Science.gov

Sample records for evaluating forest growth

  1. Evaluation of forest trees growth after sewage sludge application

    NASA Astrophysics Data System (ADS)

    Vaitkutä--, Dovilé; Balträ--Naitä--, Edita; Booth, Colin A.; Fullen, Michael A.; Pereira, Paulo

    2010-05-01

    Sewage sludge is extensively used in forest to improve soil properties. It is expected that sewage sludge rich in phosphorus, nitrogen and organic material enhance the germination of tree seedlings in poor soils. In Lithuania, the deforested soils are highly acid, and have a lack of nutrients, especially in exploited peat areas. Sewage sludge from industry contains beneficial components for the soils (such as organic matter, phosphorus, nitrogen, calcium, magnesium, etc.). However, it is also rich in heavy metals, especially Cd, Pb, Cu and Zn. High heavy metals concentrations in soil can be phytotoxic and cause reduced plant growth or plant death. The main objectives of this research was to determine the influence of industrial sewage sludge in the forestry and to highlight the idea that industrial sewage sludge containing metals does not favour development of birch and pine trees. The study was performed in Taruskos experimental plot in Panevezys region (Lithuania), amended with industrial sewage sludge ten years ago was afforestated with birch and pine seedlings. In order to observe the effects of the amendment in accumulation the mentioned metals and tree growth we collected data from trees in amended plot and control plot. The results showed that soil parameters were improved in the amended plot, in comparing with control site (higher pH, organic matter and cation exchange capacity). However, the growth of investigated trees was slower (e.g. birch roots, shoot, stem and leaves biomass was 40, 7.4, 18.6, 22% smaller than in control site. In pine case: 30, 1.2, 17, 36%, respectively; the stem height of birch was 16% and pine - 12% smaller than in control site). This reduced growth can be related with heavy metals concentration load on soil and accumulation in trees. Cu and Cd concentrations were higher in soil amended with sewage sludge comparing with control site (60 and 36%, respectively). Also, in contaminated trees Cu and Cd concentrations were higher (Cu

  2. Application of a Hybrid Forest Growth Model to Evaluate Climate Change Impacts on Productivity, Nutrient Cycling and Mortality in a Montane Forest Ecosystem.

    PubMed

    Seely, Brad; Welham, Clive; Scoullar, Kim

    2015-01-01

    Climate change introduces considerable uncertainty in forest management planning and outcomes, potentially undermining efforts at achieving sustainable practices. Here, we describe the development and application of the FORECAST Climate model. Constructed using a hybrid simulation approach, the model includes an explicit representation of the effect of temperature and moisture availability on tree growth and survival, litter decomposition, and nutrient cycling. The model also includes a representation of the impact of increasing atmospheric CO2 on water use efficiency, but no direct CO2 fertilization effect. FORECAST Climate was evaluated for its ability to reproduce the effects of historical climate on Douglas-fir and lodgepole pine growth in a montane forest in southern British Columbia, Canada, as measured using tree ring analysis. The model was subsequently used to project the long-term impacts of alternative future climate change scenarios on forest productivity in young and established stands. There was a close association between predicted sapwood production and measured tree ring chronologies, providing confidence that model is able to predict the relative impact of annual climate variability on tree productivity. Simulations of future climate change suggest a modest increase in productivity in young stands of both species related to an increase in growing season length. In contrast, results showed a negative impact on stemwood biomass production (particularly in the case of lodgepole pine) for established stands due to increased moisture stress mortality. PMID:26267446

  3. Application of a Hybrid Forest Growth Model to Evaluate Climate Change Impacts on Productivity, Nutrient Cycling and Mortality in a Montane Forest Ecosystem

    PubMed Central

    Seely, Brad; Welham, Clive; Scoullar, Kim

    2015-01-01

    Climate change introduces considerable uncertainty in forest management planning and outcomes, potentially undermining efforts at achieving sustainable practices. Here, we describe the development and application of the FORECAST Climate model. Constructed using a hybrid simulation approach, the model includes an explicit representation of the effect of temperature and moisture availability on tree growth and survival, litter decomposition, and nutrient cycling. The model also includes a representation of the impact of increasing atmospheric CO2 on water use efficiency, but no direct CO2 fertilization effect. FORECAST Climate was evaluated for its ability to reproduce the effects of historical climate on Douglas-fir and lodgepole pine growth in a montane forest in southern British Columbia, Canada, as measured using tree ring analysis. The model was subsequently used to project the long-term impacts of alternative future climate change scenarios on forest productivity in young and established stands. There was a close association between predicted sapwood production and measured tree ring chronologies, providing confidence that model is able to predict the relative impact of annual climate variability on tree productivity. Simulations of future climate change suggest a modest increase in productivity in young stands of both species related to an increase in growing season length. In contrast, results showed a negative impact on stemwood biomass production (particularly in the case of lodgepole pine) for established stands due to increased moisture stress mortality. PMID:26267446

  4. Exploring Old Growth Forests: A Teacher's Manual.

    ERIC Educational Resources Information Center

    Lemieux, Chris; Powers, Jennene; Quinby, Peter; Schultz, Caroline; Stabb, Mark

    "Exploring Old Growth Forests" is an Ontario (Canada) program that provides secondary students with hands-on experiences in old growth forests. Activity-based and student-centered, the program aims to develop student awareness of the importance of old growth forests and the need to conserve them. This manual provides teachers with background…

  5. Evaluation of growth potential of Crimean juniper (Juniperus excelsa Bieb.) seedlings for the first growing season under Tekir forest nursery conditions in Kahramanmaras, Turkey.

    PubMed

    Avsar, Mahmut D; Tonguc, Fatih

    2003-04-01

    In this study, growth potential of Crimean juniper (Juniperus excelsa Bieb.) seedlings for the first growing season under Tekir Forest Nursery conditions in Kahramanmaras was evaluated. The height growth of Crimean juniper seedlings was relatively close to that of Lebanon cedar (Cedrus libani A. Rich.) seedlings produced in the same nursery, but their root collar diameters were fairly lower than that of Lebanon cedar seedlings. According to coniferous seedling standards of Turkish Standards Institute, the height growth of Crimean juniper seedlings was fairly good, but their root collar diameters were slightly small. In this respect, that 2+0 or 1+1 Crimean juniper seedlings are used in reforestation activities in the region would be more useful than 1+0 seedlings. PMID:12974456

  6. Evidence for environmentally enhanced forest growth.

    PubMed

    Fang, Jingyun; Kato, Tomomichi; Guo, Zhaodi; Yang, Yuanhe; Hu, Huifeng; Shen, Haihua; Zhao, Xia; Kishimoto-Mo, Ayaka W; Tang, Yanhong; Houghton, Richard A

    2014-07-01

    Forests in the middle and high latitudes of the northern hemisphere function as a significant sink for atmospheric carbon dioxide (CO2). This carbon (C) sink has been attributed to two processes: age-related growth after land use change and growth enhancement due to environmental changes, such as elevated CO2, nitrogen deposition, and climate change. However, attribution between these two processes is largely controversial. Here, using a unique time series of an age-class dataset from six national forest inventories in Japan and a new approach developed in this study (i.e., examining changes in biomass density at each age class over the inventory periods), we quantify the growth enhancement due to environmental changes and its contribution to biomass C sink in Japan's forests. We show that the growth enhancement for four major plantations was 4.0∼7.7 Mg C⋅ha(-1) from 1980 to 2005, being 8.4-21.6% of biomass C sequestration per hectare and 4.1-35.5% of the country's total net biomass increase of each forest type. The growth enhancement differs among forest types, age classes, and regions. Our results provide, to our knowledge, the first ground-based evidence that global environmental changes can increase C sequestration in forests on a broad geographic scale and imply that both the traits and age of trees regulate the responses of forest growth to environmental changes. These findings should be incorporated into the prediction of forest C cycling under a changing climate. PMID:24979781

  7. Evidence for environmentally enhanced forest growth

    PubMed Central

    Fang, Jingyun; Kato, Tomomichi; Guo, Zhaodi; Yang, Yuanhe; Hu, Huifeng; Shen, Haihua; Zhao, Xia; Kishimoto-Mo, Ayaka W.; Tang, Yanhong; Houghton, Richard A.

    2014-01-01

    Forests in the middle and high latitudes of the northern hemisphere function as a significant sink for atmospheric carbon dioxide (CO2). This carbon (C) sink has been attributed to two processes: age-related growth after land use change and growth enhancement due to environmental changes, such as elevated CO2, nitrogen deposition, and climate change. However, attribution between these two processes is largely controversial. Here, using a unique time series of an age-class dataset from six national forest inventories in Japan and a new approach developed in this study (i.e., examining changes in biomass density at each age class over the inventory periods), we quantify the growth enhancement due to environmental changes and its contribution to biomass C sink in Japan’s forests. We show that the growth enhancement for four major plantations was 4.0∼7.7 Mg C⋅ha−1 from 1980 to 2005, being 8.4–21.6% of biomass C sequestration per hectare and 4.1–35.5% of the country's total net biomass increase of each forest type. The growth enhancement differs among forest types, age classes, and regions. Our results provide, to our knowledge, the first ground-based evidence that global environmental changes can increase C sequestration in forests on a broad geographic scale and imply that both the traits and age of trees regulate the responses of forest growth to environmental changes. These findings should be incorporated into the prediction of forest C cycling under a changing climate. PMID:24979781

  8. The relative contributions of forest growth and areal expansion to forest biomass carbon

    NASA Astrophysics Data System (ADS)

    Li, P.; Zhu, J.; Hu, H.; Guo, Z.; Pan, Y.; Birdsey, R.; Fang, J.

    2016-01-01

    Forests play a leading role in regional and global terrestrial carbon (C) cycles. Changes in C sequestration within forests can be attributed to areal expansion (increase in forest area) and forest growth (increase in biomass density). Detailed assessment of the relative contributions of areal expansion and forest growth to C sinks is crucial to reveal the mechanisms that control forest C sinks and it is helpful for developing sustainable forest management policies in the face of climate change. Using the Forest Identity concept and forest inventory data, this study quantified the spatial and temporal changes in the relative contributions of forest areal expansion and increased biomass growth to China's forest biomass C sinks from 1977 to 2008. Over the last 30 years, the areal expansion of forests has been a larger contributor to C sinks than forest growth for planted forests in China (62.2 % vs. 37.8 %). However, for natural forests, forest growth has made a larger contribution than areal expansion (60.4 % vs. 39.6 %). For all forests (planted and natural forests), growth in area and density has contributed equally to the total C sinks of forest biomass in China (50.4 % vs. 49.6 %).The relative contribution of forest growth of planted forests showed an increasing trend from an initial 25.3 % to 61.0 % in the later period of 1998 to 2003, but for natural forests, the relative contributions were variable without clear trends, owing to the drastic changes in forest area and biomass density over the last 30 years. Our findings suggest that afforestation will continue to increase the C sink of China's forests in the future, subject to sustainable forest growth after the establishment of plantations.

  9. The relative contributions of forest growth and areal expansion to forest biomass carbon sinks in China

    NASA Astrophysics Data System (ADS)

    Li, P.; Zhu, J.; Hu, H.; Guo, Z.; Pan, Y.; Birdsey, R.; Fang, J.

    2015-06-01

    Forests play a leading role in regional and global terrestrial carbon (C) cycles. Changes in C sequestration within forests can be attributed to areal expansion (increase in forest area) and forest growth (increase in biomass density). Detailed assessment of the relative contributions of areal expansion and forest growth to C sinks is crucial to reveal the mechanisms that control forest C sinks and is helpful for developing sustainable forest management policies in the face of climate change. Using the Forest Identity concept and forest inventory data, this study quantified the spatial and temporal changes in the relative contributions of forest areal expansion and increased biomass growth to China's forest C sinks from 1977 to 2008. Over the last 30 years, the areal expansion of forests was a larger contributor to C sinks than forest growth for all forests and planted forests in China (74.6 vs. 25.4 % for all forests, and 62.4 vs. 37.8 % for plantations). However, for natural forests, forest growth made a larger contribution than areal expansion (60.4 vs. 39.6 %). The relative contribution of forest growth of planted forests showed an increasing trend from an initial 25.3 to 61.0 % in the later period of 1998 to 2003, but for natural forests, the relative contributions were variable without clear trends owing to the drastic changes in forest area and biomass density over the last 30 years. Our findings suggest that afforestation can continue to increase the C sink of China's forests in the future subject to persistently-increasing forest growth after establishment of plantation.

  10. Botany: Constraints to growth of boreal forests

    NASA Astrophysics Data System (ADS)

    Jarvis, Paul; Linder, Sune

    2000-06-01

    Understanding how the growth of trees at high latitudes in boreal forest is controlled is important for projections of global carbon sequestration and timber production in relation to climate change. Is stem growth of boreal forest trees constrained by the length of the growing season when stem cambial cells divide, or by the length of the period when resources can be captured? In both cases, the timing of the thaw in the spring is critical: neither cambial cell division nor uptake of nutrients and carbon dioxide can occur while the soil is frozen. Here we argue, on the basis of long-term observations made in northern Saskatchewan and Sweden, that the time between the spring thaw and the autumn freeze determines the amount of annual tree growth, mainly through temperature effects on carbon-dioxide uptake in spring and on nutrient availability and uptake during summer, rather than on cambial cell division.

  11. Climate and Management Controls on Forest Growth and Forest Carbon Balance in the Western United States

    NASA Astrophysics Data System (ADS)

    Kelsey, Katharine Cashman

    Climate change is resulting in a number of rapid changes in forests worldwide. Forests comprise a critical component of the global carbon cycle, and therefore climate-induced changes in forest carbon balance have the potential to create a feedback within the global carbon cycle and affect future trajectories of climate change. In order to further understanding of climate-driven changes in forest carbon balance, I (1) develop a method to improve spatial estimates forest carbon stocks, (2) investigate the effect of climate change and forest management actions on forest recovery and carbon balance following disturbance, and (3) explore the relationship between climate and forest growth, and identify climate-driven trends in forest growth through time, within San Juan National Forest in southwest Colorado, USA. I find that forest carbon estimates based on texture analysis from LandsatTM imagery improve regional forest carbon maps, and this method is particularly useful for estimating carbon stocks in forested regions affected by disturbance. Forest recovery from disturbance is also a critical component of future forest carbon stocks, and my results indicate that both climate and forest management actions have important implications for forest recovery and carbon dynamics following disturbance. Specifically, forest treatments that use woody biomass removed from the forest for electricity production can reduce carbon emissions to the atmosphere, but climate driven changes in fire severity and forest recovery can have the opposite effect on forest carbon stocks. In addition to the effects of disturbance and recovery on forest condition, I also find that climate change is decreasing rates of forest growth in some species, likely in response to warming summer temperatures. These growth declines could result in changes of vegetation composition, or in extreme cases, a shift in vegetation type that would alter forest carbon storage. This work provides insight into both

  12. Old-growth definition for wet pine forests, woodlands, and savannas. Forest Service general technical report

    SciTech Connect

    Harms, W.R.

    1996-09-01

    All Forest Service Stations and Regions began developing old-growth definitions for specific forest types. Definitions will first be developed for broad forest types and based mainly on published information and so must be viewed accordingly. Refinements will be made by the Forest Service as new information becomes available. This document represents 1 of 35 forest types for which old-growth definition will be drafted.

  13. DRAINMOD-FOREST: Integrated Modeling of Hydrology, Soil Carbon and Nitrogen Dynamics, and Plant Growth for Drained Forests.

    PubMed

    Tian, Shiying; Youssef, Mohamed A; Skaggs, R Wayne; Amatya, Devendra M; Chescheir, G M

    2012-01-01

    We present a hybrid and stand-level forest ecosystem model, DRAINMOD-FOREST, for simulating the hydrology, carbon (C) and nitrogen (N) dynamics, and tree growth for drained forest lands under common silvicultural practices. The model was developed by linking DRAINMOD, the hydrological model, and DRAINMOD-N II, the soil C and N dynamics model, to a forest growth model, which was adapted mainly from the 3-PG model. The forest growth model estimates net primary production, C allocation, and litterfall using physiology-based methods regulated by air temperature, water deficit, stand age, and soil N conditions. The performance of the newly developed DRAINMOD-FOREST model was evaluated using a long-term (21-yr) data set collected from an artificially drained loblolly pine ( L.) plantation in eastern North Carolina, USA. Results indicated that the DRAINMOD-FOREST accurately predicted annual, monthly, and daily drainage, as indicated by Nash-Sutcliffe coefficients of 0.93, 0.87, and 0.75, respectively. The model also predicted annual net primary productivity and dynamics of leaf area index reasonably well. Predicted temporal changes in the organic matter pool on the forest floor and in forest soil were reasonable compared to published literature. Both predicted annual and monthly nitrate export were in good agreement with field measurements, as indicated by Nash-Sutcliffe coefficients above 0.89 and 0.79 for annual and monthly predictions, respectively. This application of DRAINMOD-FOREST demonstrated its capability for predicting hydrology and C and N dynamics in drained forests under limited silvicultural practices. PMID:22565258

  14. Comparison of growth response to thinning in oak forests managed as coppice with standards and high forest

    NASA Astrophysics Data System (ADS)

    Gautam, S.; Hasenauer, H.; Pietsch, S. A.

    2009-04-01

    The BIOME-BGC model integrates the main physical, biological and physiological processes based on current understanding of ecophysiology to assess forest ecosystem dynamics. This study evaluates the application of the model to assess the thinning effects on coppiced oak forests in Austria. We analyze the growth response, i.e. growth efficiency (GE), nitrogen use efficiency (NUE), water use efficiency (WUE) and radiation use efficiency (RUE) of oak forests to thinning. The results of coppice with standards and high forests simulations are analysed for differences in simulated growth response after thinning. The forest field data of the year 2006 and the respective model runs are used to evaluate model application. Strong positive relationship (r2 = 0.90) with unbiased results and statistically insignificant differences between predicted and observed volume allows the use of the model as a diagnostic tool to assess management effects. Results indicate that the coppice with standards exhibits a significantly higher yield by 2.97% (i.e. 10 cubic meters per hectare in one rotation), a higher harvest (49.9%) but a lower growing stock (19.69%) than the high forests. The higher growing stock and the lower extraction in the high forests confirm that the high forest sequestrates significantly more carbon than the coppice with standards. Results show that thinning leads to an increase in the GE, the NUE and the WUE, and to a decrease in the RUE. Although the coppice with standards forest ecosystem exhibits higher values in all studied growth parameters, only the difference in the NUE was statistically significant. This verifies that the difference in the yield between the coppice with standards and the high forests is mainly governed by the NUE difference in stands after thinning. The coppice with standards system produces an equal amount of net primary production while consuming significantly less nitrogen (16%) compared to the high forest system. In the coppice with

  15. Forest structure, stand composition, and climate-growth response in montane forests of Jiuzhaigou National Nature Reserve, China.

