecosystems within China, implying a strong correlation between socio-economic development and fire regimes. It can be concluded that the influence of human factors will increase in the future as China's economy continues to grow - an issue of concern that should be further addressed in future national fire management. Copyright © 2017 Elsevier B.V. All rights reserved.

Measuring short-term post-fire forest recovery across a burn severity gradient in a mixed pine-oak forest using multi-sensor remote sensing techniques

DOE PAGES

Meng, Ran; Wu, Jin; Zhao, Feng; ...

2018-06-01

Understanding post-fire forest recovery is pivotal to the study of forest dynamics and global carbon cycle. Field-based studies indicated a convex response of forest recovery rate to burn severity at the individual tree level, related with fire-induced tree mortality; however, these findings were constrained in spatial/temporal extents, while not detectable by traditional optical remote sensing studies, largely attributing to the contaminated effect from understory recovery. For this work, we examined whether the combined use of multi-sensor remote sensing techniques (i.e., 1m simultaneous airborne imaging spectroscopy and LiDAR and 2m satellite multi-spectral imagery) to separate canopy recovery from understory recovery wouldmore » enable to quantify post-fire forest recovery rate spanning a large gradient in burn severity over large-scales. Our study was conducted in a mixed pine-oak forest in Long Island, NY, three years after a top-killing fire. Our studies remotely detected an initial increase and then decline of forest recovery rate to burn severity across the burned area, with a maximum canopy area-based recovery rate of 10% per year at moderate forest burn severity class. More intriguingly, such remotely detected convex relationships also held at species level, with pine trees being more resilient to high burn severity and having a higher maximum recovery rate (12% per year) than oak trees (4% per year). These results are one of the first quantitative evidences showing the effects of fire adaptive strategies on post-fire forest recovery, derived from relatively large spatial-temporal domains. Our study thus provides the methodological advance to link multi-sensor remote sensing techniques to monitor forest dynamics in a spatially explicit manner over large-scales, with important implications for fire-related forest management, and for constraining/benchmarking fire effect schemes in ecological process models.« less

Measuring short-term post-fire forest recovery across a burn severity gradient in a mixed pine-oak forest using multi-sensor remote sensing techniques

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

Meng, Ran; Wu, Jin; Zhao, Feng

Understanding post-fire forest recovery is pivotal to the study of forest dynamics and global carbon cycle. Field-based studies indicated a convex response of forest recovery rate to burn severity at the individual tree level, related with fire-induced tree mortality; however, these findings were constrained in spatial/temporal extents, while not detectable by traditional optical remote sensing studies, largely attributing to the contaminated effect from understory recovery. For this work, we examined whether the combined use of multi-sensor remote sensing techniques (i.e., 1m simultaneous airborne imaging spectroscopy and LiDAR and 2m satellite multi-spectral imagery) to separate canopy recovery from understory recovery wouldmore » enable to quantify post-fire forest recovery rate spanning a large gradient in burn severity over large-scales. Our study was conducted in a mixed pine-oak forest in Long Island, NY, three years after a top-killing fire. Our studies remotely detected an initial increase and then decline of forest recovery rate to burn severity across the burned area, with a maximum canopy area-based recovery rate of 10% per year at moderate forest burn severity class. More intriguingly, such remotely detected convex relationships also held at species level, with pine trees being more resilient to high burn severity and having a higher maximum recovery rate (12% per year) than oak trees (4% per year). These results are one of the first quantitative evidences showing the effects of fire adaptive strategies on post-fire forest recovery, derived from relatively large spatial-temporal domains. Our study thus provides the methodological advance to link multi-sensor remote sensing techniques to monitor forest dynamics in a spatially explicit manner over large-scales, with important implications for fire-related forest management, and for constraining/benchmarking fire effect schemes in ecological process models.« less

Landscape fire in East Siberia: medical, ecological and economic aspects

NASA Astrophysics Data System (ADS)

Efimova, N. V.; Rukavishnikov, V. S.; Zabuga, G. A.; Elfimova, T. A.

2018-01-01

More than 40 % of the forests in Siberia region are known to have a fire danger of high classes and high burning degrees. This paper describes air pollutants emission (PM10, nitrogen oxides, sulfur dioxide and others) in East Siberian region during a 10-year period in the forests fires focus. A total of 500 to 2000 fires occurred in Irkutsk oblast during the last ten years. At an average annual forest fires cover an area of 1 109 hectares on the model territory (Bratsk city). The plane pollutant emission source with a high productivity is formed on the significant forest fire area occurred in a relatively short-term time periods. The increase in hazard ratios was registered for the ingredients of emission-specific industrial enterprises and capable of accumulating in vegetation: carbon disulphide 1.9 times, fluorine-containing substances 1.8 times during the fire. The economic loss of energy resources resulting from reduced production of firewood was estimated at 56.6 million in Irkutsk oblast. The potential risk of negative effects for the respiratory system and cardiovascular system stipulated for the acute inhalation exposure was found to increase on the days, of the fires, as evidenced by the growth of the daily mortality and morbidity rates among the population.

Simulating statistics of lightning-induced and man made fires

NASA Astrophysics Data System (ADS)

Krenn, R.; Hergarten, S.

2009-04-01

The frequency-area distributions of forest fires show power-law behavior with scaling exponents α in a quite narrow range, relating wildfire research to the theoretical framework of self-organized criticality. Examples of self-organized critical behavior can be found in computer simulations of simple cellular automata. The established self-organized critical Drossel-Schwabl forest fire model (DS-FFM) is one of the most widespread models in this context. Despite its qualitative agreement with event-size statistics from nature, its applicability is still questioned. Apart from general concerns that the DS-FFM apparently oversimplifies the complex nature of forest dynamics, it significantly overestimates the frequency of large fires. We present a straightforward modification of the model rules that increases the scaling exponent α by approximately 1•3 and brings the simulated event-size statistics close to those observed in nature. In addition, combined simulations of both the original and the modified model predict a dependence of the overall distribution on the ratio of lightning induced and man made fires as well as a difference between their respective event-size statistics. The increase of the scaling exponent with decreasing lightning probability as well as the splitting of the partial distributions are confirmed by the analysis of the Canadian Large Fire Database. As a consequence, lightning induced and man made forest fires cannot be treated separately in wildfire modeling, hazard assessment and forest management.

Effects of fire on spotted owl site occupancy in a late-successional forest

USGS Publications Warehouse

Roberts, Susan L.; van Wagtendonk, Jan W.; Miles, A. Keith; Kelt, Douglas A.

2011-01-01

The spotted owl (Strix occidentalis) is a late-successional forest dependent species that is sensitive to forest management practices throughout its range. An increase in the frequency and spatial extent of standreplacing fires in western North America has prompted concern for the persistence of spotted owls and other sensitive late-successional forest associated species. However, there is sparse information on the effects of fire on spotted owls to guide conservation policies. In 2004-2005, we surveyed for California spotted owls during the breeding season at 32 random sites (16 burned, 16 unburned) throughout late-successional montane forest in Yosemite National Park, California. Our burned areas burned at all severities, but predominately involved low to moderate fire severity. Based on an information theoretic approach, spotted owl detection and occupancy rates were similar between burned and unburned sites. Nest and roost site occupancy was best explained by a model that combined total tree basal area (positive effect) with cover by coarse woody debris (negative effect). The density estimates of California spotted owl pairs were similar in burned and unburned forests, and the overall mean density estimate for Yosemite was higher than previously reported for montane forests. Our results indicate that low to moderate severity fires, historically common within montane forests of the Sierra Nevada, California, maintain habitat characteristics essential for spotted owl site occupancy. These results suggest that managed fires that emulate the historic fire regime of these forests may maintain spotted owl habitat and protect this species from the effects of future catastrophic fires.

Impacts of fire on non-native plant recruitment in black spruce forests of interior Alaska.

PubMed

Walker, Xanthe J; Frey, Matthew D; Conway, Alexandra J; Jean, Mélanie; Johnstone, Jill F

2017-01-01

Climate change is expected to increase the extent and severity of wildfires throughout the boreal forest. Historically, black spruce (Picea mariana (Mill.) B.S.P.) forests in interior Alaska have been relatively free of non-native species, but the compounding effects of climate change and an altered fire regime could facilitate the expansion of non-native plants. We tested the effects of wildfire on non-native plant colonization by conducting a seeding experiment of non-native plants on different substrate types in a burned black spruce forest, and surveying for non-native plants in recently burned and mature black spruce forests. We found few non-native plants in burned or mature forests, despite their high roadside presence, although invasion of some burned sites by dandelion (Taraxacum officinale) indicated the potential for non-native plants to move into burned forest. Experimental germination rates were significantly higher on mineral soil compared to organic soil, indicating that severe fires that combust much of the organic layer could increase the potential for non-native plant colonization. We conclude that fire disturbances that remove the organic layer could facilitate the invasion of non-native plants providing there is a viable seed source and dispersal vector.

Land abandonment, fire recurrence and soil carbon content in the Macizo del Caroig, Eastern Spain

NASA Astrophysics Data System (ADS)

Cerdá, A.; González Peñaloza, F.; Santín, C.; Doerr, S. H.

2012-04-01

During the last 50 years two main forces have driven the fate of Mediterranean landscapes: land abandonment and forest fires (MacDonald et al., 2000; Moreira et al., 2001). Due to the economical changes suffered by the of the Mediterranean countries after the Second World War, the population migrated from the rural to the urban areas, and from South to North Europe. The land abandonment allowed the vegetation to recover and, as a consequence, an increase in forest fire took place. The soils of the abandoned land recovered the vegetation and litter layers, and consequently changes in soil properties have being found. One of these changes is the increase of soil carbon content, which is due both to vegetation recovery and to fire occurrence that increases the ash and pyrogenic carbon content in soils. Twenty plots were selected in the Macizo del Caroig in Eastern Spain on soils developed on limestone. The period of abandonment and the forest fires that had affected each plot were determined by interviews with the owners, farmers and shepherds. In addition, six (three + three) plots were selected as forest (no plough) and cultivated control plots. Each plot was sampled (10 random samples) and the organic carbon content determined. The results show that the cultivated plots have organic matter contents of 1.02 %, and the forest (Quercus ilex sp.) plots reach the highest value: 14.98 %. Within those we found values that range from 2.34 %, in the recently abandoned plots (10 year abandonment), to values of 8.23 % in the 50 year old abandoned fields.The results demonstrate that there is a recovery of the organic carbon in abandoned soils and that the forest fires do no affect this trend. The increase of soil organic matter after abandonment is a result of the recovery of vegetation(Debussche et al., 2001), which is the consequence of the end of the disturbance of forest that have affected the Mediterranean for millennia (Barbero et al., 1990). The colonization of the abandoned fields by the vegetation is very efficient (Ne'eman and Izhaki, 1996) and fire adapted species are the main types, which demonstrates that fire is part of the Mediterranean ecosystems (Pausas, 1999). The fire was not found here as a factor increasing the organic carbon in the abandoned soils, although it was found in a nearby area (Novara et al., 2011). This research confirms that the soil development in Mediterranean Type-Ecosystems (Cerdà et al., 2010) is being affected by land abandonment and fire (Doerr and Cerdà, 2005).

A risk-based approach to wildland fire budgetary planning

Treesearch

Matthew P. Thompson; David E. Calkin; Mark A. Finney; Krista M. Gebert; Michael S. Hand

2013-01-01

The financial impact of wildfire management within the USDA Forest Service challenges the ability of the agency to meet societal demands and maintain forest health. The extent of this financial crisis has been attributed to historical and continuing fire management practices, changing climatic conditions, and increasing human development in fire-prone areas, as well as...

Responses of amphibians to fire disturbance in Pacific Northwest forests: a review

Treesearch

R. Bruce Bury; Donald J. Major; David Pilliod

2002-01-01

In western North America, major wildfires often now result in stand-replacement events and natural resources losses for many decades post-burn. Fire severity has been exacerbated by past fire suppression that has allowed large fuel load accumulations. To reduce woody debris and restore the ecological integrity of western forests, prescribed burning is increasingly used...

Comparing modern and presettlement forest dynamics of a subboreal wilderness: Does spruce budworm enhance fire risk?

Treesearch

Brian R Sturtevant; Brian R Miranda; Douglas J Shinneman; Eric J Gustafson; Peter T. Wolter

2012-01-01

Insect disturbance is often thought to increase fire risk through enhanced fuel loadings, particularly in coniferous forest ecosystems. Yet insect disturbances also affect successional pathways and landscape structure that interact with fire disturbances (and vice-versa) over longer time scales. We applied a landscape succession and disturbance model (LANDIS-II) to...

Hydrologic ramifications of an increased role of wildland fire across the rangeland-dry forest continuum

USDA-ARS?s Scientific Manuscript database

The increased role of wildland fire across the rangeland-dry forest continuum in the western United States (US) presents landscape-scale consequences relative runoff and erosion. Much of the Intermountain West now exists in a state in which rangeland and woodland wildfires stimulated by invasive che...

The Impact of Indonesian Forest Fires on Singaporean Pollution and Health.

PubMed

Sheldon, Tamara L; Sankaran, Chandini

2017-05-01

Between 1990 and 2015, Indonesia lost nearly 25 percent of its forests, largely due to intentional burning to clear land for cultivation of palm oil and timber plantations.1 The neighboring "victim countries" experienced severe deteriorations in air quality as a result of these fires. For example, Singapore experienced record air pollution levels in June of 2013 and again in September of 2015 as a result of the Indonesian forest fires.2 This air pollution is associated with increased incidences of upper respiratory tract infections, acute conjunctivitis, lung disease, asthma, bronchitis, emphysema, and pneumonia, among other ailments.2 Quantifying the impact of air pollution on health outcomes is challenging because pollution levels are often nonrandom for a variety of reasons, including policy endogeneity and sorting (Dominici, Greenstone, and Sunstein 2014). In this paper we offer the first causal analysis of the transboundary health effects of the Indonesian forest burning. The Indonesian fires induce exogenous variation in Singaporean air quality. We take advantage of this by using satellite fire data to instrument for changes in Singaporean air quality. Since Singapore is only 277.6 square miles in area (two-thirds the size of New York City), air pollution resulting from the fires is homogeneously spread so that sorting is less likely to be an issue. Using a two-stage least squares approach, we find that from 2010 through mid-2016, the Indonesian fires caused a statistically significant increase in pollution levels in Singapore. Our study also provides evidence that polyclinic attendances for acute respiratory tract infections and acute conjunctivitis in Singapore increased as a result of the deterioration in air quality. The reduced form estimates show that a one standard deviation increase in our measure of fires causes a 0.7 standard deviation increase in polyclinic attendances for each of these illnesses. These findings provide causal evidence of the transboundary pollution and health impacts of the Indonesian forest burning on neighboring Singapore.

Forest wildfire increases soil microbial biomass C:N:P stoichiometry in long-term effects

NASA Astrophysics Data System (ADS)

Zhou, Xuan

2017-04-01

Boreal forest fire strongly influences carbon (C) stock in permafrost soil by thawing permafrost table which accelerated microbe decomposition process. We studied soil microbial biomass stoichiometry in a gradient of four (3 yr, 25 yr, 46 yr and more than 100 yr) ages since fire in Canada boreal forest. Soil microbial biomass (MB) in long-term after fire is significantly higher than in short-term. MB C and nitrogen (N) were mainly dominated by corresponding soil element concentration and inorganic P, while MB phosphorus (P) changes were fully explained by soil N. Fire ages and soil temperature positively increased MB N and P, indicating the negative impact by fire. Microbial C:N:P gradually increased with fire ages from 15:2:1 to 76:6:1 and then drop down to 17:2:1 in the oldest fire ages. The degree of homeostasis of microbial C, N and P are close to 1 indicates non-homoeostasis within microbial elements, while it of C:N:P is close to 8 shows a strong homeostasis within element ratios and proved microbial stoichiometric ratio is not driven by soil element ratios. In conclusion, i) microbial biomass elements highly depends on soil nutrient supply rather than fire ages; ii) wildfire decreased microbial stoichiometry immediate after fire but increased with years after fire (YF) which at least 3 times higher than > 100 fire ages; iii) microbial biomass C, N and P deviated from strict homeostasis but C:N:P ratio reflects stronger homeostasis.

Reconciling salvage logging of boreal forests with a tural-disturbance management model.

PubMed

Schmiegelow, Fiona K A; Stepnisky, David P; Stambaugh, Curtis A; Koivula, Matti

2006-08-01

In North American boreal forests, wildfire is the dominant agent of natural disturbance. A natural-disturbance model has therefore been promoted as an ecologically based approach to forest harvesting in these systems. Given accelerating resource demands, fire competes with harvest for timber and there is increasing pressure to salvage naturally burned areas. This creates a management paradox: simultaneous promotion of natural disturbance as a guide to sustainability while salvaging forests that have been naturally disturbed. The major drivers of postfire salvage in Canadian boreal forests are societal perceptions, overallocation of forest resources, and economic and policy incentives, and postfire salvage compromisesforest sustainability by diminishing the role of fire as a critical, natural process. These factors might be reconciled through consideration of fire in resource allocations and application of active adaptive management. We provide novel treatment of the role of burn severity in mediating biotic response by examining its influence on the amount, type, and distribution of live, postfire residual material, and we highlight the role of fire in shaping spatial and temporal patterns in forest biodiversity. Maintenance of natural postfire forests is a critical component of an ecosystem-based approach to forest management in boreal systems. Nevertheless, presentpracticesfocus heavily on expediting removal of timber from burned forests, despite increasing evidence that postfire communities differ markedly from postharvest systems, and there is a mismatch between emerging management models and past management practices. Policies that recognize the critical role of fire in these systems and facilitate enhanced understanding of natural system dynamics in support of development of sustainable management practices are urgently needed.

Future Wildfire and Managed Fire Interactions in the Lake Tahoe Basin

NASA Astrophysics Data System (ADS)

Scheller, R.; Kretchun, A.

2017-12-01

Managing large forested landscape in the context of a changing climate and altered disturbance regimes presents new challenges and require integrated assessments of forest disturbance, management, succession, and the carbon cycle. Successful management under these circumstances will require information about trade-offs among multiple objectives and opportunities for spatially optimized landscape-scale management. Improved information about the effects of climate on forest communities, disturbance feedbacks, and the effectiveness of mitigation strategies enables actionable options for landscape managers. We evaluated the effects of fire suppression, wildfires, and forest fuel (thinning) treatments on the long-term carbon storage potential for Lake Tahoe Basin (LTB) forests under various climate futures. We simulated management scenarios that encompass fuel treatments across the larger landscape, beyond the Wildland Urban Interface. We improved upon current fire modeling under climate change via an integrated fire modeling module that, a) explicitly captures the influence of climate, fuels, topography, active fire management (e.g., fire suppression), and fuel treatments, and b) can be parameterized from available data, e.g., remote sensing, field reporting, fire databases, expert opinion. These improvements increase geographic flexibility and decrease reliance on broad historical fire regime statistics - imperfect targets for a no analog future and require minimal parameterization and calibration. We assessed the interactions among fuel treatments, prescribe fire, fire suppression, and stochastically recurring wildfires. Predicted changes in climate and ignition patterns in response to future climatic conditions, vegetation dynamics, and fuel treatments indicate larger potential long-term effects on C emissions, forest structure, and forest composition than prior studies.

The influence of burn severity on post-fire vegetation recovery and albedo change during early succession in North American boreal forests

NASA Astrophysics Data System (ADS)

Jin, Y.; Randerson, J. T.; Goetz, S. J.; Beck, P. S.; Loranty, M. M.; Goulden, M.

2011-12-01

Severity of burning can influence multiple aspects of forest composition, carbon cycling, and climate forcing. We quantified how burn severity affected vegetation recovery and albedo change during early succession in Canadian boreal regions by combining satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Canadian Large Fire Data Base (LFDB). We used the difference Normalized Burn Ratio (dNBR) and changes in spring albedo derived from MODIS 500m albedo product as measures of burn severity. We found that the most severe burns had the greatest reduction in summer EVI in first year after fire, indicating greater loss of vegetation cover immediately following fire. By 5-7 years after fire, summer EVI for all severity classes had recovered to within 90-110% of pre-fire levels. Burn severity had a positive effect on the increase of post-fire spring albedo during the first 7 years after fire, and a shift from low to moderate or moderate to severe fires led to amplification of the post-fire albedo increase by approximately 30%. Fire-induced increases in both spring and summer albedo became progressively larger with stand age from years 1-7, with the trend in spring albedo likely driven by continued losses of needles and branches from trees killed by the fire (and concurrent losses of black carbon coatings on remaining debris), and the summer trend associated with increases in leaf area of short-stature herbs and shrubs. Our results suggest that increases in burn severity and carbon losses observed in some areas of boreal forests (e.g., Turetsky et al., 2011) may be at least partly offset by increases in negative forcing associated with changes in surface albedo.

Effects of prescribed fire and post-fire rainfall on mercury mobilization and subsequent contamination assessment in a legacy mine site in Victoria, Australia.

PubMed

Abraham, Joji; Dowling, Kim; Florentine, Singarayer

2018-01-01

Prescribed fire conducted in fire-prone areas is a cost-effective choice for forest management, but it also affects many of the physicochemical and bio-geological properties of the forest soil, in a similar manner to wild fires. The aim of this study is to investigate the nature of the mercury mobilization after a prescribed fire and the subsequent temporal changes in concentration. A prescribed fire was conducted in a legacy mine site in Central Victoria, Australia, in late August 2015 and soil sample collection and analyses were carried out two days before and two days after the fire, followed by collection at the end of each season and after an intense rainfall event in September 2016. Results revealed the occurrence of mercury volatilization (8.3-97%) during the fire, and the mercury concentration displayed a significant difference (p < 0.05) before and immediately after the fire. Integrated assessment with number of pollution indices has shown that the study site is extremely contaminated with mercury during all the sampling events, and this poses a serious ecological risk due to the health impacts of mercury on human and ecosystems. In times of climate fluctuation with concomitant increase in forest fire (including prescribed fire), and subsequent precipitation and runoff, the potential for an increased amount of mercury being mobilized is of heighted significance. Therefore, it is recommended that prescribed fire should be cautiously considered as a forest management strategy in any mercury affected landscapes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of the Fire Regime and Drivers of Fires in the West African Tropical Forest

NASA Astrophysics Data System (ADS)

Dwomoh, F. K.; Wimberly, M. C.

2016-12-01

The Upper Guinean forest (UGF), encompassing the tropical regions of West Africa, is a globally significant biodiversity hotspot and a critically important socio-economic and ecological resource for the region. However, the UGF is one of the most human-disturbed tropical forest ecosystems with the only remaining large patches of original forests distributed in protected areas, which are embedded in a hotspot of climate stress & land use pressures, increasing their vulnerability to fire. We hypothesized that human impacts and climate interact to drive spatial and temporal variability in fire, with fire exhibiting distinctive seasonality and sensitivity to drought in areas characterized by different population densities, agricultural practices, vegetation types, and levels of forest degradation. We used the MODIS active fire product to identify and characterize fire activity in the major ecoregions of the UGF. We used TRMM rainfall data to measure climatic variability and derived indicators of human land use from a variety of geospatial datasets. We employed time series modeling to identify the influences of drought indices and other antecedent climatic indicators on temporal patterns of active fire occurrence. We used a variety of modeling approaches to assess the influences of human activities and land cover variables on the spatial pattern of fire activity. Our results showed that temporal patterns of fire activity in the UGF were related to precipitation, but these relationships were spatially heterogeneous. The pattern of fire seasonality varied geographically, reflecting both climatological patterns and agricultural practices. The spatial pattern of fire activity was strongly associated with vegetation gradients and anthropogenic activities occurring at fine spatial scales. The Guinean forest-savanna mosaic ecoregion had the most fires. This study contributes to our understanding of UGF fire regime and the spatio-temporal dynamics of tropical forest fires in response to intense human and climatic drivers.

Multi-trophic resilience of boreal lake ecosystems to forest fires

USGS Publications Warehouse

Lewis, Tyler L.; Lindberg, Mark S.; Schmutz, Joel A.; Bertram, M.R.

2014-01-01

Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.

Multi-trophic resilience of boreal lake ecosystems to forest fires.

PubMed

Lewis, Tyler L; Lindberg, Mark S; Schmutz, Joel A; Bertram, Mark R

2014-05-01

Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll a levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.

Using synthetic polymers to reduce soil erosion after forest fires in Mediterranean soils

NASA Astrophysics Data System (ADS)

Lado, Marcos; Ben-Hur, Meni; Inbar, Assaf

2010-05-01

Forest fires are a major environmental problem in the Mediterranean region because they result in a loss of vegetation cover, changes in biodiversity, increases in greenhouse gasses emission and a potential increase of runoff and soil erosion. The large increases in runoff and sediment yields after high severity fires have been attributed to several factors, among them: increase in soil water repellency; soil sealing by detached particles and by ash particles, and the loss of a surface cover. The presence of a surface cover increases infiltration, and decreases runoff and erosion by several mechanisms which include: rainfall interception, plant evapotranspiration, preservation of soil structure by increasing soil organic matter, and increasing surface roughness. The loss of vegetation cover as a result of fire leaves the surface of the soil exposed to the direct impact of the raindrops, and therefore the sensitivity of the soil to runoff generation and soil loss increases. In this work, we propose a new method to protect soils against post-fire erosion based on the application of synthetic polymers to the soil. Laboratory rainfall simulations and field runoff plots were used to analyze the suitability of the application of synthetic polymers to reduce soil erosion and stabilize soil structure in Mediterranean soils. The combination of these two processes will potentially favor a faster recovery of the vegetation structure. This method has been successfully applied in arable land, however it has not been tested in burnt forests. The outcome of this study may provide important managerial tools for forest management following fires.

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.

Acorn viability following prescribed fire in upland hardwood forests

Treesearch

Katie Greenberg; Tara Keyser; Stan Zarnoch; Kris Connor

2012-01-01

Restoration of structure and function of mixed-oak (Quercus spp.) forests is a focal issue of forest land managers in the eastern United States due to widespread regeneration failure and poor overstory recruitment of oaks, particularly on productive sites. Prescribed fire is increasingly used as a tool in oak ecosystem restoration, with the goal of reducing competition...

Shortleaf pine-bluestem restoration for red-cockaded woodpeckers in the Ouachita Mountains: Implications for other taxa

Treesearch

Ronald E. Thill; D. Craig Rudolph; Nancy E. Koerth

2004-01-01

The more xeric south- and west-facing slopes of the Ouachita Mountains of west-central Arkansas once supported fire-maintained shortleaf pine (Pinus echinata) forests with a well-developed herbaceous understory. Fire suppression following the original harvest of these forests resulted in forests with increasingly abundant woody vegetation in the...

Study of landscape change under forest harvesting and climate warming-induced fire disturbance

Treesearch

S. He Hong; David J. Mladenoff; Eric J. Gustafson

2002-01-01

We examined tree species responses under forest harvesting and an increased fire disturbance scenario due to climate warming in northern Wisconsin where northern hardwood and boreal forests are currently predominant. Individual species response at the ecosystem scale was simulated with a gap model, which integrates soil, climate and species data, stratified by...

Focused sunlight factor of forest fire danger assessment using Web-GIS and RS technologies

NASA Astrophysics Data System (ADS)

Baranovskiy, Nikolay V.; Sherstnyov, Vladislav S.; Yankovich, Elena P.; Engel, Marina V.; Belov, Vladimir V.

2016-08-01

Timiryazevskiy forestry of Tomsk region (Siberia, Russia) is a study area elaborated in current research. Forest fire danger assessment is based on unique technology using probabilistic criterion, statistical data on forest fires, meteorological conditions, forest sites classification and remote sensing data. MODIS products are used for estimating some meteorological conditions and current forest fire situation. Geonformation technologies are used for geospatial analysis of forest fire danger situation on controlled forested territories. GIS-engine provides opportunities to construct electronic maps with different levels of forest fire probability and support raster layer for satellite remote sensing data on current forest fires. Web-interface is used for data loading on specific web-site and for forest fire danger data representation via World Wide Web. Special web-forms provide interface for choosing of relevant input data in order to process the forest fire danger data and assess the forest fire probability.

Meta-analysis of avian and small-mammal response to fire severity and fire surrogate treatments in U.S. fire-prone forests.

PubMed

Fontaine, Joseph B; Kennedy, Patricia L

2012-07-01

Management in fire-prone ecosystems relies widely upon application of prescribed fire and/or fire surrogate (e.g., forest thinning) treatments to maintain biodiversity and ecosystem function. Recently, published literature examining wildlife response to fire and fire management has increased rapidly. However, none of this literature has been synthesized quantitatively, precluding assessment of consistent patterns of wildlife response among treatment types. Using meta-analysis, we examined the scientific literature on vertebrate demographic responses to burn severity (low/moderate, high), fire surrogates (forest thinning), and fire and fire surrogate combined treatments in the most extensively studied fire-prone, forested biome (forests of the United States). Effect sizes (magnitude of response) and their 95% confidence limits (response consistency) were estimated for each species-by-treatment combination with two or more observations. We found 41 studies of 119 bird and 17 small-mammal species that examined short-term responses (< or =4 years) to thinning, low/moderate- and high-severity fire, and thinning plus prescribed fire; data on other taxa and at longer time scales were too sparse to permit quantitative assessment. At the stand scale (<50 ha), thinning and low/moderate-severity fire demonstrated similar response patterns in these forests. Combined thinning plus prescribed fire produced a higher percentage of positive responses. High-severity fire provoked stronger responses, with a majority of species possessing higher or lower effect sizes relative to fires of lower severity. In the short term and at fine spatial scales, fire surrogate forest-thinning treatments appear to effectively mimic low/moderate-severity fire, whereas low/moderate-severity fire is not a substitute for high-severity fire. The varied response of taxa to each of the four conditions considered makes it clear that the full range of fire-based disturbances (or their surrogates) is necessary to maintain a full complement of vertebrate species, including fire-sensitive taxa. This is especially true for high-severity fire, where positive responses from many avian taxa suggest that this disturbance (either as wildfire or prescribed fire) should be included in management plans where it is consistent with historic fire regimes and where maintenance of regional vertebrate biodiversity is a goal.

Assessing Potential Future Carbon Dynamics with Climate Change and Fire Management in a Mountainous Landscape on the Olympic Peninsula, Washington, USA

NASA Astrophysics Data System (ADS)

Kennedy, R. S.

2010-12-01

Forests of the mountainous landscapes of the maritime Pacific Northwestern USA may have high carbon sequestration potential via their high productivity and moderate to infrequent fire regimes. With climate change, there may be shifts in incidence and severity of fire, especially in the drier areas of the region, via changes to forest productivity and hydrology, and consequent effects to C sequestration and forest structure. To explore this issue, I assessed potential effects of fire management (little fire suppression/wildland fire management/highly effective fire suppression) under two climate change scenarios on future C sequestration dynamics (amounts and spatial pattern) in Olympic National Park, WA, over a 500-year simulation period. I used the simulation platform FireBGCv2, which contains a mechanistic, individual tree succession model, a spatially explicit climate-based biophysical model that uses daily weather data, and a spatially explicit fire model incorporating ignition, spread, and effects on ecosystem components. C sequestration patterns varied over time and spatial and temporal patterns differed somewhat depending on the climate change scenario applied and the fire management methods employed. Under the more extreme climate change scenario with little fire suppression, fires were most frequent and severe and C sequestration decreased. General trends were similar under the more moderate climate change scenario, as compared to current climate, but spatial patterns differed. Both climate change scenarios under highly effective fire suppression showed about 50% of starting total C after the initial transition phase, whereas with 10% fire suppression both scenarios exhibited about 10% of starting amounts. Areas of the landscape that served as refugia for older forest under increasing frequency of high severity fire were also hotspots for C sequestration in a landscape experiencing increasing frequency of disturbance with climate change.

Understory response to varying fire frequencies after 20 years of prescribed burning in an upland oak forest

USGS Publications Warehouse

Burton, J.A.; Hallgren, S.W.; Fuhlendorf, S.D.; Leslie, David M.

2011-01-01

Ecosystems in the eastern United States that were shaped by fire over thousands of years of anthropogenic burning recently have been subjected to fire suppression resulting in significant changes in vegetation composition and structure and encroachment by invasive species. Renewed interest in use of fire to manage such ecosystems will require knowledge of effects of fire regime on vegetation. We studied the effects of one aspect of the fire regime, fire frequency, on biomass, cover and diversity of understory vegetation in upland oak forests prescribe-burned for 20 years at different frequencies ranging from zero to five fires per decade. Overstory canopy closure ranged from 88 to 96% and was not affected by fire frequency indicating high tolerance of large trees for even the most frequent burning. Understory species richness and cover was dominated by woody reproduction followed in descending order by forbs, C3 graminoids, C4 grasses, and legumes. Woody plant understory cover did not change with fire frequency and increased 30% from one to three years after a burn. Both forbs and C3 graminoids showed a linear increase in species richness and cover as fire frequency increased. In contrast, C4 grasses and legumes did not show a response to fire frequency. The reduction of litter by fire may have encouraged regeneration of herbaceous plants and helped explain the positive response of forbs and C3 graminoids to increasing fire frequency. Our results showed that herbaceous biomass, cover, and diversity can be managed with long-term prescribed fire under the closed canopy of upland oak forests. ?? 2011 Springer Science+Business Media B.V.

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, U.S.A.

PubMed

Fraver, Shawn; Jain, Theresa; Bradford, John B; D'Amato, Anthony W; Kastendick, Doug; Palik, Brian; Shinneman, Doug; Stanovick, John

2011-09-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and wildfire-provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions.

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, USA

USGS Publications Warehouse

Fraver, S.; Jain, T.; Bradford, J.B.; D'Amato, A.W.; Kastendick, D.; Palik, B.; Shinneman, D.; Stanovick, J.

2011-01-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and ildfire- provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions. ?? 2011 by the Ecological Society of America.

Impact of forest fires on the concentrations of polychlorinated dibenzo-p-dioxin and dibenzofurans in coastal waters of central Chile.

PubMed

Salamanca, Marco; Chandía, Cristian; Hernández, Aldo

2016-12-15

The relationship between the occurrence of forest fires in central Chile and the total concentration of dioxins and furans (PCDD/F) in nearby coastal waters was analyzed. The data for this analysis was obtained from a long-term environmental monitoring program (PROMNA) in the Bio-Bio Region. Quantification of PCDD/F was performed using HRGC/HRMS at the MSS laboratory in England. Between 2006 and 2014, peaks were observed in February 2007 and 2012. These concentration maxima coincided with major forest fires in the Bio-Bio Region and particularly with those in the Itata River Basin. The January 2012 fires generated an intense short-term response that was associated with atmospheric transport which increases medium toxicity furan-type congeners concentrations (TCDF, PCDF and HxCDF) and six months later a concentration increase of low toxicity dioxin-type congeners was observed (OCDD, HpCDD and HxCDD) coinciding with maximum winter river flow. These results suggest that forest fires near the coastal zone are responsible for increases in PCDD/F concentration observed in the study area. Copyright © 2016 Elsevier B.V. All rights reserved.

Understanding the drivers of post-fire albedo and radiative forcing across Alaska and Canada: implications for management.

NASA Astrophysics Data System (ADS)

Potter, S.; Solvik, K.; Erb, A.; Goetz, S. J.; Johnstone, J. F.; Mack, M. C.; Randerson, J. T.; Roman, M. O.; Schaaf, C. L.; Turetsky, M. R.; Veraverbeke, S.; Wang, Z.; Rogers, B. M.

2017-12-01

Boreal forest dynamics including succession, composition, carbon cycling, and surface-atmosphere energy exchanges are largely driven by fire. In Alaska and Canada, burned area and fire frequency have increased since the 1970s, and are projected to continue increasing into the 21st century. In contrast to other biomes, alterations to surface albedo from fires in North American boreal forests are one of the primary feedbacks to climate. Understanding how altered fire regimes impact vegetation composition and energy budgets is therefore critical to forecasting regional and global climate change. High-severity fires cause winter and spring albedo to increase due to increased snow exposure and replacement of evergreen conifers by deciduous broadleaf trees. Although summer albedo decreases initially due to the deposition of black carbon and charred surfaces, it typically increases for several decades thereafter when younger and brighter deciduous trees dominate. The net effect of these albedo changes is expected to result in substantive radiative cooling, but there has been little research to examine how albedo trajectories differ spatially and temporally as a result of differences in burn severity, species composition, topography, climate and soil properties, and what the associated implications for future energy balances are. Here we investigate drivers of post-fire monthly albedo trajectories across Canada and Alaska using a new Collection V006 500 m MODIS daily blue-sky albedo product and historical fires from the Canadian and Alaskan National Fire Databases. The impacts of varying fuel type, landscape position, soils, climate, and burn severity on monthly albedo trajectories are explored using a Random Forest model. This information is then used to predict long-term monthly albedo and radiative forcing for fires that occurred during the MODIS era (2001-2012). We find that higher severity burns in denser forests and environmental conditions that promote either deciduous vegetation or slower tree growth result in the largest increases in post fire albedo and radiative cooling. This understanding and our geospatial products may be relevant for management focused on limiting the climate impacts from intensifying boreal fire regimes.

Estimation of wildfire size and risk changes due to fuels treatments

Treesearch

M. A. Cochrane; C. J. Moran; M. C. Wimberly; A. D. Baer; M. A. Finney; K. L. Beckendorf; J. Eidenshink; Z. Zhu

2012-01-01

Human land use practices, altered climates, and shifting forest and fire management policies have increased the frequency of large wildfires several-fold. Mitigation of potential fire behaviour and fire severity have increasingly been attempted through pre-fire alteration of wildland fuels using mechanical treatments and prescribed fires. Despite annual treatment of...

Effect of Experimentally Manipulated Fire Regimes on the Response of Forests to Drought

NASA Astrophysics Data System (ADS)

Refsland, T. K.; Knapp, B.; Fraterrigo, J.