    PubMed

    Schwartz, Mark W; Dolanc, Christopher R; Gao, Hui; Strauss, Sharon Y; Schwartz, Ari C; Williams, John N; Tang, Ya

    2013-01-01

    Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20(th) century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth. PMID:23951188

  16. Forest Structure, Stand Composition, and Climate-Growth Response in Montane Forests of Jiuzhaigou National Nature Reserve, China

    PubMed Central

    Schwartz, Mark W.; Dolanc, Christopher R.; Gao, Hui; Strauss, Sharon Y.; Schwartz, Ari C.; Williams, John N.; Tang, Ya

    2013-01-01

    Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20th century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth. PMID:23951188

  17. Winter climate limits subantarctic low forest growth and establishment.

    PubMed

    Harsch, Melanie A; McGlone, Matt S; Wilmshurst, Janet M

    2014-01-01

    Campbell Island, an isolated island 600 km south of New Zealand mainland (52 °S, 169 °E) is oceanic (Conrad Index of Continentality  =  -5) with small differences between mean summer and winter temperatures. Previous work established the unexpected result that a mean annual climate warming of c. 0.6 °C since the 1940's has not led to upward movement of the forest limit. Here we explore the relative importance of summer and winter climatic conditions on growth and age-class structure of the treeline forming species, Dracophyllum longifolium and Dracophyllum scoparium over the second half of the 20th century. The relationship between climate and growth and establishment were evaluated using standard dendroecological methods and local climate data from a meteorological station on the island. Growth and establishment were correlated against climate variables and further evaluated within hierarchical regression models to take into account the effect of plot level variables. Winter climatic conditions exerted a greater effect on growth and establishment than summer climatic conditions. Establishment is maximized under warm (mean winter temperatures >7 °C), dry winters (total winter precipitation <400 mm). Growth, on the other hand, is adversely affected by wide winter temperature ranges and increased rainfall. The contrasting effect of winter warmth on growth and establishment suggests that winter temperature affects growth and establishment through differing mechanisms. We propose that milder winters enhance survival of seedlings and, therefore, recruitment, but increases metabolic stress on established plants, resulting in lower growth rates. Future winter warming may therefore have complex effects on plant growth and establishment globally. PMID:24691026

  18. Structure and development of old-growth, unmanaged second-growth, and extended rotation Pinus resinosa forests in Minnesota, USA

    USGS Publications Warehouse

    Silver, Emily J.; D'Amato, Anthony W.; Fraver, Shawn; Palik, Brian J.; Bradford, John B.

    2013-01-01

    The structure and developmental dynamics of old-growth forests often serve as important baselines for restoration prescriptions aimed at promoting more complex structural conditions in managed forest landscapes. Nonetheless, long-term information on natural patterns of development is rare for many commercially important and ecologically widespread forest types. Moreover, the effectiveness of approaches recommended for restoring old-growth structural conditions to managed forests, such as the application of extended rotation forestry, has been little studied. This study uses several long-term datasets from old growth, extended rotation, and unmanaged second growth Pinus resinosa (red pine) forests in northern Minnesota, USA, to quantify the range of variation in structural conditions for this forest type and to evaluate the effectiveness of extended rotation forestry at promoting the development of late-successional structural conditions. Long-term tree population data from permanent plots for one of the old-growth stands and the extended rotation stands (87 and 61 years, respectively) also allowed for an examination of the long-term structural dynamics of these systems. Old-growth forests were more structurally complex than unmanaged second-growth and extended rotation red pine stands, due in large part to the significantly higher volumes of coarse woody debris (70.7 vs. 11.5 and 4.7 m3/ha, respectively) and higher snag basal area (6.9 vs. 2.9 and 0.5 m2/ha, respectively). In addition, old-growth forests, although red pine-dominated, contained a greater abundance of other species, including Pinus strobus, Abies balsamea, and Picea glauca relative to the other stand types examined. These differences between stand types largely reflect historic gap-scale disturbances within the old-growth systems and their corresponding structural and compositional legacies. Nonetheless, extended rotation thinning treatments, by accelerating advancement to larger tree diameter

  19. Observed forest sensitivity to climate implies large changes in 21st century North American forest growth.

    PubMed

    Charney, Noah D; Babst, Flurin; Poulter, Benjamin; Record, Sydne; Trouet, Valerie M; Frank, David; Enquist, Brian J; Evans, Margaret E K

    2016-09-01

    Predicting long-term trends in forest growth requires accurate characterisation of how the relationship between forest productivity and climatic stress varies across climatic regimes. Using a network of over two million tree-ring observations spanning North America and a space-for-time substitution methodology, we forecast climate impacts on future forest growth. We explored differing scenarios of increased water-use efficiency (WUE) due to CO2 -fertilisation, which we simulated as increased effective precipitation. In our forecasts: (1) climate change negatively impacted forest growth rates in the interior west and positively impacted forest growth along the western, southeastern and northeastern coasts; (2) shifting climate sensitivities offset positive effects of warming on high-latitude forests, leaving no evidence for continued 'boreal greening'; and (3) it took a 72% WUE enhancement to compensate for continentally averaged growth declines under RCP 8.5. Our results highlight the importance of locally adapted forest management strategies to handle regional differences in growth responses to climate change. PMID:27434040

  20. Responses in the growth of the northern forests to a CO{sub 2}-induced climatic change, as evaluated by the Frankfurt Biosphere Model -- (FBM)

    SciTech Connect

    Haeger, C.; Wuerth, G.; Wagner, U.; Kohlmaier, G.H.

    1996-06-01

    The Frankfurt Biosphere Model (FBM), a mechanistic and prognostic compartment model of the terrestrial biosphere, has been developed to simulate the carbon exchange fluxes between the vegetation and the atmosphere with a spatial resolution of 0.5{degree} x 0.5{degree} on a global scale. In this contribution the authors use the FBM to assess the possible changes in the response of the northern forest biomes under a future 2{times}CO{sub 2} climate. The development of these ecosystems from its initial seedling state to its climax state is simulated under different climatic conditions. The 2{times}CO{sub 2} climate for these simulations was provided by the GCM of the MPI fuer Meteorologie in Hamburg (ECHAM). The differences in vegetation growth under contemporary and future climate can be assessed by performing three model runs with the same parameterization but with different driving climatic variables for each vegetation type and location: (1) a simulation run with present climate conditions; (2) a simulation run under 2{times}CO{sub 2} climate conditions; and (3) which is same as (2) but with the assumption of a CO{sub 2} fertilization effect.

  1. Responses in the growth of the northern forest biomes to a CO{sub 2}-induced climatic change, as evaluated by the Frankfurt Biosphere Model (FBM)

    SciTech Connect

    Hager, C.; Wurth, G.; Wagner, U.; Kohlmaier, G.H.

    1996-12-31

    The Frankfurt Biosphere Model (FBM), a mechanistic, seasonal and prognostic compartment model of the terrestrial biosphere, has been developed in recent years to simulate the carbon exchange fluxes between the vegetation and the atmosphere with a spatial resolution of 0.5{degree} x 0.5{degree} on a global scale. In this contribution the authors use the FBM to assess the possible changes in the transient response of the northern forest biomes under a future 2 {times} CO{sub 2} climate. The development of these ecosystems from its initial seedling state to its climax state is simulated under different climatic conditions. In their simulations the 2 {times} CO{sub 2} climate provided by the GCM of the MPI fuer Meteorologie in Hamburg (ECHAM) is used. The differences in vegetation`s growth under contemporary and future climate can be assessed by performing two model runs with the same parameterization but with different driving climatic variables for each vegetation type and location.

  2. Information system of forest growth and productivity by site quality type and elements of forest

    NASA Astrophysics Data System (ADS)

    Khlyustov, V.

    2012-04-01

    Information system of forest growth and productivity by site quality type and elements of forest V.K. Khlustov Head of the Forestry Department of Russian State Agrarian University named after K.A.Timiryazev doctor of agricultural sciences, professor The efficiency of forest management can be improved substantially by development and introduction of principally new models of forest growth and productivity dynamics based on regionalized site specific parameters. Therefore an innovative information system was developed. It describes the current state and gives a forecast for forest stand parameters: growth, structure, commercial and biological productivity depend on type of site quality. In contrast to existing yield tables, the new system has environmental basis: site quality type. The information system contains set of multivariate statistical models and can work at the level of individual trees or at the stand level. The system provides a graphical visualization, as well as export of the emulation results. The System is able to calculate detailed description of any forest stand based on five initial indicators: site quality type, site index, stocking, composition, and tree age by elements of the forest. The results of the model run are following parameters: average diameter and height, top height, number of trees, basal area, growing stock (total, commercial with distribution by size, firewood and residuals), live biomass (stem, bark, branches, foliage). The system also provides the distribution of mentioned above forest stand parameters by tree diameter classes. To predict the future forest stand dynamics the system require in addition the time slot only. Full set of forest parameters mention above will be provided by the System. The most conservative initial parameters (site quality type and site index) can be kept in the form of geo referenced polygons. In this case the system would need only 3 dynamic initial parameters (stocking, composition and age) to

  3. Direct observation of morphological evolution of a catalyst during carbon nanotube forest growth: new insights into growth and growth termination.

    PubMed

    Jeong, Seojeong; Lee, Jaegeun; Kim, Hwan-Chul; Hwang, Jun Yeon; Ku, Bon-Cheol; Zakharov, Dmitri N; Maruyama, Benji; Stach, Eric A; Kim, Seung Min

    2016-01-28

    In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests. PMID:26700058

  4. Direct observation of morphological evolution of a catalyst during carbon nanotube forest growth: new insights into growth and growth termination

    NASA Astrophysics Data System (ADS)

    Jeong, Seojeong; Lee, Jaegeun; Kim, Hwan-Chul; Hwang, Jun Yeon; Ku, Bon-Cheol; Zakharov, Dmitri N.; Maruyama, Benji; Stach, Eric A.; Kim, Seung Min

    2016-01-01

    In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests.In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05547d

  5. Evidence for a recent increase in forest growth

    PubMed Central

    McMahon, Sean M.; Parker, Geoffrey G.; Miller, Dawn R.

    2010-01-01

    Forests and their soils contain the majority of the earth’s terrestrial carbon stocks. Changes in patterns of tree growth can have a huge impact on atmospheric cycles, biogeochemical cycles, climate change, and biodiversity. Recent studies have shown increases in biomass across many forest types. This increase has been attributed to climate change. However, without knowing the disturbance history of a forest, growth could also be caused by normal recovery from unknown disturbances. Using a unique dataset of tree biomass collected over the past 22 years from 55 temperate forest plots with known land-use histories and stand ages ranging from 5 to 250 years, we found that recent biomass accumulation greatly exceeded the expected growth caused by natural recovery. We have also collected over 100 years of local weather measurements and 17 years of on-site atmospheric CO2 measurements that show consistent increases in line with globally observed climate-change patterns. Combined, these observations show that changes in temperature and CO2 that have been observed worldwide can fundamentally alter the rate of critical natural processes, which is predicted by biogeochemical models. Identifying this rate change is important to research on the current state of carbon stocks and the fluxes that influence how carbon moves between storage and the atmosphere. These results signal a pressing need to better understand the changes in growth rates in forest systems, which influence current and future states of the atmosphere and biosphere. PMID:20133710

  6. Forests fuel fish growth in freshwater deltas

    PubMed Central

    Tanentzap, Andrew J.; Szkokan-Emilson, Erik J.; Kielstra, Brian W.; Arts, Michael T.; Yan, Norman D.; Gunn, John M.

    2014-01-01

    Aquatic ecosystems are fuelled by biogeochemical inputs from surrounding lands and within-lake primary production. Disturbances that change these inputs may affect how aquatic ecosystems function and deliver services vital to humans. Here we test, using a forest cover gradient across eight separate catchments, whether disturbances that remove terrestrial biomass lower organic matter inputs into freshwater lakes, thereby reducing food web productivity. We focus on deltas formed at the stream-lake interface where terrestrial-derived particulate material is deposited. We find that organic matter export increases from more forested catchments, enhancing bacterial biomass. This transfers energy upwards through communities of heavier zooplankton, leading to a fourfold increase in weights of planktivorous young-of-the-year fish. At least 34% of fish biomass is supported by terrestrial primary production, increasing to 66% with greater forest cover. Habitat tracers confirm fish were closely associated with individual catchments, demonstrating that watershed protection and restoration increase biomass in critical life-stages of fish. PMID:24915965

  7. Forests fuel fish growth in freshwater deltas.

    PubMed

    Tanentzap, Andrew J; Szkokan-Emilson, Erik J; Kielstra, Brian W; Arts, Michael T; Yan, Norman D; Gunn, John M

    2014-01-01

    Aquatic ecosystems are fuelled by biogeochemical inputs from surrounding lands and within-lake primary production. Disturbances that change these inputs may affect how aquatic ecosystems function and deliver services vital to humans. Here we test, using a forest cover gradient across eight separate catchments, whether disturbances that remove terrestrial biomass lower organic matter inputs into freshwater lakes, thereby reducing food web productivity. We focus on deltas formed at the stream-lake interface where terrestrial-derived particulate material is deposited. We find that organic matter export increases from more forested catchments, enhancing bacterial biomass. This transfers energy upwards through communities of heavier zooplankton, leading to a fourfold increase in weights of planktivorous young-of-the-year fish. At least 34% of fish biomass is supported by terrestrial primary production, increasing to 66% with greater forest cover. Habitat tracers confirm fish were closely associated with individual catchments, demonstrating that watershed protection and restoration increase biomass in critical life-stages of fish. PMID:24915965

  8. Forest biomass carbon sinks in East Asia, with special reference to the relative contributions of forest expansion and forest growth.

    PubMed

    Fang, Jingyun; Guo, Zhaodi; Hu, Huifeng; Kato, Tomomichi; Muraoka, Hiroyuki; Son, Yowhan

    2014-06-01

    Forests play an important role in regional and global carbon (C) cycles. With extensive afforestation and reforestation efforts over the last several decades, forests in East Asia have largely expanded, but the dynamics of their C stocks have not been fully assessed. We estimated biomass C stocks of the forests in all five East Asian countries (China, Japan, North Korea, South Korea, and Mongolia) between the 1970s and the 2000s, using the biomass expansion factor method and forest inventory data. Forest area and biomass C density in the whole region increased from 179.78 × 10(6) ha and 38.6 Mg C ha(-1) in the 1970s to 196.65 × 10(6) ha and 45.5 Mg C ha(-1) in the 2000s, respectively. The C stock increased from 6.9 Pg C to 8.9 Pg C, with an averaged sequestration rate of 66.9 Tg C yr(-1). Among the five countries, China and Japan were two major contributors to the total region's forest C sink, with respective contributions of 71.1% and 32.9%. In China, the areal expansion of forest land was a larger contributor to C sinks than increased biomass density for all forests (60.0% vs. 40.0%) and for planted forests (58.1% vs. 41.9%), while the latter contributed more than the former for natural forests (87.0% vs. 13.0%). In Japan, increased biomass density dominated the C sink for all (101.5%), planted (91.1%), and natural (123.8%) forests. Forests in South Korea also acted as a C sink, contributing 9.4% of the total region's sink because of increased forest growth (98.6%). Compared to these countries, the reduction in forest land in both North Korea and Mongolia caused a C loss at an average rate of 9.0 Tg C yr(-1), equal to 13.4% of the total region's C sink. Over the last four decades, the biomass C sequestration by East Asia's forests offset 5.8% of its contemporary fossil-fuel CO2 emissions. PMID:24464906

  9. Carbon Uptake and Storage in Old-Growth and Second-Growth Forests in Central Vermont

    NASA Astrophysics Data System (ADS)

    Lloyd, A. H.; Weisser, O.

    2013-12-01

    Managing forests towards the goal of maximizing carbon uptake and storage provides an important tool for climate change mitigation. There is significant spatial and temporal variation among forests, even within an ecosystem type, in annual uptake and storage of carbon. Understanding the causes for that variation is important in refining management practices and restoration goals that promote carbon storage. We explore the variation in carbon storage and uptake among forests differing in age in central Vermont, comparing young, intermediate-aged, and old-growth forests. We generally expected that younger forests would have a higher annual uptake of carbon than older forests. Significant uncertainty exists, however, about the temporal trajectory from a young, rapidly growing forest to an old-growth forest that may be in a steady-state, with no net uptake of carbon. Within each forest, we compare differences among functional groups of species (e.g., hardwoods versus softwoods) in contribution to overall forest carbon uptake and storage. Our study sites include an old-growth hemlock/mixed hardwood forest that has not been directly affected by human activities, and which contains trees upwards of 350 years old; a 130-year-old mixed hardwood forest that has recolonized former pasture land; and a 90-year-old mixed hardwood forest on formerly agricultural floodplain land. Carbon storage in live and dead biomass pools was estimated from allometric equations, based on repeated measurements of tree diameters in permanently marked study plots. Historical patterns of carbon storage in living biomass were estimated by reconstructing tree diameter from measured increment cores, and then estimating the living biomass in each year. As expected, the old-growth forest stored almost twice the C in live biomass as the two second-growth forests, which stored equivalent amounts of carbon, despite the difference in age. Dead biomass was a larger pool of C in the old-growth forest than in

  10. Biodiversity Promotes Tree Growth during Succession in Subtropical Forest

    PubMed Central

    Barrufol, Martin; Schmid, Bernhard; Bruelheide, Helge; Chi, Xiulian; Hector, Andrew; Ma, Keping; Michalski, Stefan; Tang, Zhiyao; Niklaus, Pascal A.

    2013-01-01

    Losses of plant species diversity can affect ecosystem functioning, with decreased primary productivity being the most frequently reported effect in experimental plant assemblages, including tree plantations. Less is known about the role of biodiversity in natural ecosystems, including forests, despite their importance for global biogeochemical cycling and climate. In general, experimental manipulations of tree diversity will take decades to yield final results. To date, biodiversity effects in natural forests therefore have only been reported from sample surveys or meta-analyses with plots not initially selected for diversity. We studied biomass and growth of subtropical forests stands in southeastern China. Taking advantage of variation in species recruitment during secondary succession, we adopted a comparative study design selecting forest plots to span a gradient in species richness. We repeatedly censored the stem diameter of two tree size cohorts, comprising 93 species belonging to 57 genera and 33 families. Tree size and growth were analyzed in dependence of species richness, the functional diversity of growth-related traits, and phylogenetic diversity, using both general linear and structural equation modeling. Successional age covaried with diversity, but differently so in the two size cohorts. Plot-level stem basal area and growth were positively related with species richness, while growth was negatively related to successional age. The productivity increase in species-rich, functionally and phylogenetically diverse plots was driven by both larger mean sizes and larger numbers of trees. The biodiversity effects we report exceed those from experimental studies, sample surveys and meta-analyses, suggesting that subtropical tree diversity is an important driver of forest productivity and re-growth after disturbance that supports the provision of ecological services by these ecosystems. PMID:24303037

  11. Biodiversity promotes tree growth during succession in subtropical forest.

    PubMed

    Barrufol, Martin; Schmid, Bernhard; Bruelheide, Helge; Chi, Xiulian; Hector, Andrew; Ma, Keping; Michalski, Stefan; Tang, Zhiyao; Niklaus, Pascal A

    2013-01-01

    Losses of plant species diversity can affect ecosystem functioning, with decreased primary productivity being the most frequently reported effect in experimental plant assemblages, including tree plantations. Less is known about the role of biodiversity in natural ecosystems, including forests, despite their importance for global biogeochemical cycling and climate. In general, experimental manipulations of tree diversity will take decades to yield final results. To date, biodiversity effects in natural forests therefore have only been reported from sample surveys or meta-analyses with plots not initially selected for diversity. We studied biomass and growth of subtropical forests stands in southeastern China. Taking advantage of variation in species recruitment during secondary succession, we adopted a comparative study design selecting forest plots to span a gradient in species richness. We repeatedly censored the stem diameter of two tree size cohorts, comprising 93 species belonging to 57 genera and 33 families. Tree size and growth were analyzed in dependence of species richness, the functional diversity of growth-related traits, and phylogenetic diversity, using both general linear and structural equation modeling. Successional age covaried with diversity, but differently so in the two size cohorts. Plot-level stem basal area and growth were positively related with species richness, while growth was negatively related to successional age. The productivity increase in species-rich, functionally and phylogenetically diverse plots was driven by both larger mean sizes and larger numbers of trees. The biodiversity effects we report exceed those from experimental studies, sample surveys and meta-analyses, suggesting that subtropical tree diversity is an important driver of forest productivity and re-growth after disturbance that supports the provision of ecological services by these ecosystems. PMID:24303037

  12. Similar biodiversity of ectomycorrhizal fungi in set-aside plantations and ancient old-growth broadleaved forests

    PubMed Central

    Spake, Rebecca; van der Linde, Sietse; Newton, Adrian C.; Suz, Laura M.; Bidartondo, Martin I.; Doncaster, C. Patrick

    2016-01-01

    Setting aside overmature planted forests is currently seen as an option for preserving species associated with old-growth forests, such as those with dispersal limitation. Few data exist, however, on the utility of set-aside plantations for this purpose, or the value of this habitat type for biodiversity relative to old-growth semi-natural ecosystems. Here, we evaluate the contribution of forest type relative to habitat characteristics in determining species richness and composition in seven forest blocks, each containing an ancient old-growth stand (> 1000 yrs) paired with a set-aside even-aged planted stand (ca. 180 yrs). We investigated the functionally important yet relatively neglected ectomycorrhizal fungi (EMF), a group for which the importance of forest age has not been assessed in broadleaved forests. We found that forest type was not an important determinant of EMF species richness or composition, demonstrating that set-aside can be an effective option for conserving ancient EMF communities. Species richness of above-ground EMF fruiting bodies was principally related to the basal area of the stand (a correlate of canopy cover) and tree species diversity, whilst richness of below-ground ectomycorrhizae was driven only by tree diversity. Our results suggest that overmature planted forest stands, particularly those that are mixed-woods with high basal area, are an effective means to connect and expand ecological networks of ancient old-growth forests in historically deforested and fragmented landscapes for ectomycorrhizal fungi. PMID:26917858

  13. Does forest fragmentation affect the same way all growth-forms?

    PubMed

    Rodríguez-Loinaz, Gloria; Amezaga, Ibone; Onaindia, Miren

    2012-02-01

    Fragmentation of natural habitats is one of the main causes of the loss of biodiversity. However, all plants do not respond to habitat fragmentation in the same way due to differences in species traits. We studied the effect of patch size and isolation on the biodiversity of vegetation in the mixed-oak forests in the north of the Iberian Peninsula. The aim was to evaluate whether all the growth-forms of vegetation are equally affected by forest fragmentation in order to improve the management strategies to restore this type of vegetation. This study has shown that the effect of the area and spatial isolation of the patches was not the same for the different growth-forms. Fragmentation had a mainly negative effect on the richness and diversity of forest specialist species, especially ferns and herbaceous growth-forms. Moreover, the presence and/or cover of woodland herbaceous species (such as Lamiastrum galeobdolon and Helleborus viridis) and of woodland ferns (namely Asplenium adiantum-nigrum, Asplenium trichomanes, Polystichum setiferum, Dryopteris affinis) were negatively affected by patch size, possibly due to the reduction of habitat quality. These species have been replaced by more generalist species (such as Cardamine pratensis, Cirsium sp., Pulmonaria longifolia or Rumex acetosella) in small patches. Patch isolation had a negative effect on the presence of forest specialist species (namely, L. galeobdolon, Frangula alnus, Hypericum androsaemum, A. adiantum-nigrum and Athyrium filix-femina) and favored colonization by more generalist species such as Cirsium sp., Calluna vulgaris, Erica arborea or Ulex sp. Thus, in this region special attention should be paid to the conservation of forest specialist species, especially ferns and herbs. In conservation policy focused on forest specialist species, the most valuable species in forest ecosystems, conservation of large forest areas should be promoted. PMID:21924813

  14. Tree growth and competition in an old-growth Picea abies forest of boreal Sweden: influence of tree spatial patterning

    USGS Publications Warehouse

    Fraver, Shawn; D'Amato, Anthony W.; Bradford, John B.; Jonsson, Bengt Gunnar; Jönsson, Mari; Esseen, Per-Anders

    2013-01-01

    Question: What factors best characterize tree competitive environments in this structurally diverse old-growth forest, and do these factors vary spatially within and among stands? Location: Old-growth Picea abies forest of boreal Sweden. Methods: Using long-term, mapped permanent plot data augmented with dendrochronological analyses, we evaluated the effect of neighbourhood competition on focal tree growth by means of standard competition indices, each modified to include various metrics of trees size, neighbour mortality weighting (for neighbours that died during the inventory period), and within-neighbourhood tree clustering. Candidate models were evaluated using mixed-model linear regression analyses, with mean basal area increment as the response variable. We then analysed stand-level spatial patterns of competition indices and growth rates (via kriging) to determine if the relationship between these patterns could further elucidate factors influencing tree growth. Results: Inter-tree competition clearly affected growth rates, with crown volume being the size metric most strongly influencing the neighbourhood competitive environment. Including neighbour tree mortality weightings in models only slightly improved descriptions of competitive interactions. Although the within-neighbourhood clustering index did not improve model predictions, competition intensity was influenced by the underlying stand-level tree spatial arrangement: stand-level clustering locally intensified competition and reduced tree growth, whereas in the absence of such clustering, inter-tree competition played a lesser role in constraining tree growth. Conclusions: Our findings demonstrate that competition continues to influence forest processes and structures in an old-growth system that has not experienced major disturbances for at least two centuries. The finding that the underlying tree spatial pattern influenced the competitive environment suggests caution in interpreting traditional tree

  15. Uncertainty about future nitrogen availability dominates boreal forest growth projections

    NASA Astrophysics Data System (ADS)

    Mäkelä, Annikki; Kalliokoski, Tuomo; Peltoniemi, Mikko

    2015-04-01

    There is broad consensus among scientists that the capacity of forests in the boreal zone to take up carbon will increase as a result of climate change. However, boreal forests are strongly nitrogen limited. This may hamper the potential increase in GPP for forest productivity and carbon sequestration, but little is known about the impact of climate change on nitrogen availability in forests. Here we use OptiPipe, a model of optimal carbon and nitrogen co-allocation to analyse the role of nitrogen availability in growth limitation under climate change in Finland. We predict changes in metabolic rates related to the C balance using existing models and data, and we explore three alternative, plausible scenarios of N availability under climate change. Three climate scenarios based on three SRES emissions scenarios - B1 (low), A1B (moderate) and A2 (high) - are used for projecting changes of daily temperature, precipitation, vapour pressure deficit and solar radiation for periods 2011-2040, 2041-2070 and 2071-2100. We use a mean among 8 climate models. CO2 concentrations corresponding to the SRES scenarios come from (IPCC, 2007: Climate Change 2007: The Physical Science Basis) The results will be presented across Finland on a 10 km x 10 km grid. The results indicate that NPP and woody growth will increase under climate change if N availability is also increasing. If N availability is limited, volume growth will to reduce, because maintenance costs (respiration and turnover) increase. If N availability increases relatively as much or more than C availability, reduced allocation requirements to fine roots will lead to more foliage with higher photosynthetic capacity, thus increasing woody volume growth disproportionately. These results are attributable to optimised carbon and nitrogen co-allocation. In order to reduce the uncertainty of growth predictions, a better understanding of the mechanisms related to N availability is needed.

  16. Nutrient status and plant growth effects of forest soils in the Basin of Mexico.

    PubMed

    Fenn, M E; Perea-Estrada, V M; de Bauer, L I; Pérez-Suárez, M; Parker, D R; Cetina-Alcalá, V M

    2006-03-01

    The nutrient status of forest soils in the Mexico City Air Basin was evaluated by observing plant growth responses to fertilization with N, P or both nutrients combined. P deficiency was the most frequent condition for soil from two high pollution sites and N deficiency was greatest at a low N deposition site. Concentrations of Pb and Ni, and to a lesser extent Zn and Co, were higher at the high pollution sites. However, positive plant growth responses to P and sometimes to N, and results of wheat root elongation bioassays, suggest that heavy metal concentrations were not directly phytotoxic. Further studies are needed to determine if heavy metal toxicity to mycorrhizal symbionts of eucalyptus (Eucalyptus camaldulensis Dehnh.) from high pollution sites may explain the P deficiency and stunted growth. P deficiency is expected to limit the capacity for biotic N retention in N saturated forested watersheds in the Basin of Mexico dominated by Andisols. PMID:16168537

  17. Relationships Between Shallow Groundwater and Tree Growth in a Northern Wisconsin Forest

    NASA Astrophysics Data System (ADS)

    Ciruzzi, D. M.; Steven, L. I.

    2015-12-01

    As drought variability increases across forests in the United States, it is critical to evaluate ecosystem attributes that reduce drought vulnerability. Groundwater has been shown to sustain tree growth and transpiration in arid and semi-arid ecosystems during drought, yet this relationship has yet to be extensively explored in mesic environments. This research aims to investigate groundwater-tree interactions in a north temperate forest in northern Wisconsin with attention to drought stress. We question if trees in areas of shallow groundwater with lower inter-annual variability will have higher and more consistent tree growth rates during drought conditions. Historic water table measurements monitored in the Trout Lake watershed include a decline in groundwater levels by ~1 m caused by a prolonged drought from 2006-2013. Within the watershed, we examined tree growth response between wet and dry years across sites covering a 1-9 m depth to groundwater gradient over the past 30 years. Combined with remotely sensed vegetation indices and tree core chronologies, we show regions and individual trees influenced by groundwater depth variability, respectively. Generally, vegetation indices and tree growth rates were higher during years of shallower spring and summer groundwater. By exploring the influences of shallow groundwater on tree growth in temperate forests, groundwater conferred drought resistance may be mapped for sustainable management.

  18. Climate indices strongly influence old-growth forest carbon exchange

    DOE PAGESBeta

    Wharton, Sonia; Falk, Matthias

    2016-04-13

    We present a decade and a half (1998–2013) of carbon dioxide fluxes from an old-growth stand in the American Pacific Northwest to identify ecosystem-level responses to Pacific teleconnection patterns, including the El Niño/Southern Oscillation (ENSO). This study provides the longest, continuous record of old-growth eddy flux data to date from one of the longest running Fluxnet stations in the world. From 1998 to 2013, average annual net ecosystem exchange (FNEE) at Wind River AmeriFlux was –32 ± 84 g C m–2 yr–1 indicating that the late seral forest is on average a small net sink of atmospheric carbon. However, interannualmore » variability is high (>300 g C m–2 yr–1) and shows that the stand switches from net carbon sink to source in response to climate drivers associated with ENSO. The old-growth forest is a much stronger sink during La Niña years (mean FNEE = –90 g C m–2 yr–1) than during El Niño when the stand turns carbon neutral or into a small net carbon source (mean FNEE = +17 g C m–2 yr–1). Forest inventory data dating back to the 1930s show a similar correlation with the lower frequency Pacific North American (PNA) and Pacific Decadal Oscillation (PDO) whereby higher aboveground net primary productivity (FANPP) is associated with cool phases of both the PNA and PDO. Furthermore, these measurements add evidence that carbon exchange in old-growth stands may be more sensitive to climate variability across shorter time scales than once thought.« less

  19. Climate indices strongly influence old-growth forest carbon exchange

    NASA Astrophysics Data System (ADS)

    Wharton, Sonia; Falk, Matthias

    2016-04-01

    We present a decade and a half (1998–2013) of carbon dioxide fluxes from an old-growth stand in the American Pacific Northwest to identify ecosystem-level responses to Pacific teleconnection patterns, including the El Niño/Southern Oscillation (ENSO). This study provides the longest, continuous record of old-growth eddy flux data to date from one of the longest running Fluxnet stations in the world. From 1998 to 2013, average annual net ecosystem exchange (F NEE) at Wind River AmeriFlux was ‑32 ± 84 g C m‑2 yr‑1 indicating that the late seral forest is on average a small net sink of atmospheric carbon. However, interannual variability is high (>300 g C m‑2 yr‑1) and shows that the stand switches from net carbon sink to source in response to climate drivers associated with ENSO. The old-growth forest is a much stronger sink during La Niña years (mean F NEE = ‑90 g C m‑2 yr‑1) than during El Niño when the stand turns carbon neutral or into a small net carbon source (mean F NEE = +17 g C m‑2 yr‑1). Forest inventory data dating back to the 1930s show a similar correlation with the lower frequency Pacific North American (PNA) and Pacific Decadal Oscillation (PDO) whereby higher aboveground net primary productivity (F ANPP) is associated with cool phases of both the PNA and PDO. These measurements add evidence that carbon exchange in old-growth stands may be more sensitive to climate variability across shorter time scales than once thought.

  20. Old-growth definition for Red River bottom forests in the eastern United States. Forest Service general technical report

    SciTech Connect

    Shear, T.; Young, M.; Kellison, R.

    1997-05-01

    Our goal was to develop a description of old-growth red river bottom forests of the Southeastern United States. We compared the characteristics of forests described in the scientific literature and forests we examined to various published criteria for old-growth condition. Because red rivers are a relatively new landscape feature (most < 250 years old, resulting from human-induced soil erosion) and because dramatic changes to their floodplains continue to occur, we do not believe that any old-growth red river forests exist. All the stands along these rivers present at European settlement have been cut and/or otherwise severely altered. In the dynamic landscape after settlement, there have been no opportunities for new old-growth forests to develop. Stands older than 50 to 60 years are rare. Therefore, we propose a stand condition called older growth and list the characteristics. With time and stable site conditions, we believe that old-growth and red river forests can develop from older-growth forests.

  1. Carbon storage in old-growth forests of the Mid-Atlantic: toward better understanding the eastern forest carbon sink.

    PubMed

    McGarvey, Jennifer C; Thompson, Jonathan R; Epstein, Howard E; Shugart, Herman H

    2015-02-01

    Few old-growth stands remain in the matrix of secondary forests that dominates the eastern North American landscape. These remnant stands offer insight on the potential carbon (C) storage capacity of now-recovering secondary forests. We surveyed the remaining old-growth forests on sites characteristic of the general Mid-Atlantic United States and estimated the size of multiple components of forest C storage. Within and between old-growth stands, variability in C density is high and related to overstory tree species composition. The sites contain 219 ± 46 Mg C/ha (mean ± SD), including live and dead aboveground biomass, leaf litter, and the soil O horizon, with over 20% stored in downed wood and snags. Stands dominated by tulip poplar (Liriodendron tulipifera) store the most live biomass, while the mixed oak (Quercus spp.) stands overall store more dead wood. Total C density is 30% higher (154 Mg C/ha), and dead wood C density is 1800% higher (46 Mg C/ha) in the old-growth forests than in the surrounding younger forests (120 and 5 Mg C/ha, respectively). The high density of dead wood in old growth relative to secondary forests reflects a stark difference in historical land use and, possibly, the legacy of the local disturbance (e.g., disease) history. Our results demonstrate the potential for dead wood to maintain the sink capacity of secondary forests for many decades to come. PMID:26240851

  2. A study of substrate factor on carbon nanotube forest growth

    NASA Astrophysics Data System (ADS)

    Read, Carlos; Call, Robert; Shen, T. C.

    2010-10-01

    Carbon Nanotube Forests (CNFs) are vertically grown carbon nanotubes. They can be as tall as millimeters with radii from less than one nm (single-walled) to more than a hundred nm (multi-walled). Their high surface to volume ratio provides a unique material system for EM radiation absorption, dry adhesive and biosensor applications. There have been numerous, but not all consistent reports on successful CNF growth. We find that the optimal growth conditions depend critically on the substrate, at least by the spray pyrolysis method we have adopted. To determine the substrate factor, we have investigated two grades of copper, stainless steel, silicon and quartz as substrates on which the catalytic particles and carbon source are delivered simultaneously by a ferrocine-xylene solution. We find that the interplay of lateral and in-diffusion of the iron atoms and interactions with existing gas molecules such as H2, O2, H2O on the substrates dictate the CNF growth.

  3. Complementary models of tree species-soil relationships in old-growth temperate forests

    USGS Publications Warehouse

    Cross, Alison; Perakis, Steven S.

    2011-01-01

    Ecosystem level studies identify plant soil feed backs as important controls on soil nutrient availability,particularly for nitrogen and phosphorus. Although site and species specific studies of tree species soil relationships are relatively common,comparatively fewer studies consider multiple coexisting speciesin old-growth forests across a range of sites that vary underlying soil fertility. We characterized patterns in forest floor and mineral soil nutrients associated with four common tree species across eight undisturbed old-growth forests in Oregon, USA, and used two complementary conceptual models to assess tree species soil relationships. Plant soil feedbacks that could reinforce sitelevel differences in nutrient availability were assessed using the context dependent relationships model, where by relative species based differences in each soil nutrient divergedorconvergedas nutrient status changed across sites. Tree species soil relationships that did not reflect strong feedbacks were evaluated using a site independent relationships model, where by forest floor and surface mineral soil nutrient tools differed consistently by tree species across sites,without variation in deeper mineral soils. We found that theorganically cycled elements carbon, nitrogen, and phosphorus exhibited context-dependent differences among species in both forest floor and mineral soil, and most of ten followed adivergence model,where by species differences were greatest at high-nutrient sites. These patterns are consistent with the oryemphasizing biotic control of these elements through plant soil feedback mechanisms. Site independent species differences were strongest for pool so if the weather able cations calcium, magnesium, potassium,as well as phosphorus, in mineral soils. Site independent species differences in forest floor nutrients we reattributable too nespecies that displayed significant greater forest floor mass accumulation. Our finding confirmed that site-independent and

  4. [Evaluation of economic forest ecosystem services in China].

    PubMed

    Wang, Bing; Lu, Shao-Wei

    2009-02-01

    This paper quantitatively evaluated the economic forest ecosystem services in the provinces of China in 2003, based on the long-term and continuous observations of economic forest ecosystems in this country, the sixth China national forest resources inventory data, and the price parameter data from the authorities in the world, and by applying the law of market value, the method of substitution of the expenses, and the law of the shadow project. The results showed that in 2003, the total value of economic forest ecosystem services in China was 11763.39 x 10(8) yuan, and the total value of the products from economic forests occupied 19.3% of the total ecosystem services value, which indicated that the economic forests not only provided society direct products, but also exhibited enormous eco-economic value. The service value of the functions of economic forests was in the order of water storage > C fixation and O2 release > biodiversity conservation > erosion control > air quality purification > nutrient cycle. The spatial pattern of economic forest ecosystem services in the provinces of China had the same trend with the spatial distribution of water and heat resources and biodiversity. To understand the differences of economic forest ecosystem services in the provinces of China was of significance in alternating the irrational arrangement of our present forestry production, diminishing the abuses of forest management, and establishing high grade, high efficient, and modernized economic forests. PMID:19459385

  5. Effects of selective logging on tropical forest tree growth

    NASA Astrophysics Data System (ADS)

    Figueira, Adelaine Michela E. S.; Miller, Scott D.; de Sousa, Cleilim Albert D.; Menton, Mary C.; Maia, Augusto R.; Da Rocha, Humberto R.; Goulden, Michael L.