2017-12-01

Climate change is expected to increase drought stress in many forests and alter fire regimes. Fire can reduce tree density and thus competition for limited water, but the effects of changing fire regimes on forest productivity during drought remain poorly understood. We measured the annual ring-widths of adult oak (Quercus spp.) trees in Mark Twain National Forest, Missouri USA that experienced unburned, annual or periodic (every 4 years) surface fire treatments from 1951 - 2015. Severe drought events were identified using the BILJOU water balance model. We determined the effect of fire treatment on stand-level annual growth rates as well as stand-level resistance and resilience to drought, defined as the drought-induced reduction in growth and post-drought recovery in growth, respectively. During favorable wet years, annual and periodic fire treatments reduced annual growth rates by approximately 10-15% relative to unburned controls (P < 0.001). Stand-level growth rates declined 22-40% during drought events (P < 0.001), but fire-driven changes to stand basal area had no effect on the resistance or resilience of trees to drought. The decline in annual growth rates of burned stands during favorable wet years was likely caused by increased nitrogen (N) limitation in burned plots. After 60 years of treatment, burned plots experienced 30% declines in total soil N relative to unburned plots. Our finding that drought resistance and resilience were similar across all treatments suggest that fire-driven reductions in stand density may have negligible effects on soil moisture availability during drought. Our results highlight that climate-fire interactions can have important long-term effects on forest productivity.

Linking tree demography to climate change feedbacks: fire, larch forests, and carbon pools of the Siberian Arctic

NASA Astrophysics Data System (ADS)

Alexander, H. D.; Loranty, M. M.; Natali, S.; Pena, H., III; Ludwig, S.; Spektor, V.; Davydov, S. P.; Zimov, N.; Mack, M. C.

2017-12-01

Fire severity is increasing in larch forests of the Siberian Arctic as climate warms, and initial fire impacts on tree demographic processes could be an especially important determinant of long-term forest structure and carbon (C) dynamics. We hypothesized that (1) larch forest regrowth post-fire is largely determined by residual soil organic layer (SOL) depth because of the SOL's role as a seedbed and thermal regulator, and (2) changes in post-fire larch recruitment impact C accumulation through stand density impacts on understory microclimate and permafrost thaw. We tested these hypotheses by (1) experimentally creating a soil burn severity gradient in a Cajander larch (Larix cajanderi Mayr.) forest near Cherskiy, Russia and (2) quantifying C pools across a stand density gradient within a 75-year old fire scar. From 2012-2015, we added larch seeds to plots burned at different severities and monitored recruitment along with permafrost and active layer (i.e., subject to annual freeze-thaw) conditions (SOL depth, temperature, moisture, and thaw depth). Across the density gradient, we inventoried larch trees and harvested ground-layer vegetation to estimate aboveground contribution to C pools. We quantified woody debris C pools and sampled belowground C pools (soil, fine roots, and coarse roots) in the organic + upper (0-10 cm) mineral soil. Larch recruits were rare in unburned and low severity plots, but a total of 6 new germinants m-2 were tallied in moderate and high severity plots during the study. Seedling survival for > 1 year was only 40 and 25% on moderate and high severity treatments, respectively, but yielded net larch recruitment of 2 seedlings m-2, compared to 0.3 seedlings m-2 on low severity plots. Density of both total and established recruits increased with decreasing residual SOL depth, which correlated with increased soil temperature, moisture, and thaw depth. At 75-year post-fire, total C pools increased with increased larch density, largely due to increased tree aboveground C pools and decreased ground-layer vegetation C pools, which corresponded to higher canopy cover, cooler soils, and shallower active layer depths. Our findings highlight the potential for a climate-driven increase in fire severity to alter tree recruitment, successional dynamics, and C cycling in Siberian larch forests.

Evaluation of carbon uptake and emissions by forests in Korea during the last thirty years (1973-2002).

PubMed

Choi, Sung-Deuk; Chang, Yoon-Seok

2006-06-01

The contribution of Korean forests to carbon sequestration for anthropogenic carbon emissions was evaluated. In addition, monitoring of carbon species released from forest fires was conducted. Despite a high carbon uptake by Korean forests, a tremendous increase in fossil fuel burning resulted in a small contribution by forests to carbon removal. The removal efficiency had a 5-31% range with an average of 12% during the period 1973-2002. In 2000, the amount of carbon released from burned trees corresponded to 1.6% of carbon uptake by forests. The distribution of surface CO concentration (ppb) derived from MOPITT (Measurement of Pollution in the Troposphere) showed high CO levels over the East/Japan Sea on April 10, 2000 when the largest forest fires occurred along the east coast of Korea. Trajectory analysis and ground CO measurements also indicated that CO levels over the East/Japan Sea were influenced by forest fires. This study suggests that continuous monitoring of carbon emissions from forest fires is needed for a more reliable estimate of carbon flux in the environment.

Post-Wildfire Peak Discharge Prediction Methods in Northern New Mexico

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

Ronstadt, Jackie A.

Recent changes in climate have resulted in a decrease in precipitation and snowpack amounts and increased temperatures in the western United States. As the climate warms, there are also changes to runoff amounts and water availability. Drier and warmer conditions coupled with forest management practices have led to an increase in the frequency and size of forest fires. The 2000 Cerro Grande fire in Los Alamos, New Mexico burned over 43,000 acres and 200 structures. Eleven years later, the Las Conchas fire burned over 156,000 acres and 100 structures, including areas previously burned in 2000, and was considered the largestmore » fire in New Mexico’s history. Both fires burned ponderosa, juniper, piñon and mixed conifer forests, resulting in dramatic decreases in vegetation, changes to surface soils, and alterations to the hydrologic cycle (decreased evapotranspiration, decreased infiltration, increased runoff volume and peak discharge, and decreased time to peak discharge) in surrounding watersheds. The frequency of large, intense “mega-fires” are predicted to increase, thus there is a potential for more post-fire flood damage and more surface water resources to be altered due to water quality issues.« less

Estimating evapotranspiration change due to forest treatment and fire at the basin scale in the Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Roche, J. W.; Goulden, M.; Bales, R. C.

2017-12-01

Increased forest evapotranspiration (ET) coupled with snowpack decreases in a warming climate is likely to decrease runoff and increase forest drought stress. Field experiments and modeling suggest that forest thinning can reduce ET and thus increase potential runoff relative to untreated areas. We investigated the potential magnitude and duration of ET decreases resulting from forest-thinning treatments and fire using a robust empirical relation between Landsat-derived mean-annual normalized difference vegetation index (NDVI) and annual ET measured at flux towers. Among forest treatments, the minimum observed NDVI change required to produce a significant departure from control plots with NDVI of about 0.70 was -0.07 units, corresponding to a basal-area reduction of 3.1 m2 ha-1, and equivalent to an estimated ET reduction of -102 mm yr-1. Intensive thinning in highly productive forests that approached pre-fire-exclusion densities reduced basal area by 40-50%, generating estimated ET reductions of 152-216 mm yr-1 over five years following treatment. Between 1990 and 2008, fires in the American River basin generated more than twice the ET reduction per unit area than those in the Kings River basin, corresponding to greater water and energy limitations in the latter and greater fire severity in the former. A rough extrapolation of these results to the entire American River watershed, much of which would have burned naturally during this 19-year period, could result in ET reductions that approach 10% of full natural flows for drought years and 5% averaged over all years. This work demonstrates the potential utility to estimate forest ET change at the patch scale, which in turn may allow managers to estimate thinning benefits in areas lacking detailed hydrologic measurements.

Midstory reduction treatments with a Shinn SC-1

Treesearch

Dana Mitchell; Bob Rummer

1999-01-01

Fire control and exclusion have led to an increase in the non-commercial midstory and understory components of forest stands on the Croatan National Forest near the coast of North Carolina. The growth of this vegetation has created a fire risk in the wildland-urban interface. The use of a mechanical fuel management treatment is being explored in areas where fire...

Effects of fire severity on plant nutrient uptake reinforce alternate pathways of succession in boreal forests

Treesearch

A. Shenoy; K. Kielland; J.F. Johnstone

2013-01-01

Fire activity in the North American boreal region is projected to increase under a warming climate and trigger changes in vegetation composition. In black spruce forests of interior Alaska, fire severity impacts residual organic layer depth which is strongly linked to the relative dominance of deciduous versus coniferous trees in early succession. These alternate...

Ecosystem restoration treatments affect soil physical and chemical properties in Appalachian mixed oak forests

Treesearch

Ralph E.J. Boerner; Jennifer a. Brinkman; Daniel A. Yaussy

2007-01-01

This study presents an analysis of the effect of ecosystem restoration treatments on soil properties in the oak forests of southern Ohio. The treatments were (1) prescribed fire, (2) mechanical thinning, (3) fire and thinning, and (4) passive management (control). Fire and thinning resulted in increased mineral soil exposure, with the effect decreasing by the fourth...

Spatial mapping and analysis of aerosols during a forest fire using computational mobile microscopy

NASA Astrophysics Data System (ADS)

Wu, Yichen; Shiledar, Ashutosh; Luo, Yi; Wong, Jeffrey; Chen, Cheng; Bai, Bijie; Zhang, Yibo; Tamamitsu, Miu; Ozcan, Aydogan

2018-02-01

Forest fires are a major source of particulate matter (PM) air pollution on a global scale. The composition and impact of PM are typically studied using only laboratory instruments and extrapolated to real fire events owing to a lack of analytical techniques suitable for field-settings. To address this and similar field test challenges, we developed a mobilemicroscopy- and machine-learning-based air quality monitoring platform called c-Air, which can perform air sampling and microscopic analysis of aerosols in an integrated portable device. We tested its performance for PM sizing and morphological analysis during a recent forest fire event in La Tuna Canyon Park by spatially mapping the PM. The result shows that with decreasing distance to the fire site, the PM concentration increases dramatically, especially for particles smaller than 2 µm. Image analysis from the c-Air portable device also shows that the increased PM is comparatively strongly absorbing and asymmetric, with an aspect ratio of 0.5-0.7. These PM features indicate that a major portion of the PM may be open-flame-combustion-generated element carbon soot-type particles. This initial small-scale experiment shows that c-Air has some potential for forest fire monitoring.

Interactive effects of frequent burning and timber harvesting on above ground carbon biomass in temperate eucalypt forests

NASA Astrophysics Data System (ADS)

Collins, Luke; Penman, Trent; Ximenes, Fabiano; Bradstock, Ross

2015-04-01

The sequestration of carbon has been identified as an important strategy to mitigate the effects of climate change. Fuel reduction burning and timber harvesting are two common co-occurring management practices within forests. Frequent burning and timber harvesting may alter forest carbon pools through the removal and redistribution of biomass and demographic and structural changes to tree communities. Synergistic and antagonistic interactions between frequent burning and harvesting are likely to occur, adding further complexity to the management of forest carbon stocks. Research aimed at understanding the interactive effects of frequent fire and timber harvesting on carbon biomass is lacking. This study utilised data from two long term (25 - 30 years) manipulative burning experiments conducted in southern Australia in temperate eucalypt forests dominated by resprouting canopy species. Specifically we examined the effect of fire frequency and harvesting on (i) total biomass of above ground carbon pools and (ii) demographic and structural characteristics of live trees. We also investigated some of the mechanisms driving these changes. Frequent burning reduced carbon biomass by up to 20% in the live tree carbon pool. Significant interactions occurred between fire and harvesting, whereby the reduction in biomass of trees >20 cm diameter breast height (DBH) was amplified by increased fire frequency. The biomass of trees <20 cm DBH increased with harvesting intensity in frequently burnt areas, but was unaffected by harvesting intensity in areas experiencing low fire frequency. Biomass of standing and fallen coarse woody debris was relatively unaffected by logging and fire frequency. Fire and harvesting significantly altered stand structure over the study period. Comparison of pre-treatment conditions to current conditions revealed that logged sites had a significantly greater increase in the number of small trees (<40 cm DBH) than unlogged sites. Logged sites showed a significant decrease in the number of large trees (>60 cm DBH) over the study period, while unlogged sites showed an increase. Frequently burnt logged sites showed the greatest reduction in large trees, presumably due to increased fire related mortality and collapse. Analysis of tree survival and growth data suggest that mortality rate is increased and growth rate reduced in frequently burnt areas compared to unburnt areas. Our findings suggest that future shifts towards more frequent fire (both prescribed fire and wildfire) could potentially lead to broad scale reductions in carbon sequestration in temperate forests and woodlands dominated by resprouting canopy species. Reductions in carbon sequestration associated with frequent burning will potentially be amplified in intensively harvested landscapes.

Beyond reducing fire hazard: fuel treatment impacts on overstory tree survival

Treesearch

Brandon M. Collins; Adrian J. Das; John J. Battles; Danny L. Fry; Kevin D. Krasnow; Scott L. Stephens

2014-01-01

Fuel treatment implementation in dry forest types throughout the western United States is likely to increase in pace and scale in response to increasing incidence of large wildfires. While it is clear that properly implemented fuel treatments are effective at reducing hazardous fire potential, there are ancillary ecological effects that can impact forest...

Analysis of USDA Forest Service fire-related expenditures 1970-1995

Treesearch

Ervin G. Schuster; David A. Cleaves; Enoch F. Bell

1997-01-01

Forest Service expenditures for fire presuppression and suppression activities increased from $61 million in FY 1970 to $951 million in FY 1994. Yet, real (net of inflation) expenditures have not increased significantly since FY 1970, if FY 1994 expenditures are excluded. During any given year, 56 percent of suppression expenditures are spent on supplies and services,...

Resistance of the boreal forest to high burn rates.

PubMed

Héon, Jessie; Arseneault, Dominique; Parisien, Marc-André

2014-09-23

Boreal ecosystems and their large carbon stocks are strongly shaped by extensive wildfires. Coupling climate projections with records of area burned during the last 3 decades across the North American boreal zone suggests that area burned will increase by 30-500% by the end of the 21st century, with a cascading effect on ecosystem dynamics and on the boreal carbon balance. Fire size and the frequency of large-fire years are both expected to increase. However, how fire size and time since previous fire will influence future burn rates is poorly understood, mostly because of incomplete records of past fire overlaps. Here, we reconstruct the length of overlapping fires along a 190-km-long transect during the last 200 y in one of the most fire-prone boreal regions of North America to document how fire size and time since previous fire will influence future fire recurrence. We provide direct field evidence that extreme burn rates can be sustained by a few occasional droughts triggering immense fires. However, we also show that the most fire-prone areas of the North American boreal forest are resistant to high burn rates because of overabundant young forest stands, thereby creating a fuel-mediated negative feedback on fire activity. These findings will help refine projections of fire effect on boreal ecosystems and their large carbon stocks.

Resistance of the boreal forest to high burn rates

PubMed Central

Héon, Jessie; Arseneault, Dominique; Parisien, Marc-André

2014-01-01

Boreal ecosystems and their large carbon stocks are strongly shaped by extensive wildfires. Coupling climate projections with records of area burned during the last 3 decades across the North American boreal zone suggests that area burned will increase by 30–500% by the end of the 21st century, with a cascading effect on ecosystem dynamics and on the boreal carbon balance. Fire size and the frequency of large-fire years are both expected to increase. However, how fire size and time since previous fire will influence future burn rates is poorly understood, mostly because of incomplete records of past fire overlaps. Here, we reconstruct the length of overlapping fires along a 190-km-long transect during the last 200 y in one of the most fire-prone boreal regions of North America to document how fire size and time since previous fire will influence future fire recurrence. We provide direct field evidence that extreme burn rates can be sustained by a few occasional droughts triggering immense fires. However, we also show that the most fire-prone areas of the North American boreal forest are resistant to high burn rates because of overabundant young forest stands, thereby creating a fuel-mediated negative feedback on fire activity. These findings will help refine projections of fire effect on boreal ecosystems and their large carbon stocks. PMID:25201981

Simulating the Effects of Fire on Forests in the Russian Far East: Integrating a Fire Danger Model and the FAREAST Forest Growth Model Across a Complex Landscape

NASA Astrophysics Data System (ADS)

Sherman, N. J.; Loboda, T.; Sun, G.; Shugart, H. H.; Csiszar, I.

2008-12-01

The remaining natural habitat of the critically endangered Amur tiger (Panthera tigris altaica) and Amur leopard (Panthera pardus orientalis) is a vast, biologically and topographically diverse area in the Russian Far East (RFE). Although wildland fire is a natural component of ecosystem functioning in the RFE, severe or repeated fires frequently re-set the process of forest succession, which may take centuries to return the affected forests to the pre-fire state and thus significantly alters habitat quality and long-term availability. The frequency of severe fire events has increased over the last 25 years, leading to irreversible modifications of some parts of the species' habitats. Moreover, fire regimes are expected to continue to change toward more frequent and severe events under the influence of climate change. Here we present an approach to developing capabilities for a comprehensive assessment of potential Amur tiger and leopard habitat availability throughout the 21st century by integrating regionally parameterized fire danger and forest growth models. The FAREAST model is an individual, gap-based model that simulates forest growth in a single location and demonstrates temporally explicit forest succession leading to mature forests. Including spatially explicit information on probabilities of fire occurrence at 1 km resolution developed from the regionally specific remotely -sensed data-driven fire danger model improves our ability to provide realistic long-term projections of potential forest composition in the RFE. This work presents the first attempt to merge the FAREAST model with a fire disturbance model, to validate its outputs across a large region, and to compare it to remotely-sensed data products as well as in situ assessments of forest structure. We ran the FAREAST model at 1,000 randomly selected points within forested areas in the RFE. At each point, the model was calibrated for temperature, precipitation, slope, elevation, and fire probability. The output of the model includes biomass estimates for 44 tree species that occur in the RFE, grouped by genus. We compared the model outputs with land cover classifications derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data and LIDAR-based estimates of biomass across the entire region, and Russian forest inventory records at selected sites. Overall, we find that the FAREAST estimates of forest biomass and general composition are consistent with the observed distribution of forest types.

Thermal biology of eastern box turtles in a longleaf pine system managed with prescribed fire.

PubMed

Roe, John H; Wild, Kristoffer H; Hall, Carlisha A

2017-10-01

Fire can influence the microclimate of forest habitats by removing understory vegetation and surface debris. Temperature is often higher in recently burned forests owing to increased light penetration through the open understory. Because physiological processes are sensitive to temperature in ectotherms, we expected fire-maintained forests to improve the suitability of the thermal environment for turtles, and for turtles to seasonally associate with the most thermally-optimal habitats. Using a laboratory thermal gradient, we determined the thermal preference range (T set ) of eastern box turtles, Terrapene carolina, to be 27-31°C. Physical models simulating the body temperatures experienced by turtles in the field revealed that surface environments in a fire-maintained longleaf pine forest were 3°C warmer than adjacent unburned mixed hardwood/pine forests, but the fire-maintained forest was never of superior thermal quality owing to wider T e fluctuations above T set and exposure to extreme and potentially lethal temperatures. Radiotracked turtles using fire-managed longleaf pine forests maintained shell temperatures (T s ) approximately 2°C above those at a nearby unburned forest, but we observed only moderate seasonal changes in habitat use which were inconsistent with thermoregulatory behavior. We conclude that turtles were not responding strongly to the thermal heterogeneity generated by fire in our system, and that other aspects of the environment are likely more important in shaping habitat associations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Land cover, more than monthly fire weather, drives fire-size distribution in Southern Québec forests: Implications for fire risk management.

PubMed

Marchal, Jean; Cumming, Steve G; McIntire, Eliot J B

2017-01-01

Fire activity in North American forests is expected to increase substantially with climate change. This would represent a growing risk to human settlements and industrial infrastructure proximal to forests, and to the forest products industry. We modelled fire size distributions in southern Québec as functions of fire weather and land cover, thus explicitly integrating some of the biotic interactions and feedbacks in a forest-wildfire system. We found that, contrary to expectations, land-cover and not fire weather was the primary driver of fire size in our study region. Fires were highly selective on fuel-type under a wide range of fire weather conditions: specifically, deciduous forest, lakes and to a lesser extent recently burned areas decreased the expected fire size in their vicinity compared to conifer forest. This has large implications for fire risk management in that fuels management could reduce fire risk over the long term. Our results imply, for example, that if 30% of a conifer-dominated landscape were converted to hardwoods, the probability of a given fire, occurring in that landscape under mean fire weather conditions, exceeding 100,000 ha would be reduced by a factor of 21. A similarly marked but slightly smaller effect size would be expected under extreme fire weather conditions. We attribute the decrease in expected fire size that occurs in recently burned areas to fuel availability limitations on fires spread. Because regenerating burned conifer stands often pass through a deciduous stage, this would also act as a negative biotic feedback whereby the occurrence of fires limits the size of nearby future for some period of time. Our parameter estimates imply that changes in vegetation flammability or fuel availability after fires would tend to counteract shifts in the fire size distribution favoring larger fires that are expected under climate warming. Ecological forecasts from models neglecting these feedbacks may markedly overestimate the consequences of climate warming on fire activity, and could be misleading. Assessments of vulnerability to climate change, and subsequent adaptation strategies, are directly dependent on integrated ecological forecasts. Thus, we stress the need to explicitly incorporate land-cover's direct effects and feedbacks in simulation models of coupled climate-fire-fuels systems.

Stratifying Tropical Fires by Land Cover: Insights into Amazonian Fires, Aerosol Loading, and Regional Deforestation

NASA Technical Reports Server (NTRS)

TenHoeve, J. E.; Remer, L. A.; Jacobson, M. Z.

2010-01-01

This study analyzes changes in the number of fires detected on forest, grass, and transition lands during the 2002-2009 biomass burning seasons using fire detection data and co-located land cover classifications from the Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the total number of detected fires correlates well with MODIS mean aerosol optical depth (AOD) from year to year, in accord with other studies. However, we also show that the ratio of forest to savanna fires varies substantially from year to year. Forest fires have trended downward, on average, since the beginning of 2006 despite a modest increase in 2007. Our study suggests that high particulate matter loading detected in 2007 was likely due to a large number of savanna/agricultural fires that year. Finally, we illustrate that the correlation between annual Brazilian deforestation estimates and MODIS fires is considerably higher when fires are stratified by MODIS-derived land cover classifications.

Fire regimes of remnant pitch pine communities in the Ridge and Valley Region of central Pennsylvania, USA. Forests

Treesearch

Joseph Marschall; Michael Stambaugh; Benjamin Jones; Richard Guyette; Patrick Brose; Daniel C. Dey

2016-01-01

Many fire-adapted ecosystems in the northeastern U.S. are converting to fire-intolerant vegetation communities due to fire suppression in the 20th century. Prescribed fire and other vegetation management activities that increase resilience and resistance to global changes are increasingly being implemented, particularly on public lands. For many fire-dependent...

Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed.

PubMed

Dunnette, Paul V; Higuera, Philip E; McLauchlan, Kendra K; Derr, Kelly M; Briles, Christy E; Keefe, Margaret H

2014-08-01

Wildfires can significantly alter forest carbon (C) storage and nitrogen (N) availability, but the long-term biogeochemical legacy of wildfires is poorly understood. We obtained a lake-sediment record of fire and biogeochemistry from a subalpine forest in Colorado, USA, to examine the nature, magnitude, and duration of decadal-scale, fire-induced ecosystem change over the past c. 4250 yr. The high-resolution record contained 34 fires, including 13 high-severity events within the watershed. High-severity fires were followed by increased sedimentary N stable isotope ratios (δ15N) and bulk density, and decreased C and N concentrations--reflecting forest floor destruction, terrestrial C and N losses, and erosion. Sustained low sediment C : N c. 20-50 yr post-fire indicates reduced terrestrial organic matter subsidies to the lake. Low sedimentary δ15N c. 50-70 yr post-fire, coincident with C and N recovery, suggests diminishing terrestrial N availability during stand development. The magnitude of post-fire changes generally scaled directly with inferred fire severity. Our results support modern studies of forest successional C and N accumulation and indicate pronounced, long-lasting biogeochemical impacts of wildfires in subalpine forests. However, even repeated high-severity fires over millennia probably did not deplete C or N stocks, because centuries between high-severity fires allowed for sufficient biomass recovery. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Evaluating the impacts of wildland fires on caribou in interior Alaska

USGS Publications Warehouse

Joly, Kyle; Adams, Layne G.; Dale, Bruce W.; Collins, William

2002-01-01

Caribou are found throughout the boreal forests of interior Alaska, a region subject to chronic and expansive wildland fires. Fruticose lichens, if available, constitute the majority of the winter diet of caribou throughout their range and are common in mature boreal forests but largely absent from early successional stages. Fire, the dominant ecological driving force, increases vegetative diversity and productivity across the landscape but may reduce the availability of caribou winter forage for decades.Increasingly, wildland fire regimes are influenced by humans seeking to reduce fire hazards or mitigate the effects of years of fire suppression. Consequently, biologists have debated the importance of forage lichens to the dynamics of caribou populations, and land managers have questioned the importance of fire regime to wintering caribou. To better understand the impacts of wildland fire on caribou, we are simultaneously investigating the relationships between fire history, caribou movements, forage lichen availability, and caribou nutritional performance on their winter range.

Duration of fuels reduction following prescribed fire in coniferous forests of U.S. national parks in California and the Colorado Plateau

USGS Publications Warehouse

van Mantgem, Phillip J.; Lalemand, Laura; Keifer, MaryBeth; Kane, Jeffrey M.

2016-01-01

Prescribed fire is a widely used forest management tool, yet the long-term effectiveness of prescribed fire in reducing fuels and fire hazards in many vegetation types is not well documented. We assessed the magnitude and duration of reductions in surface fuels and modeled fire hazards in coniferous forests across nine U.S. national parks in California and the Colorado Plateau. We used observations from a prescribed fire effects monitoring program that feature standard forest and surface fuels inventories conducted pre-fire, immediately following an initial (first-entry) prescribed fire and at varying intervals up to >20 years post-fire. A subset of these plots was subjected to prescribed fire again (second-entry) with continued monitoring. Prescribed fire effects were highly variable among plots, but we found on average first-entry fires resulted in a significant post-fire reduction in surface fuels, with litter and duff fuels not returning to pre-fire levels over the length of our observations. Fine and coarse woody fuels often took a decade or longer to return to pre-fire levels. For second-entry fires we found continued fuels reductions, without strong evidence of fuel loads returning to levels observed immediately prior to second-entry fire. Following both first- and second-entry fire there were increases in estimated canopy base heights, along with reductions in estimated canopy bulk density and modeled flame lengths. We did not find evidence of return to pre-fire conditions during our observation intervals for these measures of fire hazard. Our results show that prescribed fire can be a valuable tool to reduce fire hazards and, depending on forest conditions and the measurement used, reductions in fire hazard can last for decades. Second-entry prescribed fire appeared to reinforce the reduction in fuels and fire hazard from first-entry fires.

Restoring forest structure and process stabilizes forest carbon in wildfire-prone southwestern ponderosa pine forests.

PubMed

Hurteau, Matthew D; Liang, Shuang; Martin, Katherine L; North, Malcolm P; Koch, George W; Hungate, Bruce A

2016-03-01

Changing climate and a legacy of fire-exclusion have increased the probability of high-severity wildfire, leading to an increased risk of forest carbon loss in ponderosa pine forests in the southwestern USA. Efforts to reduce high-severity fire risk through forest thinning and prescribed burning require both the removal and emission of carbon from these forests, and any potential carbon benefits from treatment may depend on the occurrence of wildfire. We sought to determine how forest treatments alter the effects of stochastic wildfire events on the forest carbon balance. We modeled three treatments (control, thin-only, and thin and burn) with and without the occurrence of wildfire. We evaluated how two different probabilities of wildfire occurrence, 1% and 2% per year, might alter the carbon balance of treatments. In the absence of wildfire, we found that thinning and burning treatments initially reduced total ecosystem carbon (TEC) and increased net ecosystem carbon balance (NECB). In the presence of wildfire, the thin and burn treatment TEC surpassed that of the control in year 40 at 2%/yr wildfire probability, and in year 51 at 1%/yr wildfire probability. NECB in the presence of wildfire showed a similar response to the no-wildfire scenarios: both thin-only and thin and burn treatments increased the C sink. Treatments increased TEC by reducing both mean wildfire severity and its variability. While the carbon balance of treatments may differ in more productive forest types, the carbon balance benefits from restoring forest structure and fire in southwestern ponderosa pine forests are clear.

Forest-Fire Prevention Knowledge and Attitudes of Residents of Utah County, Utah, With Comparisons to Butte County, California

ERIC Educational Resources Information Center

Christiansen, John R.; And Others

The use of land for outdoor recreation is becoming more and more important, and the increased use of the land has raised the risk of man-caused forest fires. The purposes of this study were (1) to determine the kinds and numbers of visits that people are making to public forests, (2) to identify the social characteristics of forest users, (3) to…

Modeling the effects of fire severity and climate warming on active layer and soil carbon dynamics of black spruce forests across the landscape in interior Alaska

USGS Publications Warehouse

Genet, H.; McGuire, Anthony David; Barrett, K.; Breen, A.; Euskirchen, E.S.; Johnstone, J.F.; Kasischke, E.S.; Melvin, A.M.; Bennett, A.; Mack, M.C.; Rupp, T.S.; Schuur, A.E.G.; Turetsky, M.R.; Yuan, F.

2013-01-01

There is a substantial amount of carbon stored in the permafrost soils of boreal forest ecosystems, where it is currently protected from decomposition. The surface organic horizons insulate the deeper soil from variations in atmospheric temperature. The removal of these insulating horizons through consumption by fire increases the vulnerability of permafrost to thaw, and the carbon stored in permafrost to decomposition. In this study we ask how warming and fire regime may influence spatial and temporal changes in active layer and carbon dynamics across a boreal forest landscape in interior Alaska. To address this question, we (1) developed and tested a predictive model of the effect of fire severity on soil organic horizons that depends on landscape-level conditions and (2) used this model to evaluate the long-term consequences of warming and changes in fire regime on active layer and soil carbon dynamics of black spruce forests across interior Alaska. The predictive model of fire severity, designed from the analysis of field observations, reproduces the effect of local topography (landform category, the slope angle and aspect and flow accumulation), weather conditions (drought index, soil moisture) and fire characteristics (day of year and size of the fire) on the reduction of the organic layer caused by fire. The integration of the fire severity model into an ecosystem process-based model allowed us to document the relative importance and interactions among local topography, fire regime and climate warming on active layer and soil carbon dynamics. Lowlands were more resistant to severe fires and climate warming, showing smaller increases in active layer thickness and soil carbon loss compared to drier flat uplands and slopes. In simulations that included the effects of both warming and fire at the regional scale, fire was primarily responsible for a reduction in organic layer thickness of 0.06 m on average by 2100 that led to an increase in active layer thickness of 1.1 m on average by 2100. The combination of warming and fire led to a simulated cumulative loss of 9.6 kgC m−2 on average by 2100. Our analysis suggests that ecosystem carbon storage in boreal forests in interior Alaska is particularly vulnerable, primarily due to the combustion of organic layer thickness in fire and the related increase in active layer thickness that exposes previously protected permafrost soil carbon to decomposition.

Beyond reducing fire hazard: fuel treatment impacts on overstory tree survival

USGS Publications Warehouse

Collins, Brandon M.; Das, Adrian J.; Battles, John J.; Fry, Danny L.; Krasnow, Kevin D.; Stephens, Scott L.

2014-01-01

Fuel treatment implementation in dry forest types throughout the western United States is likely to increase in pace and scale in response to increasing incidence of large wildfires. While it is clear that properly implemented fuel treatments are effective at reducing hazardous fire potential, there are ancillary ecological effects that can impact forest resilience either positively or negatively depending on the specific elements examined, as well as treatment type, timing, and intensity. In this study, we use overstory tree growth responses, measured seven years after the most common fuel treatments, to estimate forest health. Across the five species analyzed, observed mortality and future vulnerability were consistently low in the mechanical-only treatment. Fire-only was similar to the control for all species except Douglas-fir, while mechanical-plus-fire had high observed mortality and future vulnerability for white fir and sugar pine. Given that overstory trees largely dictate the function of forests and services they provide (e.g., wildlife habitat, carbon sequestration, soil stability) these results have implications for understanding longer-term impacts of common fuel treatments on forest resilience.

Land cover, more than monthly fire weather, drives fire-size distribution in Southern Québec forests: Implications for fire risk management

PubMed Central

Marchal, Jean; Cumming, Steve G.; McIntire, Eliot J. B.

2017-01-01

Fire activity in North American forests is expected to increase substantially with climate change. This would represent a growing risk to human settlements and industrial infrastructure proximal to forests, and to the forest products industry. We modelled fire size distributions in southern Québec as functions of fire weather and land cover, thus explicitly integrating some of the biotic interactions and feedbacks in a forest-wildfire system. We found that, contrary to expectations, land-cover and not fire weather was the primary driver of fire size in our study region. Fires were highly selective on fuel-type under a wide range of fire weather conditions: specifically, deciduous forest, lakes and to a lesser extent recently burned areas decreased the expected fire size in their vicinity compared to conifer forest. This has large implications for fire risk management in that fuels management could reduce fire risk over the long term. Our results imply, for example, that if 30% of a conifer-dominated landscape were converted to hardwoods, the probability of a given fire, occurring in that landscape under mean fire weather conditions, exceeding 100,000 ha would be reduced by a factor of 21. A similarly marked but slightly smaller effect size would be expected under extreme fire weather conditions. We attribute the decrease in expected fire size that occurs in recently burned areas to fuel availability limitations on fires spread. Because regenerating burned conifer stands often pass through a deciduous stage, this would also act as a negative biotic feedback whereby the occurrence of fires limits the size of nearby future for some period of time. Our parameter estimates imply that changes in vegetation flammability or fuel availability after fires would tend to counteract shifts in the fire size distribution favoring larger fires that are expected under climate warming. Ecological forecasts from models neglecting these feedbacks may markedly overestimate the consequences of climate warming on fire activity, and could be misleading. Assessments of vulnerability to climate change, and subsequent adaptation strategies, are directly dependent on integrated ecological forecasts. Thus, we stress the need to explicitly incorporate land-cover’s direct effects and feedbacks in simulation models of coupled climate–fire–fuels systems. PMID:28609467

Assessing risks to spotted owls from forest thinning in fire-adapted forests of the western United States

Treesearch

Danny C. Lee; Larry L. Irwin

2005-01-01

Concern for viable spotted owl (Strix occidentalis) populations has played prominently in the management of western forests in the United States. Historically, much of the debate has focused on the impacts of commercial timber harvest. Increasingly, the conflict is shifting to the habitat needs of owls versus the need for active management of fire-...

History and legacy of fire effects in the South Carolina piedmont and coastal regions

Treesearch

Lindsay H. Fairchilds; Carl C. Trettin

2006-01-01

Agriculture, fire suppression, and urbanization have drastically altered natural forest processes and conditions since humankind settled in the Southeastern United States. Today, many of South Carolina’s forests are dense and overstocked, with high fuel loads. These conditions increase the susceptibility of forests to southern pine beetle attack and wildfire. These...

Estimating small mammal abundance on fuels treatment units in southwestern ponderosa pine forests

Treesearch

Sarah J. Converse; Brett G. Dickson; Gary C. White; William M. Block

2004-01-01

In many North American forests, post-European settlement fire suppression efforts have resulted in the excessive accumulation of forest fuels and changes to the historic fire regime, thereby increasing the risk of catastrophic wildfires (Cooper 1960; Dodge 1972; Covington and Moore 1994). To reduce this risk, it is necessary to develop treatments that will remove...

Comparing modern and presettlement forest dynamics of a subboreal wilderness: Does spruce budworm enhance fire risk?

USGS Publications Warehouse

Sturtevant, Brian R.; Miranda, Brian R.; Shinneman, Douglas J.; Gustafson, Eric J.; Wolter, Peter T.

2012-01-01

Insect disturbance is often thought to increase fire risk through enhanced fuel loadings, particularly in coniferous forest ecosystems. Yet insect disturbances also affect successional pathways and landscape structure that interact with fire disturbances (and vice-versa) over longer time scales. We applied a landscape succession and disturbance model (LANDIS-II) to evaluate the relative strength of interactions between spruce budworm (Choristoneura fumiferana) outbreaks and fire disturbances in the Boundary Waters Canoe Area (BWCA) in northern Minnesota (USA). Disturbance interactions were evaluated for two different scenarios: presettlement forests and fire regimes vs. contemporary forests and fire regimes. Forest composition under the contemporary scenario trended toward mixtures of deciduous species (primarily Betula papyrifera and Populus spp.) and shade-tolerant conifers (Picea mariana, Abies balsamea, Thuja occidentalis), with disturbances dominated by a combination of budworm defoliation and high-severity fires. The presettlement scenario retained comparatively more “big pines” (i.e., Pinus strobus, P. resinosa) and tamarack (L. laricina), and experienced less budworm disturbance and a comparatively less-severe fire regime. Spruce budworm disturbance decreased area burned and fire severity under both scenarios when averaged across the entire 300-year simulations. Contrary to past research, area burned and fire severity during outbreak decades were each similar to that observed in non-outbreak decades. Our analyses suggest budworm disturbances within forests of the BWCA have a comparatively weak effect on long-term forest composition due to a combination of characteristics. These include strict host specificity, fine-scaled patchiness created by defoliation damage, and advance regeneration of its primary host, balsam fir (A. balsamea) that allows its host to persist despite repeated disturbances. Understanding the nature of the three-way interaction between budworm, fire, and composition has important ramifications for both fire mitigation strategies and ecosystem restoration initiatives. We conclude that budworm disturbance can partially mitigate long-term future fire risk by periodically reducing live ladder fuel within the mixed forest types of the BWCA but will do little to reverse the compositional trends caused in part by reduced fire rotations.

Managing Fire Risk During Drought: The Influence of Certification and El Nino on Fire-Driven Forest Conversion for Oil Palm in Southeast Asia

NASA Technical Reports Server (NTRS)

Noojipady, Praveen; Morton, Douglas C.; Schroeder, Wilfrid; Carlson, Kimberly M.; Huang, Chengquan; Gibbs, Holly K.; Burns, David; Walker, Nathalie F.; Prince, Stephen D.

2017-01-01

Indonesia and Malaysia have emerged as leading producers of palm oil in the past several decades, expanding production through the conversion of tropical forests to industrial plantations. Efforts to produce "sustainable" palm oil, including certification by the Roundtable on Sustainable Palm Oil (RSPO), include guidelines designed to reduce the environmental impact of palm oil production. Fire-driven deforestation is prohibited by law in both countries and a stipulation of RSPO certification, yet the degree of environmental compliance isunclear, especially during El Niño events when drought conditions increase fire risk. Here, we used time series of satellite data to estimate the spatial and temporal patterns of fire-driven deforestation on and around oil palm plantations. In Indonesia, fire-driven deforestation accounted for one-quarter of total forest losses on both certified and noncertified plantations. After the first plantations in Indonesia received RSPO certification in 2009,forest loss and fire-driven deforestation declined on certified plantations but did not stop altogether. Oil palm expansion in Malaysia rarely involved fire; only 5 % of forest loss on certified plantations had coincident activefire detections. Interannual variability in fire detections was strongly influenced by El Nino and the timing of certification. Fire activity during the 2002, 2004, and 2006 El Nino events was similar among oil palm plantations in Indonesia that would later become certified, noncertified plantations, and surrounding areas. However, total fire activity was 75% and 66% lower on certified plantations than noncertified plantations during the 2009 and 2015 El Nino events, respectively. The decline in fire activity on certified plantations, including during drought periods, highlights the potential for RSPO certification to safeguard carbon stocks in peatlands and remaining forests in accordance with legislation banning fires. However, aligning certification standards with satellite monitoring capabilities will be critical to realize sustainable palm oil production and meet industry commitments to zero forestation.

Waterfowl populations are resilient to immediate and lagged impacts of wildfires in the boreal forest

USGS Publications Warehouse

Lewis, Tyler; Schmutz, Joel A.; Amundson, Courtney L.; Lindberg, Mark S.

2016-01-01

Summary 1. Wildfires are the principal disturbance in the boreal forest, and their size and frequency are increasing as the climate warms. Impacts of fires on boreal wildlife are largely unknown, especially for the tens of millions of waterfowl that breed in the region. This knowledge gap creates significant barriers to the integrative management of fires and waterfowl, leading to fire policies that largely disregard waterfowl. 2. Waterfowl populations across the western boreal forest of North America have been monitored annually since 1955 by the Waterfowl Breeding Population and Habitat Survey (BPOP), widely considered the most extensive wildlife survey in the world. Using these data, we examined impacts of forest fires on abundance of two waterfowl guilds – dabblers and divers. We modelled waterfowl abundance in relation to fire extent (i.e. amount of survey transect burned) and time since fire, examining both immediate and lagged fire impacts. 3. From 1955 to 2014, >1100 fires in the western boreal forest intersected BPOP survey transects, and many transects burned multiple times. Nonetheless, fires had no detectable impact on waterfowl abundance; annual transect counts of dabbler and diver pairs remained stable from the pre- to post-fire period. 4. The absence of fire impacts on waterfowl abundance extended from the years immediately following the fire to those more than a decade afterwards. Likewise, the amount of transect burned did not influence waterfowl abundance, with similar pair counts from the pre- to post-fire period for small (1–20% burned), medium (21–60%) and large (>60%) burns. 5. Policy implications. Waterfowl populations appear largely resilient to forest fires, providing initial evidence that current policies of limited fire suppression, which predominate throughout much of the boreal forest, have not been detrimental to waterfowl populations. Likewise, fire-related management actions, such as prescribed burning or targeted suppression, seem to have limited impacts on waterfowl abundance and productivity. For waterfowl managers, our results suggest that adaptive models of waterfowl harvest, which annually guide hunting quotas, do not need to emphasize fires when integrating climate change effects.

Are prescribed fire and thinning dominant processes affecting snag occurrence at a landscape scale?

DOE PAGES

Zarnoch, Stanley J.; Blake, John I.; Parresol, Bernard R.

2014-11-01

Snags are standing dead trees that are an important component in the nesting habitat of birds and other species. Although snag availability is believed to limit populations in managed and non-managed forests, little data are available to evaluate the relative effect of stand conditions and management on snag occurrence. We analyzed point sample data from an intensive forest inventory within an 80,000 ha landscape for four major forest types to support the hypotheses that routine low-intensity prescribed fire would increase, and thinning would decrease, snag occurrence. We employed path analysis to define a priori causal relationships to determine the directmore » and indirect effects of site quality, age, relative stand density index and fire for all forest types and thinning effects for loblolly pine and longleaf pine. Stand age was an important direct effect for loblolly pine, mixed pine-hardwoods and hardwoods, but not for longleaf pine. Snag occurrence in loblolly pine was increased by prescribed fire and decreased by thinning which confirmed our initial hypotheses. Although fire was not important in mixed pine-hardwoods, it was for hardwoods but the relationship depended on site quality. For longleaf pine the relative stand density index was the dominant variable affecting snag occurrence, which increased as the density index decreased. Site quality, age and thinning had significant indirect effects on snag occurrence in longleaf pine through their effects on the density index. Although age is an important condition affecting snag occurrence for most forest types, path analysis revealed that fire and density management practices within certain forest types can also have major beneficial effects, particularly in stands less than 60 years old.« less

Resilience of Mediterranean terrestrial ecosystems and fire severity in semiarid areas: Responses of Aleppo pine forests in the short, mid and long term.

PubMed

González-De Vega, S; De Las Heras, J; Moya, D

2016-12-15

In recent decades, the fire regime of the Mediterranean Basin has been disturbed by various factors: climate change; forest management policies; land cover; changed landscape. Size and severity have notably increased, which in turn have increased large fires events with >500ha burned (high severity). In spite of Mediterranean ecosystems' high resilience to fire, these changes have implied more vulnerability and reduced natural recovery with irreparable long-term negative effects. Knowledge of the response of ecosystems to increasing severity, mainly in semiarid areas, is still lacking, which is needed to rehabilitate and restore burned areas. Our approach assessed the resilience concept by focusing on the recovery of ecosystem functions and services, measured as changes in the composition and diversity of plant community vegetation and structure. This will be validated in the long term as a model of ecosystem response. Also, depending on the pre-fire characteristics of vegetation, fire severity and the post-fire management, this approach will lead to tools that can be applied to implement post-fire restoration efforts in order to help decision making in planning activities. Regarding Mediterranean ecosystems' ability to recover after wildfires, this study concludes that pre-fire communities are resilient in these fire-prone areas, but the window for natural recovery in semiarid areas of Aleppo pine forest in SE Iberian Peninsula varied from 3 to 15 post-fire years. Fire severity was also key for effects on the ecosystem: the vegetation types of areas burned with low and medium severity recovered naturally, while those areas with a high-severity burn induced shrublands. We concluded that very strong regeneration activity exists in the short term, and that the negative effects of medium- and high-severity fire are evidenced in the mid and long term, which affect natural recovery. Adaptive forest management to rehabilitate and restore burned Mediterranean ecosystems should be implemented. Copyright © 2016 Elsevier B.V. All rights reserved.

Forest-fire models

Treesearch

Haiganoush Preisler; Alan Ager

2013-01-01

For applied mathematicians forest fire models refer mainly to a non-linear dynamic system often used to simulate spread of fire. For forest managers forest fire models may pertain to any of the three phases of fire management: prefire planning (fire risk models), fire suppression (fire behavior models), and postfire evaluation (fire effects and economic models). In...

Fire decreases arthropod abundance but increases diversity: Early and late season prescribed fire effects in a Sierra Nevada mixed-conifer forest

USGS Publications Warehouse

Ferrenberg, Scott; Schwilk, Dylan W.; Knapp, Eric E.; Groth, Eric; Keeley, Jon E.

2006-01-01

Prior to fire suppression in the 20th century, the mixed-conifer forests of the Sierra Nevada, California, U.S.A., historically burned in frequent fires that typically occurred during the late summer and early fall. Fire managers have been attempting to restore natural ecosystem processes through prescription burning, and have often favored burning during the fall in order to mimic historical fire regimes. Increasingly, however, prescription burning is also being done during the late spring and early summer in order to expand the window of opportunity for needed fuel reduction burning. The effect of prescribed fires outside of the historical fire season on forest arthropods is not known. The objective of this study was to compare the short-term effects of prescribed fires ignited in the early and late fire season on forest floor arthropods. Arthropod abundance and diversity were assessed using pitfall trapping in replicated burn units in Sequoia National Park, California. Overall, abundance of arthropods was lower in the burn treatments than in the unburned control. However, diversity tended to be greater in the burn treatments. Fire also altered the relative abundances of arthropod feeding guilds. No significant differences in arthropod community structure were found between early and late season burn treatments. Instead, changes in the arthropod community appeared to be driven largely by changes in fuel loading, vegetation, and habitat heterogeneity, all of which differed more between the burned and unburned treatments than between early and late season burn treatments.

Conserving old-growth forest diversity in disturbance-prone landscapes.

PubMed

Spies, Thomas A; Hemstrom, Miles A; Youngblood, Andrew; Hummel, Susan

2006-04-01

A decade after its creation, the Northwest Forest Plan is contributing to the conservation of old-growth forests on federal land. However the success and outlook for the plan are questionable in the dry provinces, where losses of old growth to wildfire have been relatively high and risks of further loss remain. We summarize the state of knowledge of old-growth forests in the plan area, identify challenges to conserve them, and suggest some conservation approaches that might better meet the goals of the plan. Historically, old-growth forests in these provinces ranged from open, patchy stands, maintained by frequent low-severity fire, to a mosaic of dense and open stands maintained by mixed-severity fires. Old-growth structure and composition were spatially heterogeneous, varied strongly with topography and elevation, and were shaped by a complex disturbance regime of fire, insects, and disease. With fire suppression and cutting of large pines (Pinus spp.) and Douglas-firs (Pseudotsuga menziesii [Mirbel] Franco), old-growth diversity has declined and dense understories have developed across large areas. Challenges to conserving these forests include a lack of definitions needed for planning of fire-dependent old-growth stands and landscapes, and conflicts in conservation goals that can be resolved only at the landscape level. Fire suppression has increased the area of the dense, older forest favored by Northern Spotted Owls (Strix occidentalis caurina) but increased the probability of high-severity fire. The plan allows for fuel reduction in late-successional reserves; fuel treatments, however apparently have not happened at a high enough rate or been applied in a landscape-level approach. Landscape-level strategies are needed that prioritize fuel treatments by vegetation zones, develop shaded fuel breaks in strategic positions, and thin and apply prescribed fire to reduce ladder fuels around remaining old trees. Evaluations of the current and alternative strategies are needed to determine whether the current reserve-matrix approach is the best strategy to meet plan goals in these dynamic landscapes.

A review of the relationships between drought and forest fire in the United States.

PubMed

Littell, Jeremy S; Peterson, David L; Riley, Karin L; Liu, Yongquiang; Luce, Charles H

2016-07-01

The historical and presettlement relationships between drought and wildfire are well documented in North America, with forest fire occurrence and area clearly increasing in response to drought. There is also evidence that drought interacts with other controls (forest productivity, topography, fire weather, management activities) to affect fire intensity, severity, extent, and frequency. Fire regime characteristics arise across many individual fires at a variety of spatial and temporal scales, so both weather and climate - including short- and long-term droughts - are important and influence several, but not all, aspects of fire regimes. We review relationships between drought and fire regimes in United States forests, fire-related drought metrics and expected changes in fire risk, and implications for fire management under climate change. Collectively, this points to a conceptual model of fire on real landscapes: fire regimes, and how they change through time, are products of fuels and how other factors affect their availability (abundance, arrangement, continuity) and flammability (moisture, chemical composition). Climate, management, and land use all affect availability, flammability, and probability of ignition differently in different parts of North America. From a fire ecology perspective, the concept of drought varies with scale, application, scientific or management objective, and ecosystem. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Database of in-situ field measurements for estimates of fuel consumption and fire emissions in Siberia

NASA Astrophysics Data System (ADS)

Kukavskaya, Elena; Conard, Susan; Buryak, Ludmila; Ivanova, Galina; Soja, Amber; Kalenskaya, Olga; Zhila, Sergey; Zarubin, Denis; Groisman, Pavel

2016-04-01

Wildfires show great variability in the amount of fuel consumed and carbon emitted to the atmosphere. Various types of models are used to calculate global or large scale regional fire emissions. However, in the databases used to estimate fuel consumptions, data for Russia are typically under-represented. Meanwhile, the differences in vegetation and fire regimes in the boreal forests in North America and Eurasia argue strongly for the need of regional ecosystem-specific data. For about 15 years we have been collecting field data on fuel loads and consumption in different ecosystem types of Siberia. We conducted a series of experimental burnings of varying fireline intensity in Scots pine and larch forests of central Siberia to obtain quantitative and qualitative data on fire behavior and carbon emissions. In addition, we examined wildfire behavior and effects in different vegetation types including Scots pine, Siberian pine, fir, birch, poplar, and larch-dominated forests; evergreen coniferous shrubs; grasslands, and peats. We investigated various ecosystem zones of Siberia (central and southern taiga, forest-steppe, steppe, mountains) in the different subjects of the Russian Federation (Krasnoyarsk Kray, Republic of Khakassia, Republic of Buryatia, Tuva Republic, Zabaikalsky Kray). To evaluate the impact of forest practices on fire emissions, burned and unburned logged sites and forest plantations were examined. We found large variations of fuel consumption and fire emission rates among different vegetation types depending on growing conditions, fire behavior characteristics and anthropogenic factors. Changes in the climate system result in an increase in fire frequency, area burned, the number of extreme fires, fire season length, fire season severity, and the number of ignitions from lightning. This leads to an increase of fire-related emissions of carbon to the atmosphere. The field measurement database we compiled is required for improving accuracy of existing biomass burning models and for use by air quality agencies in developing regional strategies to mitigate negative smoke impacts on human health and environment. The research was supported by the Grant of the President of the Russian Federation MK-4646.2015.5, RFBR grant # 15-04-06567, and the NASA LCLUC Program.

Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands

USGS Publications Warehouse

Turetsky, M.R.; Kane, E.S.; Harden, J.W.; Ottmar, R.D.; Manies, K.L.; Hoy, E.; Kasischke, E.S.

2011-01-01

Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult to assess. Here, we examined the depth of ground-layer combustion in 178 sites dominated by black spruce in Alaska, using data collected from 31 fire events between 1983 and 2005. We show that the depth of burning increased as the fire season progressed when the annual area burned was small. However, deep burning occurred throughout the fire season when the annual area burned was large. Depth of burning increased late in the fire season in upland forests, but not in peatland and permafrost sites. Simulations of wildfire-induced carbon losses from Alaskan black spruce stands over the past 60 years suggest that ground-layer combustion has accelerated regional carbon losses over the past decade, owing to increases in burn area and late-season burning. As a result, soils in these black spruce stands have become a net source of carbon to the atmosphere, with carbon emissions far exceeding decadal uptake.

Providing the Fire Risk Map in Forest Area Using a Geographically Weighted Regression Model with Gaussin Kernel and Modis Images, a Case Study: Golestan Province

NASA Astrophysics Data System (ADS)

Shah-Heydari pour, A.; Pahlavani, P.; Bigdeli, B.

2017-09-01

According to the industrialization of cities and the apparent increase in pollutants and greenhouse gases, the importance of forests as the natural lungs of the earth is felt more than ever to clean these pollutants. Annually, a large part of the forests is destroyed due to the lack of timely action during the fire. Knowledge about areas with a high-risk of fire and equipping these areas by constructing access routes and allocating the fire-fighting equipment can help to eliminate the destruction of the forest. In this research, the fire risk of region was forecasted and the risk map of that was provided using MODIS images by applying geographically weighted regression model with Gaussian kernel and ordinary least squares over the effective parameters in forest fire including distance from residential areas, distance from the river, distance from the road, height, slope, aspect, soil type, land use, average temperature, wind speed, and rainfall. After the evaluation, it was found that the geographically weighted regression model with Gaussian kernel forecasted 93.4% of the all fire points properly, however the ordinary least squares method could forecast properly only 66% of the fire points.

Pyro-eco-hydrologic feedbacks and catchment co-evolution in fire-prone forested uplands

NASA Astrophysics Data System (ADS)

Sheridan, Gary; Inbar, Assaf; Lane, Patrick; Nyman, Petter

2017-04-01

The south east Australian forested uplands are characterized by complex and inter-correlated spatial patterns in standing biomass, soil depth/quality, and fire regimes, even within areas with similar rainfall, geology and catenary position. These system properties have traditionally been investigated independently, however recent research in the areas of post fire hydrology and erosion, and new insights into forest structure, fuel moisture, and flammability, suggest the presence of critical co-evolutionary feedbacks between fire, soils and vegetation that may explain the observed system states. To test this hypothesis we started with a published ecohydrologic model, modifying and extending the algorithms to capture feedbacks between hyrology and fire, and between fire, vegetation and soil production and erosion. The model was parameterized and calibrated with new data from instrumented forested hillslopes across energy and rainfall gradients generated by selecting sites with a range of aspect (energy) and elevation (rainall). The calibrated model was able to reasonably replicate the observed patterns of standing biomass, water balance, fire interval, and soil depth. The catchment co-evolution/feedback modelling approach to understanding patterns of vegetation, soils and fire regimes provides a promising new paradigm for predicting the response of forested se Australian catchments to declining rainfall and increasing temperatures under climate change.

Identifying the location of fire refuges in wet forest ecosystems.

PubMed

Berry, Laurence E; Driscoll, Don A; Stein, John A; Blanchard, Wade; Banks, Sam C; Bradstock, Ross A; Lindenmayer, David B

2015-12-01

The increasing frequency of large, high-severity fires threatens the survival of old-growth specialist fauna in fire-prone forests. Within topographically diverse montane forests, areas that experience less severe or fewer fires compared with those prevailing in the landscape may present unique resource opportunities enabling old-growth specialist fauna to survive. Statistical landscape models that identify the extent and distribution of potential fire refuges may assist land managers to incorporate these areas into relevant biodiversity conservation strategies. We used a case study in an Australian wet montane forest to establish how predictive fire simulation models can be interpreted as management tools to identify potential fire refuges. We examined the relationship between the probability of fire refuge occurrence as predicted by an existing fire refuge model and fire severity experienced during a large wildfire. We also examined the extent to which local fire severity was influenced by fire severity in the surrounding landscape. We used a combination of statistical approaches, including generalized linear modeling, variogram analysis, and receiver operating characteristics and area under the curve analysis (ROC AUC). We found that the amount of unburned habitat and the factors influencing the retention and location of fire refuges varied with fire conditions. Under extreme fire conditions, the distribution of fire refuges was limited to only extremely sheltered, fire-resistant regions of the landscape. During extreme fire conditions, fire severity patterns were largely determined by stochastic factors that could not be predicted by the model. When fire conditions were moderate, physical landscape properties appeared to mediate fire severity distribution. Our study demonstrates that land managers can employ predictive landscape fire models to identify the broader climatic and spatial domain within which fire refuges are likely to be present. It is essential that within these envelopes, forest is protected from logging, roads, and other developments so that the ecological processes related to the establishment and subsequent use of fire refuges are maintained.

Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest

PubMed Central

Dore, Sabina; Fry, Danny L.; Collins, Brandon M.; Vargas, Rodrigo; York, Robert A.; Stephens, Scott L.

2016-01-01

Forest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60–70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related stresses. PMID:26918460

Climate and Wildfire in Mountains of the Western United States

NASA Astrophysics Data System (ADS)

Alfaro, E.; Westerling, A. L.; Cayan, D. R.

2004-12-01

Since the mid-1980s, there has been a dramatic increase in the area burned in wildfires in mountain forests of the western United States, with mean annual area burned nearly three and a half times higher compared to the preceding one and a half decades.(1) Concomitant increases in variability in annual area burned and in fire suppression costs pose a serious challenge for land management in the mountainous West. The variance in annual area burned since 1987 is nineteen times its previous level. Since managers must be prepared for the worst possible scenarios in every fire season, increased uncertainty about the scale of the western fire season each year imposes high costs on public agencies. Annual real suppression costs in western forests have more than doubled for the Forest Service since 1987, while the variance in annual suppression costs is over four times higher. Although federal agencies' fire suppression budgets have increased recently, they are still close to what would be spent in an "average" year that seldom occurs, while costs tend to fluctuate between low and high extremes. Modeling area burned and suppression costs as a function of climate variability alone, Westerling (2004, unpublished work) found that the probability of the Forest Service's suppression expenses exceeding the current annual suppression budget has exceeded 50% since 1987, a substantial increase from the one-in-three chance over the preceding 40 years. Recent progress in our understanding of the links between climate and wildfire, and in our ability to forecast some aspects of both climate and wildfire season severity a season or more in advance, offers some hope that these costs might be ameliorated through the integration of climate information into fire and fuels management. In addition to the effects of climate variability on wildfire, long-term biomass accumulations in some western ecosystems have fueled an increasing incidence of large, stand-replacing wildfires where such fires were previously rare. These severe large fires can result in erosion and changes in vegetation type, with consequences for water quality, stream flow, future biological productivity of the affected areas, and habitat loss for endangered species. Apart from their deleterious ecological consequences, severe fires can also dramatically affect amenity values for public lands and for homeowners living in the wildland-urban interface. In the National Fire Plan, land management agencies have committed to reducing fuels on millions of hectares of public lands. The primary means are mechanical removal, prescribed fire and wildland fire use. The Forest Service estimates they will need to spend hundreds of millions of dollars per year to meet their fuel reduction targets, while efforts in recent years have not kept up with the current rate of biomass increase. Use of climate information for targeting resources and scheduling prescribed burns could increase the efficiency of these efforts. In this study we review the fire history since 1970 for western mountain forests, and demonstrate apparent links between regional climate variability and decadal-scale changes in annual area burned. This analysis explores how wildfire size and frequency have varied over the past thirty-five years by elevation and latitude, and how climate indices such as precipitation, temperature, drought indices and the timing of spring runoff vary in importance for fire season severity by elevation in forests around the western United States.

Long-term persistence and fire resilience of oak shrubfields in dry conifer forests of northern New Mexico

USGS Publications Warehouse

Guiterman, Christopher H.; Margolis, Ellis; Allen, Craig D.; Falk, Donald A.; Swetnam, Thomas W.

2017-01-01

Extensive high-severity fires are creating large shrubfields in many dry conifer forests of the interior western USA, raising concerns about forest-to-shrub conversion. This study evaluates the role of disturbance in shrubfield formation, maintenance and succession in the Jemez Mountains, New Mexico. We compared the environmental conditions of extant Gambel oak (Quercus gambelii) shrubfields with adjoining dry conifer forests and used dendroecological methods to determine the multi-century fire history and successional dynamics of five of the largest shrubfields (76–340 ha). Across the study area, 349 shrubfields (5–368 ha) occur in similar topographic and climate settings as dry conifer forests. This suggests disturbance, rather than other biophysical factors, may explain their origins and persistence. Gambel oak ages and tree-ring fire scars in our sampled shrubfields indicate they historically (1664–1899) burned concurrently with adjoining conifer forests and have persisted for over 115 years in the absence of fire. Aerial imagery from 1935 confirmed almost no change in sampled shrubfield patch sizes or boundaries over the twentieth century. The largest shrubfield we identified is less than 4% the size of the largest conifer-depleted and substantially shrub-dominated area recently formed in the Jemez following extensive high-severity wildfires, indicating considerable departure from historical patterns and processes. Projected hotter droughts and increasingly large high-severity fires could trigger more forest-to-shrub transitions and maintain existing shrubfields, inhibiting conifer forest recovery. Restoration of surface fire regimes and associated historical forest structures likely could reduce the rate and patch size of dry conifer forests being converted to shrubfields.

Regime Shifts and Weakened Environmental Gradients in Open Oak and Pine Ecosystems

PubMed Central

Hanberry, Brice B.; Dey, Dan C.; He, Hong S.

2012-01-01

Fire suppression allows tree species that are intolerant of fire stress to increase their distribution, potentially resulting in disruption of historical species-environmental relationships. To measure changes between historical General Land Office surveys (1815 to 1850) and current USDA Forest Inventory and Assessment surveys (2004 to 2008), we compared composition, distribution, and site factors of 21 tree species or species groups in the Missouri Ozarks. We used 24 environmental variables and random forests as a classification method to model distributions. Eastern redcedar, elms, maples, and other fire-sensitive species have increased in dominance in oak forests, with concurrent reductions by oak species; specific changes varied by ecological subsection. Ordinations displayed loss of separation between formerly distinctive oak and fire-sensitive tree species groups. Distribution maps showed decreased presence of disturbance-dependent oak and pine species and increased presence of fire-sensitive species that generally expanded from subsections protected from fire along rivers to upland areas, except for eastern redcedar, which expanded into these subsections. Large scale differences in spatial gradients between past and present communities paralleled reduced influence of local topographic gradients in the varied relief of the Missouri Ozarks, as fire-sensitive species have moved to higher, drier, and sunnier sites away from riverine corridors. Due to changes in land use, landscapes in the Missouri Ozarks, eastern United States, and world-wide are changing from open oak and pine-dominated ecosystems to novel oak-mixed species forests, although at fine scales, forests are becoming more diverse in tree species today. Fire suppression weakened the influence by environmental gradients over species dominance, allowing succession from disturbance-dependent oaks to an alternative state of fire-sensitive species. Current and future research and conservation that rely on historical relationships and ecological principles based on disturbance across the landscape will need to incorporate modern interactions among species for resources into management plans and projections. PMID:22848467

Regime shifts and weakened environmental gradients in open oak and pine ecosystems.

PubMed

Hanberry, Brice B; Dey, Dan C; He, Hong S

2012-01-01

Fire suppression allows tree species that are intolerant of fire stress to increase their distribution, potentially resulting in disruption of historical species-environmental relationships. To measure changes between historical General Land Office surveys (1815 to 1850) and current USDA Forest Inventory and Assessment surveys (2004 to 2008), we compared composition, distribution, and site factors of 21 tree species or species groups in the Missouri Ozarks. We used 24 environmental variables and random forests as a classification method to model distributions. Eastern redcedar, elms, maples, and other fire-sensitive species have increased in dominance in oak forests, with concurrent reductions by oak species; specific changes varied by ecological subsection. Ordinations displayed loss of separation between formerly distinctive oak and fire-sensitive tree species groups. Distribution maps showed decreased presence of disturbance-dependent oak and pine species and increased presence of fire-sensitive species that generally expanded from subsections protected from fire along rivers to upland areas, except for eastern redcedar, which expanded into these subsections. Large scale differences in spatial gradients between past and present communities paralleled reduced influence of local topographic gradients in the varied relief of the Missouri Ozarks, as fire-sensitive species have moved to higher, drier, and sunnier sites away from riverine corridors. Due to changes in land use, landscapes in the Missouri Ozarks, eastern United States, and world-wide are changing from open oak and pine-dominated ecosystems to novel oak-mixed species forests, although at fine scales, forests are becoming more diverse in tree species today. Fire suppression weakened the influence by environmental gradients over species dominance, allowing succession from disturbance-dependent oaks to an alternative state of fire-sensitive species. Current and future research and conservation that rely on historical relationships and ecological principles based on disturbance across the landscape will need to incorporate modern interactions among species for resources into management plans and projections.

Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA

Treesearch

Matthew B. Dickinson; Todd F. Hutchinson; Mark Dietenberger; Frederick Matt; Matthew P. Peters; Jian Yang

2016-01-01

Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to...

A fuel treatment reduces potential fire severity and increases suppression efficiency in a Sierran mixed conifer forest

Treesearch

Jason J. Moghaddas

2006-01-01

Fuel treatments are being widely implemented on public and private lands across the western U.S. While scientists and managers have an understanding of how fuel treatments can modify potential fire behavior under modeled conditions, there is limited information on how treatments perform under real wildfire conditions in Sierran mixed conifer forests. The Bell Fire...

Consumption and reaccumulation of forest fuels in oak shelterwood stands managed with prescribed fire

Treesearch

Patrick H. Brose

2016-01-01

In the shelterwood-burn technique, a moderate- to high-intensity growing-season prescribed fire is essential to achieve desired oak regeneration goals. These levels of fire intensity are dependent on the increased fuel loadings created by the preceding first removal cut. However, the loadings of forest fuels and their fluctuation during implementation of the...

Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed-conifer forest

USGS Publications Warehouse

Schwilk, Dylan W.; Knapp, Eric E.; Ferrenberg, Scott; Keeley, Jon E.; Caprio, Anthony C.

2006-01-01

Over the last century, fire exclusion in the forests of the Sierra Nevada has allowed surface fuels to accumulate and has led to increased tree density. Stand composition has also been altered as shade tolerant tree species crowd out shade intolerant species. To restore forest structure and reduce the risk of large, intense fires, managers have increasingly used prescription burning. Most fires prior to EuroAmerican settlement occurred during the late summer and early fall and most prescribed burning has taken place during the latter part of this period. Poor air quality and lack of suitable burn windows during the fall, however, have resulted in a need to conduct more prescription burning earlier in the season. Previous reports have suggested that burning during the time when trees are actively growing may increase mortality rates due to fine root damage and/or bark beetle activity. This study examines the effects of fire on tree mortality and bark beetle attacks under prescription burning during early and late season. Replicated early season burn, late season burn and unburned control plots were established in an old-growth mixed conifer forest in the Sierra Nevada that had not experienced a fire in over 120 years. Although prescribed burns resulted in significant mortality of particularly the smallest tree size classes, no difference between early and late season burns was detected. Direct mortality due to fire was associated with fire intensity. Secondary mortality due to bark beetles was not significantly correlated with fire intensity. The probability of bark beetle attack on pines did not differ between early and late season burns, while the probability of bark beetle attack on firs was greater following early season burns. Overall tree mortality appeared to be primarily the result of fire intensity rather than tree phenology at the time of the burns. Early season burns are generally conducted under higher fuel moisture conditions, leading to less fuel consumption and potentially less injury to trees. This reduction in fire severity may compensate for relatively modest increases in bark beetle attack probabilities on some tree species, ultimately resulting in a forest structure that differs little between early and late season prescribed burning treatments.

Long-term temporal changes in the occurrence of a high forest fire danger in Finland

NASA Astrophysics Data System (ADS)

Mäkelä, H. M.; Laapas, M.; Venäläinen, A.

2012-08-01

Climate variation and change influence several ecosystem components including forest fires. To examine long-term temporal variations of forest fire danger, a fire danger day (FDD) model was developed. Using mean temperature and total precipitation of the Finnish wildfire season (June-August), the model describes the climatological preconditions of fire occurrence and gives the number of fire danger days during the same time period. The performance of the model varied between different regions in Finland being best in south and west. In the study period 1908-2011, the year-to-year variation of FDD was large and no significant increasing or decreasing tendencies could be found. Negative slopes of linear regression lines for FDD could be explained by the simultaneous, mostly not significant increases in precipitation. Years with the largest wildfires did not stand out from the FDD time series. This indicates that intra-seasonal variations of FDD enable occurrence of large-scale fires, despite the whole season's fire danger is on an average level. Based on available monthly climate data, it is possible to estimate the general fire conditions of a summer. However, more detailed input data about weather conditions, land use, prevailing forestry conventions and socio-economical factors would be needed to gain more specific information about a season's fire risk.

A new parameterization of the post-fire snow albedo effect

NASA Astrophysics Data System (ADS)

Gleason, K. E.; Nolin, A. W.

2013-12-01

Mountain snowpack serves as an important natural reservoir of water: recharging aquifers, sustaining streams, and providing important ecosystem services. Reduced snowpacks and earlier snowmelt have been shown to affect fire size, frequency, and severity in the western United States. In turn, wildfire disturbance affects patterns of snow accumulation and ablation by reducing canopy interception, increasing turbulent fluxes, and modifying the surface radiation balance. Recent work shows that after a high severity forest fire, approximately 60% more solar radiation reaches the snow surface due to the reduction in canopy density. Also, significant amounts of pyrogenic carbon particles and larger burned woody debris (BWD) are shed from standing charred trees, which concentrate on the snowpack, darken its surface, and reduce snow albedo by 50% during ablation. Although the post-fire forest environment drives a substantial increase in net shortwave radiation at the snowpack surface, driving earlier and more rapid melt, hydrologic models do not explicitly incorporate forest fire disturbance effects to snowpack dynamics. The objective of this study was to parameterize the post-fire snow albedo effect due to BWD deposition on snow to better represent forest fire disturbance in modeling of snow-dominated hydrologic regimes. Based on empirical results from winter experiments, in-situ snow monitoring, and remote sensing data from a recent forest fire in the Oregon High Cascades, we characterized the post-fire snow albedo effect, and developed a simple parameterization of snowpack albedo decay in the post-fire forest environment. We modified the recession coefficient in the algorithm: α = α0 + K exp (-nr) where α = snowpack albedo, α0 = minimum snowpack albedo (≈0.4), K = constant (≈ 0.44), -n = number of days since last major snowfall, r = recession coefficient [Rohrer and Braun, 1994]. Our parameterization quantified BWD deposition and snow albedo decay rates and related these forest disturbance effects to radiative heating and snow melt rates. We validated our parameterization of the post-fire snow albedo effect at the plot scale using a physically-based, spatially-distributed snow accumulation and melt model, and in-situ eddy covariance and snow monitoring data. This research quantified wildfire impacts to snow dynamics in the Oregon High Cascades, and provided a new parameterization of post-fire drivers to changes in high elevation winter water storage.

Measuring and modeling carbon balance in mountainous Northern Rocky mixed conifer forests

NASA Astrophysics Data System (ADS)

Hudiburg, T. W.; Berardi, D.; Stenzel, J.

2016-12-01

Drought and wildfire caused by changing precipitation patterns, increased temperatures, increased fuel loads, and decades of fire suppression are reducing forest carbon uptake from local to continental scales. This trend is especially widespread in Idaho and the intermountain west and has important implications for climate change and forest management options. Given the key role of forests in climate regulation, understanding forest response to drought and the feedbacks to the atmosphere is a key research and policy-relevant priority globally. As temperature, fire, and precipitation regimes continue to change and there is increased risk of forest mortality, measurements and modeling at temporal and spatial scales that are conducive to understanding the impacts and underlying mechanisms of carbon and nutrient cycling become critically important. Until recently, sub-daily measurements of ecosystem carbon balance have been limited in remote, mountainous terrain (e.g Northern Rocky mountain forests). Here, we combine new measurement technology and state-of-the-art ecosystem modeling to determine the impact of drought on the total carbon balance of a mature, mixed-conifer forest in Northern Idaho. Our findings indicate that drought had no impact on aboveground NPP, despite early growing season reductions in soil moisture and fine root biomass compared to non-drought years in the past. Modeled estimates of net ecosystem production (NEP) suggest that a simultaneous reduction in heterotrophic respiration increased the carbon sink for this forest. This has important implications for forest management, such as thinning where the objectives are to increase forest resilience to fire and drought, but may decrease NEP.

Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands

Treesearch

Merritt R. Turetsky; Evan S. Kane; Jennifer W. Harden; Roger D. Ottmar; Kristen L. Maines; Elizabeth Hoy; Eric S. Kasischke

2010-01-01

Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult...

Fire, Carbon and Climate Change in Boreal Forests

NASA Astrophysics Data System (ADS)

Flannigan, M. D.; Amiro, B. D.; Logan, K. A.

2005-12-01

Disturbances are the major stand-renewing agents for much of the circumboreal forest. In Canada, fire has received much of the attention in carbon cycle science because it affects about 3 million ha of Canadian forest annually, impacts air quality, and can threaten life, property and infrastructure. Fire affects the carbon balance through three processes. First, carbon and other greenhouse gases are emitted to the atmosphere during the combustion process. We estimate this to average about 27 Tg C/year in Canada over the past 40 years, which is close to 20% of industrial carbon emissions. However, in some years this can exceed 100 Tg C. Efforts are underway to estimate global fire activity and greenhouse gas emissions using observations, remote sensing and modelling. The second process is the decomposition of fire-killed vegetation. This forms a pool of coarse woody debris that can take decades to decompose, or can be quite rapid, depending on the post-fire environment. The third process is succession of vegetation following fire, a dynamic process that involves the interplay among species establishment and competition. Weather and climate affects all of these processes. Estimates of the future environment indicate that much of boreal Canada will experience warmer and drier conditions, although there will be regional differences and transient effects. The projections suggest that we may experience a doubling of area burned over the next century because of anthropogenic climate changes. This may have further implications to the global carbon budget by increasing atmospheric carbon dioxide concentrations. This increase in fire activity may lead to a positive feedback cycle with the increased release of greenhouse gases. A run-away scenario is unlikely because young successional boreal vegetation often does not burn as readily and would limit the positive feedback cycle. Also, changes to the forest composition following fire increases surface albedo and alters the energy balance; effects that may cause climate cooling. However, the impacts of landscape feedbacks and human intervention limiting future fire are not well known.

Effects of multiple interacting disturbances and salvage logging on forest carbon stocks

USGS Publications Warehouse

Bradford, J.B.; Fraver, S.; Milo, A.M.; D'Amato, A.W.; Palik, B.; Shinneman, D.J.

2012-01-01

Climate change is anticipated to increase the frequency of disturbances, potentially impacting carbon stocks in terrestrial ecosystems. However, little is known about the implications of either multiple disturbances or post-disturbance forest management activities on ecosystem carbon stocks. This study quantified how forest carbon stocks responded to stand-replacing blowdown and wildfire, both individually and in combination with and without post-disturbance salvage operations, in a sub-boreal jack pine ecosystem. Individually, blowdown or fire caused similar decreases in live carbon and total ecosystem carbon. However, whereas blowdown increased carbon in down woody material and forest floor, fire increased carbon in standing snags, a difference that may have consequences for long-term carbon cycling patterns. Fire after the blowdown caused substantial additional reduction in ecosystem carbon stocks, suggesting that potential increases in multiple disturbance events may represent a challenge for sustaining ecosystem carbon stocks. Salvage logging, as examined here, decreased carbon stored in snags and down woody material but had no significant effect on total ecosystem carbon stocks.