    2008-03-01

    We combined measurements of tree growth and carbon dioxide exchange to investigate the effects of selective logging on the Aboveground Live Biomass (AGLB) of a tropical rain forest in the Amazon. Most of the measurements began at least 10 months before logging and continued at least 36 months after logging. The logging removed ˜15% of the trees with Diameter at Breast Height (DBH) greater than 35 cm, which resulted in an instantaneous 10% reduction in AGLB. Both wood production and mortality increased following logging, while Gross Primary Production (GPP) was unchanged. The ratio of wood production to GPP (the wood Carbon Use Efficiency or wood CUE) more than doubled following logging. Small trees (10 cm < DBH < 35 cm) accounted for most of the enhanced wood production. Medium trees (35 cm < DBH < 55 cm) that were within 30 m of canopy gaps created by the logging also showed increased growth. The patterns of enhanced growth are most consistent with logging-induced increases in light availability. The AGLB continued to decline over the study, as mortality outpaced wood production. Wood CUE and mortality remained elevated throughout the 3 years of postlogging measurements. The future trajectory of AGLB and the forest's carbon balance are uncertain, and will depend on how long it takes for heterotrophic respiration, mortality, and CUE to return to prelogging levels.

  6. Comparison of Nitrogen Cycling Between Old Growth Forests and Secondary Forests in the U.S. Mid-Atlantic

    NASA Astrophysics Data System (ADS)

    Walker, R. H.; Epstein, H. E.; McGarvey, J.; Thompson, J.; Mills, A. L.

    2014-12-01

    Throughout the eastern United States, forests are experiencing regrowth, and the sequestration of carbon (C) associated with this regrowth makes these forests a key component of greenhouse gas mitigation strategies (Albani et al., 2006). Through production and decomposition of plant biomass, the C and nitrogen (N) cycles are closely coupled, suggesting that N has a major impact on the cycling of C in N-limited Mid-Atlantic forest systems. The majority of C and N in a temperate forest system is located in the soil organic matter (Templer et al., 2012), so understanding soil N is important for estimating the potential for C sequestration in soils as Mid-Atlantic forests mature (Knicker, 2010). Due to the scarcity of old growth forest stands in the region, previous empirical studies of Mid-Atlantic forests in the old growth stage of succession are limited. I sampled soil C and N in twenty-five remnant old growth forests and matched secondary stands in the Mid-Atlantic to identify differences in soil organic C and N mass and concentrations of nitrate and ammonium. No significant differences were observed between the old growth and secondary growth concentrations of inorganic N species, N fraction, and C:N ratio. Rather, secondary growth values for these variables were found to have significant, positive linear relationships with old growth values, indicating that biotic and abiotic factors varying on a regional scale are driving variability seen in these N characteristics. Further, this suggests that as forest stands reach approximately 75 years in age, these N characteristics are largely established and not likely to change significantly as stands enter the old growth successional stage. Both N fraction and O-horizon depth were shown to have significant negative correlations with old growth stand age. These results indicate that old growth forest stands have a more efficient microbial decomposer community, which could have significant implications for both soil N and

  7. The effect of size and competition on tree growth rate in old-growth coniferous forests

    USGS Publications Warehouse

    Das, Adrian

    2012-01-01

    Tree growth and competition play central roles in forest dynamics. Yet models of competition often neglect important variation in species-specific responses. Furthermore, functions used to model changes in growth rate with size do not always allow for potential complexity. Using a large data set from old-growth forests in California, models were parameterized relating growth rate to tree size and competition for four common species. Several functions relating growth rate to size were tested. Competition models included parameters for tree size, competitor size, and competitor distance. Competitive strength was allowed to vary by species. The best ranked models (using Akaike’s information criterion) explained between 18% and 40% of the variance in growth rate, with each species showing a strong response to competition. Models indicated that relationships between competition and growth varied substantially among species. The results also suggested that the relationship between growth rate and tree size can be complex and that how we model it can affect not only our ability to detect that complexity but also whether we obtain misleading results. In this case, for three of four species, the best model captured an apparent and unexpected decline in potential growth rate for the smallest trees in the data set.

  8. Conterminous U.S. Forest Disturbance Dynamics Evaluated from Landsat Time Series Stacks

    NASA Astrophysics Data System (ADS)

    Goward, S. N.; Kennedy, R. E.; Masek, J.; Cohen, W. B.; Moisen, G. G.; Huang, C.; Thomas, N.; Schleeweis, K.

    2009-12-01

    Current substantial North America carbon emissions are partially offset by carbon uptake in growing forests. Much of this forest sink is attributed to either forest regrowth on abandoned agricultural lands or woody encroachment. However, the magnitude and sustainability of forest carbon sequestration is highly uncertain, particularly because forest disturbance and regrowth dynamics are not well understood. Disturbance events, including harvest, fire, insect and storm damage, and disease, strongly impact carbon dynamics through biomass removal, decay of in situ dead biomass, and changes in growth rates. These disturbance/regrowth uncertainties make prediction of the future role of North American forests and woodlands in carbon sequestration difficult. Within the North American Forest Dynamics (NAFD) project, a core activity of the North American Carbon Program (NACP), we are evaluating forest disturbance and regrowth patterns by combining U.S. Forest Service Forest Inventory and Analysis (FIA) field observations with biennial time series Landsat imagery. Phase I of the NAFD study examined US national forest dynamics and disturbance history from 23 Landsat time series stacks (LTSS) sample locations for the time period 1984-2005. Sites were statistically sampled to support derivation of unbiased national estimates of disturbance rates. Phase I results show a mean disturbance rate of 2.09 M ha/yr in the east and 0.75 M ha/yr in the western forests for this time period. These estimates suggest that eastern forests are replaced every 78 years, with western forests replacement occurring every 122 years. These results are somewhat lower than previous estimates from forest inventory data. Our results also show significant inter-annual variation in disturbance rates which are driven by regional and localized events. We see a large increase in disturbance rates for western forests from 1999-2002, with the greatest increase related to stacks located in the Interior West

  9. Climate-driven speedup of alpine treeline forest growth in the Tianshan Mountains, Northwestern China.

    PubMed

    Qi, Zhaohuan; Liu, Hongyan; Wu, Xiuchen; Hao, Qian

    2015-02-01

    Forest growth is sensitive to interannual climatic change in the alpine treeline ecotone (ATE). Whether the alpine treeline ecotone shares a similar pattern of forest growth with lower elevational closed forest belt (CFB) under changing climate remains unclear. Here, we reported an unprecedented acceleration of Picea schrenkiana forest growth since 1960s in the ATE of Tianshan Mountains, northwestern China by a stand-total sampling along six altitudinal transects with three plots in each transect: one from the ATE between the treeline and the forest line, and the other two from the CFB. All the sampled P. schrenkiana forest patches show a higher growth speed after 1960 and, comparatively, forest growth in the CFB has sped up much slower than that in the ATE. The speedup of forest growth at the ATE is mainly accounted for by climate factors, with increasing temperature suggested to be the primary driver. Stronger water deficit as well as more competition within the CFB might have restricted forest growth there more than that within the ATE, implying biotic factors were also significant for the accelerated forest growth in the ATE, which should be excluded from simulations and predictions of warming-induced treeline dynamics. PMID:25099555

  10. Carbon nanotube forests growth using catalysts from atomic layer deposition

    SciTech Connect

    Chen, Bingan; Zhang, Can; Esconjauregui, Santiago; Xie, Rongsi; Zhong, Guofang; Robertson, John; Bhardwaj, Sunil; Cepek, Cinzia

    2014-04-14

    We have grown carbon nanotubes using Fe and Ni catalyst films deposited by atomic layer deposition. Both metals lead to catalytically active nanoparticles for growing vertically aligned nanotube forests or carbon fibres, depending on the growth conditions and whether the substrate is alumina or silica. The resulting nanotubes have narrow diameter and wall number distributions that are as narrow as those grown from sputtered catalysts. The state of the catalyst is studied by in-situ and ex-situ X-ray photoemission spectroscopy. We demonstrate multi-directional nanotube growth on a porous alumina foam coated with Fe prepared by atomic layer deposition. This deposition technique can be useful for nanotube applications in microelectronics, filter technology, and energy storage.

  11. Conterminous U.S. Forest Disturbance Dynamics Evaluated from Landsat Time Series Stacks

    NASA Astrophysics Data System (ADS)

    Thomas, N.; Goward, S. N.; Kennedy, R. E.; Huang, C.; Schleeweis, K.; Masek, J. G.; Cohen, W. B.; Moisen, G.

    2010-12-01

    Current substantial North America carbon emissions are partially offset by carbon uptake in growing forests. Much of this forest sink is attributed to either forest regrowth on abandoned agricultural lands or woody encroachment. However, the magnitude and persistence of forest carbon sequestration is uncertain, particularly because forest disturbance and regrowth dynamics are not well understood. Disturbance events, including harvest, fire, insect and storm damage, and disease, strongly impact carbon dynamics through biomass removal, decay of in situ dead biomass, and changes in growth rates. These disturbance/regrowth uncertainties make prediction of the future role of North American forests and woodlands in carbon sequestration difficult. Within the North American Forest Dynamics (NAFD) project, a core activity of the North American Carbon Program (NACP), we are evaluating forest disturbance patterns by integrating U.S. Forest Service Forest Inventory and Analysis (FIA) field observations with biennial time series Landsat imagery. The NAFD study has examined conterminous U.S. national forest dynamics from a statistical sample of 50 U.S. Landsat World Reference System locations for derivation of an unbiased estimate of U.S. national annual disturbance rates. For each location a biennial Landsat time series stack (LTSS) was compiled, processed and analyzed for disturbance events for the time period 1984-2005. Our results show significant inter-annual disturbance rate variations within and between sites primarily driven by regional and localized events. A large increase in western forest disturbance rates is observed from 1999-2002, with the greatest increase related to stacks located in the Interior West. Eastern forests show higher rates from 1997 to 2000 and lower disturbance rates in the early 1990’s and 2000s, with southern forests variations dominating the eastern variability. When considering the mean disturbance rates for the eastern and western U.S. as

  12. Biomass Accumulation Rates of Amazonian Secondary Forest and Biomass of Old-Growth Forests from Landsat Time Series and GLAS

    NASA Astrophysics Data System (ADS)

    Helmer, E.; Lefsky, M. A.; Roberts, D.

    2009-12-01

    We estimate the age of humid lowland tropical forests in Rondônia, Brazil, from a somewhat densely spaced time series of Landsat images (1975-2003) with an automated procedure, the Threshold Age Mapping Algorithm (TAMA), first described here. We then estimate a landscape-level rate of aboveground woody biomass accumulation of secondary forest by combining forest age mapping with biomass estimates from the Geoscience Laser Altimeter System (GLAS). Though highly variable, the estimated average biomass accumulation rate of 8.4 Mg ha-1 yr-1 agrees well with ground-based studies for young secondary forests in the region. In isolating the lowland forests, we map land cover and general types of old-growth forests with decision tree classification of Landsat imagery and elevation data. We then estimate aboveground live biomass for seven classes of old-growth forest. TAMA is simple, fast, and self-calibrating. By not using between-date band or index differences or trends, it requires neither image normalization nor atmospheric correction. In addition, it uses an approach to map forest cover for the self-calibrations that is novel to forest mapping with satellite imagery; it maps humid secondary forest that is difficult to distinguish from old-growth forest in single-date imagery; it does not assume that forest age equals time since disturbance; and it incorporates Landsat Multispectral Scanner (MSS) imagery. Variations on the work that we present here can be applied to other forested landscapes. Applications that use image time series will be helped by the free distribution of coregistered Landsat imagery, which began in December 2008, and of the Ice Cloud and land Elevation Satellite (ICESat) Vegetation Product, which simplifies the use of GLAS data. Finally, we demonstrate here for the first time how the optical imagery of fine spatial resolution that is viewable on Google Earth provides a new source of reference data for remote sensing applications related to land cover

  13. Classification of forest growth stage using Landsat TM data

    NASA Astrophysics Data System (ADS)

    Fujisaki, Ikuko; Gerard, Patrick D.; Evans, David L.

    2005-09-01

    This study examined the utility of polytomous logistic regression in pixel classification of remotely sensed images by the growth stage of forests. For a population of grouped continuous categories, the assumption of normal distribution of independent variables, which is often required in multivariate classification methods, may not be appropriate. Two types of polytomous logistic regression procedures, multinomial and cumulative logistic regression, were used to classify Landsat TM data by growth stage (regeneration-immature, intermediate, and mature) of loblolly pine (Pinus taeda L.) forest in the east central Mississippi. Multinomial logistic regression is typically used for analysis of unordered categorical data. Cumulative logistic regression is one of the most commonly used methods of ordinal logistic regression which is generally preferred to analyze ordered categorical data, although, it imposes restrictions on the data. Three hundred sample points were located randomly throughout the study site and vectors of pixel values of four bands of Landsat TM data were used to predict growth stage at each sample location. The results were compared to that of parametric and nonparametric discriminant analysis, k-nearest neighbor method. Non-normal distribution of independent variables indicated a violation of the assumptions for parametric discriminant analysis. Classification with cumulative logistic regression using four bands was performed first. However, the assumption of the model was not met. So, the classification was also performed using only band 4 which appeared to meet the assumption. The error rate of cumulative logistic regression was 39.12% with all the bands and 37.70% with band 4 alone. Although error rate with cumulative logistic regression with band 4 alone resulted in the lowest error rate, the improvement over other methods was marginal. The error rate of k-nearest neighbor method varied from 38.68 to 48.06% depending on choice of the value of k.

  14. Mapping forest structure, species gradients and growth in an urban area using lidar and hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Gu, Huan

    Urban forests play an important role in the urban ecosystem by providing a range of ecosystem services. Characterization of forest structure, species variation and growth in urban forests is critical for understanding the status, function and process of urban ecosystems, and helping maximize the benefits of urban ecosystems through management. The development of methods and applications to quantify urban forests using remote sensing data has lagged the study of natural forests due to the heterogeneity and complexity of urban ecosystems. In this dissertation, I quantify and map forest structure, species gradients and forest growth in an urban area using discrete-return lidar, airborne imaging spectroscopy and thermal infrared data. Specific objectives are: (1) to demonstrate the utility of leaf-off lidar originally collected for topographic mapping to characterize and map forest structure and associated uncertainties, including aboveground biomass, basal area, diameter, height and crown size; (2) to map species gradients using forest structural variables estimated from lidar and foliar functional traits, vegetation indices derived from AVIRIS hyperspectral imagery in conjunction with field-measured species data; and (3) to identify factors related to relative growth rates in aboveground biomass in the urban forests, and assess forest growth patterns across areas with varying degree of human interactions. The findings from this dissertation are: (1) leaf-off lidar originally acquired for topographic mapping provides a robust, potentially low-cost approach to quantify spatial patterns of forest structure and carbon stock in urban areas; (2) foliar functional traits and vegetation indices from hyperspectral data capture gradients of species distributions in the heterogeneous urban landscape; (3) species gradients, stand structure, foliar functional traits and temperature are strongly related to forest growth in the urban forests; and (4) high uncertainties in our

  15. Evaluating models of climate and forest vegetation

    NASA Technical Reports Server (NTRS)

    Clark, James S.

    1992-01-01

    Understanding how the biosphere may respond to increasing trace gas concentrations in the atmosphere requires models that contain vegetation responses to regional climate. Most of the processes ecologists study in forests, including trophic interactions, nutrient cycling, and disturbance regimes, and vital components of the world economy, such as forest products and agriculture, will be influenced in potentially unexpected ways by changing climate. These vegetation changes affect climate in the following ways: changing C, N, and S pools; trace gases; albedo; and water balance. The complexity of the indirect interactions among variables that depend on climate, together with the range of different space/time scales that best describe these processes, make the problems of modeling and prediction enormously difficult. These problems of predicting vegetation response to climate warming and potential ways of testing model predictions are the subjects of this chapter.

  16. Remote sensing of forest tree growth, vigor, and stress. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    Not Available

    1993-09-01

    The bibliography contains citations concerning the application of remote sensing to forestry with regard to forest vigor and the identification of stressed trees. The uses of stress indicators for potential location of metal deposits, distribution of groundwater, infestation by disease or insects, effects of air pollution, and general forest decline are cited. Remote sensing of seedling growth and distribution of cleared forest lands are are discussed. Remote sensing techniques for forest applications such as infrared scanners, radar techniques, aerial photography, satellite imagery, airborne laser mapping are described and evaluated. Remote sensing of crop vigor and arid lands is discussed in separate bibliographies. (Contains a minimum of 175 citations and includes a subject term index and title list.)

  17. Remote sensing of forest tree growth, vigor, and stress. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    1995-04-01

    The bibliography contains citations concerning the application of remote sensing to forestry for purposes of assessing forest vigor and the identification of stressed trees. The uses of stress indicators for potential location of metal deposits, distribution of groundwater, infestation by disease or insects, effects of air pollution, and general forest decline are cited. Remote sensing of seedling growth and distribution of cleared forest lands is discussed. Remote sensing techniques for forest applications such as infrared scanners, radar techniques, aerial photography, satellite imagery, and airborne laser mapping are described and evaluated. Remote sensing of crop vigor and arid lands is discussed in separate bibliographies. (Contains 250 citations and includes a subject term index and title list.)

  18. Ecosystem Consequences of Forest Fragmentation in the Pacific Northwest: Biogeochemical Edge Effects within Old-Growth Forest Remnants

    NASA Astrophysics Data System (ADS)

    Hayes, T. D.; Swanson, A.; D'Antonio, C. M.; Griffiths, R. P.

    2005-12-01

    Our research includes quantifying the long term impact of clear-cut edges on biogeochemical processes affecting carbon and nitrogen retention within fragmented old-growth Douglas-fir/western hemlock forests in the Pacific Northwest. In addition to quantifying the magnitude and depth of influence of edge effects on soil processes, this research seeks broader application to conservation biology, using a mechanistic approach. Along 360-m gradients spanning clear-cut to forest at nine sites, long-term monitoring of edge effects integrates microclimate, above-ground structure, litter fall, decomposition, and soil nitrogen dynamics. Abrupt changes in height and structure at edges induce increased microclimatic variability in adjacent forest, which, in turn, alters rates of nitrogen and carbon cycling in soils. Field and laboratory assays reveal increases in litter decomposition and nitrogen availability in near edge (0-30 m from edge) forest, and higher rates of litter fall and soil organic matter storage within far edge (30-120 m from edge) forest, relative to interior forest (more than 120 m from edge). Abiotic structural effects, by modulating microclimatic variability, change the complex biotic interactions involved in biogeochemical cycling in forest soils within 120 m of edges. Due to such interactions, organic-matter and nitrogen pool sizes in soil and vegetation, and net ecosystem production, vary in a nonlinear, but predictable, manner with distance into forest from edge. Mixed-effects statistical models most precisely quantify depth of influence for over 100 microclimatic, structural, and biogeochemical variables.

  19. Old-growth definition for evergreen bay forests and related seral communities. Forest Service general technical report

    SciTech Connect

    McKevlin, M.R.

    1996-09-01

    This document describes old-growth conditions in an evergreen bay forest stand. Bay forests occur throughout the Atlantic and Gulf Coastal Plains. However, they are considered rare and are present across the landscape in a patchwork mosaic with other forest types in various stages of succession. Bay forests can be found associated with pocosins. Carolina bays and sandhill seeps, stream heads, and stream margins. The dominant species include loblolly-bay, sweetbay, and redbay, hence the name evergreen bay forest. However, several other swamp species associates are common, as well as many highly flammable shrub species. This forest type is subject to infrequent, high intensity, widespread disturbances such as fire. Fire is necessary to the nutrient cycling of this forest type and in conjunction with hydrology, controls succession. These stands are frequently inundated by surface water, resulting in the development of histic soils low in fertility. Alteration of the hydrology by man and catastrophic wildfire are considered to be the greatest threats to the existence of bay forests.