Ground-fire effects on the composition of dissolved and total organic matter in forest floor and soil solutions from Scots pine forests in Germany: new insights from solid state 13C NMR analysis

NASA Astrophysics Data System (ADS)

Näthe, Kerstin; Michalzik, Beate; Levia, Delphis; Steffens, Markus

2016-04-01

Fires represent an ecosystem disturbance and are recognized to seriously pertubate the nutrient budgets of forested ecosystems. While the effects of fires on chemical, biological, and physical soil properties have been intensively studied, especially in Mediterranean areas and North America, few investigations examined the effects of fire-induced alterations in the water-bound fluxes and the chemical composition of dissolved and particulate organic carbon and nitrogen (DOC, POC, DN, PN). The exclusion of the particulate organic matter fraction (0.45 μm < POM < 500 μm) potentially results in misleading inferences and budgeting gaps when studying the effects of fires on nutrient and energy fluxes. To our best knowledge, this is the first known study to present fire-induced changes on the composition of dissolved and total organic matter (DOM, TOM) in forest floor (FF) and soil solutions (A, B horizon) from Scots pine forests in Germany. In relation to control sites, we test the effects of low-severity fires on: (1) the composition of DOM and TOM in forest floor and soil solutions; and (2) the translocated amount of particulate in relation to DOC and DN into the subsoil. The project aims to uncover the mechanisms of water-bound organic matter transport along an ecosystem profile and its compositional changes following a fire disturbance. Forest floor and soil solutions were fortnightly sampled from March to December 2014 on fire-manipulated and control plots in a Scots pine forest in Central Germany. Shortly after the experimental duff fire in April 2014 pooled solutions samples were taken for solid-state 13C NMR spectroscopy to characterize DOM (filtered solution < 0.8μm pore size) and TOM in unfiltered solutions. Independent from fire manipulation, the composition of TOM was generally less aromatic (aromaticity index [%] according to Hatcher et al., 1981) with values between 18 (FF) - 25% (B horizon) than the DOM fraction with 23 (FF) - 27% (B horizon). For DOM in FF solution, fire manipulation caused an increase in aromaticity from 23 to 27% compared to the control, due to an increase of the aryl-C and a decrease of the O-alkyl-C and alkyl-C signal. Fire effects were leveled out in the mineral soil. For TOM, fire effects became notable only in the A horizon, exhibiting a decrease in aromaticity from 22 to 18% compared to the control, due to increased O-alkyl-C and diminished aryl-C proportions. Compared to the control, fire only caused minor DOC release rates (< 10%) in the FF and mineral soil, while DN in the FF was significantly mobilized (+ 40%) by fire exhibiting annual values of 33 at the control sites compared to 46 kg DN ha-1 at the fire treated sites. Compared to the control, fire events did not significantly enhance the proportion of POC and PN in the total C and N amounts exhibiting values between 10 and 20%. To fully understand the quality and amount of translocated organic C and N compounds within soils under both ambient as well as fire environments, dissolved and particulate size fractions need to be considered.

Effect of fire on phosphorus forms in Sphagnum moss and peat soils of ombrotrophic bogs.

PubMed

Wang, Guoping; Yu, Xiaofei; Bao, Kunshan; Xing, Wei; Gao, Chuanyu; Lin, Qianxin; Lu, Xianguo

2015-01-01

The effect of burning Sphagnum moss and peat on phosphorus forms was studied with controlled combustion in the laboratory. Two fire treatments, a light fire (250 °C) and a severe fire (600 °C), were performed in a muffle furnace with 1-h residence time to simulate the effects of different forest fire conditions. The results showed that fire burning Sphagnum moss and peat soils resulted in losses of organic phosphorus (Po), while inorganic phosphorus (Pi) concentrations increased. Burning significantly changed detailed phosphorus composition and availability, with severe fires destroying over 90% of organic phosphorus and increasing the availability of inorganic P by more than twofold. Our study suggest that, while decomposition processes in ombrotrophic bogs occur very slowly, rapid changes in the form and availability of phosphorus in vegetation and litter may occur as the result of forest fires on peat soils. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Effects of Wildfire on Mortality and Resources for an Arboreal Marsupial: Resilience to Fire Events but Susceptibility to Fire Regime Change

PubMed Central

Banks, Sam C.; Knight, Emma J.; McBurney, Lachlan; Blair, David; Lindenmayer, David B.

2011-01-01

Background Big environmental disturbances have big ecological effects, yet these are not always what we might expect. Understanding the proximate effects of major disturbances, such as severe wildfires, on individuals, populations and habitats will be essential for understanding how predicted future increases in the frequency of such disturbances will affect ecosystems. However, researchers rarely have access to data from immediately before and after such events. Here we report on the effects of a severe and extensive forest wildfire on mortality, reproductive output and availability of key shelter resources for an arboreal marsupial. We also investigated the behavioural response of individuals to changed shelter resource availability in the post-fire environment. Methodology/Principal Findings We fitted proximity-logging radiotransmitters to mountain brushtail possums (Trichosurus cunninghami) before, during and after the 2009 wildfires in Victoria, Australia. Surprisingly, we detected no mortality associated with the fire, and despite a significant post-fire decrease in the proportion of females carrying pouch young in the burnt area, there was no short-term post-fire population decline. The major consequence of this fire for mountain brushtail possums was the loss of over 80% of hollow-bearing trees. The types of trees preferred as shelter sites (highly decayed dead standing trees) were those most likely to collapse after fire. Individuals adapted to resource decline by being more flexible in resource selection after the fire, but not by increased resource sharing. Conclusions/Significance Despite short-term demographic resilience and behavioural adaptation following this fire, the major loss of decayed hollow trees suggests the increased frequency of stand-replacing wildfires predicted under climate change will pose major challenges for shelter resource availability for hollow-dependent fauna. Hollow-bearing trees are typically biological legacies of previous forest generations in post-fire regrowth forests but will cease to be recruited to future regrowth forests if the interval between severe fires becomes too rapid for hollow formation. PMID:21826221

Simulated Net Ecosystem Carbon Balance of Western US Forests Under Contemporary Climate and Management

NASA Astrophysics Data System (ADS)

Yang, Z.; Law, B. E.; Jones, M. O.

2015-12-01

Previous projections of the contemporary forest carbon balance in the western US showed uncertainties associated with impacts of climate extremes and a coarse spatio-temporal resolution implemented over heterogeneous mountain regions. We modified the Community Land Model (CLM) 4.5 to produce 4km resolution forest carbon changes with drought, fire and management in the western US. We parameterized the model with species data using local plant trait observations for 30 species. To quantify uncertainty, we evaluated the model with data from flux sites, inventories and ancillary data in the region. Simulated GPP was lower than the measurements at our AmeriFlux sites by 17-22%. Simulated burned area was generally higher than Landsat observations, suggesting the model overestimates fire emissions with the new fire model. Landsat MTBS data show high severity fire represents only a small portion of the total burnt area (12-14%), and no increasing trend from 1984 to 2011. Moderate severity fire increased ~0.23%/year due to fires in the Sierra Nevada (Law & Waring 2014). Oregon, California, and Washington were a net carbon sink, and net ecosystem carbon balance (NECB) declined in California over the past 15 years, partly due to drought impacts. Fire emissions were a small portion of the regional carbon budget compared with the effect of harvest removals. Fossil fuel emissions in CA are more than 3x that of OR and WA combined, but are lower per capita. We also identified forest regions that are most vulnerable to climate-driven transformations and to evaluate the effects of management strategies on forest NECB. Differences in forest NECB among states are strongly influenced by the extent of drought (drier longer in the SW) and management intensity (higher in the PNW).

Quantifying the Carbon Balance of Forest Restoration and Wildfire under Projected Climate in the Fire-Prone Southwestern US.

PubMed

Hurteau, Matthew D

2017-01-01

Climate projections for the southwestern US suggest a warmer, drier future and have the potential to impact forest carbon (C) sequestration and post-fire C recovery. Restoring forest structure and surface fire regimes initially decreases total ecosystem carbon (TEC), but can stabilize the remaining C by moderating wildfire behavior. Previous research has demonstrated that fire maintained forests can store more C over time than fire suppressed forests in the presence of wildfire. However, because the climate future is uncertain, I sought to determine the efficacy of forest management to moderate fire behavior and its effect on forest C dynamics under current and projected climate. I used the LANDIS-II model to simulate carbon dynamics under early (2010-2019), mid (2050-2059), and late (2090-2099) century climate projections for a ponderosa pine (Pinus ponderosa) dominated landscape in northern Arizona. I ran 100-year simulations with two different treatments (control, thin and burn) and a 1 in 50 chance of wildfire occurring. I found that control TEC had a consistent decline throughout the simulation period, regardless of climate. Thin and burn TEC increased following treatment implementation and showed more differentiation than the control in response to climate, with late-century climate having the lowest TEC. Treatment efficacy, as measured by mean fire severity, was not impacted by climate. Fire effects were evident in the cumulative net ecosystem exchange (NEE) for the different treatments. Over the simulation period, 32.8-48.9% of the control landscape was either C neutral or a C source to the atmosphere and greater than 90% of the thin and burn landscape was a moderate C sink. These results suggest that in southwestern ponderosa pine, restoring forest structure and surface fire regimes provides a reasonable hedge against the uncertainty of future climate change for maintaining the forest C sink.

Quantifying the Carbon Balance of Forest Restoration and Wildfire under Projected Climate in the Fire-Prone Southwestern US

PubMed Central

2017-01-01

Climate projections for the southwestern US suggest a warmer, drier future and have the potential to impact forest carbon (C) sequestration and post-fire C recovery. Restoring forest structure and surface fire regimes initially decreases total ecosystem carbon (TEC), but can stabilize the remaining C by moderating wildfire behavior. Previous research has demonstrated that fire maintained forests can store more C over time than fire suppressed forests in the presence of wildfire. However, because the climate future is uncertain, I sought to determine the efficacy of forest management to moderate fire behavior and its effect on forest C dynamics under current and projected climate. I used the LANDIS-II model to simulate carbon dynamics under early (2010–2019), mid (2050–2059), and late (2090–2099) century climate projections for a ponderosa pine (Pinus ponderosa) dominated landscape in northern Arizona. I ran 100-year simulations with two different treatments (control, thin and burn) and a 1 in 50 chance of wildfire occurring. I found that control TEC had a consistent decline throughout the simulation period, regardless of climate. Thin and burn TEC increased following treatment implementation and showed more differentiation than the control in response to climate, with late-century climate having the lowest TEC. Treatment efficacy, as measured by mean fire severity, was not impacted by climate. Fire effects were evident in the cumulative net ecosystem exchange (NEE) for the different treatments. Over the simulation period, 32.8–48.9% of the control landscape was either C neutral or a C source to the atmosphere and greater than 90% of the thin and burn landscape was a moderate C sink. These results suggest that in southwestern ponderosa pine, restoring forest structure and surface fire regimes provides a reasonable hedge against the uncertainty of future climate change for maintaining the forest C sink. PMID:28046079

Fire severity alters the distribution of pyrogenic carbon stocks across ecosystem pools in a Californian mixed-conifer forest

NASA Astrophysics Data System (ADS)

Maestrini, Bernardo; Alvey, Erin C.; Hurteau, Matthew D.; Safford, Hugh; Miesel, Jessica R.

2017-09-01

Pyrogenic carbon (PyC) is hypothesized to play an important role in the carbon (C) cycle due to its resistance to decomposition; however, much uncertainty still exists regarding the stocks of PyC that persist on-site after the initial erosion in postfire forests. Therefore, understanding how fire characteristics influence PyC stocks is vital, particularly in the context of California forests for which an increase of high-severity fires is predicted over the next decades. We measured forest C and persistent PyC stocks in areas burned by low-to-moderate and high-severity fire, as well as in adjacent unburned areas in a California mixed-conifer forest, 2 to 3 years after wildfire. We measured C and PyC stocks in the following compartments: standing trees, downed wood, forest floor, and mineral soil (0-5 cm), and we identified PyC using the weak nitric acid digestion method. We found that the total stock of PyC did not differ among fire severity classes (overall mean 248 ± 30 g C m-2); however, fire severity influenced the distribution of PyC in the individual compartments. Areas burned by high-severity fire had 2.5 times more PyC stocked in the coarse woody debris (p < 0.05), 3.3 times more PyC stocked in standing trees (p < 0.05), and a lower PyC stock in the forest floor (-22%, p < 0.05) compared to low-to-moderate fire severity areas. These results have important implications for the permanence time of PyC, which is putatively higher in standing trees and coarse woody debris compared to the forest floor, where it is susceptible to rapid losses through erosion.

An approach to the real time risk evaluation system of boreal forest fire

NASA Astrophysics Data System (ADS)

Nakau, K.; Fukuda, M.; Kimura, K.; Hayasaka, H.; Tani, H.; Kushida, K.

2005-12-01

Huge boreal forest fire may cause massive impacts not only on global warming gas emission but also local communities. Thus, it is important to control forest fire. We collected data about boreal forest fire as satellite imagery and fire observation simultaneously in Alaska and east Siberia in summer fire seasons for these three years. Fire observation data was collected from aircraft flying between Japan and Europe. Fire detection results were compared with observed data to evaluate the accuracy and earliness of automatic detection. NOAA and MODIS satellite images covering Alaska and East Siberia are collected. We are also developing fire expansion simulation model to forecast the possible fire expansion area. On the basis of fire expansion forecast, risk analysis of possible fire expansion for decision aid of fire-fighting activities will be analyzed. To identify the risk of boreal forest fire and public concern about forest fire, we collected local news paper in Fairbanks, AK and discuss the statistics of articles related to forest fire on the newspaper.

Integrating remotely sensed fires for predicting deforestation for REDD.

PubMed

Armenteras, Dolors; Gibbes, Cerian; Anaya, Jesús A; Dávalos, Liliana M

2017-06-01

Fire is an important tool in tropical forest management, as it alters forest composition, structure, and the carbon budget. The United Nations program on Reducing Emissions from Deforestation and Forest Degradation (REDD+) aims to sustainably manage forests, as well as to conserve and enhance their carbon stocks. Despite the crucial role of fire management, decision-making on REDD+ interventions fails to systematically include fires. Here, we address this critical knowledge gap in two ways. First, we review REDD+ projects and programs to assess the inclusion of fires in monitoring, reporting, and verification (MRV) systems. Second, we model the relationship between fire and forest for a pilot site in Colombia using near-real-time (NRT) fire monitoring data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The literature review revealed fire remains to be incorporated as a key component of MRV systems. Spatially explicit modeling of land use change showed the probability of deforestation declined sharply with increasing distance to the nearest fire the preceding year (multi-year model area under the curve [AUC] 0.82). Deforestation predictions based on the model performed better than the official REDD early-warning system. The model AUC for 2013 and 2014 was 0.81, compared to 0.52 for the early-warning system in 2013 and 0.68 in 2014. This demonstrates NRT fire monitoring is a powerful tool to predict sites of forest deforestation. Applying new, publicly available, and open-access NRT fire data should be an essential element of early-warning systems to detect and prevent deforestation. Our results provide tools for improving both the current MRV systems, and the deforestation early-warning system in Colombia. © 2017 by the Ecological Society of America.

Spatial patterns of large natural fires in Sierra Nevada wilderness areas

USGS Publications Warehouse

Collins, B.M.; Kelly, M.; van Wagtendonk, J.W.; Stephens, S.L.

2007-01-01

The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels. ?? 2007 Springer Science+Business Media, Inc.

The pollen record of a 20th century spruce beetle (Dendroctonus rufipennis) outbreak in a Colorado subalpine forest, USA

Treesearch

R. Scott Anderson; Susan J. Smith; Ann M. Lynch; Brian W. Geils

2010-01-01

The frequency and intensity of ecosystem disturbance, including outbreaks of forest insects and forest fires, is expected to increase in the future as a result of higher temperatures and prolonged drought. While many studies have concentrated on the future climatic impacts on fire, little is known about the impact of future climate on insect infestation....

Predicting post-fire hillslope erosion in forest lands of the western United States

Treesearch

Mary Ellen Miller; Lee H. MacDonald; Peter R. Robichaud; William J. Elliot

2011-01-01

Many forests and their associated water resources are at increasing risk from large and severe wildfires due to high fuel accumulations and climate change. Extensive fuel treatments are being proposed, but it is not clear where such treatments should be focussed. The goals of this project were to: (1) predict potential post-fire erosion rates for forests and shrublands...

Effects of prescribed fire on nutrient pools and losses from glades occurring within oak-hickory forests of central Kentucky

Treesearch

T. L. E. Trammell; Charles Rhoades; P. A. Bukaveckas

2004-01-01

Forest openings, also known as glades, arise through a variety of mechanisms including disturbance (fire and blow downs) and local variation in soil or bedrock geology. They are common in many forest types and are often dominated by locally rare herbaceous species. Prescribed burning is increasingly used as a management approach for maintaining glades although...

Fuel treatments and landform modify landscape patterns of burn severity in an extreme fire event

Treesearch

Susan J. Prichard; Maureen C. Kennedy

2014-01-01

Under a rapidly warming climate, a critical management issue in semiarid forests of western North America is how to increase forest resilience to wildfire. We evaluated relationships between fuel reduction treatments and burn severity in the 2006 Tripod Complex fires, which burned over 70 000 ha of mixed-conifer forests in the North Cascades range of Washington State...

Changes of forest cover and disturbance regimes in the mountain forests of the Alps☆

PubMed Central

Bebi, P.; Seidl, R.; Motta, R.; Fuhr, M.; Firm, D.; Krumm, F.; Conedera, M.; Ginzler, C.; Wohlgemuth, T.; Kulakowski, D.

2017-01-01

Natural disturbances, such as avalanches, snow breakage, insect outbreaks, windthrow or fires shape mountain forests globally. However, in many regions over the past centuries human activities have strongly influenced forest dynamics, especially following natural disturbances, thus limiting our understanding of natural ecological processes, particularly in densely-settled regions. In this contribution we briefly review the current understanding of changes in forest cover, forest structure, and disturbance regimes in the mountain forests across the European Alps over the past millennia. We also quantify changes in forest cover across the entire Alps based on inventory data over the past century. Finally, using the Swiss Alps as an example, we analyze in-depth changes in forest cover and forest structure and their effect on patterns of fire and wind disturbances, based on digital historic maps from 1880, modern forest cover maps, inventory data on current forest structure, topographical data, and spatially explicit data on disturbances. This multifaceted approach presents a long-term and detailed picture of the dynamics of mountain forest ecosystems in the Alps. During pre-industrial times, natural disturbances were reduced by fire suppression and land-use, which included extraction of large amounts of biomass that decreased total forest cover. More recently, forest cover has increased again across the entire Alps (on average +4% per decade over the past 25–115 years). Live tree volume (+10% per decade) and dead tree volume (mean +59% per decade) have increased over the last 15–40 years in all regions for which data were available. In the Swiss Alps secondary forests that established after 1880 constitute approximately 43% of the forest cover. Compared to forests established previously, post-1880 forests are situated primarily on steep slopes (>30°), have lower biomass, a more aggregated forest structure (primarily stem-exclusion stage), and have been more strongly affected by fires, but less affected by wind disturbance in the 20th century. More broadly, an increase in growing stock and expanding forest areas since the mid-19th century have - along with climatic changes - contributed to an increasing frequency and size of disturbances in the Alps. Although many areas remain intensively managed, the extent, structure, and dynamics of the forests of the Alps reflect natural drivers more strongly today than at any time in the past millennium. PMID:28860675

Changes of forest cover and disturbance regimes in the mountain forests of the Alps.

PubMed

Bebi, P; Seidl, R; Motta, R; Fuhr, M; Firm, D; Krumm, F; Conedera, M; Ginzler, C; Wohlgemuth, T; Kulakowski, D

2017-03-15

Natural disturbances, such as avalanches, snow breakage, insect outbreaks, windthrow or fires shape mountain forests globally. However, in many regions over the past centuries human activities have strongly influenced forest dynamics, especially following natural disturbances, thus limiting our understanding of natural ecological processes, particularly in densely-settled regions. In this contribution we briefly review the current understanding of changes in forest cover, forest structure, and disturbance regimes in the mountain forests across the European Alps over the past millennia. We also quantify changes in forest cover across the entire Alps based on inventory data over the past century. Finally, using the Swiss Alps as an example, we analyze in-depth changes in forest cover and forest structure and their effect on patterns of fire and wind disturbances, based on digital historic maps from 1880, modern forest cover maps, inventory data on current forest structure, topographical data, and spatially explicit data on disturbances. This multifaceted approach presents a long-term and detailed picture of the dynamics of mountain forest ecosystems in the Alps. During pre-industrial times, natural disturbances were reduced by fire suppression and land-use, which included extraction of large amounts of biomass that decreased total forest cover. More recently, forest cover has increased again across the entire Alps (on average +4% per decade over the past 25-115 years). Live tree volume (+10% per decade) and dead tree volume (mean +59% per decade) have increased over the last 15-40 years in all regions for which data were available. In the Swiss Alps secondary forests that established after 1880 constitute approximately 43% of the forest cover. Compared to forests established previously, post-1880 forests are situated primarily on steep slopes (>30°), have lower biomass, a more aggregated forest structure (primarily stem-exclusion stage), and have been more strongly affected by fires, but less affected by wind disturbance in the 20th century. More broadly, an increase in growing stock and expanding forest areas since the mid-19th century have - along with climatic changes - contributed to an increasing frequency and size of disturbances in the Alps. Although many areas remain intensively managed, the extent, structure, and dynamics of the forests of the Alps reflect natural drivers more strongly today than at any time in the past millennium.

Comparing effects of climate warming, fire, and timber harvesting on a boreal forest landscape in northeastern China.

PubMed

Li, Xiaona; He, Hong S; Wu, Zhiwei; Liang, Yu; Schneiderman, Jeffrey E

2013-01-01

Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1-40 years), early stage (41-80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest.

Interactions of forest disturbance-recovery dynamics with a changing climate

NASA Astrophysics Data System (ADS)

Anderson-Teixeira, K. J.; Miller, A. D.; Tepley, A. J.; Bennett, A. C.; Wang, M.

2015-12-01

As the climate changes, altered disturbance-recovery dynamics in forests worldwide are likely to result in significant biogeochemical and biophysical feedbacks to the climate system. Climate shapes forest disturbance events including tree mortality and fire, with consequent climate feedbacks. For instance, in forests globally, drought increases tree mortality rates, having a stronger impact on larger trees and resulting in greater feedbacks to climate change than would occur if drought sensitivities were equal across tree size classes. Forest regeneration and associated biogeochemical and biophysical feedbacks are also shaped by climate: across the tropics the rate of biomass accumulation is faster in everwet than in seasonally dry climates, and in the Klamath region (N California / S Oregon), post-fire vegetation dynamics and microclimate are shaped by aridity. Forest recovery dynamics will be affected by elevated CO2 and climate change; for instance, models predict that forest regeneration rate, successional dynamics, and climate feedbacks will all be altered under elevated CO2. In combination, climatic impacts on disturbance and recovery can result in dramatic shifts in forest cover on the landscape level. For instance, in fire-prone forested landscapes, forest cover decreases with increasing frequency of high-severity fire and decreasing forest recovery rate, both of which could be altered by climate change, producing rapid loss of forest on the landscape level. Such effects may be amplified by the existence of alternative stable states, which can cause systems to experience non-reversible changes in cover type. Critical transitions in landscape-level forest cover would have significant biogeochemical and biophysical feedbacks. Thus, altered disturbance-recovery dynamics under a changing climate may have sudden and dramatic impacts on forest-climate interactions.

Forest structure and downed woody debris in boreal temperate, and tropical forest fragments

Treesearch

William A. Gould; Grizelle Gonzalez; Andrew T. Hudak; Teresa Nettleton Hollingsworth; Jamie Hollingsworth

2008-01-01

Forest fragmentation affects the heterogeneity of accumulated fuels by increasing the diversity of forest types and by increasing forest edges. This heterogeneity has implications in how we manage fuels, fire, and forests. Understanding the relative importance of fragmentation on woody biomass within a single climatic regime, and along climatic gradients, will improve...

Contribution of forest fires to concentrations of particulate matter in Singapore

NASA Astrophysics Data System (ADS)

Spracklen, D. V.; Reddington, C.; Yoshioka, M.; Arnold, S.; Balasubramanian, R.

2013-12-01

Singapore is regularly exposed to substantial levels of transboundary air pollution arising from uncontrolled forest and peat fires from specific regions within Southeast Asia. This air pollution has detrimental impacts on the lives of Singapore residents and on sensitive ecosystems. In June 2013, forest fires resulted in concentrations of particulate matter greatly exceeding levels recommended for human health, causing substantial public concern. We apply two different methods to quantify the impact of forest fires on the concentrations of particulate matter with diameter less than 2.5 micrometres (PM2.5) in Singapore. Firstly, we use a global aerosol model (GLOMAP) in combination with fire emissions from GFED3 to simulate PM2.5 concentrations over the period 1998-2009. We evaluate simulated PM2.5 concentrations against long-term observations from Singapore. To identify the contributions of fires from different source regions to PM2.5 concentrations we run multiple simulations with and without fire emissions from specific regions across Southeast Asia. Secondly, we apply an atmospheric back trajectory model in combination with the GFED3 fire emissions to calculate exposure of air masses arriving in Singapore to fire emissions. Both methods use meteorology from the European Centre for Medium Range Weather Forecasts and are consistent with the large-scale atmospheric flow from the assimilated observations. We find that both methods give consistent results, with forest fires increasing PM2.5 concentrations in Singapore predominately during April to October. Forest and peat fires in Sumatra and Kalimantan cause the greatest degradation of air quality in Singapore. The contribution of fires to PM2.5 concentrations in Singapore exhibits strong interannual variability. During years with a strong contribution from fires, our simulations show that the prevention of fires in southern Sumatra would reduce regional PM2.5 concentrations around Singapore by more than a factor of two, potentially allowing Singapore to meet World Health Organisation guidelines for annual mean concentrations of PM2.5. Acting to reduce forest and peat fires in southern Sumatra, in particular provinces of Lampung, South Sumatra and Jambi, and southern Kalimantan would likely have the greatest environmental benefits to Singapore and surrounding regions.

Impacts of prescribed fire on Pinus rigida Mill. in upland forests of the Atlantic Coastal Plain.

PubMed

Carlo, Nicholas J; Renninger, Heidi J; Clark, Kenneth L; Schäfer, Karina V R

2016-08-01

A comparative analysis of the impacts of prescribed fire on three upland forest stands in the Northeastern Atlantic Plain, NJ, USA, was conducted. Effects of prescribed fire on water use and gas exchange of overstory pines were estimated via sap-flux rates and photosynthetic measurements on Pinus rigida Mill. Each study site had two sap-flux plots, one experiencing prescribed fire and one control (unburned) plot for comparison before and after the fire. We found that photosynthetic capacity in terms of Rubisco-limited carboxylation rate and intrinsic water-use efficiency was unaffected, while light compensation point and dark respiration rate were significantly lower in the burned vs control plots post-fire. Furthermore, quantum yield in pines in the pine-dominated stands was less affected than pines in the mixed oak/pine stand, as there was an increase in quantum yield in the oak/pine stand post-fire compared with the control (unburned) plot. We attribute this to an effect of forest type but not fire per se. Average daily sap-flux rates of the pine trees increased compared with control (unburned) plots in pine-dominated stands and decreased in the oak/pine stand compared with control (unburned) plots, potentially due to differences in fuel consumption and pre-fire sap-flux rates. Finally, when reference canopy stomatal conductance was analyzed, pines in the pine-dominated stands were more sensitive to changes in vapor pressure deficit (VPD), while stomatal responses of pines in the oak/pine stand were less affected by VPD. Therefore, prescribed fire affects physiological functioning and water use of pines, but the effects may be modulated by forest stand type and fuel consumption pattern, which suggests that these factors may need to be taken into account for forest management in fire-dominated systems. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Prioritizing forest fuels treatments based on the probability of high-severity fire restores adaptive capacity in Sierran forests.

PubMed

Krofcheck, Daniel J; Hurteau, Matthew D; Scheller, Robert M; Loudermilk, E Louise

2018-02-01

In frequent fire forests of the western United States, a legacy of fire suppression coupled with increases in fire weather severity have altered fire regimes and vegetation dynamics. When coupled with projected climate change, these conditions have the potential to lead to vegetation type change and altered carbon (C) dynamics. In the Sierra Nevada, fuels reduction approaches that include mechanical thinning followed by regular prescribed fire are one approach to restore the ability of the ecosystem to tolerate episodic fire and still sequester C. Yet, the spatial extent of the area requiring treatment makes widespread treatment implementation unlikely. We sought to determine if a priori knowledge of where uncharacteristic wildfire is most probable could be used to optimize the placement of fuels treatments in a Sierra Nevada watershed. We developed two treatment placement strategies: the naive strategy, based on treating all operationally available area and the optimized strategy, which only treated areas where crown-killing fires were most probable. We ran forecast simulations using projected climate data through 2,100 to determine how the treatments differed in terms of C sequestration, fire severity, and C emissions relative to a no-management scenario. We found that in both the short (20 years) and long (100 years) term, both management scenarios increased C stability, reduced burn severity, and consequently emitted less C as a result of wildfires than no-management. Across all metrics, both scenarios performed the same, but the optimized treatment required significantly less C removal (naive=0.42 Tg C, optimized=0.25 Tg C) to achieve the same treatment efficacy. Given the extent of western forests in need of fire restoration, efficiently allocating treatments is a critical task if we are going to restore adaptive capacity in frequent-fire forests. © 2017 John Wiley & Sons Ltd.

Did the summer 2003 forest fires in Portugal affect air quality over Europe?

NASA Astrophysics Data System (ADS)

Miranda, A. I.; Martins, V.; Sá, E.; Carvalho, A.; Amorim, J. H.; Borrego, C.

2009-04-01

A forest fire is a large-scale natural combustion process consuming various types, sizes and ages of botanical specimen growing outdoors in a defined geographical area. Although wildland fires are an integral part of ecosystems management and are essential to maintain functional ecosystems their dimensions can give rise to disastrous results. Due to the frequency of occurrence and the magnitude of effects on the environment, health, economy and security, forest fires have increasingly become a major subject of concern for decision-makers, firefighters, researchers and citizens in general. Among their consequences, is the emission of various environmentally significant gases and solid particulate matter to the atmosphere that interfere with local, regional and global phenomena in the biosphere. Smoke from forest fires contains important amounts of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), nitrogen oxides (NOx), ammonia (NH3), particulate matter (PM) (that is usually referred in terms of particles with a mean diameter less than 2.5 μm, or PM2.5, and particles with a mean diameter less than 10 μm, or PM10), non-methane hydrocarbons (NMHC) and other chemical compounds. These air pollutants can cause serious consequences to local and regional air quality by reducing visibility, contributing to smog and impairing air quality in general, thus threatening human health and ecosystems. Pollutants emitted from forest fires are transported, chemically transformed, and dispersed in the atmosphere. Although major wildfires are limited to some hundreds of hectares, their impacts, with no natural or political boundaries, can be felt and reported far beyond the physical limits of the fire spread. Depending on meteorological conditions, smoke plumes and haze layers can persist in the atmosphere for long periods of time and prevailing conditions will influence the chemical and optical characteristics of the plume. The extreme fire events occurred in the summer of 2003 in Portugal highlighted the need to better analyze the link between forest fires and air quality. Portugal faced in 2003, the worst fire season ever recorded and this is clearly reflected in the values measured by the air quality-monitoring networks. There were 4,645 fires burning 8.6% of the total Portuguese forest area. The main purpose of this paper is to evaluate the contribution of summer 2003 Portuguese fires to air quality impairment in Europe. Portuguese forest fire emissions, namely CO2, CO, CH4, PM10, PM2.5, NMHC, NOx, SO2 and NH3, were estimated throughout the summer of 2003, based on specific southern European emissions factors, on type of vegetation and area burned. LOTOS-EUROS, which is an operational 3D chemistry transport model aimed to simulate air pollution in the lower troposphere, was specifically adapted to simulate forest fire emissions. The modelling system was applied first at a continental scale (with 0.5° x 0.25°, approximately 35 km x 25 km) and then to mainland Portugal domain, using the same physics and a simple one-way nesting technique, with 17.5 km x 12.5 km horizontal resolution. The simulation period covered the entire summer, aiming to estimate hourly concentration values of gaseous and particulate pollutants levels in the air. A baseline simulation (BS) was carried out, only including the "conventional" anthropogenic and biogenic emissions, and a forest fire simulation (FS), which also considered emissions from large forest fires (area burned higher than 100 ha). Hence, forest fire emissions values were added to the anthropogenic and biogenic grid emissions, according to the fire location and assuming a uniform fire spread and a constant injection altitude in the dynamic mixing layer. The modelling system indicates a severe degradation of particulate matter and ozone (O3) concentrations due to forest fires, not only in Portugal, but also in United Kingdom, France and Spain. Modelling results were compared to background monitoring data from the European Air quality dataBase (AIRBASE). A statistical analysis was performed to evaluate the simulations results, using some statistical parameters such as the root mean square error (RMSE), the systematic error (BIAS) and the Pearson correlation coefficient (r). The model performance increased substantially when forest fire emissions were included.

A High-Resolution Chronology of Rapid Forest Transitions following Polynesian Arrival in New Zealand

PubMed Central

McWethy, David B.; Wilmshurst, Janet M.; Whitlock, Cathy; Wood, Jamie R.; McGlone, Matt S.

2014-01-01

Human-caused forest transitions are documented worldwide, especially during periods when land use by dense agriculturally-based populations intensified. However, the rate at which prehistoric human activities led to permanent deforestation is poorly resolved. In the South Island, New Zealand, the arrival of Polynesians c. 750 years ago resulted in dramatic forest loss and conversion of nearly half of native forests to open vegetation. This transformation, termed the Initial Burning Period, is documented in pollen and charcoal records, but its speed has been poorly constrained. High-resolution chronologies developed with a series of AMS radiocarbon dates from two lake sediment cores suggest the shift from forest to shrubland occurred within decades rather than centuries at drier sites. We examine two sites representing extreme examples of the magnitude of human impacts: a drier site that was inherently more vulnerable to human-set fires and a wetter, less burnable site. The astonishing rate of deforestation at the hands of small transient populations resulted from the intrinsic vulnerability of the native flora to fire and from positive feedbacks in post-fire vegetation recovery that increased landscape flammability. Spatially targeting burning in highly-flammable seral vegetation in forests rarely experiencing fire was sufficient to create an alternate fire-prone stable state. The New Zealand example illustrates how seemingly stable forest ecosystems can experience rapid and permanent conversions. Forest loss in New Zealand is among the fastest ecological transitions documented in the Holocene; yet equally rapid transitions can be expected in present-day regions wherever positive feedbacks support alternate fire-inhibiting, fire-prone stable states. PMID:25372150

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

Zarnoch, Stanley J.; Blake, John I.; Parresol, Bernard R.

Snags are standing dead trees that are an important component in the nesting habitat of birds and other species. Although snag availability is believed to limit populations in managed and non-managed forests, little data are available to evaluate the relative effect of stand conditions and management on snag occurrence. We analyzed point sample data from an intensive forest inventory within an 80,000 ha landscape for four major forest types to support the hypotheses that routine low-intensity prescribed fire would increase, and thinning would decrease, snag occurrence. We employed path analysis to define a priori causal relationships to determine the directmore » and indirect effects of site quality, age, relative stand density index and fire for all forest types and thinning effects for loblolly pine and longleaf pine. Stand age was an important direct effect for loblolly pine, mixed pine-hardwoods and hardwoods, but not for longleaf pine. Snag occurrence in loblolly pine was increased by prescribed fire and decreased by thinning which confirmed our initial hypotheses. Although fire was not important in mixed pine-hardwoods, it was for hardwoods but the relationship depended on site quality. For longleaf pine the relative stand density index was the dominant variable affecting snag occurrence, which increased as the density index decreased. Site quality, age and thinning had significant indirect effects on snag occurrence in longleaf pine through their effects on the density index. Although age is an important condition affecting snag occurrence for most forest types, path analysis revealed that fire and density management practices within certain forest types can also have major beneficial effects, particularly in stands less than 60 years old.« less

The pyrogeography of eastern boreal Canada from 1901 to 2012 simulated with the LPJ-LMfire model

NASA Astrophysics Data System (ADS)

Chaste, Emeline; Girardin, Martin P.; Kaplan, Jed O.; Portier, Jeanne; Bergeron, Yves; Hély, Christelle

2018-03-01

Wildland fires are the main natural disturbance shaping forest structure and composition in eastern boreal Canada. On average, more than 700 000 ha of forest burns annually and causes as much as CAD 2.9 million worth of damage. Although we know that occurrence of fires depends upon the coincidence of favourable conditions for fire ignition, propagation, and fuel availability, the interplay between these three drivers in shaping spatiotemporal patterns of fires in eastern Canada remains to be evaluated. The goal of this study was to reconstruct the spatiotemporal patterns of fire activity during the last century in eastern Canada's boreal forest as a function of changes in lightning ignition, climate, and vegetation. We addressed this objective using the dynamic global vegetation model LPJ-LMfire, which we parametrized for four plant functional types (PFTs) that correspond to the prevalent tree genera in eastern boreal Canada (Picea, Abies, Pinus, Populus). LPJ-LMfire was run with a monthly time step from 1901 to 2012 on a 10 km2 resolution grid covering the boreal forest from Manitoba to Newfoundland. Outputs of LPJ-LMfire were analyzed in terms of fire frequency, net primary productivity (NPP), and aboveground biomass. The predictive skills of LPJ-LMfire were examined by comparing our simulations of annual burn rates and biomass with independent data sets. The simulation adequately reproduced the latitudinal gradient in fire frequency in Manitoba and the longitudinal gradient from Manitoba towards southern Ontario, as well as the temporal patterns present in independent fire histories. However, the simulation led to the underestimation and overestimation of fire frequency at both the northern and southern limits of the boreal forest in Québec. The general pattern of simulated total tree biomass also agreed well with observations, with the notable exception of overestimated biomass at the northern treeline, mainly for PFT Picea. In these northern areas, the predictive ability of LPJ-LMfire is likely being affected by the low density of weather stations, which leads to underestimation of the strength of fire-weather interactions and, therefore, vegetation consumption during extreme fire years. Agreement between the spatiotemporal patterns of fire frequency and the observed data across a vast portion of the study area confirmed that fire therein is strongly ignition limited. A drier climate coupled with an increase in lightning frequency during the second half of the 20th century notably led to an increase in fire activity. Finally, our simulations highlighted the importance of both climate and fire in vegetation: despite an overarching CO2-induced enhancement of NPP in LPJ-LMfire, forest biomass was relatively stable because of the compensatory effects of increasing fire activity.