  20. Assessing the effects of management on forest growth across France: insights from a new functional–structural model

    PubMed Central

    Guillemot, Joannès; Delpierre, Nicolas; Vallet, Patrick; François, Christophe; Martin-StPaul, Nicolas K.; Soudani, Kamel; Nicolas, Manuel; Badeau, Vincent; Dufrêne, Eric

    2014-01-01

    Background and Aims The structure of a forest stand, i.e. the distribution of tree size features, has strong effects on its functioning. The management of the structure is therefore an important tool in mitigating the impact of predicted changes in climate on forests, especially with respect to drought. Here, a new functional–structural model is presented and is used to assess the effects of management on forest functioning at a national scale. Methods The stand process-based model (PBM) Castanea was coupled to a stand structure module (SSM) based on empirical tree-to-tree competition rules. The calibration of the SSM was based on a thorough analysis of intersite and interannual variability of competition asymmetry. The coupled Castanea–SSM model was evaluated across France using forest inventory data, and used to compare the effect of contrasted silvicultural practices on simulated stand carbon fluxes and growth. Key Results The asymmetry of competition varied consistently with stand productivity at both spatial and temporal scales. The modelling of the competition rules enabled efficient prediction of changes in stand structure within the Castanea PBM. The coupled model predicted an increase in net primary productivity (NPP) with management intensity, resulting in higher growth. This positive effect of management was found to vary at a national scale across France: the highest increases in NPP were attained in forests facing moderate to high water stress; however, the absolute effect of management on simulated stand growth remained moderate to low because stand thinning involved changes in carbon allocation at the tree scale. Conclusions This modelling approach helps to identify the areas where management efforts should be concentrated in order to mitigate near-future drought impact on national forest productivity. Around a quarter of the French temperate oak and beech forests are currently in zones of high vulnerability, where management could thus mitigate

  1. Forest stand growth dynamics in Central Europe have accelerated since 1870

    PubMed Central

    Pretzsch, Hans; Biber, Peter; Schütze, Gerhard; Uhl, Enno; Rötzer, Thomas

    2014-01-01

    Forest ecosystems have been exposed to climate change for more than 100 years, whereas the consequences on forest growth remain elusive. Based on the oldest existing experimental forest plots in Central Europe, we show that, currently, the dominant tree species Norway spruce and European beech exhibit significantly faster tree growth (+32 to 77%), stand volume growth (+10 to 30%) and standing stock accumulation (+6 to 7%) than in 1960. Stands still follow similar general allometric rules, but proceed more rapidly through usual trajectories. As forest stands develop faster, tree numbers are currently 17–20% lower than in past same-aged stands. Self-thinning lines remain constant, while growth rates increase indicating the stock of resources have not changed, while growth velocity and turnover have altered. Statistical analyses of the experimental plots, and application of an ecophysiological model, suggest that mainly the rise in temperature and extended growing seasons contribute to increased growth acceleration, particularly on fertile sites. PMID:25216297

  2. Plant hydraulic traits govern forest water use and growth

    NASA Astrophysics Data System (ADS)

    Matheny, Ashley; Bohrer, Gil; Fiorella, Rich; Mirfenderesgi, Golnazalsadat

    2016-04-01

    species, like red maple. Advanced plant hydrodynamic models, including the FETCH2 model, are able to capture the effects that traits regulating water loss (e. g. isohydry/anisohydry, conductivity of woody tissue, and rooting depth) impose upon transpiration at scales of a single tree to a whole forest. The integration of detailed knowledge of species-specific hydraulic traits, available through the TRY Global Plant Trait Database, provides biologically relevant constraints for the governing parameters within these modeling systems. By incorporating the effects of plant hydraulic traits at the leaf, stem, and root levels, with mechanistically based predictions of transpiration, growth, and mortality, we can improve simulations of the surface energy budget and global carbon and water balances.

  3. Spatial aspects of tree mortality strongly differ between young and old-growth forests.

    PubMed

    Larson, Andrew J; Lutz, James A; Donato, Daniel C; Freund, James A; Swanson, Mark E; HilleRisLambers, Janneke; Sprugel, Douglas G; Franklin, Jerry F

    2015-11-01

    Rates and spatial patterns of tree mortality are predicted to change during forest structural development. In young forests, mortality should be primarily density dependent due to competition for light, leading to an increasingly spatially uniform pattern of surviving trees. In contrast, mortality in old-growth forests should be primarily caused by contagious and spatially autocorrelated agents (e.g., insects, wind), causing spatial aggregation of surviving trees to increase through time. We tested these predictions by contrasting a three-decade record of tree mortality from replicated mapped permanent plots located in young (< 60-year-old) and old-growth (> 300-year-old) Abies amabilis forests. Trees in young forests died at a rate of 4.42% per year, whereas trees in old-growth forests died at 0.60% per year. Tree mortality in young forests was significantly aggregated, strongly density dependent, and caused live tree patterns to become more uniform through time. Mortality in old-growth forests was spatially aggregated, but was density independent and did not change the spatial pattern of surviving trees. These results extend current theory by demonstrating that density-dependent competitive mortality leading to increasingly uniform tree spacing in young forests ultimately transitions late in succession to a more diverse tree mortality regime that maintains spatial heterogeneity through time. PMID:27070005

  4. Evaluating Heterogeneous Conservation Effects of Forest Protection in Indonesia

    PubMed Central

    Shah, Payal; Baylis, Kathy

    2015-01-01

    Establishing legal protection for forest areas is the most common policy used to limit forest loss. This article evaluates the effectiveness of seven Indonesian forest protected areas introduced between 1999 and 2012. Specifically, we explore how the effectiveness of these parks varies over space. Protected areas have mixed success in preserving forest, and it is important for conservationists to understand where they work and where they do not. Observed differences in the estimated treatment effect of protection may be driven by several factors. Indonesia is particularly diverse, with the landscape, forest and forest threats varying greatly from region to region, and this diversity may drive differences in the effectiveness of protected areas in conserving forest. However, the observed variation may also be spurious and arise from differing degrees of bias in the estimated treatment effect over space. In this paper, we use a difference-in-differences approach comparing treated observations and matched controls to estimate the effect of each protected area. We then distinguish the true variation in protected area effectiveness from spurious variation driven by several sources of estimation bias. Based on our most flexible method that allows the data generating process to vary across space, we find that the national average effect of protection preserves an additional 1.1% of forest cover; however the effect of individual parks range from a decrease of 3.4% to an increase of 5.3% and the effect of most parks differ from the national average. Potential biases may affect estimates in two parks, but results consistently show Sebangau National Park is more effective while two parks are substantially less able to protect forest cover than the national average. PMID:26039754

  5. Evaluating heterogeneous conservation effects of forest protection in Indonesia.

    PubMed

    Shah, Payal; Baylis, Kathy

    2015-01-01

    Establishing legal protection for forest areas is the most common policy used to limit forest loss. This article evaluates the effectiveness of seven Indonesian forest protected areas introduced between 1999 and 2012. Specifically, we explore how the effectiveness of these parks varies over space. Protected areas have mixed success in preserving forest, and it is important for conservationists to understand where they work and where they do not. Observed differences in the estimated treatment effect of protection may be driven by several factors. Indonesia is particularly diverse, with the landscape, forest and forest threats varying greatly from region to region, and this diversity may drive differences in the effectiveness of protected areas in conserving forest. However, the observed variation may also be spurious and arise from differing degrees of bias in the estimated treatment effect over space. In this paper, we use a difference-in-differences approach comparing treated observations and matched controls to estimate the effect of each protected area. We then distinguish the true variation in protected area effectiveness from spurious variation driven by several sources of estimation bias. Based on our most flexible method that allows the data generating process to vary across space, we find that the national average effect of protection preserves an additional 1.1% of forest cover; however the effect of individual parks range from a decrease of 3.4% to an increase of 5.3% and the effect of most parks differ from the national average. Potential biases may affect estimates in two parks, but results consistently show Sebangau National Park is more effective while two parks are substantially less able to protect forest cover than the national average. PMID:26039754

  6. Status of mature and old-growth forests in the Pacific Northwest.

    PubMed

    Strittholt, James R; DellaSala, Dominick A; Jiang, Hong

    2006-04-01

    Nearly 10 million ha of federal lands in the Pacific Northwest have been managed under the Northwest Forest Plan since 1994. The plan reduced logging levels by 80%; only recently, however have inventories on status and condition of mature and old-growth forests become available. Our objectives were to (1) determine the areal extent of old (> 150 years) and mature (50-150 years) conifer forests based on 2000 Landsat 7 ETM+ imagery, (2) examine levels of protection, (3) determine the degree of additional protection afforded to old and mature conifer forests if late-successional reserves (LSRs) and inventoried roadless areas (IRAs) were fully protected, and (4) review management options to achieve greater protection of older forests. The historical extent of old-growth forest in the Pacific Northwest was roughly two-thirds (16,672,976 ha) of the total land area. Since the time of European settlement, approximately 72% of the original old-growth conifer forest has been lost, largely through logging and other developments. Of the remaining old growth, the Central and Southern Cascades and Klamath-Siskiyou account for nearly half Mature conifer area (4,758,596 ha) nearly equaled the amount of old conifer More than 78% of the old growth and 50% of mature forest were located on public lands. Approximately one-quarter (1,201,622 ha) of the old-growth conifer (or 7% of the historical old-growth area) was classified as GAP status 1 (strictly protected) or GAP status 2 (moderately protected). The total area of LSRs was slightly more than 3 million ha, approximately 36% (1,073,299 ha) of which contained old-growth conifer forest. Combined old and mature conifer within LSRs was approximately 59% of the total LSR area. The total amount of IRA for the Pacific Northwest was approximately 1,563,370 ha; of this, 526,912 ha (34%) was old growth. The combined area of old-growth conifer forest accounted for by protected areas (GAP 1 and 2), LSRs, and IRAs was 2,401,780 ha, which

  7. Increased water use efficiency but contrasting tree growth patterns in Fitzroya cupressoides forests of southern Chile during recent decades

    NASA Astrophysics Data System (ADS)

    Urrutia-Jalabert, Rocío.; Malhi, Yadvinder; Barichivich, Jonathan; Lara, Antonio; Delgado-Huertas, Antonio; Rodríguez, Carmen Gloria; Cuq, Emilio

    2015-12-01

    Little is known about how old-growth and massive forests are responding to environmental change. We investigated tree-ring growth and carbon isotopes of the long-lived and high biomass Fitzroya cupressoides in two stands growing in contrasting environmental conditions in the Coastal Range (~300 years old) and Andean Cordilleras (>1500 years old) of southern Chile. The interannual variability in δ13C was assessed for the period 1800-2010, and changes in discrimination and intrinsic water use efficiency (iWUE) were evaluated in relation to changes in climate and tree-ring growth during the last century. 13C discrimination has significantly decreased, and iWUE has increased since the 1900s in both sites. However, these trends in isotopic composition have been accompanied by different growth patterns: decreasing growth rates in the Coastal Range since the 1970s and increasing growth rates in the Andes since the 1900s. Trees growing in the Coastal Range have become more efficient in their use of water, probably due to reduced stomatal conductance caused by increases in CO2 and warming. Trees growing in the Andes have also become more water use efficient, but this has been likely due to increased photosynthetic rates. Fitzroya forests, including particularly old-growth stands, are responding to recent environmental changes, and their response has been site dependent. The growth of forests under a more Mediterranean climate influence and restrictive soil conditions in the Coastal Range has been more negatively affected by current warming and drying; while the growth of old stands in the wet Andes has been positively affected by changes in climate (decreasing cloudiness) and increasing CO2. Permanent monitoring of these endangered forests under ongoing environmental changes is needed in order to reassure the long-term preservation of this millennial-aged species.

  8. Vegetation structure determination using LIDAR data and the forest growth parameters

    NASA Astrophysics Data System (ADS)

    Rybansky, M.; Brenova, M.; Cermak, J.; van Genderen, J.; Sivertun, Å.

    2016-06-01

    The goal of this paper is to identify the main vegetation factors in the terrain, which are important for the analysis of forest structure. Such an analysis is important for forestry, rescue operations management during crises situations and disasters such as fires, storms, earthquakes and military analysis (transportation, cover, concealment, etc.). For the forest structure determination, both LIDAR and the forest growth prediction analysis were used. As main results, the vegetation height, tree spacing and stem diameters were determined

  9. Remnant Trees Affect Species Composition but Not Structure of Tropical Second-Growth Forest

    PubMed Central

    Sandor, Manette E.; Chazdon, Robin L.

    2014-01-01

    Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields. PMID:24454700

  10. Toward detection of CO2 fertilization of tree growth and biomass accumulation in Amazon forests

    NASA Astrophysics Data System (ADS)

    Chambers, J. Q.; Negron Juarez, R. I.; Di Vittorio, A. V.; Marra, D.; Rifai, S. W.; Ribeiro, G.; Higuchi, N.

    2012-12-01

    Synthesis studies of old-growth tropical forest plot networks indicate a pantropical net carbon sink of more than 1 Pg C/yr. However a number of confounding factors limit our ability to attribute these changes to direct CO2 fertilization of tree growth and forest productivity. Of primary importance is determining if the plots adequately sample natural disturbance and recovery gradients, and the larger landscape successional mosaic. In addition, forest biomass dynamics which include tree growth, recruitment and mortality can interact in complex ways with changes in forest productivity and biomass accumulation. This study represents a novel approach to determine the sensitivity of different sampling strategies for detecting tropical forest CO2 fertilization while accounting for these confounding factors. Our approach, developed for Amazon forests in Brazil and Peru, combines extensive field plot data on biomass dynamics, remote sensing analyses to generate disturbance probability distribution functions, and individual-based simulation modeling for placing plot-level results into a landscape context. Results indicate that forest plots significantly larger than 10 ha are required to maximize the signal-to-noise ratio for detecting CO2 fertilization. We also present a field sampling strategy for quantifying site-to-site differences in forest biomass accumulation rates, which is useful for detecting regional differences in tropical forest sensitivity to rising atmospheric CO2 concentration. Overall, this approach is useful in developing field campaigns that explicitly account for landscape heterogeneity in testing key predictions of Earth system models.

  11. [Forest ecosystem service and its evaluation in China].

    PubMed

    Fang, Jin; Lu, Shaowei; Yu, Xinxiao; Rao, Liangyi; Niu, Jianzhi; Xie, Yuanyuan; Zhag, Zhenming

    2005-08-01

    Facing the relative lag of forest ecosystem service and estimation in China, this paper proposed to quickly carry out the research on the evaluation of forest ecosystem service. On the basis of the classification of forest ecosystem types in China, the service of artificial and semi-artificial forest ecosystems was investigated, which was divided into eight types, i.e., timber and other products, recreation and eco-tourism, water storage, C fixation and O2 release, nutrient cycling, air quality purifying, erosion control, and habitat provision. According to the assessment index system for global ecosystem service proposed by Costanza et al., a series of assessment index system suitable for Chinese forest ecosystem service was set up, by which, the total value of forest ecosystem service in China was estimated to be 30 601.20 x 10(8) yuan x yr(-1), including direct and indirect economic value about 1 920.23 x 10(8) and 28 680.97 x 10(8) yuan x yr(-1), respectively. The indirect value was as 14.94 times as the direct one. The research aimed to bring natural resources and environment factors into the account system of national economy quickly, and to realize the green GDP at last, which would be helpful to realize sustainable development and environment protection. PMID:16262073

  12. Recent Tree-growth Responses to Warming Vary by Geographic Region and Ecosystem Type within the Boreal Forest-tundra Transition Zone in Alaska

    NASA Astrophysics Data System (ADS)

    Sherriff, R.; Miller, A. E.

    2015-12-01

    A critical concern for boreal ecosystems centers on broad-scale responses to warming; i.e., where warming will lead to declining growth and mortality, or enhanced growth and greater productivity. However, few studies have synthesized tree growth along biogeographic gradients in an attempt to address this issue. We sought to develop a broader understanding of how trees have responded to recent warming for a dominant conifer species from the southern boreal to the western forest margin, an area expected to show signs of an early-stage boreal biome shift. A new 30-site network of ring-width chronologies (1216 trees >4cm dbh) were evaluated for growth differences in Picea glauca across low-elevation, closed forests, open woodlands, and altitudinal treeline from southern interior boreal forest to the western forest-tundra margin. Regional temperature records were used to evaluate 1) whether tree growth near western treeline, which experiences cooler summers but warmer winters than in the interior, showed greater sensitivity to temperature than interior sites, 2) if the temperature-growth response varied through time, across ecosystem types, and by tree age, and 3) if there was a temperature-growth threshold. Positive growth trends since the 1980s in many open stands were consistent with the predicted expansion of western and altitudinal treeline. However, years with temperatures >13oC corresponded with a growth plateau or decline at all but the altitudinal treeline sites regardless of geographic location. Closed-canopy stands showed growth declines, high spruce beetle activity, and less resiliency to further warming. Warming leads to markedly different responses according to ecosystem type and biogeographical setting at the boreal forest-tundra margin. Low-elevation forests are less resilient to further warming where temperatures have already reached threshold levels and further spruce beetle outbreaks occur, even at the western margin of boreal forest.

  13. Growth Decline Linked to Warming-Induced Water Limitation in Hemi-Boreal Forests

    PubMed Central

    Wu, Xiuchen; Liu, Hongyan; Guo, Dali; Anenkhonov, Oleg A.; Badmaeva, Natalya K.; Sandanov, Denis V.

    2012-01-01

    Hemi-boreal forests, which make up the transition from temperate deciduous forests to boreal forests in southern Siberia, have experienced significant warming without any accompanying increase in precipitation during the last 80 years. This climatic change could have a profound impact on tree growth and on the stability of forest ecosystems in this region, but at present evidence for these impacts is lacking. In this study, we report a recent dramatic decline in the growth of hemi-boreal forests, based on ring width measurements from three dominant tree-species (Pinus sylvestris, Larix sibirica and Larix gmelinii), sampled from eight sites in the region. We found that regional tree growth has become increasingly limited by low soil water content in the pre- and early-growing season (from October of the previous year to July of the current year) over the past 80 years. A warming-induced reduction in soil water content has also increased the climate sensitivity of these three tree species. Beginning in the mid-1980s, a clear decline in growth is evident for both the pine forests and the larch forests, although there are increasing trends in the proxy of soil water use efficiencies. Our findings are consistent with those from other parts of the world and provide valuable insights into the regional carbon cycle and vegetation dynamics, and should be useful for devising adaptive forest management strategies. PMID:22916142

  14. Growth decline linked to warming-induced water limitation in hemi-boreal forests.

    PubMed

    Wu, Xiuchen; Liu, Hongyan; Guo, Dali; Anenkhonov, Oleg A; Badmaeva, Natalya K; Sandanov, Denis V

    2012-01-01

    Hemi-boreal forests, which make up the transition from temperate deciduous forests to boreal forests in southern Siberia, have experienced significant warming without any accompanying increase in precipitation during the last 80 years. This climatic change could have a profound impact on tree growth and on the stability of forest ecosystems in this region, but at present evidence for these impacts is lacking. In this study, we report a recent dramatic decline in the growth of hemi-boreal forests, based on ring width measurements from three dominant tree-species (Pinus sylvestris, Larix sibirica and Larix gmelinii), sampled from eight sites in the region. We found that regional tree growth has become increasingly limited by low soil water content in the pre- and early-growing season (from October of the previous year to July of the current year) over the past 80 years. A warming-induced reduction in soil water content has also increased the climate sensitivity of these three tree species. Beginning in the mid-1980s, a clear decline in growth is evident for both the pine forests and the larch forests, although there are increasing trends in the proxy of soil water use efficiencies. Our findings are consistent with those from other parts of the world and provide valuable insights into the regional carbon cycle and vegetation dynamics, and should be useful for devising adaptive forest management strategies. PMID:22916142

  15. Old-growth and mature forests near spotted owl nests in western Oregon

    NASA Technical Reports Server (NTRS)

    Ripple, William J.; Johnson, David H.; Hershey, K. T.; Meslow, E. Charles

    1995-01-01

    We investigated how the amount of old-growth and mature forest influences the selection of nest sites by northern spotted owls (Strix occidentalis caurina) in the Central Cascade Mountains of Oregon. We used 7 different plot sizes to compare the proportion of mature and old-growth forest between 30 nest sites and 30 random sites. The proportion of old-growth and mature forest was significantly greater at nests sites than at random sites for all plot sizes (P less than or equal to 0.01). Thus, management of the spotted owl might require setting the percentage of old-growth and mature forest retained from harvesting at least 1 standard deviation above the mean for the 30 nest sites we examined.

  16. EVALUATION OF METRIC PRECISION FOR A RIPARIAN FOREST SURVEY

    EPA Science Inventory

    This paper evaluates the performance of a protocol to monitor riparian forests in western Oregon based on the quality of the data obtained from a recent field survey. Precision and accuracy are the criteria used to determine the quality of 19 field metrics. The field survey con...

  17. Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees.

    PubMed

    Li, Xuefei; Schmid, Bernhard; Wang, Fei; Paine, C E Timothy

    2016-01-01

    Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species. PMID:26953884

  18. Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees

    PubMed Central

    Li, Xuefei; Schmid, Bernhard; Wang, Fei; Paine, C. E. Timothy

    2016-01-01

    Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species. PMID:26953884

  19. Soil-calcium depletion linked to acid rain and forest growth in the eastern United States

    USGS Publications Warehouse

    Lawrence, Gregory B.; Huntington, T.G.

    1999-01-01

    Since the discovery of acid rain in the 1970's, scientists have been concerned that deposition of acids could cause depletion of calcium in forest soils. Research in the 1980's showed that the amount of calcium in forest soils is controlled by several factors that are difficult to measure. Further research in the 1990's, including several studies by the U.S. Geological Survey, has shown that (1) calcium in forest soils has decreased at locations in the northeastern and southeastern U.S., and (2) acid rain and forest growth (uptake of calcium from the soil by roots) are both factors contributing to calcium depletion.

  20. The dynamic of annual carbon allocation to wood in European forests is consistent with a combined source-sink limitation of growth: implications for modelling

    NASA Astrophysics Data System (ADS)

    Guillemot, J.; Martin-StPaul, N. K.; Dufrêne, E.; François, C.; Soudani, K.; Ourcival, J. M.; Delpierre, N.

    2015-02-01

    The extent to which forest growth is limited by carbon (C) supply (source control) or by cambial activity (sink control) will condition the response of trees to global changes. However, the physiological processes responsible for the limitation of forest growth are still under debate. The aim of this study is to evaluate the key drivers of the annual carbon allocation to wood along large soil and climate regional gradients in five tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex, Quercus robur and Picea abies). Combining field measurements and process-based simulations at 49 sites (931 site-years), we assessed the stand biomass growth dependences at both inter-site and inter-annual scales. Specifically, the relative influence of forest C balance (source control), direct environmental control (water and temperature controls of sink activity) and allocation adjustments related to age, past climate conditions, competition intensity and soil nutrient availability on growth were quantified. The inter-site variability in stand C allocation to wood was predominantly driven by an age-related decline. The direct control of temperature or water stress on sink activity (i.e. independently from their effects on C supply) exerted a strong influence on the annual stand woody growth in all the species considered, including deciduous temperate species. The lagged effect of the past environment conditions was a significant driver of the annual C allocation to wood. Carbon supply appeared to strongly limit growth only in deciduous temperate species. We provide an evaluation of the spatio-temporal dynamics of annual carbon allocation to wood in European forests. Our study supports the premise that European forest growth is under a complex control including both source and sink limitations. The relative influences of the different growth drivers strongly vary across years and spatial ecological gradients. We suggest a

  1. Phosphorus limits Eucalyptus grandis seedling growth in an unburnt rain forest soil

    PubMed Central

    Tng, David Y. P.; Janos, David P.; Jordan, Gregory J.; Weber, Ellen; Bowman, David M. J. S.

    2014-01-01

    Although rain forest is characterized as pyrophobic, pyrophilic giant eucalypts grow as rain forest emergents in both temperate and tropical Australia. In temperate Australia, such eucalypts depend on extensive, infrequent fires to produce conditions suitable for seedling growth. Little is known, however, about constraints on seedlings of tropical giant eucalypts. We tested whether seedlings of Eucalyptus grandis experience edaphic constraints similar to their temperate counterparts. We hypothesized that phosphorous addition would alleviate edaphic constraints. We grew seedlings in a factorial experiment combining fumigation (to simulate nutrient release and soil pasteurization by fire), soil type (E. grandis forest versus rain forest soil) and phosphorus addition as factors. We found that phosphorus was the principal factor limiting E. grandis seedling survival and growth in rain forest soil, and that fumigation enhanced survival of seedlings in both E. grandis forest and rain forest soil. We conclude that similar to edaphic constraints on temperate giant eucalypts, mineral nutrient and biotic attributes of a tropical rain forest soil may hamper E. grandis seedling establishment. In rain forest soil, E. grandis seedlings benefited from conditions akin to a fire-generated ashbed (i.e., an “ashbed effect”). PMID:25339968

  2. Phosphorus limits Eucalyptus grandis seedling growth in an unburnt rain forest soil.

    PubMed

    Tng, David Y P; Janos, David P; Jordan, Gregory J; Weber, Ellen; Bowman, David M J S

    2014-01-01

    Although rain forest is characterized as pyrophobic, pyrophilic giant eucalypts grow as rain forest emergents in both temperate and tropical Australia. In temperate Australia, such eucalypts depend on extensive, infrequent fires to produce conditions suitable for seedling growth. Little is known, however, about constraints on seedlings of tropical giant eucalypts. We tested whether seedlings of Eucalyptus grandis experience edaphic constraints similar to their temperate counterparts. We hypothesized that phosphorous addition would alleviate edaphic constraints. We grew seedlings in a factorial experiment combining fumigation (to simulate nutrient release and soil pasteurization by fire), soil type (E. grandis forest versus rain forest soil) and phosphorus addition as factors. We found that phosphorus was the principal factor limiting E. grandis seedling survival and growth in rain forest soil, and that fumigation enhanced survival of seedlings in both E. grandis forest and rain forest soil. We conclude that similar to edaphic constraints on temperate giant eucalypts, mineral nutrient and biotic attributes of a tropical rain forest soil may hamper E. grandis seedling establishment. In rain forest soil, E. grandis seedlings benefited from conditions akin to a fire-generated ashbed (i.e., an "ashbed effect"). PMID:25339968

  3. An individual-based growth and competition model for coastal redwood forest restoration

    USGS Publications Warehouse

    van Mantgem, Phillip J.; Das, Adrian J.

    2014-01-01

    Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth.

  4. Factors Affecting the Growth Behavior of De-lonized Water Assisted Carbon Nanotube Forests.

    PubMed

    Adusumilli, Siva P; Westgate, Charles R

    2015-09-01

    The aim of this work is to analyze the conditions for producing water assisted carbon nanotubes (WA-CNT) forests by varying parameters that include growth temperature; de-ionized (DI) water flow; carbon-containing gas flow; and thereby determine the length, impurities and catalyst utilization in the CNT forest. Most importantly, the impact of water molecules on the length and catalyst utilization of the CNT forest was investigated. The CNT forests with lengths up to 140 microns were grown using a chemical vapor deposition technique at atmospheric pressure. The forest bundles had weak adhesion with the substrate which allows them to be peeled off easily, enabling easy transfer to other substrates. The characterization of CNT forest were carried out using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HR-TEM) techniques. PMID:26716218

  5. Diverse growth trends and climate responses across Eurasia’s boreal forest

    NASA Astrophysics Data System (ADS)

    Hellmann, Lena; Agafonov, Leonid; Charpentier Ljungqvist, Fredrik; Churakova (Sidorova, Olga; Düthorn, Elisabeth; Esper, Jan; Hülsmann, Lisa; Kirdyanov, Alexander V.; Moiseev, Pavel; Myglan, Vladimir S.; Nikolaev, Anatoly N.; Reinig, Frederick; Schweingruber, Fritz H.; Solomina, Olga; Tegel, Willy; Büntgen, Ulf

    2016-07-01

    The area covered by boreal forests accounts for ∼16% of the global and 22% of the Northern Hemisphere landmass. Changes in the productivity and functioning of this circumpolar biome not only have strong effects on species composition and diversity at regional to larger scales, but also on the Earth’s carbon cycle. Although temporal inconsistency in the response of tree growth to temperature has been reported from some locations at the higher northern latitudes, a systematic dendroecological network assessment is still missing for most of the boreal zone. Here, we analyze the geographical patterns of changes in summer temperature and precipitation across northern Eurasia >60 °N since 1951 AD, as well as the growth trends and climate responses of 445 Pinus, Larix and Picea ring width chronologies in the same area and period. In contrast to widespread summer warming, fluctuations in precipitation and tree growth are spatially more diverse and overall less distinct. Although the influence of summer temperature on ring formation is increasing with latitude and distinct moisture effects are restricted to a few southern locations, growth sensitivity to June–July temperature variability is only significant at 16.6% of all sites (p ≤ 0.01). By revealing complex climate constraints on the productivity of Eurasia’s northern forests, our results question the a priori suitability of boreal tree-ring width chronologies for reconstructing summer temperatures. This study further emphasizes regional climate differences and their role on the dynamics of boreal ecosystems, and also underlines the importance of free data access to facilitate the compilation and evaluation of massively replicated and updated dendroecological networks.

  6. Interactions of climate and regional landscape physiography on high elevation forest growth

    NASA Astrophysics Data System (ADS)

    Kelsey, K.; Barger, N. N.; Neff, J. C.

    2014-12-01

    Forests of the western United States are in a period of rapid change, due in part to climate driven changes in life history processes of trees such as growth, establishment, and mortality. These changes in forest condition are of particular concern in the American Southwest where climate conditions are projected to become increasingly hot and dry throughout the next century. While lower elevation trees of the American Southwest are already experiencing decreased radial growth in response to moisture stress, the response of high elevation trees to future climate is highly uncertain. Here we use dendro-climatological techniques to explore the climate-mediated changes in radial tree growth over time in the high elevation forests of southwestern Colorado by sampling 450 Engelmann Spruce and 350 Subalpine Fir from 22 sites across varying aspect, elevation, slope and soil type. Our results indicate variable and frequently opposing growth responses of individuals of the same species to climate variables; 52% of Engelmann Spruce sampled (233 individuals) exhibited positive growth responses to warm summer monthly mean temperatures with the remaining 48% exhibiting negative growth response to warm summer temperatures. We found similarly opposing results for growth response to monthly precipitation and vapor pressure deficit. In this presentation we explore the physiological factors responsible for variable climate-growth relationships within these species. Our results suggest a complex response of high elevation forest growth to climate change, and indicate that efforts to constrain future growth in this region will be contingent on both climatic and local physiographic factors.

  7. Forests synchronize their growth in contrasting Eurasian regions in response to climate warming.

    PubMed

    Shestakova, Tatiana A; Gutiérrez, Emilia; Kirdyanov, Alexander V; Camarero, Jesús Julio; Génova, Mar; Knorre, Anastasia A; Linares, Juan Carlos; Resco de Dios, Víctor; Sánchez-Salguero, Raúl; Voltas, Jordi

    2016-01-19

    Forests play a key role in the carbon balance of terrestrial ecosystems. One of the main uncertainties in global change predictions lies in how the spatiotemporal dynamics of forest productivity will be affected by climate warming. Here we show an increasing influence of climate on the spatial variability of tree growth during the last 120 y, ultimately leading to unprecedented temporal coherence in ring-width records over wide geographical scales (spatial synchrony). Synchrony in growth patterns across cold-constrained (central Siberia) and drought-constrained (Spain) Eurasian conifer forests have peaked in the early 21st century at subcontinental scales (∼ 1,000 km). Such enhanced synchrony is similar to that observed in trees co-occurring within a stand. In boreal forests, the combined effects of recent warming and increasing intensity of climate extremes are enhancing synchrony through an earlier start of wood formation and a stronger impact of year-to-year fluctuations of growing-season temperatures on growth. In Mediterranean forests, the impact of warming on synchrony is related mainly to an advanced onset of growth and the strengthening of drought-induced growth limitations. Spatial patterns of enhanced synchrony represent early warning signals of climate change impacts on forest ecosystems at subcontinental scales. PMID:26729860

  8. Structure and dynamics of an upland old- growth forest at Redwood National Park, California

    USGS Publications Warehouse

    van Mantgem, Philip J.; Stuart, John D.

    2011-01-01

    Many current redwood forest management targets are based on old-growth conditions, so it is critical that we understand the variability and range of conditions that constitute these forests. Here we present information on the structure and dynamics from six one-hectare forest monitoring plots in an upland old-growth forest at Redwood National Park, California. We surveyed all stems =20 cm DBH in 1995 and 2010, allowing us to estimate any systematic changes in these stands. Stem size distributions for all species and for redwood (Sequoia sempervirens (D. Don) Endl.) alone did not appreciably change over the 15 year observation interval. Recruitment and mortality rates were roughly balanced, as were basal area dynamics (gains from recruitment and growth versus losses from mortality). Similar patterns were found for Sequoia alone. The spatial structure of stems at the plots suggested a random distribution of trees, though the pattern for Sequoia alone was found to be significantly clumped at small scales (< 5 m) at three of the six plots. These results suggest that these forests, including populations of Sequoia, have been generally stable over the past 15 years at this site, though it is possible that fire exclusion may be affecting recruitment of smaller Sequoia (< 20 cm DBH). The non-uniform spatial arrangement of stems also suggests that restoration prescriptions for second-growth redwood forests that encourage uniform spatial arrangements do not appear to mimic current upland old-growth conditions.

  9. Forests synchronize their growth in contrasting Eurasian regions in response to climate warming

    PubMed Central

    Shestakova, Tatiana A.; Gutiérrez, Emilia; Kirdyanov, Alexander V.; Camarero, Jesús Julio; Génova, Mar; Knorre, Anastasia A.; Linares, Juan Carlos; Sánchez-Salguero, Raúl; Voltas, Jordi

    2016-01-01

    Forests play a key role in the carbon balance of terrestrial ecosystems. One of the main uncertainties in global change predictions lies in how the spatiotemporal dynamics of forest productivity will be affected by climate warming. Here we show an increasing influence of climate on the spatial variability of tree growth during the last 120 y, ultimately leading to unprecedented temporal coherence in ring-width records over wide geographical scales (spatial synchrony). Synchrony in growth patterns across cold-constrained (central Siberia) and drought-constrained (Spain) Eurasian conifer forests have peaked in the early 21st century at subcontinental scales (∼1,000 km). Such enhanced synchrony is similar to that observed in trees co-occurring within a stand. In boreal forests, the combined effects of recent warming and increasing intensity of climate extremes are enhancing synchrony through an earlier start of wood formation and a stronger impact of year-to-year fluctuations of growing-season temperatures on growth. In Mediterranean forests, the impact of warming on synchrony is related mainly to an advanced onset of growth and the strengthening of drought-induced growth limitations. Spatial patterns of enhanced synchrony represent early warning signals of climate change impacts on forest ecosystems at subcontinental scales. PMID:26729860

  10. An old-growth subtropical Asian evergreen forest as a large carbon sink

    NASA Astrophysics Data System (ADS)

    Tan, Zheng-Hong; Zhang, Yi-Ping; Schaefer, Douglas; Yu, Gui-Rui; Liang, Naishen; Song, Qing-Hai

    2011-03-01

    Old-growth forests are primarily found in mountain ranges that are less favorable or accessible for land use. Consequently, there are fewer scientific studies on old-growth forests. The eddy covariance method has been widely used as an alternative approach to studying an ecosystem's carbon balance, but only a few eddy flux sites are located in old-growth forest. This fact will hinder our ability to test hypotheses such as whether or not old-growth forests are carbon neutral. The eddy covariance approach was used to examine the carbon balance of a 300-year-old subtropical evergreen broadleaved forest that is located in the center of the largest subtropical land area in the world. The post-QA/QC (quality assurance and control) eddy covariance based NEP was ˜ 9 tC ha -1 yr -1, which suggested that this forest acts as a large carbon sink. The inventory data within the footprint of the eddy flux show that ˜6 tC ha -1 yr -1 was contributed by biomass and necromass. The large-and-old trees sequestered carbon. Approximately 60% of the biomass increment is contributed by the growth of large trees (DBH > 60 cm). The high-altitude-induced low temperature and the high diffusion-irradiation ratio caused by cloudiness were suggested as two reasons for the large carbon sink in the forest we studied. To analyze the complex structure and terrain of this old-growth forest, this study suggested that biometric measurements carried out simultaneously with eddy flux measurements were necessary.

  11. Carbon storage in mountainous headwater streams: The role of old-growth forest and logjams

    NASA Astrophysics Data System (ADS)

    Beckman, Natalie D.; Wohl, Ellen

    2014-03-01

    We measured wood piece characteristics and particulate organic matter (POM) in stored sediments in 30 channel-spanning logjams along headwater streams in the Colorado Front Range, USA. Logjams are on streams flowing through old-growth (>200 years), disturbed (<200 years, natural disturbance), or altered (<200 years, logged) subalpine conifer forest. We examined how channel-spanning logjams influence riverine carbon storage (measured as the total volatile carbon fraction of stored sediment and instream wood). Details of carbon storage associated with logjams reflect age and disturbance history of the adjacent riparian forest. A majority of the carbon within jams is stored as wood. Wood volume is significantly larger in old-growth and disturbed reaches than in altered reaches. Carbon storage also differs in relation to forest characteristics. Sediment from old-growth streams has significantly higher carbon content than altered streams. Volume of carbon stored in jam sediment correlates with jam wood volume in old-growth and disturbed forests, but not in altered forests. Forest stand age and wood volume within a jam explain 43% of the variation of carbon stored in jam sediment. First-order estimates of the amount of carbon stored within a stream reach show an order of magnitude difference between disturbed and altered reaches. Our first-order estimates of reach-scale riverine carbon storage suggest that the carbon per hectare stored in streams is on the same order of magnitude as the carbon stored as dead biomass in terrestrial subalpine forests of the region. Of particular importance, old-growth forest correlates with more carbon storage in rivers.

  12. Rapid warming accelerates tree growth decline in semi-arid forests of Inner Asia.

    PubMed

    Liu, Hongyan; Park Williams, A; Allen, Craig D; Guo, Dali; Wu, Xiuchen; Anenkhonov, Oleg A; Liang, Eryuan; Sandanov, Denis V; Yin, Yi; Qi, Zhaohuan; Badmaeva, Natalya K

    2013-08-01

    Forests around the world are subject to risk of high rates of tree growth decline and increased tree mortality from combinations of climate warming and drought, notably in semi-arid settings. Here, we assess how climate warming has affected tree growth in one of the world's most extensive zones of semi-arid forests, in Inner Asia, a region where lack of data limits our understanding of how climate change may impact forests. We show that pervasive tree growth declines since 1994 in Inner Asia have been confined to semi-arid forests, where growing season water stress has been rising due to warming-induced increases in atmospheric moisture demand. A causal link between increasing drought and declining growth at semi-arid sites is corroborated by correlation analyses comparing annual climate data to records of tree-ring widths. These ring-width records tend to be substantially more sensitive to drought variability at semi-arid sites than at semi-humid sites. Fire occurrence and insect/pathogen attacks have increased in tandem with the most recent (2007-2009) documented episode of tree mortality. If warming in Inner Asia continues, further increases in forest stress and tree mortality could be expected, potentially driving the eventual regional loss of current semi-arid forests. PMID:23564688

  13. Waveband evaluation of proposed thematic mapper in forest cover classification

    NASA Technical Reports Server (NTRS)

    Latty, R. S.; Hoffer, R. M.