Israel wildfires: future trends, impacts and mitigation strategies

NASA Astrophysics Data System (ADS)

Wittenberg, Lea

2017-04-01

Forest fires in the Euro-Mediterranean region burn about 450,000 ha each year. In Israel, the frequency and extent of wildfires have been steadily increasing over the past decades, culminating in several large and costly fires in 2010, 2012 and 2016. The extensive development of forest areas since the 1950's and the accumulation of fuel in the forests, has led to increased occurrences of high intensity fires. Land-use changes and human population growth are the most prevailing and common determinant of wildfire occurrence and impacts. Climate extremes, possibly already a sign of regional climate change, are another frequent determinant of increasing wildfire risk. Therefore, the combination of extreme dry spells, high fuel loads and increased anthropogenic pressure on the open spaces result in an overall amplified wildfire risk. These fires not only cause loss of life and damage to properties but also carry serious environmental repercussions. Combustion of standing vegetation and the leaf litter leave the soil bare and vulnerable to runoff and erosion, thereby increasing risks of flooding. Today, all of Israel's open spaces, forests, natural parks, major metropolitan centers, towns and villages are embedded within the wildland urban interface (WUI). Typically, wildfires near or in the WUI occur on uplands and runoff generated from the burned area poses flooding risks in urban and agricultural zones located downstream. Post-fire management aims at reducing associated hazards as collapsing trees and erosion risk. Often the time interval between a major fire and the definition of priority sites is in the order of days-to-weeks since administrative procedures, financial estimates and implementation of post-fire salvage logging operations require time. Defining the magnitude of the burn scar and estimating its potential impact on runoff and erosion must therefore be done quickly. A post-fire burn severity, runoff and erosion model is a useful tool in estimating potential risks and management strategic. Moreover, national agencies and local authorities must decide on a range of post-fire measures to mitigate risks quickly since most large fires occur late in summer shortly before the winter season. Possible climate changes, socio-economic trends, and intense land use pressures are contributing factors in a national challenge to deal with forest fires along the WUI. However, in order to support integrated fire preparedness, response, management and recovery at the national, regional and local scales, stronger research and planning effort are required. This includes long-term monitoring programs and a systematic, standardized data acquisition scheme, compiling fire history, landscape-fire spread, mitigation and assessment of the immediate fire effects, land use changes and weather data. Knowledge of both short and long-term impacts of wildfire is essential for effective risk assessment, policy formulation and wildfire management.

The biodiversity cost of carbon sequestration in tropical savanna.

PubMed

Abreu, Rodolfo C R; Hoffmann, William A; Vasconcelos, Heraldo L; Pilon, Natashi A; Rossatto, Davi R; Durigan, Giselda

2017-08-01

Tropical savannas have been increasingly viewed as an opportunity for carbon sequestration through fire suppression and afforestation, but insufficient attention has been given to the consequences for biodiversity. To evaluate the biodiversity costs of increasing carbon sequestration, we quantified changes in ecosystem carbon stocks and the associated changes in communities of plants and ants resulting from fire suppression in savannas of the Brazilian Cerrado, a global biodiversity hotspot. Fire suppression resulted in increased carbon stocks of 1.2 Mg ha -1 year -1 since 1986 but was associated with acute species loss. In sites fully encroached by forest, plant species richness declined by 27%, and ant richness declined by 35%. Richness of savanna specialists, the species most at risk of local extinction due to forest encroachment, declined by 67% for plants and 86% for ants. This loss highlights the important role of fire in maintaining biodiversity in tropical savannas, a role that is not reflected in current policies of fire suppression throughout the Brazilian Cerrado. In tropical grasslands and savannas throughout the tropics, carbon mitigation programs that promote forest cover cannot be assumed to provide net benefits for conservation.

A framework for developing safe and effective large-fire response in a new fire management paradigm

Treesearch

Christopher J. Dunn; Matthew P. Thompson; David E. Calkin

2017-01-01

The impacts of wildfires have increased in recent decades because of historical forest and fire management, a rapidly changing climate, and an increasingly populated wildland urban interface. This increasingly complex fire environment highlights the importance of developing robust tools to support risk-informed decision making. While tools have been developed to aid...

Fire management and woody invasive plants in oak ecosystems

Treesearch

Joanne. Rebbeck

2012-01-01

The use of prescribed fire to sustain oak forests has increased rapidly in the last decade as the threat of poor regeneration and increased dominance of shade tolerant or fire sensitive tree species grows. While prescribed fire can favor oak regeneration, it may also increase the invasion and expansion of nonnative invasive plant species (NNIS). Little is known about...

Estimating forest species composition using a multi-sensor approach

Treesearch

P.T. Wolter

2009-01-01

The magnitude, duration, and frequency of forest disturbance caused by the spruce budworm and forest tent caterpillar has increased over the last century due to a shift in forest species composition linked to historical fire suppression, forest management, and pesticide application that has fostered the increase in dominance of host tree species. Modeling approaches...

Post-Disturbance Plant Community Dynamics following a Rare Natural-Origin Fire in a Tsuga canadensis Forest

PubMed Central

Murray, Bryan D.; Holmes, Stacie A.; Webster, Christopher R.; Witt, Jill C.

2012-01-01

Opportunities to directly study infrequent forest disturbance events often lead to valuable information about vegetation dynamics. In mesic temperate forests of North America, stand-replacing crown fire occurs infrequently, with a return interval of 2000–3000 years. Rare chance events, however, may have profound impacts on the developmental trajectories of forest ecosystems. For example, it has been postulated that stand-replacing fire may have been an important factor in the establishment of eastern hemlock (Tsuga canadensis) stands in the northern Great Lakes region. Nevertheless, experimental evidence linking hemlock regeneration to non-anthropogenic fire is limited. To clarify this potential relationship, we monitored vegetation dynamics following a rare lightning-origin crown fire in a Wisconsin hemlock-hardwood forest. We also studied vegetation in bulldozer-created fire breaks and adjacent undisturbed forest. Our results indicate that hemlock establishment was rare in the burned area but moderately common in the scarified bulldozer lines compared to the reference area. Early-successional, non-arboreal species including Rubus spp., Vaccinium angustifolium, sedges (Carex spp.), grasses, Epilobium ciliatum, and Pteridium aquilinium were the most abundant post-fire species. Collectively, our results suggest that competing vegetation and moisture stress resulting from drought may reduce the efficacy of scarification treatments as well as the usefulness of fire for preparing a suitable seedbed for hemlock. The increasing prevalence of growing-season drought suggests that silvicultural strategies based on historic disturbance regimes may need to be reevaluated for mesic species. PMID:22928044

Fortifying the forest: Thinning and burning increase resistance to a bark beetle outbreak and promote forest resilience

Treesearch

Sharon M. Hood; Stephen Baker; Anna Sala

2016-01-01

Fire frequency in low-elevation coniferous forests in western North America has greatly declined since the late 1800s. In many areas, this has increased tree density and the proportion of shade-tolerant species, reduced resource availability, and increased forest susceptibility to forest insect pests and high-severity wildfire. In response, treatments are...

Development of a Method for Selecting Optimum Sites for the Automatic Mountain Meteorology Observation Station (AMOS) to Improve Predictability of Forest Fires in Inaccessible Area

NASA Astrophysics Data System (ADS)

Yoon, S.; Won, M.; Jang, K.; Lim, J.

2016-12-01

As there has been a recent increase in the case of forest fires in North Korea descending southward through the De-Militarized Zone (DMZ), ensuring proper response to such events has been a challenge. Therefore, in order to respond and manage these forest fires appropriately, an improvement in the forest fire predictability through integration of mountain weather information observed at the most optimal site is necessary. This study is a proactive case in which a spatial analysis and an on-site assessment method were developed for selecting an optimum site for a mountain weather observation in national forest. For spatial analysis, the class 1 and 2 forest fire danger areas for the past 10 years, accessibility maximum 100m, Automatic Weather Station (AWS) redundancy within 2.5km, and mountain terrains higher than 200m were analyzed. A final overlay analysis was performed to select the candidates for the field assessment. The sites selected through spatial analysis were quantitatively evaluated based on the optimal meteorological environment, forest and hiking trail accessibility, AWS redundancy, and supply of wireless communication and solar powered electricity. The sites with total score of 70 and higher were accepted as adequate. At the final selected sites, an AMOS was established, and integration of mountain and Korea Meteorological Administration (KMA) weather data improved the forest fire predictability in South Korea by 10%. Given these study results, we expect that establishing an automatic mountain meteorology observation station at the optimal sites in inaccessible area and integrating mountain weather data will improve the predictability of forest fires.

Managing fire risk during drought: the influence of certification and El Niño on fire-driven forest conversion for oil palm in Southeast Asia

NASA Astrophysics Data System (ADS)

Noojipady, Praveen; Morton, Douglas C.; Schroeder, Wilfrid; Carlson, Kimberly M.; Huang, Chengquan; Gibbs, Holly K.; Burns, David; Walker, Nathalie F.; Prince, Stephen D.

2017-08-01

Indonesia and Malaysia have emerged as leading producers of palm oil in the past several decades, expanding production through the conversion of tropical forests to industrial plantations. Efforts to produce sustainable palm oil, including certification by the Roundtable on Sustainable Palm Oil (RSPO), include guidelines designed to reduce the environmental impact of palm oil production. Fire-driven deforestation is prohibited by law in both countries and a stipulation of RSPO certification, yet the degree of environmental compliance is unclear, especially during El Niño events when drought conditions increase fire risk. Here, we used time series of satellite data to estimate the spatial and temporal patterns of fire-driven deforestation on and around oil palm plantations. In Indonesia, fire-driven deforestation accounted for one-quarter of total forest losses on both certified and noncertified plantations. After the first plantations in Indonesia received RSPO certification in 2009, forest loss and fire-driven deforestation declined on certified plantations but did not stop altogether. Oil palm expansion in Malaysia rarely involved fire; only 5 % of forest loss on certified plantations had coincident active fire detections. Interannual variability in fire detections was strongly influenced by El Niño and the timing of certification. Fire activity during the 2002, 2004, and 2006 El Niño events was similar among oil palm plantations in Indonesia that would later become certified, noncertified plantations, and surrounding areas. However, total fire activity was 75 % and 66 % lower on certified plantations than noncertified plantations during the 2009 and 2015 El Niño events, respectively. The decline in fire activity on certified plantations, including during drought periods, highlights the potential for RSPO certification to safeguard carbon stocks in peatlands and remaining forests in accordance with legislation banning fires. However, aligning certification standards with satellite monitoring capabilities will be critical to realize sustainable palm oil production and meet industry commitments to zero deforestation.

Economic information on the historical behavior of forest fires in the forest lands in the state of Parana, Brazil

Treesearch

Vitor Afonso Hoeflich; Alexandre França Tetto; Antonio Carlos Batista

2013-01-01

It is widely acknowledged that the fires have caused severe impact in the world, and their frequency and intensity tend to increase as a result of ongoing climate changes which have occurred over the past decades. It should be also noted that the urban-rural interface has attracted the attention of governments by the concentration of the number of fire...

Fire Patterns and Drivers of Fires in the West African Tropical Forest

NASA Astrophysics Data System (ADS)

Dwomoh, F. K.; Wimberly, M. C.

2015-12-01

The West African tropical forest (referred to as the Upper Guinean forest, UGF), is a global biodiversity hotspot providing vital ecosystem services for the region's socio-economic and environmental wellbeing. It is also one of the most fragmented and human-modified tropical forest ecosystems, with the only remaining large patches of original forests contained in protected areas. However, these remnant forests are susceptible to continued fire-mediated degradation and forest loss due to intense climatic, demographic and land use pressures. We analyzed human and climatic drivers of fire activity in the sub-region to better understand the spatial and temporal patterns of these risks. We utilized MODIS active fire and burned area products to identify fire activity within the sub-region. We measured climatic variability using TRMM rainfall data and derived indicators of human land use from a variety of geospatial datasets. We used a boosted regression trees model to determine the influences of predictor variables on fire activity. Our analyses indicated that the spatial and temporal variability of precipitation is a key driving factor of fire activity in the UGF. Anthropogenic effects on fire activity in the area were evident through the influences of agriculture and low-density populations. These human footprints in the landscape make forests more susceptible to fires through forest fragmentation, degradation, and fire spread from agricultural areas. Forested protected areas within the forest savanna mosaic experienced frequent fires, whereas the more humid forest areas located in the south and south-western portions of the study area had fewer fires as these rainforests tend to offer some buffering against fire encroachment. These results improve characterization of UGF fire regime and expand our understanding of the spatio-temporal dynamics of tropical forest fires in response to human and climatic pressures.

Forest fires in Himalayan region during 2016 - Aerosol load and smoke plume heights detection by multi sensor observations

NASA Astrophysics Data System (ADS)

Kumar, S.; Dumka, U. C.

2017-12-01

The forest fires are common events over the Central Himalayan region during the pre-monsoon season (March - June) of every year. Forest fire plays a crucial role in governing the vegetation structure, ecosystem, climate change as well as in atmospheric chemistry. In regional and global scales, the combustion of forest and grassland vegetation releases large volumes of smoke, aerosols, and other chemically active species that significantly influence Earth's radiative budget and atmospheric chemistry, impacting air quality and risks to human health. During the year 2016, massive forest fires have been recorded over the Central Himalayan region of Uttarakhand which continues for several weeks. To study this event we used the multi-satellite observations of aerosols and pollutants during pre-fire, fire and post-fire period over the central Himalayan region. The data used in this study are active fire count and aerosol optical depth (AOD) from MODerate-resolution Imaging Spectroradiometer (MODIS), aerosol index and gases pollutants from Ozone Monitoring Instrument (OMI), along with vertical profiles of aerosols and smoke plume height information from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). The result shows that the mean fire counts were maximum in April. The daily average AOD value shows an increasing trend during the fire events. The mean value of AOD before the massive fire (25 April), during the fire (30 April) and post fire (5 May) periods are 0.3, 1.2 and 0.6 respectively. We find an increasing trend of total columnar NO2 over the Uttarakhand region during the massive fire event. Space-born Lidar (CALIPSO) retrievals show the extent of smoke plume heights beyond the planetary boundary layer up to 6 km during the peak burning day (April 30). The HYSPLIT air mass forward trajectory shows the long-range transportation of smoke plumes. The results of the present study provide valuable information for addressing smoke plume and aerosol transport in the Himalayan region. The implication of this study and the details of the analysis will be presented during the conference.

Gis-Based Multi-Criteria Decision Analysis for Forest Fire Risk Mapping

NASA Astrophysics Data System (ADS)

Akay, A. E.; Erdoğan, A.

2017-11-01

The forested areas along the coastal zone of the Mediterranean region in Turkey are classified as first-degree fire sensitive areas. Forest fires are major environmental disaster that affects the sustainability of forest ecosystems. Besides, forest fires result in important economic losses and even threaten human lives. Thus, it is critical to determine the forested areas with fire risks and thereby minimize the damages on forest resources by taking necessary precaution measures in these areas. The risk of forest fire can be assessed based on various factors such as forest vegetation structures (tree species, crown closure, tree stage), topographic features (slope and aspect), and climatic parameters (temperature, wind). In this study, GIS-based Multi-Criteria Decision Analysis (MCDA) method was used to generate forest fire risk map. The study was implemented in the forested areas within Yayla Forest Enterprise Chiefs at Dursunbey Forest Enterprise Directorate which is classified as first degree fire sensitive area. In the solution process, "extAhp 2.0" plug-in running Analytic Hierarchy Process (AHP) method in ArcGIS 10.4.1 was used to categorize study area under five fire risk classes: extreme risk, high risk, moderate risk, and low risk. The results indicated that 23.81 % of the area was of extreme risk, while 25.81 % was of high risk. The result indicated that the most effective criterion was tree species, followed by tree stages. The aspect had the least effective criterion on forest fire risk. It was revealed that GIS techniques integrated with MCDA methods are effective tools to quickly estimate forest fire risk at low cost. The integration of these factors into GIS can be very useful to determine forested areas with high fire risk and also to plan forestry management after fire.

The Teakettle experiment

Treesearch

Malcolm P. North

2002-01-01

A critical question in the Sierra Nevada concerns how to use disturbance effectively to restore forest ecosystems after nearly a century of fire suppression. With increases in stem densities and ladder fuels, many forests require a combination of stand thinning and controlled burning to mimic natural fire intensity. In spite of their widespread use, the different...

Predicted effects of prescribed burning and harvesting on forest recovery and sustainability in southwest Georgia, USA.

PubMed

Garten, Charles T

2006-12-01

A model-based analysis of the effect of prescribed burning and forest thinning or clear-cutting on stand recovery and sustainability was conducted at Fort Benning, GA, in the southeastern USA. Two experiments were performed with the model. In the first experiment, forest recovery from degraded soils was predicted for 100 years with or without prescribed burning. In the second experiment simulations began with 100 years of predicted stand growth, then forest sustainability was predicted for an additional 100 years under different combinations of prescribed burning and forest harvesting. Three levels of fire intensity (low, medium, and high), that corresponded to 17%, 33%, and 50% consumption of the forest floor C stock by fire, were evaluated at 1-, 2-, and 3-year fire return intervals. Relative to the control (no fire), prescribed burning with a 2- or 3-year return interval caused only a small reduction in predicted steady state soil C stocks (< or =25%) and had no effect on steady state tree wood biomass, regardless of fire intensity. Annual high intensity burns did adversely impact forest recovery and sustainability (after harvesting) on less sandy soils, but not on more sandy soils that had greater N availability. Higher intensity and frequency of ground fires increased the chance that tree biomass would not return to pre-harvest levels. Soil N limitation was indicated as the cause of unsustainable forests when prescribed burns were too frequent or too intense to permit stand recovery.

Fire ecology of western Montana forest habitat types

Treesearch

William C. Fischer; Anne F. Bradley

1987-01-01

Provides information on fire as an ecological factor for forest habitat types in western Montana. Identifies Fire Groups of habitat types based on fire's role in forest succession. Describes forest fuels and suggests considerations for fire management.

Potential changes in forest composition could reduce impacts of climate change on boreal wildfires.

PubMed

Terrier, Aurélie; Girardin, Martin P; Périé, Catherine; Legendre, Pierre; Bergeron, Yves

2013-01-01

There is general consensus that wildfires in boreal forests will increase throughout this century in response to more severe and frequent drought conditions induced by climate change. However, prediction models generally assume that the vegetation component will remain static over the next few decades. As deciduous species are less flammable than conifer species, it is reasonable to believe that a potential expansion of deciduous species in boreal forests, either occurring naturally or through landscape management, could offset some of the impacts of climate change on the occurrence of boreal wildfires. The objective of this study was to determine the potential of this offsetting effect through a simulation experiment conducted in eastern boreal North America. Predictions of future fire activity were made using multivariate adaptive regression splines (MARS) with fire behavior indices and ecological niche models as predictor variables so as to take into account the effects of changing climate and tree distribution on fire activity. A regional climate model (RCM) was used for predictions of future fire risk conditions. The experiment was conducted under two tree dispersal scenarios: the status quo scenario, in which the distribution of forest types does not differ from the present one, and the unlimited dispersal scenario, which allows forest types to expand their range to fully occupy their climatic niche. Our results show that future warming will create climate conditions that are more prone to fire occurrence. However, unlimited dispersal of southern restricted deciduous species could reduce the impact of climate change on future fire occurrence. Hence, the use of deciduous species could be a good option for an efficient strategic fire mitigation strategy aimed at reducing fire Propagation in coniferous landscapes and increasing public safety in remote populated areas of eastern boreal Canada under climate change.

Measuring and Modeling the Effects of Alternate Post-Fire Successional Trajectories on Boreal Forest Carbon Dynamics

NASA Astrophysics Data System (ADS)

Loranty, M. M.; Goetz, S. J.; Mack, M. C.; Alexander, H. D.; Beck, P. S.

2011-12-01

High latitude ecosystems are experiencing amplified climate warming, and recent evidence suggests concurrent intensification of fire disturbance regimes. In central Alaskan boreal forests, severe burns consume more of the soil organic layer, resulting in increased establishment of deciduous seedlings and altered post-fire stand composition with increased deciduous dominance. Quantifying differences in ecosystem carbon (C) dynamics between forest successional trajectories in response to burn severity is essential for understanding potential changes in regional or global feedbacks between boreal forests and climate. We used the Biome BioGeochemical Cycling model (Biome-BGC) to quantify differences in C stocks and fluxes associated with alternate post-fire successional trajectories related to fire severity. A version of Biome-BGC that allows alternate competing vegetation types was calibrated against a series of aboveground biomass observations from chronosequences of stands with differing post-fire successional trajectories characterized by the proportion of deciduous biomass. The model was able to reproduce observed patterns of biomass accumulation after fire, with stands dominated by deciduous species sequestering more C at a faster rate than stands dominated by conifers. Modeled C fluxes suggest that stands dominated by deciduous species are a stronger sink of atmospheric C soon after disturbance than coniferous stands. These results agree with the few available C flux observations. We use a historic database in conjunction with a map of deciduous canopy cover to explore the consequences of ongoing and potential future changes in the fire regime on central Alaskan C balance.

Multi-Level Wild Land Fire Fighting Management Support System for an Optimized Guidance of Ground and Air Forces

NASA Astrophysics Data System (ADS)

Almer, Alexander; Schnabel, Thomas; Perko, Roland; Raggam, Johann; Köfler, Armin; Feischl, Richard

2016-04-01

Climate change will lead to a dramatic increase in damage from forest fires in Europe by the end of this century. In the Mediterranean region, the average annual area affected by forest fires has quadrupled since the 1960s (WWF, 2012). The number of forest fires is also on the increase in Central and Northern Europe. The Austrian forest fire database shows a total of 584 fires for the period 2012 to 2014, while even large areas of Sweden were hit by forest fires in August 2014, which were brought under control only after two weeks of intense fire-fighting efforts supported by European civil protection modules. Based on these facts, the improvements in forest fire control are a major international issue in the quest to protect human lives and resources as well as to reduce the negative environmental impact of these fires to a minimum. Within this paper the development of a multi-functional airborne management support system within the frame of the Austrian national safety and security research programme (KIRAS) is described. The main goal of the developments is to assist crisis management tasks of civil emergency teams and armed forces in disaster management by providing multi spectral, near real-time airborne image data products. As time, flexibility and reliability as well as objective information are crucial aspects in emergency management, the used components are tailored to meet these requirements. An airborne multi-functional management support system was developed as part of the national funded project AIRWATCH, which enables real-time monitoring of natural disasters based on optical and thermal images. Airborne image acquisition, a broadband line of sight downlink and near real-time processing solutions allow the generation of an up-to-date geo-referenced situation map. Furthermore, this paper presents ongoing developments for innovative extensions and research activities designed to optimize command operations in national and international fire-fighting missions. The ongoing development focuses on the following topics: (1) Development of a multi-level management solution to coordinate and guide different airborne and terrestrial deployed firefighting modules as well as related data processing and data distribution activities. (2) Further, a targeted control of the thermal sensor based on a rotating mirror system to extend the "area performance" (covered area per hour) in time critical situations for the monitoring requirements during forest fire events. (3) Novel computer vision methods for analysis of thermal sensor signatures, which allow an automatic classification of different forest fire types and situations. (4) A module for simulation-based decision support for planning and evaluation of resource usage and the effectiveness of performed fire-fighting measures. (5) Integration of wearable systems to assist ground teams in rescue operations as well as a mobile information system into innovative command and fire-fighting vehicles. In addition, the paper gives an outlook on future perspectives including a first concept for the integration of the near real-time multilevel forest fire fighting management system into an "EU Civil Protection Team" to support the EU civil protection modules and the Emergency Response Coordination Centre in Brussels. Keywords: Airborne sensing, multi sensor imaging, near real-time fire monitoring, simulation-based decision support, forest firefighting management, firefighting impact analysis.

Fire intensity drives post-fire temporal pattern of soil carbon accumulation in Australian fire-prone forests.

PubMed

Sawyer, Robert; Bradstock, Ross; Bedward, Michael; Morrison, R John

2018-01-01

The impact of fire on global C cycles is considerable but complex. Nevertheless, studies on patterns of soil C accumulation following fires of differing intensity over time are lacking. Our study utilised 15 locations last burnt by prescribed fire (inferred low intensity) and 18 locations last burnt by wildfire (inferred high intensity), with time since fire (TSF) up to 43years, in a homogenous forest type in south eastern Australia. Following a stratified approach to mineral soil sampling, the soil % total C (% C Tot ) and % recalcitrant pyrogenic C (% RPC), were estimated. Generalised additive models indicated increases in % C Tot at TSF >30years in sites last burnt by wildfire. Estimates in sites last subjected to prescribed fire however, remained constant across the TSF chronosequence. There was no significant difference in % C Tot between the different fire types for the first 20years after fire. In the first 10years after wildfires, % RPC was elevated, declining to a minimum at ca. TSF 25years. After prescribed fires, % RPC was unaffected by TSF. Differences in response of % C Tot and % RPC to fire type may reflect the strength of stimulation of early successional processes and extent of charring. The divergent response to fire type in % C Tot was apparent at TSF longer than the landscape average fire return interval (i.e., 15 to 20years). Thus, any attempt to increase C sequestration in soils would require long-term exclusion of fire. Conversely, increased fire frequency is likely to have negligible impact on soil C stocks in these forests. Further investigation of the effects of fire frequency, fire intensity combinations and interaction of fire with other disturbances will enhance prediction of the likely impact of imposed or climatically induced changes to fire regimes on soil C. Copyright © 2017 Elsevier B.V. All rights reserved.

A perfect storm: multiple stressors interact to drive postfire regeneration failure of lodgepole pine and Douglas-fir forests in Yellowstone

NASA Astrophysics Data System (ADS)

Hansen, W. D.; Braziunas, K. H.; Rammer, W.; Seidl, R.; Turner, M. G.

2017-12-01

Twenty-first century forests will experience increased stress as environmental conditions and disturbance regimes change. Whether forests retain their structure or transitions to alternate states, particularly when affected by multiple stressors, remains unresolved. Subalpine forests in Yellowstone National Park, WY experience large severe wildfires, and postfire-tree regeneration is necessary to assure resilience. Drying is projected, causing frequent larger wildfires that could reduce seed supply and drought that could constrain postfire-seedling establishment. We asked what combinations of warming-drying conditions, increased fire frequency, and increased burned-patch size cause postfire tree-regeneration failure in Yellowstone? We conducted a simulation experiment to identify combinations of fire frequency, fire size, postfire climate, substrate type, and elevation where lodgepole-pine and Douglas-fir regeneration failed. We expected postfire densities to be reduced if burned-patch sizes exceeded effective dispersal distance, sequential fires burned before trees reached reproductive maturity, or drought occurred after fire. We also expected regeneration failure only where multiple stressors occurred simultaneously at low elevation or on poor substrates.Douglas-fir stands were most vulnerable to regeneration failure. 98% of simulated Douglas-fir stands located in the middle of large burned patches failed to regenerate 30 years post fire. Lodgepole-pine stands in the middle of large burned patches failed to regenerate if they were also located at low elevations (93%) or at higher elevations on soils with poor water retention (73%). Stands of serotinous lodgepole (i.e., trees with closed cones that open when heated) also failed to regenerate if fire recurred before trees were reproductively mature (82%). Drought constrained postfire regeneration, yet, enhanced establishment due to release from cold-temperatures during mid-to-late 21st century often outweighed drought effects. Postfire tree regeneration arises from the interplay between multiple factors; some constraining establishment and others enhancing it. To understand 21st-century climate and fire effects on postfire tree regeneration and forest resilience, a reductionist approach is insufficient.

Barren-ground caribou (Rangifer tarandus groenlandicus) behaviour after recent fire events; integrating caribou telemetry data with Landsat fire detection techniques.

PubMed

Rickbeil, Gregory J M; Hermosilla, Txomin; Coops, Nicholas C; White, Joanne C; Wulder, Michael A

2017-03-01

Fire regimes are changing throughout the North American boreal forest in complex ways. Fire is also a major factor governing access to high-quality forage such as terricholous lichens for barren-ground caribou (Rangifer tarandus groenlandicus). Additionally, fire alters forest structure which can affect barren-ground caribou's ability to navigate in a landscape. Here, we characterize how the size and severity of fires are changing across five barren-ground caribou herd ranges in the Northwest Territories and Nunavut, Canada. Additionally, we demonstrate how time since fire, fire severity, and season result in complex changes in caribou behavioural metrics estimated using telemetry data. Fire disturbances were identified using novel gap-free Landsat surface reflectance composites from 1985 to 2011 across all herd ranges. Burn severity was estimated using the differenced normalized burn ratio. Annual area burned and burn severity were assessed through time for each herd and related to two behavioural metrics: velocity and relative turning angle. Neither annual area burned nor burn severity displayed any temporal trend within the study period. However, certain herds, such as the Ahiak/Beverly, have more exposure to fire than other herds (i.e. Cape Bathurst had a maximum forested area burned of less than 4 km 2 ). Time since fire and burn severity both significantly affected velocity and relative turning angles. During fall, winter, and spring, fire virtually eliminated foraging-focused behaviour for all 26 years of analysis while more severe fires resulted in a marked increase in movement-focused behaviour compared to unburnt patches. Between seasons, caribou used burned areas as early as 1-year postfire, demonstrating complex, nonlinear reactions to time since fire, fire severity, and season. In all cases, increases in movement-focused behaviour were detected postfire. We conclude that changes in caribou behaviour immediately postfire are primarily driven by changes in forest structure rather than changes in terricholous lichen availability. © 2016 John Wiley & Sons Ltd.

Spatially-Explicit Holocene Drought Reconstructions in Amazonian Forests

NASA Astrophysics Data System (ADS)

McMichael, C.; Bush, M. B.

2014-12-01

Climate models predict increasing drought in Amazonian forests over the next century, and the synergy of drought and fire may lead to forest dieback. El Niño Southern Oscillation (ENSO) and the Atlantic Multi-decadal Oscillation (AMO) are two primary drivers of Amazonian drought, and each process has a spatially distinct manifestation in the Basin. Paleoecological reconstructions can contextualize the forest response to past drought periods. Stalagmite and lake sediment records have documented that the early- to mid-Holocene, i.e. 10,000 - 5000 calibrated years before present (cal yr BP), was among the driest periods of the last 100,000 years in western Amazonia. Climatic conditions became wetter and more similar to the modern climate over the last 4000 cal yr BP, and fires rarely occurred in the absence of human activity. Yet there are currently no drought and fire reconstructions that examine the spatially explicit patterns of drought during the Holocene. Here, we present regional drought histories from southwestern and northeastern sections Amazonia for the last 10,000 years that document the drought-fire dynamics resulting from both climatic processes. Our reconstructions were based on a compilation of dated soil charcoal fragments (N= 291) collected from within Amazonia sensu stricto, which were analyzed by region using summed probability analysis. The compiled soil charcoal dates contained limited evidence of fire over the last 10,000 years in some regions. Fire frequency rose markedly across the Basin, however, during the last 2000 years, indicating an increased human presence. Fire probabilities, and thus droughts, had similar increasing trajectories between southwestern and northeastern Amazonia from 1500-1100 cal yr BP, which decoupled from 1100-740 cal yr BP, and then regained synchronicity from 740-500 cal yr BP. Fire probability declined markedly after 500 yr cal BP, coincident with European arrival to the Americas. Native populations were decimated, and fire probabilities returned to similar levels before the rise 2000 years ago. These results suggested that the synergy of humans plus drought have played a large role in historical fire regimes in Amazonian forests for the last 2000 years.

Mechanical mastication as a fuels treatment in southeastern forests

Treesearch

Jesse K. Kreye; J. Morgan Varner; Leda N. Kobziar

2016-01-01

Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity. Despite its widespread adoption, it remains unclear how mastication impacts fuels, fire behavior, or plant communities  across Southeastern forest ecosystems. We evaluated these...

Changes in stand structure and tree vigor with repeated prescribed fire in an Appalachian hardwood forest

Treesearch

Mary A. Arthur; Beth A. Blankenship; Angela Schörgendorfer; David L. Loftis; Heather D. Alexander

2015-01-01

Without large scale disturbances to alter forest structure and open the canopy, historically oak-dominated forests of the central and Appalachian hardwood regions of eastern North America are shifting to dominance by shade-tolerant, ‘mesophytic’ species. In response, prescribed fire is applied with increasing frequency and spatial extent to decrease non-oak species and...

Contrasting impacts of climate and competition on large sugar pine growth and defense in a fire-excluded forest of the Central Sierra Nevada

Treesearch

Andrew Slack; Jeffrey Kane; Eric Knapp; Rosemary Sherriff

2017-01-01

Many forest ecosystems with a large pine component in the western United States have experienced environmental stress associated with climate change and increased competition with forest densification in the absence of fire. Information on how changes in climate and competition affect carbon allocation to tree growth and defense is needed to anticipate changes to tree...

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

Genet, Helene; McGuire, A. David; Barrett, K.

There is a substantial amount of carbon stored in the permafrost soils of boreal forest ecosystems, where it is currently protected from decomposition. The surface organic horizons insulate the deeper soil from variations in atmospheric temperature. The removal of these insulating horizons through consumption by fire increases the vulnerability of permafrost to thaw, and the carbon stored in permafrost to decomposition. In this study we ask how warming and fire regime may influence spatial and temporal changes in active layer and carbon dynamics across a boreal forest landscape in interior Alaska. To address this question, we (1) developed and testedmore » a predictive model of the effect of fire severity on soil organic horizons that depends on landscape-level conditions and (2) used this model to evaluate the long-term consequences of warming and changes in fire regime on active layer and soil carbon dynamics of black spruce forests across interior Alaska. The predictive model of fire severity, designed from the analysis of field observations, reproduces the effect of local topography (landform category, the slope angle and aspect and flow accumulation), weather conditions (drought index, soil moisture) and fire characteristics (day of year and size of the fire) on the reduction of the organic layercaused by fire. The integration of the fire severity model into an ecosystem process-based model allowed us to document the relative importance and interactions among local topography, fire regime and climate warming on active layer and soil carbon dynamics. Lowlands were more resistant to severe fires and climate warming, showing smaller increases in active layer thickness and soil carbon loss compared to drier flat uplands and slopes. In simulations that included the effects of both warming and fire at the regional scale, fire was primarily responsible for a reduction in organic layer thickness of 0.06 m on average by 2100 that led to an increase in active layer thickness of 1.1 m on average by 2100. The combination of warming and fire led to a simulated cumulative loss of 9.6 kgC m 2 on average by 2100. Our analysis suggests that ecosystem carbon storage in boreal forests in interior Alaska is particularly vulnerable, primarily due to the combustion of organic layer thickness in fire and the related increase in active layer thickness that exposes previously protected permafrost soil carbon to decomposition.« less

Opposing resonses to ecological gradients structure amphibian and reptile communities across a temperate grassland-savanna-forest landscape

USGS Publications Warehouse

Grundel, Ralph; Beamer, David; Glowacki, Gary A.; Frohnapple, Krystal; Pavlovic, Noel B.

2014-01-01

Temperate savannas are threatened across the globe. If we prioritize savanna restoration, we should ask how savanna animal communities differ from communities in related open habitats and forests. We documented distribution of amphibian and reptile species across an open-savanna–forest gradient in the Midwest U.S. to determine how fire history and habitat structure affected herpetofaunal community composition. The transition from open habitats to forests was a transition from higher reptile abundance to higher amphibian abundance and the intermediate savanna landscape supported the most species overall. These differences warn against assuming that amphibian and reptile communities will have similar ecological responses to habitat structure. Richness and abundance also often responded in opposite directions to some habitat characteristics, such as cover of bare ground or litter. Herpetofaunal community species composition changed along a fire gradient from infrequent and recent fires to frequent but less recent fires. Nearby (200-m) wetland cover was relatively unimportant in predicting overall herpetofaunal community composition while fire history and fire-related canopy and ground cover were more important predictors of composition, diversity, and abundance. Increased developed cover was negatively related to richness and abundance. This indicates the importance of fire history and fire related landscape characteristics, and the negative effects of development, in shaping the upland herpetofaunal community along the native grassland–forest continuum.

Effects of fire disturbance on soil respiration in the non-growing season in a Larix gmelinii forest in the Daxing'an Mountains, China.