    1981-01-01

    This study involved the evaluation of the characteristics of multispectral scanner data relative to forest cover type mapping, using NASA's NS-001 multispectral scanner to simulate the proposed Thematic Mapper (TM). The objectives were to determine: (1) the optimum number of wavebands to utilize in computer classifications of TM data; (2) which channel combinations provide the highest expected classification accuracy; and (3) the relative merit of each channel in the context of the cover classes examined. Transformed divergence was used as a measure of statistical distance between spectral class densities associated with each of twelve cover classes. The maximum overall mean pair-wise transformed divergence was used as the basis for evaluating all possible waveband combinations available for use in computer-assisted forest cover classifications.

  14. The process-based stand growth model Formix 3-Q applied in a GIS environment for growth and yield analysis in a tropical rain forest.

    PubMed

    Ditzer, T.; Glauner, R.; Förster, M.; Köhler, P.; Huth, A.

    2000-03-01

    Managing tropical rain forests is difficult because few long-term field data on forest growth and the impact of harvesting disturbance are available. Growth models may provide a valuable tool for managers of tropical forests, particularly if applied to the extended forest areas of up to 100,000 ha that typically constitute the so-called forest management units (FMUs). We used a stand growth model in a geographic information system (GIS) environment to simulate tropical rain forest growth at the FMU level. We applied the process-based rain forest growth model Formix 3-Q to the 55,000 ha Deramakot Forest Reserve (DFR) in Sabah, Malaysia. The FMU was considered to be composed of single and independent small-scale stands differing in site conditions and forest structure. Field data, which were analyzed with a GIS, comprised a terrestrial forest inventory, site and soil analyses (water, nutrients, slope), the interpretation of aerial photographs of the present vegetation and topographic maps. Different stand types were determined based on a classification of site quality (three classes), slopes (four classes), and present forest structure (four strata). The effects of site quality on tree allometry (height-diameter curve, biomass allometry, leaf area) and growth (increment size) are incorporated into Formix 3-Q. We derived allometric relations and growth factors for different site conditions from the field data. Climax forest structure at the stand level was shown to depend strongly on site conditions. Simulated successional pattern and climax structure were compared with field observations. Based on the current management plan for the DFR, harvesting scenarios were simulated for stands on different sites. The effects of harvesting guidelines on forest structure and the implications for sustainable forest management at Deramakot were analyzed. Based on the stand types and GIS analysis, we also simulated undisturbed regeneration of the logged-over forest in the DFR at

  15. An evaluation of imaging spectrometry for estimating forest canopy chemistry

    NASA Technical Reports Server (NTRS)

    Wessman, Carol A.; Aber, John D.; Peterson, David L.

    1989-01-01

    High spectral resolution Airborne Imaging Spectrometer (AIS) data were acquired over 20 well-studied Wisconsin forest sites to evaluate the potential of remote sensing for estimating forest canopy chemistry. Intensive nutrient cycling research in these forests demonstrates that canopy lignin content is strongly related to measured annual nitrogen mineralization at the undisturbed sites and may serve as an accurate index for nitrogen cycling rates. Ground measurements were made of foliar biomass and canopy nitrogen and lignin content, the latter within two weeks of the AIS overflight. The spectral data were transformed using derivative techniques modified from laboratroy spectroscopy. Stepwise regression assisted in determining combinations of wavelengths most highly correlated with canopy chemistry and biomass. Strong correlations between AIS data and total canopy lignin content in deciduous forests and canopy lignin concentration (total lignin/biomass) in both deciduous and coniferous stands indicate that imaging spectrometry can be used to estimate canopy lignin content and, from that, the spatial distribution of annual nitrogen mineralization rates.

  16. Low temperature growth of ultra-high mass density carbon nanotube forests on conductive supports

    NASA Astrophysics Data System (ADS)

    Sugime, Hisashi; Esconjauregui, Santiago; Yang, Junwei; D'Arsié, Lorenzo; Oliver, Rachel A.; Bhardwaj, Sunil; Cepek, Cinzia; Robertson, John

    2013-08-01

    We grow ultra-high mass density carbon nanotube forests at 450 °C on Ti-coated Cu supports using Co-Mo co-catalyst. X-ray photoelectron spectroscopy shows Mo strongly interacts with Ti and Co, suppressing both aggregation and lifting off of Co particles and, thus, promoting the root growth mechanism. The forests average a height of 0.38 μm and a mass density of 1.6 g cm-3. This mass density is the highest reported so far, even at higher temperatures or on insulators. The forests and Cu supports show ohmic conductivity (lowest resistance ˜22 kΩ), suggesting Co-Mo is useful for applications requiring forest growth on conductors.

  17. Seedling growth responses to soil resources in the understory of a wet tropical forest.

    PubMed

    Holste, Ellen K; Kobe, Richard K; Vriesendorp, Corine F

    2011-09-01

    Plant growth responses to resources may be an important mechanism that influences species' distributions, coexistence, and community structure. Irradiance is considered the most important resource for seedling growth in the understory of wet tropical forests, but multiple soil nutrients and species have yet to be examined simultaneously with irradiance under field conditions. To identify potentially limiting resources, we modeled tree seedling growth as a function of irradiance and soil nutrients across five sites, spanning a soil fertility gradient in old-growth, wet tropical forests at La Selva Biological Station, Costa Rica. We measured an array of soil nutrients including total nitrogen (total N), inorganic N (nitrate [NO3-] and ammonium [NH4+]), phosphate (PO4-), and sum of base cations (SBC; potassium, magnesium, and calcium). Shade in the forest understory did not preclude seedling growth correlations with soil nutrients. Irradiance was a significant predictor of growth in 52% of the species, inorganic N in 54% (NO3- in 32%; NH4+ in 34%), total N in 47%, SBC in 39%, and PO4- in 29%. Overall, growth was correlated with both irradiance and soil nutrients in 45% of species and with soil nutrients only in an additional 48%; rarely was irradiance alone correlated with growth. Contrary to expectations, the magnitudes of growth effects, assessed as the maximum growth response to significant resources for each species, were similar for irradiance and most soil nutrients. Among species whose growth correlated with soil nutrients, the rank importance of nutrient effects was SBC, followed by N (total N, NO3-, and/or NH4+) and PO4-. Species' growth responsiveness (i.e., magnitudes of effect) to irradiance and soil nutrients was negatively correlated with species' shade tolerance (survival under 1% full sun). In this broad survey of species and resources, the nearly ubiquitous effects of soil nutrients on seedling growth challenge the idea that soil nutrients are less

  18. A model inter-comparison study of forest growth on two coastal and boreal forest landscapes in Canada

    NASA Astrophysics Data System (ADS)

    Bernier, P. Y.; Wang, Z.; Grant, R. F.; Arain, A.; Chen, B.; Chen, J.; Coops, N.; Govind, A.; Guindon, L.; Hember, R.; Kurz, W. A.; Peng, C.; Price, D. T.; Stinson, G.; Sun, J.; Trofymow, J. A.

    2009-05-01

    Projection of carbon stocks in Canada is presently accomplished using CBM-CFS3, an inventory-based model. We have performed a comparison exercise among 6 process-based models of forest growth (Can-IBIS, INTEC, ECOSYS, 3PG, TRIPLEX, CN-CLASS) and CBM-CFS3 as part of an effort to better capture inter-annual climate variability in the carbon accounting of Canada's forests. Comparisons were made on multi-decadal simulations for a Pacific Coastal Douglas-fir forest (2500ha, Oyster River, British Columbia) and a Boreal Black Spruce forest (3825ha, Chibougamau, Quebec). Models were initiated using reconstructions of forest composition and biomass from 1920 (Oyster River, OR) and 1928 (Chibougamau, CH), followed by transition to current forest composition as derived from recent forest inventories (OR 1999, CH 1998). Forest management events and natural disturbances over the simulation period were provided as maps and disturbance impacts on a number of carbon pools were simulated using the same transfer coefficients parameters as CBM-CFS3. Simulations were conducted from 1920 to 2006 for OR, and from 1928 to 1998 for CH. For CH, final above-ground tree biomass in 1998 was also extracted from the independent forest inventory. The coastal OR area initially contained about four times more ecosystem C than the boreal CH area. CBM- CFS3 simulations suggest a decline in ecosystem carbon by about 200 Mg C ha-1, dominated by a loss of biomass and woody debris C, over the 86-year period in OR as the entire area transitioned from coastal old- growth to second growth conditions. In CH, a smaller proportion of the area was affected by management and the CBM-CFS3 estimated a small net increase in total ecosystem C of about 11 Mg C ha-1 over 70 years, almost all attributed to increased biomass. Changes in tree biomass at CH were 10% less than estimates derived by difference between successive inventories. The source of this small simulation bias is attributable to the underlying growth

  19. Predicting long-term streamflow variability in moist eucalypt forests using forest growth models and a sapwood area index

    NASA Astrophysics Data System (ADS)

    Jaskierniak, D.; Kuczera, G.; Benyon, R.

    2016-04-01

    A major challenge in surface hydrology involves predicting streamflow in ungauged catchments with heterogeneous vegetation and spatiotemporally varying evapotranspiration (ET) rates. We present a top-down approach for quantifying the influence of broad-scale changes in forest structure on ET and hence streamflow. Across three catchments between 18 and 100 km2 in size and with regenerating Eucalyptus regnans and E. delegatensis forest, we demonstrate how variation in ET can be mapped in space and over time using LiDAR data and commonly available forest inventory data. The model scales plot-level sapwood area (SA) to the catchment-level using basal area (BA) and tree stocking density (N) estimates in forest growth models. The SA estimates over a 69 year regeneration period are used in a relationship between SA and vegetation induced streamflow loss (L) to predict annual streamflow (Q) with annual rainfall (P) estimates. Without calibrating P, BA, N, SA, and L to Q data, we predict annual Q with R2 between 0.68 and 0.75 and Nash Sutcliffe efficiency (NSE) between 0.44 and 0.48. To remove bias, the model was extended to allow for runoff carry-over into the following year as well as minor correction to rainfall bias, which produced R2 values between 0.72 and 0.79, and NSE between 0.70 and 0.79. The model under-predicts streamflow during drought periods as it lacks representation of ecohydrological processes that reduce L with either reduced growth rates or rainfall interception during drought. Refining the relationship between sapwood thickness and forest inventory variables is likely to further improve results.

  20. Capturing old-growth values for use in forest decision-making.

    PubMed

    Owen, Rochelle J; Duinker, Peter N; Beckley, Thomas M

    2009-02-01

    Old-growth forests have declined significantly across the world. Decisions related to old growth are often mired in challenges of value diversity, conflict, data gaps, and resource pressures. This article describes old-growth values of citizens and groups in Nova Scotia, Canada, for integration in sustainable forest management (SFM) decision-making. The study is based on data from 76 research subjects who participated in nine field trips to forest stands. Research subjects were drawn from Aboriginal groups, environmental organizations, forestry professionals, and rural and urban publics. Diaries, group discussions, and rating sheets were used to elicit information during the field trips. Findings show that different elicitation techniques can influence the articulation of intensity with which some values are held. In addition, certain values are more often associated with old-growth than with other forest-age classes. Some values associated with old-growth are considered more important than others, and some silvicultural treatments are perceived to compromise old-growth values more than others. Demographic characteristics, such as constituency group, gender, and age, are shown to influence value priorities. Ideas on how to incorporate old-growth values into SFM decision-making are highlighted. PMID:18463917

  1. Capturing Old-Growth Values for Use in Forest Decision-Making

    NASA Astrophysics Data System (ADS)

    Owen, Rochelle J.; Duinker, Peter N.; Beckley, Thomas M.

    2009-02-01

    Old-growth forests have declined significantly across the world. Decisions related to old growth are often mired in challenges of value diversity, conflict, data gaps, and resource pressures. This article describes old-growth values of citizens and groups in Nova Scotia, Canada, for integration in sustainable forest management (SFM) decision-making. The study is based on data from 76 research subjects who participated in nine field trips to forest stands. Research subjects were drawn from Aboriginal groups, environmental organizations, forestry professionals, and rural and urban publics. Diaries, group discussions, and rating sheets were used to elicit information during the field trips. Findings show that different elicitation techniques can influence the articulation of intensity with which some values are held. In addition, certain values are more often associated with old-growth than with other forest-age classes. Some values associated with old-growth are considered more important than others, and some silvicultural treatments are perceived to compromise old-growth values more than others. Demographic characteristics, such as constituency group, gender, and age, are shown to influence value priorities. Ideas on how to incorporate old-growth values into SFM decision-making are highlighted.

  2. Re-evaluation of forest biomass carbon stocks and lessons from the world's most carbon-dense forests

    PubMed Central

    Keith, Heather; Mackey, Brendan G.; Lindenmayer, David B.

    2009-01-01

    From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized. PMID:19553199

  3. Comparisons of Aquatic Invertebrate Assemblages in Small, Old Growth and Second Growth Forested Catchments of the H.J. Andrews Experimental Forest, Oregon

    NASA Astrophysics Data System (ADS)

    Frady, C. H.; Johnson, S. L.; Li, J. L.

    2005-05-01

    In small streams, riparian vegetation often composes the food base for many aquatic invertebrates. Forest harvest can result in major changes to riparian vegetation. If abundance, richness, or community structure of invertebrate assemblages is affected by removal of riparian vegetation, are legacies of these practices evident 20-40 years post-harvest? If so, are these differences uniform through time, or are they temporally dependant? We investigated stream invertebrate assemblage dynamics between old growth and second growth forest types and across seasons in six small-basins in the H.J. Andrews Experimental Forest. Individual basins range from 500m to 1000m in elevation and 12.4ha to 98.1ha in area. Six benthic samples and four, 1-week emergence samples were collected in each basin each season (June 2003 through May 2004). Preliminary results from benthic samples suggest strong changes in community structure between seasons as additional taxa not found in summer (i.e. Agathon, Anagapetus, Chernokrilus, and Rhyacophila "angelita group") were collected in autumn and winter samples. However, results from summer comparisons demonstrate no differences in benthic and emergence abundance (p = 0.47, and p = 0.98, respectively) or benthic richness (p = 0.41) between old growth and second growth invertebrate assemblages.

  4. A Novel Modelling Approach for Predicting Forest Growth and Yield under Climate Change.

    PubMed

    Ashraf, M Irfan; Meng, Fan-Rui; Bourque, Charles P-A; MacLean, David A

    2015-01-01

    Global climate is changing due to increasing anthropogenic emissions of greenhouse gases. Forest managers need growth and yield models that can be used to predict future forest dynamics during the transition period of present-day forests under a changing climatic regime. In this study, we developed a forest growth and yield model that can be used to predict individual-tree growth under current and projected future climatic conditions. The model was constructed by integrating historical tree growth records with predictions from an ecological process-based model using neural networks. The new model predicts basal area (BA) and volume growth for individual trees in pure or mixed species forests. For model development, tree-growth data under current climatic conditions were obtained using over 3000 permanent sample plots from the Province of Nova Scotia, Canada. Data to reflect tree growth under a changing climatic regime were projected with JABOWA-3 (an ecological process-based model). Model validation with designated data produced model efficiencies of 0.82 and 0.89 in predicting individual-tree BA and volume growth. Model efficiency is a relative index of model performance, where 1 indicates an ideal fit, while values lower than zero means the predictions are no better than the average of the observations. Overall mean prediction error (BIAS) of basal area and volume growth predictions was nominal (i.e., for BA: -0.0177 cm(2) 5-year(-1) and volume: 0.0008 m(3) 5-year(-1)). Model variability described by root mean squared error (RMSE) in basal area prediction was 40.53 cm(2) 5-year(-1) and 0.0393 m(3) 5-year(-1) in volume prediction. The new modelling approach has potential to reduce uncertainties in growth and yield predictions under different climate change scenarios. This novel approach provides an avenue for forest managers to generate required information for the management of forests in transitional periods of climate change. Artificial intelligence technology

  5. A Novel Modelling Approach for Predicting Forest Growth and Yield under Climate Change

    PubMed Central

    Ashraf, M. Irfan; Meng, Fan-Rui; Bourque, Charles P.-A.; MacLean, David A.

    2015-01-01

    Global climate is changing due to increasing anthropogenic emissions of greenhouse gases. Forest managers need growth and yield models that can be used to predict future forest dynamics during the transition period of present-day forests under a changing climatic regime. In this study, we developed a forest growth and yield model that can be used to predict individual-tree growth under current and projected future climatic conditions. The model was constructed by integrating historical tree growth records with predictions from an ecological process-based model using neural networks. The new model predicts basal area (BA) and volume growth for individual trees in pure or mixed species forests. For model development, tree-growth data under current climatic conditions were obtained using over 3000 permanent sample plots from the Province of Nova Scotia, Canada. Data to reflect tree growth under a changing climatic regime were projected with JABOWA-3 (an ecological process-based model). Model validation with designated data produced model efficiencies of 0.82 and 0.89 in predicting individual-tree BA and volume growth. Model efficiency is a relative index of model performance, where 1 indicates an ideal fit, while values lower than zero means the predictions are no better than the average of the observations. Overall mean prediction error (BIAS) of basal area and volume growth predictions was nominal (i.e., for BA: -0.0177 cm2 5-year-1 and volume: 0.0008 m3 5-year-1). Model variability described by root mean squared error (RMSE) in basal area prediction was 40.53 cm2 5-year-1 and 0.0393 m3 5-year-1 in volume prediction. The new modelling approach has potential to reduce uncertainties in growth and yield predictions under different climate change scenarios. This novel approach provides an avenue for forest managers to generate required information for the management of forests in transitional periods of climate change. Artificial intelligence technology has substantial

  6. Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range

    USGS Publications Warehouse

    Cross, Alison; Perakis, Steven S.

    2011-01-01

    Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests.

  7. Emergy and Eco-exergy Evaluation of Four Forest Restoration Modes

    EPA Science Inventory

    Four different forest restoration modes (Acacia mangium plantation, mixed-native species plantation, conifer plantation and Eucalyptus plantation) were evaluated using Energy System Theory and the emergy synthesis method. In addition, the eco-exergies of the four forest restorati...