PubMed

Hu, Tongxin; Sun, Long; Hu, Haiqing; Guo, Futao

2017-01-01

In boreal forests, fire is an important part of the ecosystem that greatly influences soil respiration, which in turn affects the carbon balance. Wildfire can have a significant effect on soil respiration and it depends on the fire severity and environmental factors (soil temperature and snow water equivalent) after fire disturbance. In this study, we quantified post-fire soil respiration during the non-growing season (from November to April) in a Larix gmelinii forest in Daxing'an Mountains of China. Soil respiration was measured in the snow-covered and snow-free conditions with varying degrees of natural burn severity forests. We found that soil respiration decreases as burn severity increases. The estimated annual C efflux also decreased with increased burn severity. Soil respiration during the non-growing season approximately accounted for 4%-5% of the annual C efflux in all site types. Soil temperature (at 5 cm depth) was the predominant determinant of non-growing season soil respiration change in this area. Soil temperature and snow water equivalent could explain 73%-79% of the soil respiration variability in winter snow-covering period (November to March). Mean spring freeze-thaw cycle (FTC) period (April) soil respiration contributed 63% of the non-growing season C efflux. Our finding is key for understanding and predicting the potential change in the response of boreal forest ecosystems to fire disturbance under future climate change.

Effects of fire disturbance on soil respiration in the non-growing season in a Larix gmelinii forest in the Daxing'an Mountains, China

PubMed Central

Hu, Tongxin; Guo, Futao

2017-01-01

In boreal forests, fire is an important part of the ecosystem that greatly influences soil respiration, which in turn affects the carbon balance. Wildfire can have a significant effect on soil respiration and it depends on the fire severity and environmental factors (soil temperature and snow water equivalent) after fire disturbance. In this study, we quantified post-fire soil respiration during the non-growing season (from November to April) in a Larix gmelinii forest in Daxing'an Mountains of China. Soil respiration was measured in the snow-covered and snow-free conditions with varying degrees of natural burn severity forests. We found that soil respiration decreases as burn severity increases. The estimated annual C efflux also decreased with increased burn severity. Soil respiration during the non-growing season approximately accounted for 4%–5% of the annual C efflux in all site types. Soil temperature (at 5 cm depth) was the predominant determinant of non-growing season soil respiration change in this area. Soil temperature and snow water equivalent could explain 73%–79% of the soil respiration variability in winter snow-covering period (November to March). Mean spring freeze–thaw cycle (FTC) period (April) soil respiration contributed 63% of the non-growing season C efflux. Our finding is key for understanding and predicting the potential change in the response of boreal forest ecosystems to fire disturbance under future climate change. PMID:28665958

Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change.

PubMed

Yuan, F M; Yi, S H; McGuire, A D; Johnson, K D; Liang, J; Harden, J W; Kasischke, E S; Kurz, W A

2012-12-01

Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at -0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.

Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change

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

Yuan, Fengming; Yi, Shuhua; McGuire, A. David

2012-01-01

Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites andmore » evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ;0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.« less

Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change

USGS Publications Warehouse

Yuan, F.M.; Yi, S.H.; McGuire, A.D.; Johnson, K.D.; Liang, J.; Harden, J.W.; Kasischke, E.S.; Kurz, W.A.

2012-01-01

Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ∼0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.

The role of fire in the boreal carbon budget

USGS Publications Warehouse

Harden, J.W.; Trumbore, S.E.; Stocks, B.J.; Hirsch, A.; Gower, S.T.; O'Neill, K. P.; Kasischke, E.S.

2000-01-01

To reconcile observations of decomposition rates, carbon inventories, and net primary production (NPP), we estimated long-term averages for C exchange in boreal forests near Thompson, Manitoba. Soil drainage as defined by water table, moss cover, and permafrost dynamics, is the dominant control on direct fire emissions. In upland forests, an average of about 10-30% of annual NPP was likely consumed by fire over the past 6500 years since these landforms and ecosystems were established. This long-term, average fire emission is much larger than has been accounted for in global C cycle models and may forecast an increase in fire activity for this region. While over decadal to century times these boreal forests may be acting as slight net sinks for C from the atmosphere to land, periods of drought and severe fire activity may result in net sources of C from these systems.

Influence of fire frequency on carbon consumption in Alaskan blackspruce forests

NASA Astrophysics Data System (ADS)

Hoy, E.; Kasischke, E. S.

2014-12-01

Increasing temperatures and drier conditions within the boreal forests of Alaska have resulted in increases in burned area and fire frequency, which alter carbon storage and emissions. In particular, analyses of satellite remote sensing data showed that >20% of the area impacted by fires in interior Alaska occurred in areas that had previously burned since 1950 (e.g., short to intermediate interval fires). Field studies showed that in immature black spruce forests ~ 35 to 55 years old organic layers experienced deep burning regardless of topographic position or seasonality of burning, factors that control depth of burning in mature black spruce forests. Here, refinements were made to a carbon consumption model to account for variations in fuel loads and fraction of carbon consumed associated with fire frequency based on quantifying burned area in recently burned sites using satellite imagery. An immature black spruce (Picea mariana) fuel type (including stands of ~0-50 years) was developed which contains new ground-layer carbon consumption values in order to more accurately account for differences between various age classes of black spruce forest. Both versions of the model were used to assess carbon consumption during 100 fire events (over 4.4 x 10^6 ha of burned area) from two recent ultra-large fire years (2004 and 2005). Using the improved model to better attribute fuel type and consumption resulted in higher ground-layer carbon consumption (4.9% in 2004 and 6.8% in 2005) than previously estimated. These adjustments in ground-layer burning resulted in total carbon consumption within 2004 and 2005 of 63.5 and 42.0 Tg of carbon, respectively. Results from this research could be incorporated into larger scale modeling efforts to better assess changes in the climate-fire-vegetation dynamics in interior Alaskan boreal forests, and to understand the impacts of these changes on carbon consumption and emissions.

Dispersal limitation drives successional pathways in Central Siberian forests under current and intensified fire regimes.

PubMed

Tautenhahn, Susanne; Lichstein, Jeremy W; Jung, Martin; Kattge, Jens; Bohlman, Stephanie A; Heilmeier, Hermann; Prokushkin, Anatoly; Kahl, Anja; Wirth, Christian

2016-06-01

Fire is a primary driver of boreal forest dynamics. Intensifying fire regimes due to climate change may cause a shift in boreal forest composition toward reduced dominance of conifers and greater abundance of deciduous hardwoods, with potential biogeochemical and biophysical feedbacks to regional and global climate. This shift has already been observed in some North American boreal forests and has been attributed to changes in site conditions. However, it is unknown if the mechanisms controlling fire-induced changes in deciduous hardwood cover are similar among different boreal forests, which differ in the ecological traits of the dominant tree species. To better understand the consequences of intensifying fire regimes in boreal forests, we studied postfire regeneration in five burns in the Central Siberian dark taiga, a vast but poorly studied boreal region. We combined field measurements, dendrochronological analysis, and seed-source maps derived from high-resolution satellite images to quantify the importance of site conditions (e.g., organic layer depth) vs. seed availability in shaping postfire regeneration. We show that dispersal limitation of evergreen conifers was the main factor determining postfire regeneration composition and density. Site conditions had significant but weaker effects. We used information on postfire regeneration to develop a classification scheme for successional pathways, representing the dominance of deciduous hardwoods vs. evergreen conifers at different successional stages. We estimated the spatial distribution of different successional pathways under alternative fire regime scenarios. Under intensified fire regimes, dispersal limitation of evergreen conifers is predicted to become more severe, primarily due to reduced abundance of surviving seed sources within burned areas. Increased dispersal limitation of evergreen conifers, in turn, is predicted to increase the prevalence of successional pathways dominated by deciduous hardwoods. The likely fire-induced shift toward greater deciduous hardwood cover may affect climate-vegetation feedbacks via surface albedo, Bowen ratio, and carbon cycling. © 2015 John Wiley & Sons Ltd.

Impact of haze from forest fire to respiratory health: Indonesian experience.

PubMed

Aditama, T Y

2000-06-01

This paper will describe the impact on the human lung of haze from forest fires in Indonesia based on data collected from different provinces. Data were collected from personal reports from pulmonologists working in the area as well as from province/district health offices and hospitals. These data show that there was a significant impact of haze to the human lung. There was a significant increase in respiratory conditions, lung function complaints and other related impacts. Further studies, especially cohort studies, should be undertaken so that the long-term' impact of pollution from forest fires can be known.

Mapping regional patterns of large forest fires in Wildland-Urban Interface areas in Europe.

PubMed

Modugno, Sirio; Balzter, Heiko; Cole, Beth; Borrelli, Pasquale

2016-05-01

Over recent decades, Land Use and Cover Change (LUCC) trends in many regions of Europe have reconfigured the landscape structures around many urban areas. In these areas, the proximity to landscape elements with high forest fuels has increased the fire risk to people and property. These Wildland-Urban Interface areas (WUI) can be defined as landscapes where anthropogenic urban land use and forest fuel mass come into contact. Mapping their extent is needed to prioritize fire risk control and inform local forest fire risk management strategies. This study proposes a method to map the extent and spatial patterns of the European WUI areas at continental scale. Using the European map of WUI areas, the hypothesis is tested that the distance from the nearest WUI area is related to the forest fire probability. Statistical relationships between the distance from the nearest WUI area, and large forest fire incidents from satellite remote sensing were subsequently modelled by logistic regression analysis. The first European scale map of the WUI extent and locations is presented. Country-specific positive and negative relationships of large fires and the proximity to the nearest WUI area are found. A regional-scale analysis shows a strong influence of the WUI zones on large fires in parts of the Mediterranean regions. Results indicate that the probability of large burned surfaces increases with diminishing WUI distance in touristic regions like Sardinia, Provence-Alpes-Côte d'Azur, or in regions with a strong peri-urban component as Catalunya, Comunidad de Madrid, Comunidad Valenciana. For the above regions, probability curves of large burned surfaces show statistical relationships (ROC value > 0.5) inside a 5000 m buffer of the nearest WUI. Wise land management can provide a valuable ecosystem service of fire risk reduction that is currently not explicitly included in ecosystem service valuations. The results re-emphasise the importance of including this ecosystem service in landscape valuations to account for the significant landscape function of reducing the risk of catastrophic large fires. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Avian response to fire in pine–oak forests of Great Smoky Mountains National Park following decades of fire suppression

USGS Publications Warehouse

Rose, Eli T.; Simons, Theodore R.

2016-01-01

Fire suppression in southern Appalachian pine–oak forests during the past century dramatically altered the bird community. Fire return intervals decreased, resulting in local extirpation or population declines of many bird species adapted to post-fire plant communities. Within Great Smoky Mountains National Park, declines have been strongest for birds inhabiting xeric pine–oak forests that depend on frequent fire. The buildup of fuels after decades of fire suppression led to changes in the 1996 Great Smoky Mountains Fire Management Plan. Although fire return intervals remain well below historic levels, management changes have helped increase the amount of fire within the park over the past 20 years, providing an opportunity to study patterns of fire severity, time since burn, and bird occurrence. We combined avian point counts in burned and unburned areas with remote sensing indices of fire severity to infer temporal changes in bird occurrence for up to 28 years following fire. Using hierarchical linear models that account for the possibility of a species presence at a site when no individuals are detected, we developed occurrence models for 24 species: 13 occurred more frequently in burned areas, 2 occurred less frequently, and 9 showed no significant difference between burned and unburned areas. Within burned areas, the top models for each species included fire severity, time since burn, or both, suggesting that fire influenced patterns of species occurrence for all 24 species. Our findings suggest that no single fire management strategy will suit all species. To capture peak occupancy for the entire bird community within xeric pine–oak forests, at least 3 fire regimes may be necessary; one applying frequent low severity fire, another using infrequent low severity fire, and a third using infrequently applied high severity fire.

Multi-sensor data fusion for estimating forest species composition and abundance in northern Minnesota

Treesearch

Peter P. Wolter; Phillip A. Townsend

2011-01-01

The magnitude, duration, and frequency of forest disturbance caused by the spruce budworm and forest tent caterpillar in northern Minnesota and neighboring Ontario, Canada have increased over the last century due to a shift in forest species composition linked to historical fire suppression, forest management, and pesticide application that has fostered increased...

Ecological restoration of southwestern ponderosa pine ecosystems: A broad perspective

USGS Publications Warehouse

Allen, Craig D.; Savage, Melissa; Falk, Donald A.; Suckling, Kieran F.; Swetnam, Thomas W.; Schulke, Todd; Stacey, Peter B.; Morgan, Penelope; Hoffman, Martos; Klingel, Jon T.

2002-01-01

The purpose of this paper is to promote a broad and flexible perspective on ecological restoration of Southwestern (U.S.) ponderosa pine forests. Ponderosa pine forests in the region have been radically altered by Euro-American land uses, including livestock grazing, fire suppression, and logging. Dense thickets of young trees now abound, old-growth and biodiversity have declined, and human and ecological communities are increasingly vulnerable to destructive crown fires. A consensus has emerged that it is urgent to restore more natural conditions to these forests. Efforts to restore Southwestern forests will require extensive projects employing varying combinations of young-tree thinning and reintroduction of low-intensity fires. Treatments must be flexible enough to recognize and accommodate: high levels of natural heterogeneity; dynamic ecosystems; wildlife and other biodiversity considerations; scientific uncertainty; and the challenges of on-the-ground implementation. Ecological restoration should reset ecosystem trends toward an envelope of “natural variability,” including the reestablishment of natural processes. Reconstructed historic reference conditions are best used as general guides rather than rigid restoration prescriptions. In the long term, the best way to align forest conditions to track ongoing climate changes is to restore fire, which naturally correlates with current climate. Some stands need substantial structural manipulation (thinning) before fire can safely be reintroduced. In other areas, such as large wilderness and roadless areas, fire alone may suffice as the main tool of ecological restoration, recreating the natural interaction of structure and process. Impatience, overreaction to crown fire risks, extractive economics, or hubris could lead to widespread application of highly intrusive treatments that may further damage forest ecosystems. Investments in research and monitoring of restoration treatments are essential to refine restoration methods. We support the development and implementation of a diverse range of scientifically viable restoration approaches in these forests, suggest principles for ecologically sound restoration that immediately reduce crown fire risk and incrementally return natural variability and resilience to Southwestern forests, and present ecological perspectives on several forest restoration approaches.

Fire history of Everglades National Park and Big Cypress National Preserve, southern Florida

USGS Publications Warehouse

Smith, Thomas J.; Foster, Ann M.; Jones, John W.

2015-01-01

Fire has been used as a management tool in various ecosystems around the world. Prairies, grasslands, and savannas are fire-maintained ecosystems where fire is used to deter invasion by shrubs and trees (Grant and others, 2009; Scheintaub and others, 2009). Similarly, fire plays an important role in woodlands and forests by influencing species composition and succession such, as the use of fire in coniferous forests to prevent encroachment by hardwoods (Phillippe and others, 2011). Fire also has been used to manage wetland ecosystems for more than 50 years (Lynch, 1941; Frost, 1995). Uses have included returning marshes to early successional states, increasing forage for wildlife (Lynch, 1941). In all fire-influenced ecosystems, prescribed burns are routinely used to reduce fuel loads, reducing the possibility of catastrophic fires.

Avian community responses to post-fire forest structure: Implications for fire management in mixed conifer forests

USGS Publications Warehouse

White, Angela M.; Manley, Patricia N.; Tarbill, Gina; Richardson, T.L.; Russell, Robin E.; Safford, Hugh D.; Dobrowski, Solomon Z.

2015-01-01

Fire is a natural process and the dominant disturbance shaping plant and animal communities in many coniferous forests of the western US. Given that fire size and severity are predicted to increase in the future, it has become increasingly important to understand how wildlife responds to fire and post-fire management. The Angora Fire burned 1243 hectares of mixed conifer forest in South Lake Tahoe, California. We conducted avian point counts for the first 3 years following the fire in burned and unburned areas to investigate which habitat characteristics are most important for re-establishing or maintaining the native avian community in post-fire landscapes. We used a multi-species occurrence model to estimate how avian species are influenced by the density of live and dead trees and shrub cover. While accounting for variations in the detectability of species, our approach estimated the occurrence probabilities of all species detected including those that were rare or observed infrequently. Although all species encountered in this study were detected in burned areas, species-specific modeling results predicted that some species were strongly associated with specific post-fire conditions, such as a high density of dead trees, open-canopy conditions or high levels of shrub cover that occur at particular burn severities or at a particular time following fire. These results indicate that prescribed fire or managed wildfire which burns at low to moderate severity without at least some high-severity effects is both unlikely to result in the species assemblages that are unique to post-fire areas or to provide habitat for burn specialists. Additionally, the probability of occurrence for many species was associated with high levels of standing dead trees indicating that intensive post-fire harvest of these structures could negatively impact habitat of a considerable proportion of the avian community.

Estimating Effects of Brazilian Forest Wildfires on the Carbon Monoxide Concentration

NASA Astrophysics Data System (ADS)

Bhoi, S.; Qu, J.; Dasgupta, S.

2004-12-01

Forest wildfires have dramatically increased in recent years due to global warming and extreme dry conditions. Forest wildfires spew out a significant amount of atmospheric pollutants, such as carbon monoxide, due to incomplete burning of the biomass. According to United State Environmental Protection Agency (EPA), a high increase of carbon monoxide leads to the formation of carboxyhemoglobin in blood which decreases the oxygen intake capacity of human body and at moderate concentration angina, impaired vision and reduced brain function may occur. As compared to Northern America where significant amount of carbon monoxide released is caused by combustion devices and furnace, the increase of carbon monoxide concentration in Brazilian regions is mainly attributed to the forest fires. In this study, carbon monoxide datasets from the Measurements of pollution in the troposphere (MOPITT) have been analyzed to see the amount of increase in the carbon monoxide concentration after forest wildfires, ire, particularly in summer of 2003. The study reveals that there is a significant increase in the carbon monoxide concentration after forest fires.

A review of the main driving factors of forest fire ignition over Europe.

PubMed

Ganteaume, Anne; Camia, Andrea; Jappiot, Marielle; San-Miguel-Ayanz, Jesus; Long-Fournel, Marlène; Lampin, Corinne

2013-03-01

Knowledge of the causes of forest fires, and of the main driving factors of ignition, is an indispensable step towards effective fire prevention policies. This study analyses the factors driving forest fire ignition in the Mediterranean region including the most common human and environmental factors used for modelling in the European context. Fire ignition factors are compared to spatial and temporal variations of fire occurrence in the region, then are compared to results obtained in other areas of the world, with a special focus on North America (US and Canada) where a significant number of studies has been carried out on this topic. The causes of forest fires are varied and their distribution differs among countries, but may also differ spatially and temporally within the same country. In Europe, and especially in the Mediterranean basin, fires are mostly human-caused mainly due arson. The distance to transport networks and the distance to urban or recreation areas are among the most frequently used human factors in modelling exercises and the Wildland-Urban Interface is increasingly taken into account in the modelling of fire occurrence. Depending on the socio-economic context of the region concerned, factors such as the unemployment rate or variables linked to agricultural activity can explain the ignition of intentional and unintentional fires. Regarding environmental factors, those related to weather, fuel and topography are the most significant drivers of ignition of forest fires, especially in Mediterranean-type regions. For both human and lightning-caused fires, there is a geographical gradient of fire ignition, mainly due to variations in climate and fuel composition but also to population density for instance. The timing of fires depends on their causes. In populated areas, the timing of human-caused fires is closely linked to human activities and peaks in the afternoon whereas, in remote areas, the timing of lightning-caused fires is more linked to weather conditions and the season, with most such fires occurring in summer.

A Review of the Main Driving Factors of Forest Fire Ignition Over Europe

NASA Astrophysics Data System (ADS)

Ganteaume, Anne; Camia, Andrea; Jappiot, Marielle; San-Miguel-Ayanz, Jesus; Long-Fournel, Marlène; Lampin, Corinne

2013-03-01

Knowledge of the causes of forest fires, and of the main driving factors of ignition, is an indispensable step towards effective fire prevention policies. This study analyses the factors driving forest fire ignition in the Mediterranean region including the most common human and environmental factors used for modelling in the European context. Fire ignition factors are compared to spatial and temporal variations of fire occurrence in the region, then are compared to results obtained in other areas of the world, with a special focus on North America (US and Canada) where a significant number of studies has been carried out on this topic. The causes of forest fires are varied and their distribution differs among countries, but may also differ spatially and temporally within the same country. In Europe, and especially in the Mediterranean basin, fires are mostly human-caused mainly due arson. The distance to transport networks and the distance to urban or recreation areas are among the most frequently used human factors in modelling exercises and the Wildland-Urban Interface is increasingly taken into account in the modelling of fire occurrence. Depending on the socio-economic context of the region concerned, factors such as the unemployment rate or variables linked to agricultural activity can explain the ignition of intentional and unintentional fires. Regarding environmental factors, those related to weather, fuel and topography are the most significant drivers of ignition of forest fires, especially in Mediterranean-type regions. For both human and lightning-caused fires, there is a geographical gradient of fire ignition, mainly due to variations in climate and fuel composition but also to population density for instance. The timing of fires depends on their causes. In populated areas, the timing of human-caused fires is closely linked to human activities and peaks in the afternoon whereas, in remote areas, the timing of lightning-caused fires is more linked to weather conditions and the season, with most such fires occurring in summer.

The Habitat Susceptibility of Bali Starling (Leucopsar rothschildi Stresemann> 1912) Based on Forest Fire Vulnerability Mappin in West Bali National Park

NASA Astrophysics Data System (ADS)

Pramatana, F.; Prasetyo, L. B.; Rushayati, S. B.

2017-10-01

Bali starling is an endemic and endangered species which tend to decrease of its population in the wild. West Bali National Park (WBNP) is the only habitat of bali starling, however it is threatened nowadays by forest fire. Understanding the sensitivity of habitat to forest & land fire is urgently needed. Geographic Information System (GIS) can be used for mapping the vulnerability of forest fire. This study aims to analyze the contributed factor of forest fire, to develop vulnerability level map of forest fire in WBNP, to estimate habitat vulnerability of bali starling. The variable for mapping forest fire in WBNP were road distance, village distance, land cover, NDVI, NDMI, surface temperature, and slope. Forest fire map in WBNP was created by scoring from each variable, and classified into four classes of forest fire vulnerability which are very low (9 821 ha), low (5 015.718 ha), middle (6 778.656 ha), and high (2 126.006 ha). Bali starling existence in the middle and high vulnerability forest fire class in WBNP, consequently the population and habitat of bali starling is a very vulnerable. Management of population and habitat of bali starling in WBNP must be implemented focus on forest fire impact.

Decree No. 849/988 of 14 December 1988 setting forth regulations on the prevention and combat of forest fires.

PubMed

1989-01-01

This Uruguayan Decree sets forth regulations on the prevention and fighting of forest fires. Among other things, it does the following: 1) requires all public and private organizations, as well as all persons, to assist personally in and provide vehicles, machines, and tools for the fighting of forest fires; 2) requires the owners of property containing forests to maintain instruction in fighting fires for an adequate number of employees; 3) requires all forests to be kept cleared of vegetation capable of spreading fires and to have fire walls; 4) requires owners of forests larger than 30 hectares in size to present to the Forest Directorate an annual plan for forest fire defense; and 5) requires owners of forests larger than 30 hectares in size to maintain specified equipment for fighting fires. Persons violating the provisions of this Decree are subject to fines.

Fire effects in northeastern forests: red pine.

Treesearch

Cary Rouse

1988-01-01

Fire and red pine are closely associated. Fires can provide red pine with the mineral soil and freedom from competition it needs to become well established. Fire can also be used to control pests, increase tree growth, enhance aesthetics, and improve wildlife habitat.

Susceptibility of eastern U.S. habitats to invasion of Celastrus orbiculatus (oriental bittersweet) following fire

USGS Publications Warehouse

Leicht-Young, Stacey A.; Pavlovic, Noel B.; Grundel, Ralph

2013-01-01

Fire effects on invasive species are an important land management issue in areas subjected to prescribed fires as well as wildfires. These effects on invasive species can be manifested across life stages. The liana Celastrus orbiculatus (oriental bittersweet) is a widespread invader of eastern US habitats including those where fire management is in practice. This study examined if prescribed fire makes these habitats more susceptible to invasion of C. orbiculatus by seed at Indiana Dunes National Lakeshore. Four treatments (control, litter removed, high and low intensity fire) were applied in six habitat types (sand savanna/woodland, sand prairie, moraine prairie, sand oak forest, beech-maple forest, and oak-hickory forest) and germinating seedlings were tracked over two growing seasons. Treatment did not have a significant effect on the germination, survival, or biomass of C. orbiculatus. However, habitat type did influence these responses mostly in the first growing season. Moraine prairie, beech-maple forest, and oak-hickory forests had the greatest peak percentage of germinants. Moraine prairie had significantly greater survival than oak forest and savanna habitats. Control plots with intact litter, and the moraine prairie habitat had the tallest seedlings at germination, while tallest final heights and greatest aboveground biomass were highest in oak forest. Thus, fire and litter removal did not increase the susceptibility of these habitats to germination and survival of C. orbiculatus. These results indicate that most eastern US habitats are vulnerable to invasion by this species via seed regardless of the level or type of disturbance to the litter layer.

A numerical simulation study on the impact of smoke aerosols from Russian forest fires on the air pollution over Asia

NASA Astrophysics Data System (ADS)

Zhu, Qingzhe; Liu, Yuzhi; Jia, Rui; Hua, Shan; Shao, Tianbin; Wang, Bing

2018-06-01

Serious forest fires were observed over Siberia, particularly in the vast area between Lake Baikal and the Gulf of Ob, during the period of 18-27 July 2016 using Moderate Resolution Imaging Spectroradiometer (MODIS) data. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite simultaneously detected a multitude of smoke aerosols surrounding the same area. Combing a Lagrangian Flexible Particle dispersion model (FLEXPART) executed using the Weather Research and Forecasting (WRF) model output, the transport of smoke aerosols and the quantification of impact of Russian forest fires on the Asia were investigated. From model simulations, two transport paths were determined for the smoke plumes from the Russian forest fires. The first path was directed southwestward from Russia to Central Asia and eventually Xinjiang Province of China, furthermore, the second path was directed southeastward through Mongolia to Northeast China. The FLEXPART-WRF model simulations also revealed that the smoke aerosol concentrations entering the Central Asia, Mongolia and Northern China were approximately 60-300 μg m-3, 40-250 μg m-3 and 5-140 μg m-3, respectively. Meanwhile, the aerosol particles from these forest fires have an impact on the air quality in Asia. With the arrival of smoke aerosols from the Russian forest fires, the near-surface PM10 concentrations over Altay, Hulunbuir and Harbin increased to 61, 146 and 42 μg m-3, respectively. In conclusion, smoke aerosols from Russian forest fires can variably influence the air quality over Central Asia, Mongolia and Northern China.

The Impact of Tropical Peat Fire on Termite Assemblage in Sumatra, Indonesia: Reduced Complexity of Community Structure and Survival Strategies.

PubMed

Neoh, Kok-Boon; Bong, Lee-Jin; Muhammad, Ahmad; Itoh, Masayuki; Kozan, Osamu; Takematsu, Yoko; Yoshimura, Tsuyoshi

2016-10-01

Tropical peat swamp forests in Southeast Asia account for approximately 72% of global peatland. However, extensive forest exploitation following peat drainage for agricultural expansion has been leading to catastrophic peat fires. In this study, we compared the termite assemblage in burnt and unburnt peats in Sumatra, Indonesia. We also identified which taxonomic group is particularly resistant to fire disturbance and the traits that correlate with its persistence in fire-impacted peatlands. Overall, the termite species richness in fire-impacted peats was up to 40% lower than that of the total species found in peat swamp forests. Although the estimated species richness values in fire-impacted peats and peat swamp forests were not significantly different, fire changed termite community structure significantly. Only termites of the family Rhinotermitidae survived in the fire event, whereas members of the Termitidae that were reportedly resilient to fire and open habitats elsewhere disappeared during the fire events. The rhinotermitids found in the burnt sites were exclusively wood nesters. This suggests that the desiccation tolerance of termites in open habitat is not the simple underlying survival strategy, but tree branches and barks might have provided a refuge from heat during fire. The result also suggests that the high similarity in species composition in recently burnt peats and long burnt peats implies low species turnover. Thus, regardless of how much time had passed since the fire-impacted peats were abandoned or cultivated, the increase in habitat complexity did not favor colonization by the forest-dependent group. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

First steps towards a novel European forest fuel classification systems and a European forest fuel map

NASA Astrophysics Data System (ADS)

Sebastián-López, Ana; Urbieta, Itziar R.; de La Fuente Blanco, David; García Mateo, Rubén.; Moreno Rodríguez, José Manuel; Eftichidis, George; Varela, Vassiliki; Cesari, Véronique; Mário Ribeiro, Luís.; Viegas, Domingos Xavier; Lanorte, Antonio; Lasaponara, Rosa; Camia, Andrea; San Miguel, Jesús

2010-05-01

Forest fires burn at the local scale, but their massive occurrence causes effects which have global dimensions. Furthermore climate change projections associate global warming to a significant increase in forest fire activity. Warmer and drier conditions are expected to increase the frequency, duration and intensity of fires, and greater amounts of fuel associated with forest areas in decline may cause more frequent and larger fires. These facts create the need for establishing strategies for harmonizing fire danger rating, fire risk assessment, and fire prevention policies at a supranational level. Albeit forest fires are a permanent threat for European ecosystems, particularly in the south, there is no commonly accepted fuel classification scheme adopted for operational use by the Member States of the EU. The European Commission (EC) DG Environment and JRC have launched a set of studies following a resolution of the European Parliament on the further development and enhancement of the European Forest Fire Information System (EFFIS), the EC focal point for information on forest fires in Europe. One of the studies that are being funded is the FUELMAP project. The objective of FUELMAP is to develop a novel fuel classification system and a new European fuel map that will be based on a comprehensive classification of fuel complexes representing the various vegetation types across EU27, plus Switzerland, Croatia and Turkey. The overall work plan is grounded on a throughout knowledge of European forest landscapes and the key features of fuel situations occurring in natural areas. The method makes extended use of existing databases available in the Member States and European Institutions. Specifically, our proposed classification combines relevant information on ecoregions, land cover and uses, potential and actual vegetation, and stand structure. GIS techniques are used in order to define the geographic extent of the classification units and for identifying the main driving factors that determine the spatial distribution of the resulting fuel complexes. Furthermore, relevant parameters influencing fire potential and effects such as fuel load, live/dead ratio, and fuels' size classes' distribution are considered. National- and local-scale datasets (vegetation maps, forest inventory plots, fuel maps...) will be also studied and compared. Local ground- truth data will be used to assess the accuracy of the classification and will contribute, along with literature values and experts' opinion, to characterize the fuels' physical properties. The resulting classification aims to support the characterization of the fire potential, serve as input in fire emissions models, and be used to assess the expected impact of fire in the European landscapes. The work plan includes the development of a GIS software tool to automatically update the fuel map from modified (up-to-date) input data layers. The fuel map of Europe is mainly intended to support the implementation of the EFFIS modules that can be enhanced by the use of improved information on forest fuel properties and spatial distribution, though it is also envisaged that the results of the project might be useful for other relevant applications at different spatial scales. To this purpose, the classification will be designed with a hierarchical and flexible structure for describing heterogeneous landscapes. The work is on-going and this presentation shows the first results towards the envisaged European fuel map.

Fire ecology of forests and woodlands in Utah

Treesearch

Anne F. Bradley; Nonan V. Noste; William C. Fischer

1992-01-01

Provides information on fire as an ecological factor in forest habitat types, and in pinyon-juniper woodland and oak-maple brushland communities occurring in Utah. Identifies Fire Groups based on fire's role in forest succession. Describes forest fuels and suggests considerations for fire management.

Fire ecology of the forest habitat types of eastern Idaho and western Wyoming

Treesearch

Anne F. Bradley; William C. Fischer; Nonan V. Noste

1992-01-01

Provides information on fire as an ecological factor in the forest habitat types occurring in eastern Idaho and western Wyoming. Identifies Fire Groups based on fire's role in forest succession. Describes forest fuels and suggests considerations for fire management.

Impact of forest fires on particulate matter and ozone levels during the 2003, 2004 and 2005 fire seasons in Portugal.

PubMed

Martins, V; Miranda, A I; Carvalho, A; Schaap, M; Borrego, C; Sá, E

2012-01-01

The main purpose of this work is to estimate the impact of forest fires on air pollution applying the LOTOS-EUROS air quality modeling system in Portugal for three consecutive years, 2003-2005. Forest fire emissions have been included in the modeling system through the development of a numerical module, which takes into account the most suitable parameters for Portuguese forest fire characteristics and the burnt area by large forest fires. To better evaluate the influence of forest fires on air quality the LOTOS-EUROS system has been applied with and without forest fire emissions. Hourly concentration results have been compared to measure data at several monitoring locations with better modeling quality parameters when forest fire emissions were considered. Moreover, hourly estimates, with and without fire emissions, can reach differences in the order of 20%, showing the importance and the influence of this type of emissions on air quality. Copyright © 2011 Elsevier B.V. All rights reserved.

Simulating effects of fire disturbance and climate change on boreal forest productivity and evapotranspiration.

PubMed

Kang, Sinkyu; Kimball, John S; Running, Steven W

2006-06-01

We used a terrestrial ecosystem process model, BIOME-BGC, to investigate historical climate change and fire disturbance effects on regional carbon and water budgets within a 357,500 km(2) portion of the Canadian boreal forest. Historical patterns of increasing atmospheric CO2, climate change, and regional fire activity were used as model drivers to evaluate the relative effects of these impacts to spatial patterns and temporal trends in forest net primary production (NPP) and evapotranspiration (ET). Historical trends of increasing atmospheric CO2 resulted in overall 13% and 5% increases in annual NPP and ET from 1994 to 1996, respectively. NPP was found to be relatively sensitive to changes in air temperature (T(a)), while ET was more sensitive to precipitation (P) change within the ranges of observed climate variability (e.g., +/-2 degrees C for T(a) and +/-20% for P). In addition, the potential effect of climate change related warming on NPP is exacerbated or offset depending on whether these changes are accompanied by respective decreases or increases in precipitation. Historical fire activity generally resulted in reductions of both NPP and ET, which consumed an average of approximately 6% of annual NPP from 1959 to 1996. Areas currently occupied by dry conifer forests were found to be subject to more frequent fire activity, which consumed approximately 8% of annual NPP. The results of this study show that the North American boreal ecosystem is sensitive to historical patterns of increasing atmospheric CO2, climate change and regional fire activity. The relative impacts of these disturbances on NPP and ET interact in complex ways and are spatially variable depending on regional land cover and climate gradients.

Assessment of Burned Area and Atmospheric Gases from Multi- temporal MODIS Images (2000- 2017) in Nainital District, Uttarakhand

NASA Astrophysics Data System (ADS)

Aggarwal, R.; K V, S. B.; Dhakate, P. M.

2017-12-01

Recent times have observed a significant rate of deforestation and forest degradation. One of the major causes of forest degradation is forest fires. Forest fires though have shaped the current forest ecosystem but also have continued to degrade the system by causing loss of flora and fauna. In addition to that, forest fire leads to emission of carbon and other trace gases which contributes to global warming. The hill states in India, particularly Uttarakhand witnesses annual forest fires; which are primarily anthropogenic caused, occurring from March to June. Nainital one of the thirteen districts in Uttarakhand, has been selected as the study site. The region has diverse endemic species of vegetation, ranging from Alpine in North to moist deciduous in South. The increasing forest fire incidents in the region and limited studies on the subject, calls for landscape assessment of the complex Human Environment System (HES). It is in this context, that a greater need for monitoring forest fire incidents has been felt. Remote Sensing and GIS which are robust tool, provides continuous information of an area at various spatial and temporal resolutions. The goal of this study is to map burned area, burned severity and estimate atmospheric gas emissions in forested areas of Nainital by utilizing cloud free MODIS images from 2000- 2017. Multiple spectral indices were generated from pre and post burn dataset of MODIS to conclude the most sensitive band combination. Inter- comparison of results obtained from different spectral indices and the global MODIS MCD45A1 was carried out using linear regression analysis. Additionally, burned area estimation from satellite was compared to figures reported by forest department. There were considerable differences amongst the two which could be primarily due to differences in spatial resolution, and timings of forest fire occurrence and image acquisition. Further, estimation of various atmospheric gases was carried out based on the IPCC guidelines. Such an analysis is critically important for designing of relevant forest fire mitigation strategies. The study signifies that long term MODIS data and the rationing method is an effective technique to map and monitor the burned area, burned severity and atmospheric gas emission in the forested regions of Himalayan.

Hydrologic responses to restored wildfire regimes revealed by soil moisture-vegetation relationships

NASA Astrophysics Data System (ADS)

Boisramé, Gabrielle; Thompson, Sally; Stephens, Scott

2018-02-01

Many forested mountain watersheds worldwide evolved with frequent fire, which Twentieth Century fire suppression activities eliminated, resulting in unnaturally dense forests with high water demand. Restoration of pre-suppression forest composition and structure through a variety of management activities could improve forest resilience and water yields. This study explores the potential for "managed wildfire", whereby naturally ignited fires are allowed to burn, to alter the water balance. Interest in this type of managed wildfire is increasing, yet its long-term effects on water balance are uncertain. We use soil moisture as a spatially-distributed hydrologic indicator to assess the influence of vegetation, fire history and landscape position on water availability in the Illilouette Creek Basin in Yosemite National Park. Over 6000 manual surface soil moisture measurements were made over a period of three years, and supplemented with continuous soil moisture measurements over the top 1m of soil in three sites. Random forest and linear mixed effects models showed a dominant effect of vegetation type and history of vegetation change on measured soil moisture. Contemporary and historical vegetation maps were used to upscale the soil moisture observations to the basin and infer soil moisture under fire-suppressed conditions. Little change in basin-averaged soil moisture was inferred due to managed wildfire, but the results indicated that large localized increases in soil moisture had occurred, which could have important impacts on local ecology or downstream flows.

Do fire and insects interact in eastern forests?

Treesearch

Lynne K. Rieske-Kinney

2006-01-01

The increasing use of prescribed fire as a management strategy for manipulating forest-species composition generates questions regarding the effects on the arthropod community and the underlying processes in which arthropods play a dominant role, as well as its potential as a pest suppression strategy. Despite the apparent benefits of prescribed burning for...

Restoring fire to mixed conifer forests in the Northern Cascades

Treesearch

T. J. Leuschen

1996-01-01

Many of the ponderosa pine (Pinus ponderosa) mixed conifer stands in the Methow Valley of north-central Washington have developed understories of Douglas-fir (Pseudotsuga rnenziesii) as a result of fire exclusion. Most of the forest floor has not yet become cluttered with dead woody fuel. Instead, the live biomass has increased and...

Comparing Effects of Climate Warming, Fire, and Timber Harvesting on a Boreal Forest Landscape in Northeastern China

PubMed Central

Li, Xiaona; He, Hong S.; Wu, Zhiwei; Liang, Yu; Schneiderman, Jeffrey E.

2013-01-01

Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1–40 years), early stage (41–80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest. PMID:23573209

Simulating the impacts of fire: A computer program

NASA Astrophysics Data System (ADS)

Ffolliott, Peter F.; Guertin, D. Phillip; Rasmussen, William D.

1988-11-01

Recurrent fire has played a dominant role in the ecology of southwestern ponderosa pine forests. To assess the benefits or losses of fire in these forests, a computer simulation model, called BURN, considers vegetation (mortality, regeneration, and production of herbaceous vegetation), wildlife (populations and habitats), and hydrology (streamflow and water quality). In the formulation of the model, graphical representations (time-trend response curves) of increases or losses (compared to an unburned control) after the occurrence of fire are converted to fixedterm annual ratios, and then annuities for the simulation components. Annuity values higher than 1.0 indicate benefits, while annuity values lower than 1.0 indicate losses. Studies in southwestern ponderosa pine forests utilized in the development of BURN are described briefly.

Estimation of wildfire size and risk changes due to fuels treatments

USGS Publications Warehouse

Cochrane, M.A.; Moran, C.J.; Wimberly, M.C.; Baer, A.D.; Finney, M.A.; Beckendorf, K.L.; Eidenshink, J.; Zhu, Z.

2012-01-01

Human land use practices, altered climates, and shifting forest and fire management policies have increased the frequency of large wildfires several-fold. Mitigation of potential fire behaviour and fire severity have increasingly been attempted through pre-fire alteration of wildland fuels using mechanical treatments and prescribed fires. Despite annual treatment of more than a million hectares of land, quantitative assessments of the effectiveness of existing fuel treatments at reducing the size of actual wildfires or how they might alter the risk of burning across landscapes are currently lacking. Here, we present a method for estimating spatial probabilities of burning as a function of extant fuels treatments for any wildland fire-affected landscape. We examined the landscape effects of more than 72 000 ha of wildland fuel treatments involved in 14 large wildfires that burned 314 000 ha of forests in nine US states between 2002 and 2010. Fuels treatments altered the probability of fire occurrence both positively and negatively across landscapes, effectively redistributing fire risk by changing surface fire spread rates and reducing the likelihood of crowning behaviour. Trade offs are created between formation of large areas with low probabilities of increased burning and smaller, well-defined regions with reduced fire risk.

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure

PubMed Central

Miquelajauregui, Yosune; Cumming, Steven G.; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity. PMID:26919456

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure.

PubMed

Miquelajauregui, Yosune; Cumming, Steven G; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity.

The role of wildfires and forest succession in stream biogeochemistry within the continuous permafrost zone of Central Siberia

NASA Astrophysics Data System (ADS)

Prokushkin, Anatoly

2016-04-01

Wildfires transform boreal and subarctic forested landscapes leading to the changes in organic matter and inorganic nutrient turnover in terrestrial ecosystems. To get an insight to the fire effect on C fluxes and general hydrochemical characteristics of streams draining continuous permafrost terrains of Central Siberian Plateau (64o N 100o E), we have selected the chronosequence of basins (n = 17) which were severely affected by fires (>80% of basin area) in the time range from 1 to 116 years ago. Stream waters were sampled continuously during frost free seasons (May-September) of 2006-2015. Four streams have been equipped with water level, temperature and conductivity probes for continuous monitoring. The strongest negative effect of wildfires on dissolved organic carbon (DOC) concentrations in streams has occurred right after a fire event, and minimum mean annual concentrations of DOC appeared between 15 and 20 years elapsed after a fire. The most pronounced decrease in DOC concentrations during an annual cycle found in freshet period (May-June) and summer-fall storm events: differences of DOC concentrations among "intact" (>100 years after fire) and recent fire basins (<6 years) reached as much as 2-fold. Less differentiation among basins appears under lowflow conditions, as DOC-depleted solutes from deeper soil layers become dominating in stream flow. Following the post-fire forest recovery, the seasonal mean DOC concentrations in streams demonstrated linear growth at the rate of ca. 0.11 mgC/l/a and approached the initial values already after ca. 60 years after fire disturbance. An opposite trend (i.e. increasing load to streams after fire impact) was observed for dissolved inorganic carbon, major anions and cations. Sulfate was found to be a good tracer of fire affect as increased 200-fold in stream waters right after a fire and steady decreased at the rate [SO42-] = 3.65 x (year after fire)^-0.75 as terrestrial ecosystems were recovering after a fire. For study area, Na+ and Cl- in streams appear to be good indicators of permafrost degradation as they reflect talik formation and connection of a stream to underlying evaporitic deposits. While evidence of permafrost degradation is currently not apparent in the region, we expect increasing concentrations of Na+ and Cl- in streams of Central Siberian Plateau as permafrost degrades due to decreased fire return interval and warming temperatures. The generalized data of active layer thickness (ALT) within analyzed watersheds have demonstrated that fire-driven deepening of ALT results in increasing stream inorganic compounds concentrations. The inverse relationship found between DOC and ALT might be attributed to deeper infiltration of solutions, sorption of DOC on clay minerals, and an increasing rate of DOC microbiological mineralization to CO2 due to increased soil temperatures. Post-fire forest recovery and, particularly, the accumulation of organic mater in the moss-lichen layer and soil organic horizon on watersheds accounted for increasing mean DOC concentrations in the streams. In opposite, increased insulation of soils by organic matter accumulating on the soil surface leads to steadily decreasing ALT and constrains an infiltration of solutes to subsoil. As a result, inorganic solute loading to stream channels is tended to decrease during post-fire forest succession in permafrost affected terrains.

Main dynamics and drivers of boreal forests fire regimes during the Holocene

NASA Astrophysics Data System (ADS)

Molinari, Chiara; Lehsten, Veiko; Blarquez, Olivier; Clear, Jennifer; Carcaillet, Christopher; Bradshaw, Richard HW

2015-04-01

Forest fire is one of the most critical ecosystem processes in the boreal megabiome, and it is likely that its frequency, size and severity have had a primary role in vegetation dynamics since the Last Ice Age (Kasischke & Stocks 2000). Fire not only organizes the physical and biological attributes of boreal forests, but also affects biogeochemical cycling, particularly the carbon balance (Balshi et al. 2007). Due to their location at climatically sensitive northern latitudes, boreal forests are likely to be significantly affected by global warming with a consequent increase in biomass burning (Soja et al. 2007), a variation in vegetation structure and composition (Johnstone et al. 2004) and a rise in atmospheric carbon dioxide concentration (Bond-Lamberty et al. 2007). Even if the ecological role of wildfire in boreal forest is widely recognized, a clearer understanding of the environmental factors controlling fire dynamics and how variations in fire regimes impact forest ecosystems is essential in order to place modern fire processes in a meaningful context for projecting ecosystem behaviour in a changing environment (Kelly et al. 2013). Because fire return intervals and successional cycles in boreal forests occur over decadal to centennial timescales (Hu et al. 2006), palaeoecological research seems to be one of the most promising tool for elucidating ecosystem changes over a broad range of environmental conditions and temporal scales. Within this context, our first aim is to reconstruct spatial and temporal patterns of boreal forests fire dynamics during the Holocene based on sedimentary charcoal records. As a second step, trends in biomass burning will be statistically analysed in order to disentangle between regional and local drivers. The use of European and north-American sites will give us the unique possibility to perform a large scale analysis on one of the broadest biome in the world and to underline the different patterns of fire in these two continents. Balshi MS, McGuire AD, Zhuang Q et al. (2007) The role of historical fire disturbance in the carbon dynamics of the pan-boreal region: A process-based analysis. J. Geophys. Res. 112:G2. Bond-Lamberty B, Peckham SD, Ahl DE et al. (2007) Fire as the dominant driver of central Canadian boreal forest carbon balance. Nature 450: 89-92. Hu FS, Brubaker LB, Gavin DG et al. (2006) How climate and vegetation influence the fire regime of the Alaskan boreal biome: the Holocene perspective. Mitigation Adapt. Strateg. Glob. Chang. 11: 829-846. Johnstone JF, Chapin III FS, Foote J et al. (2004) Decadal observations of tree regeneration following fire in boreal forests. Can. J. For. Res. 34: 267-273. Kasischke ES & Stocks BJ (2000) Fire, Climate Change and Carbon Cycling in the Boreal Forest. Ecological Studies 138, Springer-Verlag, New York. Kelly RF, Chipman ML, Higuera PE et al. (2013) Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years. Proc. Natl. Acad. Sci. U.S.A. 110: 13055-13060. Soja AJ, Tchebakova NM, French NHF et al. (2007) Climate-induced boreal forest change: predictions versus current observations. Glob. Planet. Chang. 56: 274-296.

Fire ecology of Montana forest habitat types east of the Continental Divide

Treesearch

William C. Fischer; Bruce D. Clayton

1983-01-01

Provides information on fire as an ecological factor for forest habitat types occurring east of the Continental Divide in Montana. Identifies "Fire Groups" of habitat types based on fire's role in forest succession. Describes forest fuels and suggests considerations for fire management.

Prescribed fires effects on physico-chemical properties and quantity of runoff and soil erosion in a Mediterranean forest

NASA Astrophysics Data System (ADS)

Esteban Lucas-Borja, Manuel; Plaza Alvaréz, Pedro Antonio; Sagra, Javier; Alfaro Sánchez, Raquel; Moya, Daniel; Ferrandiz Gotor, Pablo; De las Heras Ibañez, Jorge

2017-04-01

Wildfires have an important influence in forest ecosystems. Contrary to high severity fire, which may have negative impacts on the ecosystems, low severity induce small changes on soil properties. Thus and in order to reduce fire risk, low-severity prescribed fires have been widely used as a fuel reduction tool and silvicultural treatment in Mediterranean forest ecosystems. However, fire may alter microsite conditions and little is known about the impact of prescribed burning on the physico-chemical properties of runoff. In this study, we compared the effects of prescribed burning on physico-chemical properties and quantity of runoff and soil erosion during twelve months after a low severity prescribed fire applied in twelve 16 m2 plot (6 burned plots and 6 control plots used for comparison) set up in the Lezuza forest (Albacete, central-eastern Spain). Physico-chemical properties and quantity of runoff and soil losses were monitored after each rainfall event (five rainfall events in total). Also, different forest stand characteristics (slope, tree density, basal area and shrub/herbal cover) affecting each plot were measured. Results showed that forest stand characteristics were very similar in all used plots. Also, physico-chemical runoff properties were highly modified after the prescribed fire, increasing water pH, carbonates, bicarbonates, total dissolved solids and organic matter content dissolved in water. Electrical conductivity, calcium, sodium, chloride and magnesium were not affected by prescribed fire. Soil losses were highly related to precipitation intensity and tree interception. Tree intercepted the rainfall and significantly reduced soil losses and also runoff quantity. In conclusion and after the first six-month experiment, the influence of prescribed fires on physico-chemical runoff properties should be taken into account for developing proper prescribed burnings guidelines.

Forest restoration treatments have subtle long-term effects on soil C and N cycling in mixed conifer forests.

PubMed

Ganzlin, Peter W; Gundale, Michael J; Becknell, Rachel E; Cleveland, Cory C

2016-07-01

Decades of fire suppression following extensive timber harvesting have left much of the forest in the intermountain western United States exceedingly dense, and forest restoration techniques (i.e., thinning and prescribed fire) are increasingly being used in an attempt to mitigate the effects of severe wildfire, to enhance tree growth and regeneration, and to stimulate soil nutrient cycling. While many of the short-term effects of forest restoration have been established, the long-term effects on soil biogeochemical and ecosystem processes are largely unknown. We assessed the effects of commonly used forest restoration treatments (thinning, burning, and thinning + burning) on nutrient cycling and other ecosystem processes 11 yr after restoration treatments were implemented in a ponderosa pine (Pinus ponderosa var. scopulorum)/Douglas fir (Pseudotsuga menziesii var. glauca) forest at the Lubrecht Fire and Fire Surrogates Study (FFS) site in western Montana, USA. Despite short-term (<3 yr) increases in soil inorganic nitrogen (N) pools and N cycling rates following prescribed fire, long-term soil N pools and N mineralization rates showed only subtle differences from untreated control plots. Similarly, despite a persistent positive correlation between fuels consumed in prescribed burns and several metrics of N cycling, variability in inorganic N pools decreased significantly since treatments were implemented, indicating a decline in N spatial heterogeneity through time. However, rates of net nitrification remain significantly higher in a thin + burn treatment relative to other treatments. Short-term declines in forest floor carbon (C) pools have persisted in the thin + burn treatment, but there were no significant long-term differences among treatments in extractable soil phosphorus (P). Finally, despite some short-term differences, long-term foliar nutrient concentrations, litter decomposition rates, and rates of free-living N fixation in the experimental plots were not different from control plots, suggesting nutrient cycles and ecosystem processes in temperate coniferous forests are resilient to disturbance following long periods of fire suppression. Overall, this study provides forest managers and policymakers valuable information showing that the effects of these commonly used restoration prescriptions on soil nutrient cycling are ephemeral and that use of repeated treatments (i.e., frequent fire) will be necessary to ensure continued restoration success. © 2016 by the Ecological Society of America.

Landscape anthropogenic disturbance in the Mediterranean ecosystem: is the current landscape sustainable?

NASA Astrophysics Data System (ADS)

Biondi, Guido; D'Andrea, Mirko; Fiorucci, Paolo; Franciosi, Chiara; Lima, Marco

2013-04-01

Mediterranean landscape during the last centuries has been subject to strong anthropogenic disturbances who shifted natural vegetation cover in a cultural landscape. Most of the natural forest were destroyed in order to allow cultivation and grazing activities. In the last century, fast growing conifer plantations were introduced in order to increase timber production replacing slow growing natural forests. In addition, after the Second World War most of the grazing areas were changed in unmanaged mediterranean conifer forest frequently spread by fires. In the last decades radical socio economic changes lead to a dramatic abandonment of the cultural landscape. One of the most relevant result of these human disturbances, and in particular the replacement of deciduous forests with coniferous forests, has been the increasing in the number of forest fires, mainly human caused. The presence of conifers and shrubs, more prone to fire, triggered a feedback mechanism that makes difficult to return to the stage of potential vegetation causing huge economic, social and environmental damages. The aim of this work is to investigate the sustainability of the current landscape. A future landscape scenario has been simulated considering the natural succession in absence of human intervention assuming the current fire regime will be unaltered. To this end, a new model has been defined, implementing an ecological succession model coupled with a simply Forest Fire Model. The ecological succession model simulates the vegetation dynamics using a rule-based approach discrete in space and time. In this model Plant Functional Types (PFTs) are used to describe the landscape. Wildfires are randomly ignited on the landscape, and their propagation is simulated using a stochastic cellular automata model. The results show that the success of the natural succession toward a potential vegetation cover is prevented by the frequency of fire spreading. The actual landscape is then unsustainable because of the high cost of fire fighting activities. The right path to success consists in development of suitable land use planning and forest management to mitigate the consequences of past anthropogenic disturbances.

Mixed-severity fire history at a forest-grassland ecotone in west central British Columbia, Canada.

PubMed

Harvey, Jill E; Smith, Dan J; Veblen, Thomas T

2017-09-01

This study examines spatially variable stand structure and fire-climate relationships at a low elevation forest-grassland ecotone in west central British Columbia, Canada. Fire history reconstructions were based on samples from 92 fire-scarred trees and stand demography from 27 plots collected over an area of about 7 km 2 . We documented historical chronologies of widespread fires and localized grassland fires between AD 1600 and 1900. Relationships between fire events, reconstructed values of the Palmer Drought Severity Index, and annual precipitation were examined using superposed epoch and bivariate event analyses. Widespread fires occurred during warm, dry years and were preceded by multiple anomalously dry, warm years. Localized fires that affected only grassland-proximal forests were more frequent than widespread fires. These localized fires showed a lagged, positive relationship with wetter conditions. The landscape pattern of forest structure provided further evidence of complex fire activity with multiple plots shown to have experienced low-, mixed-, and/or high-severity fires over the last four centuries. We concluded that this forest-grassland ecotone was characterized by fires of mixed severity, dominated by frequent, low-severity fires punctuated by widespread fires of moderate to high severity. This landscape-level variability in fire-climate relationships and patterns in forest structure has important implications for fire and grassland management in west central British Columbia and similar environments elsewhere. Forest restoration techniques such as prescribed fire and thinning are oftentimes applied at the forest-grassland ecotone on the basis that historically high frequency, low-severity fires defined the character of past fire activity. This study provides forest managers and policy makers with important information on mixed-severity fire activity at a low elevation forest-grassland ecotone, a crucial prerequisite for the effective management of these complex ecosystems. © 2017 by the Ecological Society of America.

Influence of landscape structure, topography, and forest type on spatial variation in historical fire regimes, central Oregon, USA

USGS Publications Warehouse

Merschel, Andrew; Heyerdahl, Emily K.; Spies, Thomas A; Loehman, Rachel A.

2018-01-01

Context In the interior Northwest, debate over restoring mixed-conifer forests after a century of fire exclusion is hampered by poor understanding of the pattern and causes of spatial variation in historical fire regimes. Objectives To identify the roles of topography, landscape structure, and forest type in driving spatial variation in historical fire regimes in mixed-conifer forests of central Oregon. Methods We used tree rings to reconstruct multicentury fire and forest histories at 105 plots over 10,393 ha. We classified fire regimes into four types and assessed whether they varied with topography, the location of fuel-limited pumice basins that inhibit fire spread, and an updated classification of forest type. Results We identified four fire-regime types and six forest types. Although surface fires were frequent and often extensive, severe fires were rare in all four types. Fire regimes varied with some aspects of topography (elevation), but not others (slope or aspect) and with the distribution of pumice basins. Fire regimes did not strictly co-vary with mixed-conifer forest types. Conclusions Our work reveals the persistent influence of landscape structure on spatial variation in historical fire regimes and can help inform discussions about appropriate restoration of fire-excluded forests in the interior Northwest. Where the goal is to restore historical fire regimes at landscape scales, managers may want to consider the influence of topoedaphic and vegetation patch types that could affect fire spread and ignition frequency.

Air pollution increases forest susceptibility to wildfires: a case study for the San Bernardino Mountains in southern California

Treesearch

N.E. Grulke; R.A. Minnich; T. Paine; P. Riggan

2010-01-01

Many factors increase susceptibility of forests to wildfire. Among them are increases in human population, changes in land use, fire suppression, and frequent droughts. These factors have been exacerbating forest susceptibility to wildfires over the last century in southern California. Here we report on the significant role that air pollution has on increasing forest...

A conceptual framework for predicting temperate ecosystem sensitivity to human impacts on fire regimes

Treesearch

D. B. McWethy; P. E. Higuera; C. Whitlock; T. T. Veblen; D. M. J. S. Bowman; G. J. Cary; S. G. Haberle; R. E. Keane; B. D. Maxwell; M. S. McGlone; G. L. W. Perry; J. M. Wilmshurst

2013-01-01

The increased incidence of large fires around much of the world in recent decades raises questions about human and non-human drivers of fire and the likelihood of increased fire activity in the future. The purpose of this paper is to outline a conceptual framework for examining where human-set fires and feedbacks are likely to be most pronounced in temperate forests...

Assessing crown fire potential by linking models of surface and crown fire behavior

Treesearch

Joe H. Scott; Elizabeth D. Reinhardt

2001-01-01

Fire managers are increasingly concerned about the threat of crown fires, yet only now are quantitative methods for assessing crown fire hazard being developed. Links among existing mathematical models of fire behavior are used to develop two indices of crown fire hazard-the Torching Index and Crowning Index. These indices can be used to ordinate different forest...

Frequent fire protects shortleaf pine (Pinus echinata) from introgression by loblolly pine (P. taeda).

Treesearch

John F Stewart; Rodney E Will; Kevin M Robertson; Dana Nelson

2014-01-01

Across much of the globe, fire is a major disturbance agent of forest and grassland communities. The removal of fire from previously fire-maintained ecosystems, which has occurred in many areas, changes species composition, favoring later less fire tolerant species over fire-adapted ones. A recent measured increase in the rate of hybridization between the fire-adapted...

The demise of fire and "mesophication" of forests in the eastern United States

Treesearch

Gregory J. Nowacki; Marc D. Abrams

2008-01-01

A diverse array of fire-adapted plant communities once covered the eastern United States. European settlement greatly altered fire regimes, often increasing fire occurrence (e.g., in northern hardwoods) or substantially decreasing it (e.g., in tallgrass prairies). Notwithstanding these changes, fire suppression policies, beginning around the 1920s, greatly reduced fire...

Impact of the 2002 Canadian forest fires on particulate matter air quality in Baltimore city.

PubMed

Sapkota, Amir; Symons, J Morel; Kleissl, Jan; Wang, Lu; Parlange, Marc B; Ondov, John; Breysse, Patrick N; Diette, Gregory B; Eggleston, Peyton A; Buckley, Timothy J

2005-01-01

With increasing evidence of adverse health effects associated with particulate matter (PM), the exposure impact of natural sources, such as forest fires, has substantial public health relevance. In addition to the threat to nearby communities, pollutants released from forest fires can travel thousands of kilometers to heavily populated urban areas. There was a dramatic increase in forest fire activity in the province of Quebec, Canada, during July 2002. The transport of PM released from these forest fires was examined using a combination of a moderate-resolution imaging spectroradiometer satellite image, back-trajectories using a hybrid single-particle Lagrangian integrated trajectory, and local light detection and ranging measurements. Time- and size-resolved PM was evaluated at three ambient and four indoor measurement sites using a combination of direct reading instruments (laser, time-of-flight aerosol spectrometer, nephelometer, and an oscillating microbalance). The transport and monitoring results consistently identified a forest fire related PM episode in Baltimore that occurred the first weekend of July 2002 and resulted in as much as a 30-fold increase in ambientfine PM. On the basis of tapered element oscillating microbalance measurements, the 24 h PM25 concentration reached 86 microg/m3 on July 7, 2002, exceeding the 24 h national ambient air quality standard. The episode was primarily comprised of particles less than 2.5 microm in aerodynamic diameter, highlighting the preferential transport of the fraction of PM that is of greatest health concern. Penetration of the ambient episode indoors was efficient (median indoor-to-outdoor ratio 0.91) such that the high ambient levels were similarly experienced indoors. These results are significant in demonstrating the impact of a natural source thousands of kilometers away on ambient levels of and potential exposures to air pollution within an urban center. This research highlights the significance of transboundary air pollution and the need for studies that assess the public health impacts associated with such sources and transport processes.

Climate, fire size, and biophysical setting control fire severity and spatial pattern in the northern Cascade Range, USA

Treesearch

C. Alina Cansler; Donald. McKenzie

2014-01-01

Warmer and drier climate over the past few decades has brought larger fire sizes and increased annual area burned in forested ecosystems of western North America, and continued increases in annual area burned are expected due to climate change. As warming continues, fires may also increase in severity and produce larger contiguous patches of severely burned areas. We...

Dalmatian toadflax, an invasive exotic noxious weed, threatens Flagstaff pennyroyal community following prescribed fire

Treesearch

Barbara Goodrich Phillips; Debra Crisp

2001-01-01

Many noxious weed infestations are initiated or increased by soil disturbance. With the recent emphasis on reintroduction of fire into natural ecosystems there has been increased interest in the effects of noxious weeds following fires. This paper discusses the effects of fire on Flagstaff pennyroyal, a Forest Service Region 3 sensitive plant, and the subsequent...

Evidence of fuels management and fire weather influencing fire severity in an extreme fire event

Treesearch

Jamie M. Lydersen; Brandon M. Collins; Matthew L. Brooks; John R. Matchett; Kristen L. Shive; Nicholas A. Povak; Van R. Kane; Douglas F. Smith

2017-01-01

Following changes in vegetation structure and pattern, along with a changing climate, large wildfire incidence has increased in forests throughout the western U.S. Given this increase there is great interest in whether fuels treatments and previous wildfire can alter fire severity patterns in large wildfires. We assessed the relative influence of previous fuels...

Nitrogen mineralization in aspen/conifer soils after a natural fire

Treesearch

Michael C. Amacher; Dale L. Bartos; Tracy Christopherson; Amber D. Johnson; Debra E. Kutterer

2001-01-01

We measured the effects of the 1996 Pole Creek fire, Fishlake National Forest, Utah, on available soil N and net N mineralization for three summers after the fire using an ion exchange membrane (IEM) soil core incubation method. Fire in mixed aspen/conifer increased the amount of available NH4, and a subsequent net increase in soil nitrification was observed. Release...

Diversity in Southwesterners' views of Forest Service fire management

Treesearch

P.L. Winter; G.T. Cvetkovich

2007-01-01

The risk of wildland fires is of significant concern in the southwestern United States. Although the Southwest has a long hi story as a fire· prone ecosystem, years of drought and insect infestation have increased fire risk. Paired with these ecological forces is the increased risk caused by the concentration of populations in the wildland urban interface (WUl),...

Long term effects of fire on the carbon balance in boreal forests

NASA Astrophysics Data System (ADS)

Berninger, Frank; Köster, Kaja; Pumpanen, Jukka

2013-04-01

Fire is the primary process which organizes the physical and biological attributes of the boreal biome and influences energy flows and biogeochemical cycles, particularly the carbon and nitrogen cycle. We established a forest fire chronosequence in the northern boreal forest in Lapland (Värriö Strict Nature Reserve), Finland (67°46' N, 29°35' E) that spans 160 years. Soil organic matter and its turnover were measured in and ex situ, as well as biomass of trees. The fungal biomass was assessed using soil ergosterol contents. The results indicate that fires slow down the turnover of soil organic matter for a period of at least 50 years. The turnover rate in recently burnt sites was only half of the turnover of the old forest site. Decreases in the turnover where still substantial 50 years after fire. The slow recovery of fungal biomass after fires seems to be the cause of the decrease since sites with a higher concentration of fungal biomass in the soils had shorter soil organic matter turnover rates. Increases in stand foliar biomass were less important for the turnover of soil organic matter. We tried to explore the potential importance of our finding using a simple data driven simulation model that estimates soil carbon dynamic from litter input and the measured soil carbon turnover times. The results indicate the initial post-fire slowdown of soil carbon turnover is an important component of the boreal carbon cycle. Using our fire intervals the simulated soil carbon stocks with a lower post-fire soil organic matter turnover were up to 15 % larger than simulations assuming a constant carbon turnover rate. Our sensitivity analysis indicates that the effects will be larger in areas with frequent fires. We do not know which environmental factors cause the delay in the turnover time and the effects of fires on post fire soil organic matter turnover could be considerably smaller or larger. Altogether our results fit well to published results from laboratory studies and show that post-fire depression of microbial activities are important on the ecosystem and landscape level. Since fire frequencies in boreal forests will increase in many areas as the result of climate change, it will be important to better understand the effects of fire on the soil carbon turnover and to incorporate it into carbon cycle models.

Characterization of fire regime in Sardinia (Italy)

NASA Astrophysics Data System (ADS)

Bacciu, V. M.; Salis, M.; Mastinu, S.; Masala, F.; Sirca, C.; Spano, D.

2012-12-01

In the last decades, a number of Authors highlighted the crucial role of forest fires within Mediterranean ecosystems, with impacts both negative and positive on all biosphere components and with reverberations on different scales. Fire determines the landscape structure and plant composition, but it is also the cause of enormous economic and ecological damages, beside the loss of human life. In Sardinia (Italy), the second largest island of the Mediterranean Basin, forest fires are perceived as one of the main environmental and social problems, and data are showing that the situation is worsening especially within the rural-urban peripheries and the increasing number of very large forest fires. The need for information concerning forest fire regime has been pointed out by several Authors (e.g. Rollins et al., 2002), who also emphasized the importance of understanding the factors (such as weather/climate, socio-economic, and land use) that determine spatial and temporal fire patterns. These would be used not only as a baseline to predict the climate change effect on forest fires, but also as a fire management and mitigation strategy. The main aim of this paper is, thus, to analyze the temporal and spatial patterns of fire occurrence in Sardinia (Italy) during the last three decades (1980-2010). For the analyzed period, fire statistics were provided by the Sardinian Forest Service (CFVA - Corpo Forestale e di Vigilanza Ambientale), while weather data for eight weather stations were obtained from the web site www.tutiempo.it. For each station, daily series of precipitation, mean, maximum and minimum temperature, relative humidity and wind speed were available. The present study firstly analyzed fire statistics (burned area and number of fires) according to the main fire regime characteristics (seasonality, fire return interval, fire incidence, fire size distribution). Then, fire and weather daily values were averaged to obtain monthly, seasonal and annual values, and a set of parametric and not parametric statistical tests were used to analyze the fire-weather relationships. Results showed a high inter- and intra-annual variability, also considering the different type of affected vegetation. As for other Mediterranean areas, a smaller number of large fires caused a high proportion of burned area. Land cover greatly influenced fire occurrence and fire size distribution across the landscape. Furthermore, fire activity (number of fires and area burned) showed significant correlations with weather variables, especially summer precipitation and wind, which seemed to drive the fire seasons and the fire propagation, respectively.

Frequent fire alters nitrogen transformations in ponderosa pine stands of the inland northwest.

PubMed

DeLuca, Thomas H; Sala, Anna

2006-10-01

Recurrent, low-severity fire in ponderosa pine (Pinus ponderosa)/interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests is thought to have directly influenced nitrogen (N) cycling and availability. However, no studies to date have investigated the influence of natural fire intervals on soil processes in undisturbed forests, thereby limiting our ability to understand ecological processes and successional dynamics in this important ecosystem of the Rocky Mountain West. Here, we tested the standing hypothesis that recurrent fire in ponderosa pine/Douglas-fir forests of the Inland Northwest decreases total soil N, but increases N turnover and nutrient availability. We compared soils in stands unburned over the past 69-130 years vs. stands exposed to two or more fires over the last 130 years at seven distinct locations in two wilderness areas. Mineral soil samples were collected from each of the seven sites in June and July of 2003 and analyzed for pH, total C and N, potentially mineralizable N (PMN), and extractable NH4+, NO3-, PO4(-3), Ca+2, Mg+2, and K+. Nitrogen transformations were assessed at five sites by installing ionic resin capsules in the mineral soil in August of 2003 and by conducting laboratory assays of nitrification potential and net nitrification in aerobic incubations. Total N and PMN decreased in stands subjected to multiple fires. This loss of total N and labile N was not reflected in concentrations of extractable NH4+ and NO3-. Rather, multiple fires caused an increase in NO3 sorbed on ionic resins, nitrification potential, and net nitrification in spite of the burned stands not having been exposed to fire for at least 12-17 years. Charcoal collected from a recent fire site and added to unburned soils increased nitrification potential, suggesting that the decrease of charcoal in the absence of fire may play an important role in N transformations in fire-dependent ecosystems in the long term. Interestingly, we found no consistent effect of fire frequency on extractable P or alkaline metal concentrations. Our results corroborate the largely untested hypothesis that frequent fire in ponderosa pine forests increases inorganic N availability in the long term and emphasize the need to study natural, unmanaged sites in far greater detail.

Impact of Wildfire on Solute Release in Forested Catchments, Jemez River, New Mexico, USA

NASA Astrophysics Data System (ADS)

Sanchez, R. A.; Meixner, T.; McIntosh, J. C.; Chorover, J.

2017-12-01

Wildfires represent a large disturbance to the hydrology and biogeochemistry of forested catchments. The number, size and severity of wildfires have significantly increased in the western United States since 1990. Nutrients and other elements (e.g. Ca) that were taken up and stored by biomass are released from burned vegetation during forest fires and transported downgradient via overland flow, shallow subsurface flow, and/or deep groundwater flow. Ash accumulations on hillslopes may also store particulate carbon and contain elevated concentrations of elements that maybe leached into surface and ground water over extended periods of time. In 2013, the Thompson Ridge wildfire burned headwater catchments in the Jemez River Basin Critical Zone Observatory (JRB-CZO) within the Valles Caldera National Preserve, New Mexico USA. The burn severity and area impacted were different in the three headwater catchments. This study investigated the impact of the wildfire on surface water quality, including how the fire-induced impacts evolved with time, and how biogeochemical processes controlled post-fire solute concentrations in the surface water. Comparison of pre- and post-fire surface water solute chemistry shows increases in major cations and anions following fire. Increases in nitrate and sulfate concentrations in streams after the wildfire were likely from leaching of burned biomass. The elevated NO3- and SO42- concentrations persisted for over two years, and were even higher during spring snowmelt. Meanwhile, base cation concentrations increased immediately, within a few weeks after the fire, likely related to leaching from combusted organic matter; and, over a period of approximately two months, base cation concentrations returned to pre-fire levels. Trace element behavior was also altered by fire. For example, while pre-fire aluminum concentrations in stream flow increased significantly during the wet seasons (snowmelt and monsoons), the post-fire observations do not show significant changes with increase in discharge.

The dynamics and drivers of fuel and fire in the Portuguese public forest.

PubMed

Fernandes, Paulo M; Loureiro, Carlos; Guiomar, Nuno; Pezzatti, Gianni B; Manso, Filipa T; Lopes, Luís

2014-12-15

The assumption that increased wildfire incidence in the Mediterranean Basin during the last decades is an outcome of changes in land use warrants an objective analysis. In this study we examine how annual area burned (BA) in the Portuguese public forest varied in relation to environmental and human-influenced drivers during the 1943-2011 period. Fire behaviour models were used to describe fuel hazard considering biomass removal, cover type changes, area burned, post-disturbance fuel accumulation, forest age-classes distribution and fuel connectivity. Biomass removal decreased rapidly beyond the 1940s, which, along with afforestation, increased fuel hazard until the 1980s; a subsequent decline was caused by increased fire activity. Change point analysis indicates upward shifts in BA in 1952 and in 1973, both corresponding to six-fold increases. Fire weather (expressed by the 90th percentile of the Canadian FWI during summer) increased over the study period, accounting for 18 and 36% of log(BA) variation before 1974 and after 1973, respectively. Regression modelling indicates that BA responds positively to fire weather, fuel hazard and number of fires in descending order of importance; pre-summer and 2-year lagged precipitation respectively decrease and increase BA, but the effects are minor and non-significant when both variables are included in the model. Land use conflicts (expressed through more fires) played a role, but it was afforestation and agricultural abandonment that supported the fire regime shifts, explaining weather-drought as the current major driver of BA as well. We conclude that bottom-up factors, i.e. human-induced changes in landscape flammability and ignition density, can enhance or override the influence of weather-drought on the fire regime in Mediterranean humid regions. A more relevant role of fuel control in fire management policies and practices is warranted by our findings. Copyright © 2014 Elsevier Ltd. All rights reserved.

Changing Weather Extremes Call for Early Warning of Potential for Catastrophic Fire

NASA Astrophysics Data System (ADS)

Boer, Matthias M.; Nolan, Rachael H.; Resco De Dios, Víctor; Clarke, Hamish; Price, Owen F.; Bradstock, Ross A.

2017-12-01

Changing frequencies of extreme weather events and shifting fire seasons call for enhanced capability to forecast where and when forested landscapes switch from a nonflammable (i.e., wet fuel) state to the highly flammable (i.e., dry fuel) state required for catastrophic forest fires. Current forest fire danger indices used in Europe, North America, and Australia rate potential fire behavior by combining numerical indices of fuel moisture content, potential rate of fire spread, and fire intensity. These numerical rating systems lack the physical basis required to reliably quantify forest flammability outside the environments of their development or under novel climate conditions. Here, we argue that exceedance of critical forest flammability thresholds is a prerequisite for major forest fires and therefore early warning systems should be based on a reliable prediction of fuel moisture content plus a regionally calibrated model of how forest fire activity responds to variation in fuel moisture content. We demonstrate the potential of this approach through a case study in Portugal. We use a physically based fuel moisture model with historical weather and fire records to identify critical fuel moisture thresholds for forest fire activity and then show that the catastrophic June 2017 forest fires in central Portugal erupted shortly after fuels in the region dried out to historically unprecedented levels.

Developing Custom Fire Behavior Fuel Models for Mediterranean Wildland-Urban Interfaces in Southern Italy

NASA Astrophysics Data System (ADS)

Elia, Mario; Lafortezza, Raffaele; Lovreglio, Raffaella; Sanesi, Giovanni

2015-09-01

The dramatic increase of fire hazard in wildland-urban interfaces (WUIs) has required more detailed fuel management programs to preserve ecosystem functions and human settlements. Designing effective fuel treatment strategies allows to achieve goals such as resilient landscapes, fire-adapted communities, and ecosystem response. Therefore, obtaining background information on forest fuel parameters and fuel accumulation patterns has become an important first step in planning fuel management interventions. Site-specific fuel inventory data enhance the accuracy of fuel management planning and help forest managers in fuel management decision-making. We have customized four fuel models for WUIs in southern Italy, starting from forest classes of land-cover use and adopting a hierarchical clustering approach. Furthermore, we provide a prediction of the potential fire behavior of our customized fuel models using FlamMap 5 under different weather conditions. The results suggest that fuel model IIIP (Mediterranean maquis) has the most severe fire potential for the 95th percentile weather conditions and the least severe potential fire behavior for the 85th percentile weather conditions. This study shows that it is possible to create customized fuel models directly from fuel inventory data. This achievement has broad implications for land managers, particularly forest managers of the Mediterranean landscape, an ecosystem that is susceptible not only to wildfires but also to the increasing human population and man-made infrastructures.

Developing Custom Fire Behavior Fuel Models for Mediterranean Wildland-Urban Interfaces in Southern Italy.

PubMed

Elia, Mario; Lafortezza, Raffaele; Lovreglio, Raffaella; Sanesi, Giovanni

2015-09-01

The dramatic increase of fire hazard in wildland-urban interfaces (WUIs) has required more detailed fuel management programs to preserve ecosystem functions and human settlements. Designing effective fuel treatment strategies allows to achieve goals such as resilient landscapes, fire-adapted communities, and ecosystem response. Therefore, obtaining background information on forest fuel parameters and fuel accumulation patterns has become an important first step in planning fuel management interventions. Site-specific fuel inventory data enhance the accuracy of fuel management planning and help forest managers in fuel management decision-making. We have customized four fuel models for WUIs in southern Italy, starting from forest classes of land-cover use and adopting a hierarchical clustering approach. Furthermore, we provide a prediction of the potential fire behavior of our customized fuel models using FlamMap 5 under different weather conditions. The results suggest that fuel model IIIP (Mediterranean maquis) has the most severe fire potential for the 95th percentile weather conditions and the least severe potential fire behavior for the 85th percentile weather conditions. This study shows that it is possible to create customized fuel models directly from fuel inventory data. This achievement has broad implications for land managers, particularly forest managers of the Mediterranean landscape, an ecosystem that is susceptible not only to wildfires but also to the increasing human population and man-made infrastructures.

Fire severity unaffected by spruce beetle outbreak in spruce-fir forests in southwestern Colorado.

PubMed

Andrus, Robert A; Veblen, Thomas T; Harvey, Brian J; Hart, Sarah J

2016-04-01

Recent large and severe outbreaks of native bark beetles have raised concern among the general public and land managers about potential for amplified fire activity in western North America. To date, the majority of studies examining bark beetle outbreaks and subsequent fire severity in the U.S. Rocky Mountains have focused on outbreaks of mountain pine beetle (MPB; Dendroctonus ponderosae) in lodgepole pine (Pinus contorta) forests, but few studies, particularly field studies, have addressed the effects of the severity of spruce beetle (Dendroctonus rufipennis Kirby) infestation on subsequent fire severity in subalpine Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) forests. In Colorado, the annual area infested by spruce beetle outbreaks is rapidly rising, while MPB outbreaks are subsiding; therefore understanding this relationship is of growing importance. We collected extensive field data in subalpine forests in the eastern San Juan Mountains, southwestern Colorado, USA, to investigate whether a gray-stage (< 5 yr from outbreak to time of fire) spruce beetle infestation affected fire severity. Contrary to the expectation that bark beetle infestation alters subsequent fire severity, correlation and multivariate generalized linear regression analysis revealed no influence of pre-fire spruce beetle severity on nearly all field or remotely sensed measurements of fire severity. Findings were consistent across moderate and extreme burning conditions. In comparison to severity of the pre-fire beetle outbreak, we found that topography, pre-outbreak basal area, and weather conditions exerted a stronger effect on fire severity. Our finding that beetle infestation did not alter fire severity is consistent with previous retrospective studies examining fire activity following other bark beetle outbreaks and reiterates the overriding influence of climate that creates conditions conducive to large, high-severity fires in the subalpine zone of Colorado. Both bark beetle outbreaks and wildfires have increased autonomously due to recent climate variability, but this study does not support the expectation that post-beetle outbreak forests will alter fire severity, a result that has important implications for management and policy decisions.

Distribution and relative abundance of forest birds in relation to burn severity in southeastern Arizona

USGS Publications Warehouse

Kirkpatrick, C.; Conway, C.J.; Jones, P.B.

2006-01-01

The frequency of wild and prescribed fires in montane forests of the southwestern United States has increased after a century of fire suppression and subsequent fuels accumulation. To assess the effects of recent fires (median time since fire = 6 yr) on the montane forest bird community, we surveyed birds in 8 Sky Island mountain ranges in southeastern Arizona, USA, and examined how the distribution (i.e., presence-absence) of 65 species and relative abundance of 16 species correlated with evidence of severe and less severe fire at >1,500 survey points. We detected associations between fire and bird presence-absence for 17% of the 65 species analyzed and between fire and bird relative abundance for 25% of the 16 species analyzed. Most species (73%) were positively associated with burned areas and displayed stronger associations (i.e., more extreme odds ratios) with survey points that had evidence of severe as opposed to less severe fire. Positive associations with severe fire were strong (>3 to 1 odds) for western wood-pewee (Contopus sordidulus) and house wren (Troglodytes aedon), and negative associations with severe fire were strong for warbling vireo (Vireo gilvus) and red-breasted nuthatch (Sitta canadensis). Although recent fires appear to have had a positive effect on the distribution and relative abundance of several montane forest bird species in the region, these species are not the open-woodland birds that we would have expected to have benefited from fire based on previous research. Nevertheless, our results confirm associations between fire and bird presence-absence and relative abundance reported previously for 7 species of birds. Our results also provide new information for Grace's warbler (Dendroica graciae) and greater pewee (C. pertinax), 2 species for which fire data were formerly lacking. Managers can use these data to make and test predictions about the effects of future fires, both severe and less severe, on montane forest birds in the southwestern United States.

The biodiversity cost of carbon sequestration in tropical savanna

PubMed Central

Abreu, Rodolfo C. R.; Hoffmann, William A.; Vasconcelos, Heraldo L.; Pilon, Natashi A.; Rossatto, Davi R.; Durigan, Giselda

2017-01-01

Tropical savannas have been increasingly viewed as an opportunity for carbon sequestration through fire suppression and afforestation, but insufficient attention has been given to the consequences for biodiversity. To evaluate the biodiversity costs of increasing carbon sequestration, we quantified changes in ecosystem carbon stocks and the associated changes in communities of plants and ants resulting from fire suppression in savannas of the Brazilian Cerrado, a global biodiversity hotspot. Fire suppression resulted in increased carbon stocks of 1.2 Mg ha−1 year−1 since 1986 but was associated with acute species loss. In sites fully encroached by forest, plant species richness declined by 27%, and ant richness declined by 35%. Richness of savanna specialists, the species most at risk of local extinction due to forest encroachment, declined by 67% for plants and 86% for ants. This loss highlights the important role of fire in maintaining biodiversity in tropical savannas, a role that is not reflected in current policies of fire suppression throughout the Brazilian Cerrado. In tropical grasslands and savannas throughout the tropics, carbon mitigation programs that promote forest cover cannot be assumed to provide net benefits for conservation. PMID:28875172

Changes in forest biomass and linkage to climate and forest disturbances over Northeastern China.

PubMed

Zhang, Yuzhen; Liang, Shunlin

2014-08-01

The forests of northeastern China store nearly half of the country's total biomass carbon stocks. In this study, we investigated the changes in forest biomass by using satellite observations and found that a significant increase in forest biomass took place between 2001 and 2010. To determine the possible reasons for this change, several statistical methods were used to analyze the correlations between forest biomass dynamics and forest disturbances (i.e. fires, insect damage, logging, and afforestation and reforestation), climatic factors, and forest development. Results showed that forest development was the most important contributor to the increasing trend of forest biomass from 2001 to 2010, and climate controls were the secondary important factor. Among the four types of forest disturbance considered in this study, forest recovery from fires, and afforestation and reforestation during the past few decades played an important role in short-term biomass dynamics. This study provided observational evidence and valuable information for the relationships between forest biomass and climate as well as forest disturbances. © 2014 John Wiley & Sons Ltd.

Forest Fire Advanced System Technology (FFAST): A Conceptual Design for Detection and Mapping

Treesearch

J. David Nichols; John R. Warren

1987-01-01

The Forest Fire Advanced System Technology (FFAST) project is developing a data system to provide near-real-time forest fire information to fire management at the fire Incident Command Post (ICP). The completed conceptual design defined an integrated forest fire detection and mapping system that is based upon technology available in the 1990's. System component...

Evidence for declining forest resilience to wildfires under climate change.

PubMed

Stevens-Rumann, Camille S; Kemp, Kerry B; Higuera, Philip E; Harvey, Brian J; Rother, Monica T; Donato, Daniel C; Morgan, Penelope; Veblen, Thomas T

2018-02-01

Forest resilience to climate change is a global concern given the potential effects of increased disturbance activity, warming temperatures and increased moisture stress on plants. We used a multi-regional dataset of 1485 sites across 52 wildfires from the US Rocky Mountains to ask if and how changing climate over the last several decades impacted post-fire tree regeneration, a key indicator of forest resilience. Results highlight significant decreases in tree regeneration in the 21st century. Annual moisture deficits were significantly greater from 2000 to 2015 as compared to 1985-1999, suggesting increasingly unfavourable post-fire growing conditions, corresponding to significantly lower seedling densities and increased regeneration failure. Dry forests that already occur at the edge of their climatic tolerance are most prone to conversion to non-forests after wildfires. Major climate-induced reduction in forest density and extent has important consequences for a myriad of ecosystem services now and in the future. © 2017 John Wiley & Sons Ltd/CNRS.

Modeling Forest Composition and Carbon Dynamics Under Projected Climate-Fire Interactions in the Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Liang, S.; Hurteau, M. D.; Westerling, A. L.

2014-12-01

The Sierra Nevada Mountains are occupied by a diversity of forest types that sort by elevation. The interaction of changing climate and altered disturbance regimes (e.g. fire) has the potential to drive changes in forest distribution as a function of species-specific response. Quantifying the effects of these drivers on species distributions and productivity under future climate-fire interactions is necessary for informing mitigation and adaptation efforts. In this study, we assimilated forest inventory and soil survey data and species life history traits into a landscape model, LANDIS-II, to quantify the response of forest dynamics to the interaction of climate change and large wildfire frequency in the Sierra Nevada. We ran 100-year simulations forced with historical climate and climate projections from three models (GFDL, CNRM and CCSM3) driven by the A2 emission scenario. We found that non-growing season NPP is greatly enhanced by 15%-150%, depending on the specific climate projection. The greatest increase occurs in subalpine forests. Species-specific response varied as a function of life history characteristics. The distribution of drought and fire-tolerant species, such as ponderosa pine, expanded by 7.3-9.6% from initial conditions, while drought and fire-intolerant species, such as white fir, showed little change in the absence of fire. Changes in wildfire size and frequency influence species distributions by altering the successional stage of burned patches. The range of responses to different climate models demonstrates the sensitivity of these forests to climate variability. The scale of climate projections relative to the scale of forest simulations presents a source of uncertainty, particularly at the ecotone between forest types and for identifying topographically mediated climate refugia. Improving simulations will likely require higher resolution climate projections.

Impacts of fire on forest age and runoff in mountain ash forests

USGS Publications Warehouse

Wood, S.A.; Beringer, J.; Hutley, L.B.; McGuire, A.D.; Van Dijk, A.; Kilinc, M.

2008-01-01

Runoff from mountain ash (Eucalyptus regnans F.Muell.) forested catchments has been shown to decline significantly in the few decades following fire - returning to pre-fire levels in the following centuries - owing to changes in ecosystem water use with stand age in a relationship known as Kuczera's model. We examined this relationship between catchment runoff and stand age by measuring whole-ecosystem exchanges of water using an eddy covariance system measuring forest evapotranspiration (ET) combined with sap-flow measurements of tree water use, with measurements made across a chronosequence of three sites (24, 80 and 296 years since fire). At the 296-year old site eddy covariance systems were installed above the E. regnans overstorey and above the distinct rainforest understorey. Contrary to predictions from the Kuczera curve, we found that measurements of whole-forest ET decreased by far less across stand age between 24 and 296 years. Although the overstorey tree water use declined by 1.8 mm day-1 with increasing forest age (an annual decrease of 657 mm) the understorey ET contributed between 1.2 and 1.5 mm day-1, 45% of the total ET (3 mm day-1) at the old growth forest. ?? CSIRO 2008.

Relation of weather forecasts to the prediction of dangerous forest fire conditions

Treesearch

R. H. Weidman

1923-01-01

The purpose of predicting dangerous forest-fire conditions, of course, is to reduce the great cost and damage caused by forest fires. In the region of Montana and northern Idaho alone the average cost to the United States Forest Service of fire protection and suppression is over $1,000,000 a year. Although the causes of forest fires will gradually be reduced by...

The Perfect Fire? Aging Stands in the Alaskan Boreal Forest Encounter Global Warming

NASA Astrophysics Data System (ADS)

Mann, D.; Rupp, S.; Duffy, P.

2008-12-01

The ecological responses of the boreal forest to climate change have global significance because of the large amount of carbon stored in its soils and biomass. Fire, mostly ignited by lightning, is the keystone disturbance agent in this forest. It triggers cycles of forest succession in its wake, and burning is the main avenue for carbon release back to the atmosphere. We studied the interactions between climate, fires, forest succession, and the age distributions of forest stands in a 60-million hectare region of Interior Alaska over the past 150 years. First we developed a statistical model relating climate to area burned over the period of record (1950-2005). Next we combined this model with climate reconstructions to extend the estimates of area burned back to A.D. 1860. We checked the resultant fire history against stand-age data from 5000 living trees sampled in the study region. Then we fed the history of area burned into a computer model that simulates forest succession on real landscapes. Results show striking changes in the means and variances of stand ages over the last 150 years in response to interactions between climate change and the successional dynamics of the boreal forest. Average stand age increased steadily between 1880 and 1940 and has fluctuated at high levels since then, indicating a historically unusual abundance of flammable stands. This accumulation of old stands has created the potential for unusually large fires. Some support for this conclusion comes from the unprecedented large sizes of the areas burned in 2004 and 2005. Further support comes when we add to the analysis the forecasts made by global climate models for Alaska over the next twenty years. Bracketing estimates for climate warming and precipitation change suggest that warmer, drier summers combined with aging forest stands will cause a series of unusually large fires, the like of which have not occurred in the region for >150 years. We infer that the enhanced burning of the Alaska boreal forest over the next 20 years will increase the release of trace gases from this region. We speculate that the forest will be transformed from being conifer dominated to one dominated by deciduous tree species, which could have sweeping effects on the region's other biota, its hydrology, and the role of the boreal forest in the global carbon cycle.

Influence of logging on the effects of wildfire in Siberia

NASA Astrophysics Data System (ADS)

Kukavskaya, E. A.; Buryak, L. V.; Ivanova, G. A.; Conard, S. G.; Kalenskaya, O. P.; Zhila, S. V.; McRae, D. J.

2013-12-01

The Russian boreal zone supports a huge terrestrial carbon pool. Moreover, it is a tremendous reservoir of wood products concentrated mainly in Siberia. The main natural disturbance in these forests is wildfire, which modifies the carbon budget and has potentially important climate feedbacks. In addition, both legal and illegal logging increase landscape complexity and affect burning conditions and fuel consumption. We investigated 100 individual sites with different histories of logging and fire on a total of 23 study areas in three different regions of Siberia to evaluate the impacts of fire and logging on fuel loads, carbon emissions, and tree regeneration in pine and larch forests. We found large variations of fire and logging effects among regions depending on growing conditions and type of logging activity. Logged areas in the Angara region had the highest surface and ground fuel loads (up to 135 t ha-1), mainly due to logging debris. This resulted in high carbon emissions where fires occurred on logged sites (up to 41 tC ha-1). The Shushenskoe/Minusinsk and Zabaikal regions are characterized by better slash removal and a smaller amount of carbon emitted to the atmosphere during fires. Illegal logging, which is widespread in the Zabaikal region, resulted in an increase in fire hazard and higher carbon emissions than legal logging. The highest fuel loads (on average 108 t ha-1) and carbon emissions (18-28 tC ha-1) in the Zabaikal region are on repeatedly burned unlogged sites where trees fell on the ground following the first fire event. Partial logging in the Shushenskoe/Minusinsk region has insufficient impact on stand density, tree mortality, and other forest conditions to substantially increase fire hazard or affect carbon stocks. Repeated fires on logged sites resulted in insufficient tree regeneration and transformation of forest to grasslands. We conclude that negative impacts of fire and logging on air quality, the carbon cycle, and ecosystem sustainability could be decreased by better slash removal in the Angara region, removal of trees killed by fire in the Zabaikal region, and tree planting after fires in drier conditions where natural regeneration is hampered by soil overheating and grass proliferation.

Cardiorespiratory hospitalizations associated with smoke exposure during the 1997, Southeast Asian forest fires.

PubMed

Mott, Joshua A; Mannino, David M; Alverson, Clinton J; Kiyu, Andrew; Hashim, Jamilah; Lee, Tzesan; Falter, Kenneth; Redd, Stephen C

2005-01-01

We investigated the cardiorespiratory health effects of smoke exposure from the 1997 Southeast Asian Forest Fires among persons who were hospitalized in the region of Kuching, Malaysia. We selected admissions to seven hospitals in the Kuching region from a database of all hospital admissions in the state of Sarawak during January 1, 1995 and December 31, 1998. For several cardiorespiratory disease classifications we used Holt-Winters time-series analyses to determine whether the total number of monthly hospitalizations during the forest fire period (August 1 to October 31, 1997), or post-fire period (November 1, 1997 to December 31, 1997) exceeded forecasted estimates established from a historical baseline period of January 1, 1995 to July 31, 1997. We also identified age-specific cohorts of persons whose members were admitted for specific cardiorespiratory problems during January 1 to July 31 of each year (1995--1997). We compared Kaplan-Meier survival curves of time to first readmission for the 1997 cohorts (exposed to the forest fire smoke) with the survival curves for the 1995 and 1996 cohorts (not exposed, pre-fire cohorts). The time-series analyses indicated that statistically significant fire-related increases were observed in respiratory hospitalizations, specifically those for chronic obstructive pulmonary disease (COPD) and asthma. The survival analyses indicated that persons over age 65 years with previous hospital admissions for any cause (chi2(1df) = 5.98, p = 0.015), any cardiorespiratory disease (chi2(1df) = 5.3, p = 0.02), any respiratory disease (chi2(1df) = 7.8, p = 0.005), or COPD (chi2(1df) = 3.9, p = 0.047), were significantly more likely to be rehospitalized during the follow-up period in 1997 than during the follow-up periods in the pre-fire years of 1995 or 1996. The survival functions of the exposed cohorts resumed similar trajectories to unexposed cohorts during the post-fire period of November 1, 1997 to December 31, 1998. Communities exposed to forest fire smoke during the Southeast Asian forest fires of 1997 experienced short-term increases in cardiorespiratory hospitalizations. When an air quality emergency is anticipated, persons over age 65 with histories of respiratory hospitalizations should be preidentified from existing hospitalization records and given priority access to interventions.

Numerical study of propagation of forest fires in the presence of fire breaks using an averaged setting

NASA Astrophysics Data System (ADS)

Marzaeva, S. I.; Galtseva, O. V.

2018-05-01

The forest fires spread in the pine forests have been numerically simulated using a three-dimensional mathematical model. The model was integrated with respect to the vertical coordinate because horizontal sizes of forest are much greater than the heights of trees. In this paper, the assignment and theoretical investigations of the problems of crown forest fires spread pass the firebreaks were carried out. In this context, a study ( mathematical modeling) of the conditions of forest fire spreading that would make it possible to obtain a detailed picture of the change in the temperature and component concentration fields with time, and determine as well as the limiting condition of fire propagation in forest with these fire breaks.

Characterization of the humic substances isolated from postfire soils of scotch pine forest in Togljatty city, Samara region by the 13C-NMR spectroscopy

NASA Astrophysics Data System (ADS)

Maksimova, Ekaterina; Abakumov, Evgeny

2016-04-01

Postpyrogenic soil dynamics is an informative tool for studying of soil elementary processes in extreme temperature conditions and for predicting of short time environmental changes in conditions of catastrophic landscape changes. Soil organic matter (SOM) system evolution is the most rapid process of postpyrogenic soil development. In this relation the evaluation of humus accumulation rates and humification trend were conducted with use of the classical chemical and modern spectroscopy methods. Soil restoration after spontaneous forest fires near Togljatty city (Samara region, Russia) was abandoned in 2010, and further monitoring over the next four years was organized to evaluate the speed of biogenic processes and humus accumulation dynamics. Three key soil plots were studied for estimating SOM quality changes under the forest fire effect: surface forest fire, crown forest fire and control. Total carbon and nitrogen content as well as Cha/Cfa ratios (content of humic acids/ content of fulvic acids), were estimated to assess the dynamics of soil restoration. Humic acid powders were extracted and analyzed by elemental composition and 13C-NMR spectroscopy to assess changes in humic substance structure and composition. The data obtained indicate that burning of a forest floor and sod (humic) horizon led to humus losses and decreases in total carbon stocks. As a result of the fires, the content of humic acids in the pyrogenic horizon increased, leading alterations of humus type. Greater increases in the degree of organic matter humification were observed for surface fires than crown fires. It was shown that the humus molecular composition was substantially affected by the wildfires. The data show an increase in aromaticity, a loss of oxygen-containing groups and dehydrogenation of humic acids. Humic acids in the soils of the control plots and after wildfires were significantly different, especially in the ratios of hydrogen, oxygen and carbon. The increase in the degree of humic acid aromatization was confirmed by the hydrogen/carbon ratio. Investigation of the humic acids' molecular structure by 13C-NMR showed a relative increase in aromatic compounds and decrease in aliphatic ones. In general, crown and surface fires plots are not very different in terms of 13C-NMR spectra of humic acids, however humic acids of control plot have essential differences from pyrogenic ones. This study was a contribution to the Russian foundation for basic research, project for young scientists No.14-04-32132 and 15-34-20844.

Post-wildfire logging hinders regeneration and increases fire risk.

PubMed

Donato, D C; Fontaine, J B; Campbell, J L; Robinson, W D; Kauffman, J B; Law, B E

2006-01-20

We present data from a study of early conifer regeneration and fuel loads after the 2002 Biscuit Fire, Oregon, USA, with and without postfire logging. Natural conifer regeneration was abundant after the high-severity fire. Postfire logging reduced median regeneration density by 71%, significantly increased downed woody fuels, and thus increased short-term fire risk. Additional reduction of fuels is necessary for effective mitigation of fire risk. Postfire logging can be counterproductive to the goals of forest regeneration and fuel reduction.

Mexican forest fires and their decadal variations

NASA Astrophysics Data System (ADS)

Velasco Herrera, Graciela

2016-11-01

A high forest fire season of two to three years is regularly observed each decade in Mexican forests. This seems to be related to the presence of the El Niño phenomenon and to the amount of total solar irradiance. In this study, the results of a multi-cross wavelet analysis are reported based on the occurrence of Mexican forest fires, El Niño and the total solar irradiance for the period 1970-2014. The analysis shows that Mexican forest fires and the strongest El Niño phenomena occur mostly around the minima of the solar cycle. This suggests that the total solar irradiance minima provide the appropriate climatological conditions for the occurrence of these forest fires. The next high season for Mexican forest fires could start in the next solar minimum, which will take place between the years 2017 and 2019. A complementary space analysis based on MODIS active fire data for Mexican forest fires from 2005 to 2014 shows that most of these fires occur in cedar and pine forests, on savannas and pasturelands, and in the central jungles of the Atlantic and Pacific coasts.

Meteorological factors in the Quartz Creek forest fire

Treesearch

H. T. Gisborne

1927-01-01

It is not often that a large forest fire occurs conveniently near a weather station specially equipped for measuring forest-fire weather. The 13,000-acre Quartz Creek fire on the Kaniksu National Forest during the summer of 1936 was close enough to the Priest River Experimental Forest of the Northern Rocky Mountain Forest Experiment Station for the roar of the flumes...

Boreal Forest Fire Cools Climate

NASA Astrophysics Data System (ADS)

Randerson, J. T.; Liu, H.; Flanner, M.; Chambers, S. D.; Harden, J. W.; Hess, P. G.; Jin, Y.; Mack, M. C.; Pfister, G.; Schuur, E. A.; Treseder, K. K.; Welp, L. R.; Zender, C. S.

2005-12-01

We report measurements, modeling, and analysis of carbon and energy fluxes from a boreal forest fire that occurred in interior Alaska during 1999. In the first year after the fire, ozone production, atmospheric aerosol loading, greenhouse gas emissions, soot deposition, and decreases in summer albedo contributed to a positive annual radiative forcing (RF). These effects were partly offset by an increase in fall, winter, and spring albedo from reduced canopy cover and increased exposure of snow-covered surfaces. The atmospheric lifetime of aerosols and ozone and are relatively short (days to months). The radiative effects of soot on snow are also attenuated rapidly from the deposition of fresh snow. As a result, a year after the fire, only two classes of RF mechanisms remained: greenhouse gas emissions and post-fire changes in surface albedo. Summer albedo increased rapidly in subsequent years and was substantially higher than unburned control areas (by more than 0.03) after 4 years as a result of grass and shrub establishment. Satellite measurements from MODIS of other interior Alaska burn scars provided evidence that elevated levels of spring and summer albedo (relative to unburned control areas) persisted for at least 4 decades after fire. In parallel, our chamber, eddy covariance, and biomass measurements indicated that the post-fire ecosystems switch from a source to a sink within the first decade. Taken together, the extended period of increased spring and summer albedo and carbon uptake of intermediate-aged stands appears to more than offset the initial warming pulse caused by fire emissions, when compared using the RF concept. This result suggests that management of forests in northern countries to suppress fire and preserve carbon sinks may have the opposite effect on climate as that intended.

Understorey fire frequency and the fate of burned forests in southern Amazonia.

PubMed

Morton, D C; Le Page, Y; DeFries, R; Collatz, G J; Hurtt, G C

2013-06-05

Recent drought events underscore the vulnerability of Amazon forests to understorey fires. The long-term impact of fires on biodiversity and forest carbon stocks depends on the frequency of fire damages and deforestation rates of burned forests. Here, we characterized the spatial and temporal dynamics of understorey fires (1999-2010) and deforestation (2001-2010) in southern Amazonia using new satellite-based estimates of annual fire activity (greater than 50 ha) and deforestation (greater than 10 ha). Understorey forest fires burned more than 85 500 km(2) between 1999 and 2010 (2.8% of all forests). Forests that burned more than once accounted for 16 per cent of all understorey fires. Repeated fire activity was concentrated in Mato Grosso and eastern Pará, whereas single fires were widespread across the arc of deforestation. Routine fire activity in Mato Grosso coincided with annual periods of low night-time relative humidity, suggesting a strong climate control on both single and repeated fires. Understorey fires occurred in regions with active deforestation, yet the interannual variability of fire and deforestation were uncorrelated, and only 2.6 per cent of forests that burned between 1999 and 2008 were deforested for agricultural use by 2010. Evidence from the past decade suggests that future projections of frontier landscapes in Amazonia should separately consider economic drivers to project future deforestation and climate to project fire risk.

Understorey fire frequency and the fate of burned forests in southern Amazonia

PubMed Central

Morton, D. C.; Le Page, Y.; DeFries, R.; Collatz, G. J.; Hurtt, G. C.

2013-01-01

Recent drought events underscore the vulnerability of Amazon forests to understorey fires. The long-term impact of fires on biodiversity and forest carbon stocks depends on the frequency of fire damages and deforestation rates of burned forests. Here, we characterized the spatial and temporal dynamics of understorey fires (1999–2010) and deforestation (2001–2010) in southern Amazonia using new satellite-based estimates of annual fire activity (greater than 50 ha) and deforestation (greater than 10 ha). Understorey forest fires burned more than 85 500 km2 between 1999 and 2010 (2.8% of all forests). Forests that burned more than once accounted for 16 per cent of all understorey fires. Repeated fire activity was concentrated in Mato Grosso and eastern Pará, whereas single fires were widespread across the arc of deforestation. Routine fire activity in Mato Grosso coincided with annual periods of low night-time relative humidity, suggesting a strong climate control on both single and repeated fires. Understorey fires occurred in regions with active deforestation, yet the interannual variability of fire and deforestation were uncorrelated, and only 2.6 per cent of forests that burned between 1999 and 2008 were deforested for agricultural use by 2010. Evidence from the past decade suggests that future projections of frontier landscapes in Amazonia should separately consider economic drivers to project future deforestation and climate to project fire risk. PMID:23610169

Fire ecology of the forest habitat types of northern Idaho

Treesearch

Jane Kapler Smith; William C. Fischer

1997-01-01

Provides information on fire ecology in forest habitat and community types occurring in northern Idaho. Identifies fire groups based on presettlement fire regimes and patterns of succession and stand development after fire. Describes forest fuels and suggests considerations for fire management.

Southwestern Oregon's Biscuit Fire: An Analysis of Forest Resources, Fire Severity, and Fire Hazard

Treesearch

David L. Azuma; Glenn A. Christensen

2005-01-01

This study compares pre-fire field inventory data (collected from 1993 to 1997) in relation to post-fire mapped fire severity classes and the Fire and Fuels Extension of the Forest Vegetation Simulator growth and yield model measures of fire hazard for the portion of the Siskiyou National Forest in the 2002 Biscuit fire perimeter of southwestern Oregon. Post-fire...

Fire ecology of the forest habitat types of central Idaho

Treesearch

M. F. Crane; William C. Fischer

1986-01-01

Discusses fire as an ecological factor for forest habitat types occurring in central Idaho. Identifies "Fire Groups" of habitat types based on fire's role in forest succession. Considerations for fire management are suggested.

Satellite Analysis of the Severe 1987 Forest Fires in Northern China and Southeastern Siberia

NASA Technical Reports Server (NTRS)

Cahoon, Donald R., Jr.; Stocks, Brian J.; Levine, Joel S.; Cofer, Wesley R., III; Pierson, Joseph M.

1994-01-01

Meteorological conditions, extremely conducive to fire development and spread in the spring of 1987, resulted in forest fires burning over extremely large areas in the boreal forest zone in northeastern China and the southeastern region of Siberia. The great China fire, one of the largest and most destructive forest fires in recent history, occurred during this period in the Heilongjiang Province of China. Satellite imagery is used to examine the development and areal distribution of 1987 forest fires in this region. Overall trace gas emissions to the atmosphere from these fires are determined using a satellite-derived estimate of area burned in combination with fuel consumption figures and carbon emission ratios for boreal forest fires.

Satellite analysis of the severe 1987 forest fires in northern China and southeastern Siberia

NASA Technical Reports Server (NTRS)

Cahoon, Donald R, Jr.; Stocks, Brian J.; Levine, Joel S.; Cofer, Wesley R., III; Pierson, Joseph M.

1994-01-01

Meteorological conditions, extremely conducive to fire development and spread in the spring of 1987, resulted in forest fires burning over extremely large areas in the boreal forest zone in northeastern China and the southeastern region of Siberia. The great China fire, one of the largest and most destructive forest fires in recent history, occurred during this period in the Heilongjiang Province of China. Satellite imagery is used to examine the development and areal distribution of 1987 forest fires in this region. Overall trace gas emissions to the atmosphere from these fires are determined using a satellite-derived estimate of area burned in combination with fuel consumption figures and carbon emission ratios for boreal forest fires.

North Carolina's Emerging Forest Threats: Management Options for Healthy Forests

Treesearch

Lisa Jennings; Emrys Treasure; Jennifer Moore Myers; Steve McNulty; Sean Brogan; David Jones

2012-01-01

Forest landowners are seeing increased pressure from threats like fire, insects, disease, extreme weather, and drought on their land and resources. The last decade has brought record droughts to North Carolina, increasing wildfires, expanding insect and plant invasions, and more intense hurricane and tornado events. Scientists predict increases in temperature and...

Tamm Review: Management of mixed-severity fire regime forests in Oregon, Washington, and Northern California

Treesearch

Paul F. Hessburg; Thomas A. Spies; David A. Perry; Carl N. Skinner; Alan H. Taylor; Peter M. Brown; Scott L. Stephens; Andrew J. Larson; Derek J. Churchill; Nicholas A. Povak; Peter H. Singleton; Brenda McComb; William J. Zielinski; Brandon M. Collins; R. Brion Salter; John J. Keane; Jerry F. Franklin; Greg Riegel

2016-01-01

Increasingly, objectives for forests with moderate- or mixed-severity fire regimes are to restore successionally diverse landscapes that are resistant and resilient to current and future stressors. Maintaining native species and characteristic processes requires this successional diversity, but methods to achieve it are poorly explained in the literature. In the Inland...

Lessons learned from fire use for restoring southwestern ponderosa pine ecosystems

Treesearch

Stephen S. Sackett; Sally M. Haase; Michael G. Harrington

1996-01-01

Since European settlement, the southwestern ponderosa pine ecosystem has experienced large scale alterations brought about by heavy grazing and timbering and a policy of attempted fire exclusion. These alterations are most evident as large increases in tree numbers and in forest floor organic matter. These changes have resulted in forest health problems, such...

Forests at risk: integrating risk science into fuel management strategies.

Treesearch

Jonathan Thompson

2008-01-01

The threat from wildland fire continues to grow across many regions of the Western United States. Drought, urbanization, and a buildup of fuels over the last century have contributed to increasing wildfire risk to property and highly valued natural resources. Fuel treatments, including thinning overly dense forests to reduce fuel and lower fire risk, have become a...

Effects of active forest fire on terrestrial ecosystem production and greenhouse gas emissions

NASA Astrophysics Data System (ADS)

Sannigrahi, Srikanta; Rahmat, Shahid; Bhatt, Sandeep; Rana, Virendra

2017-04-01

The forest fire is one of the most catalysing agents which degrade an ecosystems leading to the loss of net and gross primary productivity (NPP & GPP) and carbon sequestration service. Additionally, it can suppress the efficiency of service providing capacity of an ecosystem throughout the time and space. Remote sensing-based forest fire estimation in a diverse ecosystem is very much essential for mitigating the biodiversity and productivity losses due to the forest fire. Satellite-based Land Surface Temperature (LST) has been calculated for the pre-fire and fire years to identify the burn severity hotspot across all eco-regions in the Lower Himalaya region. Several burn severity indices: Normalized Burn Ratio (NBR), Burnt Area Index (BAI), Normalized Multiband Drought Index (NMDI), Soil Adjusted Vegetation Index (SAVI), Global Environmental Monitoring Index (GEMI), Enhance Vegetation Index (EVI) have been used in this study to quantify the spatial and temporal changes (delta) of the selected indices. Two Light Use Efficiency (LUE) models: Carnegie- Ames-Stanford-Approach (CASA) and Vegetation Photosynthesis Model (VPM) have been used to quantify the terrestrial Net Primary Productivity (NPP) in the pre-fire and fire years across all biomes of the region. A novel approach has been preceded in this field to demonstrate the correlation between forest fire density (FFD) and NPP. A strong positive correlation was found between burn severity indices and predicted NPP: BAI and NPP (r = 0.49), NBR and NPP: (r = 0.58), EVI and NPP: (r = 0.72), SAVI and NPP: (r = 0.67), whereas, a negative association has noted between the NMDI and NPP: (r = -0.36) during the both studied years. Results have shown that the NPP is highly correlated with the forest fire density (R2 = 0.75, RMSE = 5.03 gC m-2 month-1). The estimated LST of the individual fire days has witnessed a sharp temperature increase by > 6oC - 9oC in comparison to the non-fire days clearly indicates high fire risk (in Uttarakhand) due to the subtle water stress condition with lesser soil moisture content into the ground. Among the 13 districts, the maximum net emissions of carbon and nitrogen compounds have been observed in 7 districts (accounting for high biomass and forest cover loss by the 2016 forest fire), whereas, the rest of the 6 districts acts as the sequester of greenhouse compounds. This new approach having the potentiality of quantifying the losses of ecosystem productivity due to forest fires and could be used in broader aspects if more accurate field based observation can be obtained in the near future.

Increasing microbial diversity and nitrogen cycling potential of burnt forest soil in Spain through post-fire management

NASA Astrophysics Data System (ADS)

Pereg, Lily; Mataix-Solera, Jorge; McMillan, Mary; García-Orenes, Fuensanta

2016-04-01

Microbial diversity and function in soils are increasingly assessed by the application of molecular methods such as sequencing and PCR technology. We applied these techniques to study microbial recovery in post-fire forest soils. The recovery of forest ecosystems following severe fire is influenced by post-fire management. The removal of burnt tree stumps (salvage logging) is a common practice in Spain following fire. In some cases, the use of heavy machinery in addition to the vulnerability of soils to erosion and degradation make this management potentially damaging to soil, and therefore to the ecosystem. We hypothesized that tree removal slows down the recovery of soil biological communities including microbial and plant communities and contributes to soil degradation in the burnt affected area. The study area is located in "Sierra de Mariola Natural Park" in Alcoi, Alicante (E Spain). A big forest fire (>500 has) occurred in July 2012. The forest is composed mainly of Pinus halepensis trees with an understory of typical Mediterranean shrubs species such as Quercus coccifera, Rosmarinus officinalis, Thymus vulgaris, Brachypodium retusum, etc. Soil is classified as a Typic Xerorthent (Soil Survey Staff, 2014) developed over marls. In February 2013, salvage logging (SL) treatment, with a complete extraction of the burned wood using heavy machinery, was applied to a part of the affected forest. Plots for monitoring the effects of SL were installed in this area and in a similar nearby control (C) area, where no SL treatment was done. The recovery of soil bacterial and fungal communities post-fire with and without tree removal was analysed by using Next-Generation sequencing and the abundance of functional genes, related to nitrogen cycling, in the soil was estimated using quantitative PCR (qPCR). We will present the methods used and the results of our study in this PICO presentation.

Fuel variability following wildfire in forests with mixed severity fire regimes, Cascade Range, USA

Treesearch

Jessica L. Hudec; David L. Peterson

2012-01-01

Fire severity influences post-burn structure and composition of a forest and the potential for a future fire to burn through the area. The effects of fire on forests with mixed severity fire regimes are difficult to predict and interpret because the quantity, structure, and composition of forest fuels vary considerably. This study examines the relationship between fire...