  8. Methods of evaluating hair growth.

    PubMed

    Chamberlain, Alexander J; Dawber, Rodney P R

    2003-02-01

    For decades, scientists and clinicians have examined methods of measuring scalp hair growth. With the development of drugs that stem or even reverse the miniaturization of androgenetic alopecia, there has been a greater need for reliable, economical and minimally invasive means of measuring hair growth and, specifically, response to therapy. We review the various methods of measurement described to date, their limitations and value to the clinician. In our opinion, the potential of computer-assisted technology in this field is yet to be maximized and the currently available tools are less than ideal. The most valuable means of measurement at the present time are global photography and phototrichogram-based techniques (with digital image analysis) such as the 'TrichoScan'. Subjective scoring systems are also of value in the overall assessment of response to therapy and these are under-utilized and merit further refinement. PMID:12581076

  9. Evaluating the Suitability of Management Strategies of Pure Norway Spruce Forests in the Black Forest Area of Southwest Germany for Adaptation to or Mitigation of Climate Change

    NASA Astrophysics Data System (ADS)

    Yousefpour, Rasoul; Hanewinkel, Marc; Le Moguédec, Gilles

    2010-02-01

    The study deals with the problem of evaluating management strategies for pure stands of Norway spruce ( Picea abies Karst) to balance adaptation to and mitigation of climate change, taking into account multiple objectives of a forest owner. A simulation and optimization approach was used to evaluate the management of a 1000 ha model Age-Class forest, representing the age-class distribution of an area of 66,000 ha of pure Norway spruce forests in the Black Forest region of Southwest Germany. Eight silvicultural scenarios comprising five forest conversion schemes which were interpreted as “adaptation” strategies which aims at increasing the proportion of Beech, that is expected to better cope with climate change than the existing Norway spruce, and three conventional strategies including a “Do-nothing” alternative classified as “mitigation”, trying to keep rather higher levels of growing stock of spruce, were simulated using the empirical growth simulator BWINPro-S. A linear programming approach was adapted to simultaneously maximize the net present values of carbon sequestration and timber production subject to the two constraints of wood even flow and partial protection of the oldest (nature protection). The optimized plan, with the global utility of 11,687 €/ha in forty years, allocated a combination of silvicultural scenarios to the entire forest area. Overall, strategies classified as “mitigation” were favored, while strategies falling into the “adaptation”-category were limited to the youngest age-classes in the optimal solution. Carbon sequestration of the “Do-nothing” alternative was between 1.72 and 1.85 million tons higher than the other alternatives for the entire forest area while the differences between the adaptation and mitigation approaches were approximately 133,000 tons. Sensitivity analysis showed that a carbon price of 21 €/ t is the threshold at which carbon sequestration is promoted, while an interest rate of above 2

  10. The linkages between photosynthesis, productivity, growth and biomass in lowland Amazonian forests.

    PubMed

    Malhi, Yadvinder; Doughty, Christopher E; Goldsmith, Gregory R; Metcalfe, Daniel B; Girardin, Cécile A J; Marthews, Toby R; Del Aguila-Pasquel, Jhon; Aragão, Luiz E O C; Araujo-Murakami, Alejandro; Brando, Paulo; da Costa, Antonio C L; Silva-Espejo, Javier E; Farfán Amézquita, Filio; Galbraith, David R; Quesada, Carlos A; Rocha, Wanderley; Salinas-Revilla, Norma; Silvério, Divino; Meir, Patrick; Phillips, Oliver L

    2015-06-01

    Understanding the relationship between photosynthesis, net primary productivity and growth in forest ecosystems is key to understanding how these ecosystems will respond to global anthropogenic change, yet the linkages among these components are rarely explored in detail. We provide the first comprehensive description of the productivity, respiration and carbon allocation of contrasting lowland Amazonian forests spanning gradients in seasonal water deficit and soil fertility. Using the largest data set assembled to date, ten sites in three countries all studied with a standardized methodology, we find that (i) gross primary productivity (GPP) has a simple relationship with seasonal water deficit, but that (ii) site-to-site variations in GPP have little power in explaining site-to-site spatial variations in net primary productivity (NPP) or growth because of concomitant changes in carbon use efficiency (CUE), and conversely, the woody growth rate of a tropical forest is a very poor proxy for its productivity. Moreover, (iii) spatial patterns of biomass are much more driven by patterns of residence times (i.e. tree mortality rates) than by spatial variation in productivity or tree growth. Current theory and models of tropical forest carbon cycling under projected scenarios of global atmospheric change can benefit from advancing beyond a focus on GPP. By improving our understanding of poorly understood processes such as CUE, NPP allocation and biomass turnover times, we can provide more complete and mechanistic approaches to linking climate and tropical forest carbon cycling. PMID:25640987

  11. Spatial climate-dependent growth response of boreal mixedwood forest in western Canada

    NASA Astrophysics Data System (ADS)

    Jiang, Xinyu; Huang, Jian-Guo; Stadt, Kenneth J.; Comeau, Philip G.; Chen, Han Y. H.

    2016-04-01

    The western Canadian mixedwood boreal forests were projected to be significantly affected by regional drought. However, drought degrees were spatially different across elevations, longitudes and latitudes, which might cause different tree growth responses to climate change in different sub-regions within western Canada. In this way, regional classification of western Canadian boreal forests and understanding spatial tree growth responses to climate might be necessary for future forest management and monitoring. In this paper, tree-ring chronologies of two dominant tree species, trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench.) Voss), were obtained from mixed forest stands distributed across western Canada to study spatial tree growth response to climate based on three regional classification schemes (a phytogeographic sub-region classification, a natural sub-region classification and non-classification). Phytogeographic sub-region classification was estimated based on tree ring samples we collected in this study, while natural sub-region classification was previously developed based on analysis of regional differences in vegetation, soil, site and climate conditions. Results showed that air temperature did not significantly increase, while drought stress became more severe between 1985 to 2010. Relationships between trembling aspen growth and temperature differed between north and south parts of the study area, resulting from spatial difference in water supply. Trembling aspen growth was influenced by temperature or moisture variables of the previous years. White spruce growth was influenced primarily by moisture variables (current or previous year), and response coefficients between white spruce and drought conditions (represented by drought code) were negative in all phytogeographic sub-regions, suggesting that white spruce was more sensitive to drought stress under climate change. As a late-successional dominant species

  12. Carbon sequestration potential of second-growth forest regeneration in the Latin American tropics.

    PubMed

    Chazdon, Robin L; Broadbent, Eben N; Rozendaal, Danaë M A; Bongers, Frans; Zambrano, Angélica María Almeyda; Aide, T Mitchell; Balvanera, Patricia; Becknell, Justin M; Boukili, Vanessa; Brancalion, Pedro H S; Craven, Dylan; Almeida-Cortez, Jarcilene S; Cabral, George A L; de Jong, Ben; Denslow, Julie S; Dent, Daisy H; DeWalt, Saara J; Dupuy, Juan M; Durán, Sandra M; Espírito-Santo, Mario M; Fandino, María C; César, Ricardo G; Hall, Jefferson S; Hernández-Stefanoni, José Luis; Jakovac, Catarina C; Junqueira, André B; Kennard, Deborah; Letcher, Susan G; Lohbeck, Madelon; Martínez-Ramos, Miguel; Massoca, Paulo; Meave, Jorge A; Mesquita, Rita; Mora, Francisco; Muñoz, Rodrigo; Muscarella, Robert; Nunes, Yule R F; Ochoa-Gaona, Susana; Orihuela-Belmonte, Edith; Peña-Claros, Marielos; Pérez-García, Eduardo A; Piotto, Daniel; Powers, Jennifer S; Rodríguez-Velazquez, Jorge; Romero-Pérez, Isabel Eunice; Ruíz, Jorge; Saldarriaga, Juan G; Sanchez-Azofeifa, Arturo; Schwartz, Naomi B; Steininger, Marc K; Swenson, Nathan G; Uriarte, Maria; van Breugel, Michiel; van der Wal, Hans; Veloso, Maria D M; Vester, Hans; Vieira, Ima Celia G; Bentos, Tony Vizcarra; Williamson, G Bruce; Poorter, Lourens

    2016-05-01

    Regrowth of tropical secondary forests following complete or nearly complete removal of forest vegetation actively stores carbon in aboveground biomass, partially counterbalancing carbon emissions from deforestation, forest degradation, burning of fossil fuels, and other anthropogenic sources. We estimate the age and spatial extent of lowland second-growth forests in the Latin American tropics and model their potential aboveground carbon accumulation over four decades. Our model shows that, in 2008, second-growth forests (1 to 60 years old) covered 2.4 million km(2) of land (28.1% of the total study area). Over 40 years, these lands can potentially accumulate a total aboveground carbon stock of 8.48 Pg C (petagrams of carbon) in aboveground biomass via low-cost natural regeneration or assisted regeneration, corresponding to a total CO2 sequestration of 31.09 Pg CO2. This total is equivalent to carbon emissions from fossil fuel use and industrial processes in all of Latin America and the Caribbean from 1993 to 2014. Ten countries account for 95% of this carbon storage potential, led by Brazil, Colombia, Mexico, and Venezuela. We model future land-use scenarios to guide national carbon mitigation policies. Permitting natural regeneration on 40% of lowland pastures potentially stores an additional 2.0 Pg C over 40 years. Our study provides information and maps to guide national-level forest-based carbon mitigation plans on the basis of estimated rates of natural regeneration and pasture abandonment. Coupled with avoided deforestation and sustainable forest management, natural regeneration of second-growth forests provides a low-cost mechanism that yields a high carbon sequestration potential with multiple benefits for biodiversity and ecosystem services. PMID:27386528

  13. Carbon sequestration potential of second-growth forest regeneration in the Latin American tropics

    PubMed Central

    Chazdon, Robin L.; Broadbent, Eben N.; Rozendaal, Danaë M. A.; Bongers, Frans; Zambrano, Angélica María Almeyda; Aide, T. Mitchell; Balvanera, Patricia; Becknell, Justin M.; Boukili, Vanessa; Brancalion, Pedro H. S.; Craven, Dylan; Almeida-Cortez, Jarcilene S.; Cabral, George A. L.; de Jong, Ben; Denslow, Julie S.; Dent, Daisy H.; DeWalt, Saara J.; Dupuy, Juan M.; Durán, Sandra M.; Espírito-Santo, Mario M.; Fandino, María C.; César, Ricardo G.; Hall, Jefferson S.; Hernández-Stefanoni, José Luis; Jakovac, Catarina C.; Junqueira, André B.; Kennard, Deborah; Letcher, Susan G.; Lohbeck, Madelon; Martínez-Ramos, Miguel; Massoca, Paulo; Meave, Jorge A.; Mesquita, Rita; Mora, Francisco; Muñoz, Rodrigo; Muscarella, Robert; Nunes, Yule R. F.; Ochoa-Gaona, Susana; Orihuela-Belmonte, Edith; Peña-Claros, Marielos; Pérez-García, Eduardo A.; Piotto, Daniel; Powers, Jennifer S.; Rodríguez-Velazquez, Jorge; Romero-Pérez, Isabel Eunice; Ruíz, Jorge; Saldarriaga, Juan G.; Sanchez-Azofeifa, Arturo; Schwartz, Naomi B.; Steininger, Marc K.; Swenson, Nathan G.; Uriarte, Maria; van Breugel, Michiel; van der Wal, Hans; Veloso, Maria D. M.; Vester, Hans; Vieira, Ima Celia G.; Bentos, Tony Vizcarra; Williamson, G. Bruce; Poorter, Lourens

    2016-01-01

    Regrowth of tropical secondary forests following complete or nearly complete removal of forest vegetation actively stores carbon in aboveground biomass, partially counterbalancing carbon emissions from deforestation, forest degradation, burning of fossil fuels, and other anthropogenic sources. We estimate the age and spatial extent of lowland second-growth forests in the Latin American tropics and model their potential aboveground carbon accumulation over four decades. Our model shows that, in 2008, second-growth forests (1 to 60 years old) covered 2.4 million km2 of land (28.1% of the total study area). Over 40 years, these lands can potentially accumulate a total aboveground carbon stock of 8.48 Pg C (petagrams of carbon) in aboveground biomass via low-cost natural regeneration or assisted regeneration, corresponding to a total CO2 sequestration of 31.09 Pg CO2. This total is equivalent to carbon emissions from fossil fuel use and industrial processes in all of Latin America and the Caribbean from 1993 to 2014. Ten countries account for 95% of this carbon storage potential, led by Brazil, Colombia, Mexico, and Venezuela. We model future land-use scenarios to guide national carbon mitigation policies. Permitting natural regeneration on 40% of lowland pastures potentially stores an additional 2.0 Pg C over 40 years. Our study provides information and maps to guide national-level forest-based carbon mitigation plans on the basis of estimated rates of natural regeneration and pasture abandonment. Coupled with avoided deforestation and sustainable forest management, natural regeneration of second-growth forests provides a low-cost mechanism that yields a high carbon sequestration potential with multiple benefits for biodiversity and ecosystem services. PMID:27386528

  14. Biomass accumulation rates of Amazonian secondary forest and biomass of old-growth forests from Landsat time series and the Geoscience Laser Altimeter System

    NASA Astrophysics Data System (ADS)

    Helmer, Eileen H.; Lefsky, Michael A.; Roberts, Dar A.

    2009-01-01

    We estimate the age of humid lowland tropical forests in Rondônia, Brazil, from a somewhat densely spaced time series of Landsat images (1975-2003) with an automated procedure, the Threshold Age Mapping Algorithm (TAMA), first described here. We then estimate a landscape-level rate of aboveground woody biomass accumulation of secondary forest by combining forest age mapping with biomass estimates from the Geoscience Laser Altimeter System (GLAS). Though highly variable, the estimated average biomass accumulation rate of 8.4 Mg ha-1 yr-1 agrees well with ground-based studies for young secondary forests in the region. In isolating the lowland forests, we map land cover and general types of old-growth forests with decision tree classification of Landsat imagery and elevation data. We then estimate aboveground live biomass for seven classes of old-growth forest. TAMA is simple, fast, and self-calibrating. By not using between-date band or index differences or trends, it requires neither image normalization nor atmospheric correction. In addition, it uses an approach to map forest cover for the self-calibrations that is novel to forest mapping with satellite imagery; it maps humid secondary forest that is difficult to distinguish from old-growth forest in single-date imagery; it does not assume that forest age equals time since disturbance; and it incorporates Landsat Multispectral Scanner imagery. Variations on the work that we present here can be applied to other forested landscapes. Applications that use image time series will be helped by the free distribution of coregistered Landsat imagery, which began in December 2008, and of the Ice Cloud and land Elevation Satellite Vegetation Product, which simplifies the use of GLAS data. Finally, we demonstrate here for the first time how the optical imagery of fine spatial resolution that is viewable on Google Earth provides a new source of reference data for remote sensing applications related to land cover.

  15. Chronic water stress reduces tree growth and the carbon sink of deciduous hardwood forests.

    PubMed

    Brzostek, Edward R; Dragoni, Danilo; Schmid, Hans Peter; Rahman, Abdullah F; Sims, Daniel; Wayson, Craig A; Johnson, Daniel J; Phillips, Richard P

    2014-08-01

    Predicted decreases in water availability across the temperate forest biome have the potential to offset gains in carbon (C) uptake from phenology trends, rising atmospheric CO2 , and nitrogen deposition. While it is well established that severe droughts reduce the C sink of forests by inducing tree mortality, the impacts of mild but chronic water stress on forest phenology and physiology are largely unknown. We quantified the C consequences of chronic water stress using a 13-year record of tree growth (n = 200 trees), soil moisture, and ecosystem C balance at the Morgan-Monroe State Forest (MMSF) in Indiana, and a regional 11-year record of tree growth (n > 300 000 trees) and water availability for the 20 most dominant deciduous broadleaf tree species across the eastern and midwestern USA. We show that despite ~26 more days of C assimilation by trees at the MMSF, increasing water stress decreased the number of days of wood production by ~42 days over the same period, reducing the annual accrual of C in woody biomass by 41%. Across the deciduous forest region, water stress induced similar declines in tree growth, particularly for water-demanding 'mesophytic' tree species. Given the current replacement of water-stress adapted 'xerophytic' tree species by mesophytic tree species, we estimate that chronic water stress has the potential to decrease the C sink of deciduous forests by up to 17% (0.04 Pg C yr(-1) ) in the coming decades. This reduction in the C sink due to mesophication and chronic water stress is equivalent to an additional 1-3 days of global C emissions from fossil fuel burning each year. Collectively, our results indicate that regional declines in water availability may offset the growth-enhancing effects of other global changes and reduce the extent to which forests ameliorate climate warming. PMID:24421179

  16. Changes in growth of pristine boreal North American forests from 1950 to 2005 driven by landscape demographics and species traits

    NASA Astrophysics Data System (ADS)

    Girardin, M. P.; Guo, X. J.; Bernier, P. Y.; Raulier, F.; Gauthier, S.

    2012-01-01

    In spite of the many factors that are occurring and known for positively affecting the growth of forests, some boreal forests across North America have recently felt the adverse impacts of environmental changes. Knowledge of causes for productivity declines in North American boreal forests remains limited and this is owed to the large spatial and temporal scales involved, and the many plant processes affected. Here, the response of pristine eastern boreal North American (PEBNA) forests to ongoing climatic changes is examined using in situ data, community ecology statistics, and species-specific model simulations of carbon exchanges forced by contemporary climatic data. To examine trends in forest growth, we used a recently acquired collection of tree-ring width data from 252 sample plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree growth data highlight a dominating forest growth decline in overmature forests (age > 120 yr) from 1950 to 2005. In contrast, improving growth conditions are seen in jack pine and mature (70-120 yr) black spruce stands. Multivariate analysis of climate and growth relationships suggests that responses of PEBNA forests to climate are dependent on demographic and species traits via their mediation of temperature and water stress constraints. In support of this hypothesis, the simulation experiment suggests that in old-growth black spruce stands the benefit to growth brought on by a longer growing season may have been low in comparison with the increasing moisture stress and respiration losses caused by warmer summer temperatures. Predicted increases in wildfire frequency in PEBNA forests will likely enhance the positive response of landscape-level forest growth to climate change by shifting the forest distribution to younger age classes while also enhancing the jack pine component.

  17. Changes in growth of pristine boreal North American forests from 1950 to 2005 driven by landscape demographics and species traits

    NASA Astrophysics Data System (ADS)

    Girardin, M. P.; Guo, X. J.; Bernier, P. Y.; Raulier, F.; Gauthier, S.

    2012-07-01

    In spite of the many factors that are occurring and known for positively affecting the growth of forests, some boreal forests across North America have recently felt the adverse impacts of environmental changes. Knowledge of causes for productivity declines in North American boreal forests remains limited, and this is owed to the large spatial and temporal scales involved, and the many plant processes affected. Here, the response of pristine eastern boreal North American (PEBNA) forests to ongoing climatic changes is examined using in situ data, community ecology statistics, and species-specific model simulations of carbon exchanges forced by contemporary climatic data. To examine trends in forest growth, we used a recently acquired collection of tree-ring width data from 252 sample plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree growth data highlight a dominating forest growth decline in overmature forests (age > 120 years) from 1950 to 2005. In contrast, improving growth conditions are seen in jack pine and mature (70-120 years) black spruce stands. Multivariate analysis of climate and growth relationships suggests that responses of PEBNA forests to climate are dependent on demographic and species traits via their mediation of temperature and water stress constraints. In support of this hypothesis, the simulation experiment suggests that in old-growth black spruce stands the benefit to growth brought on by a longer growing season may have been low in comparison with the increasing moisture stress and respiration losses caused by warmer summer temperatures. Predicted increases in wildfire frequency in PEBNA forests will likely enhance the positive response of landscape-level forest growth to climate change by shifting the forest distribution to younger age classes while also enhancing the jack pine component.

  18. Evaluation of metric precision for a riparian forest survey.

    PubMed

    Barker, Jerry R; Bollman, Michael; Ringold, Paul L; Sackinger, Jennifer; Cline, Steven P

    2002-04-01

    This article evaluates the performance of a protocol to monitor riparian forests in western Oregon, United States based on the quality of the data obtained from a field survey. Precision is the criteria used to determine the quality of 19 field and 6 derived metrics. The derived metrics were calculated from the field data. The survey consisted of 110 riparian sites on public and private lands that were sampled during the summers of 1996 and 1997. In order to calculate metric precision, some of the field plots were re-measured. Metric precision was defined in terms of the coefficient of variability (CV) and standard deviation and then compared with a pre-defined data quality objective (DQO). A metric was considered precise if the CV met or exceeded the DQO. The geomorphology metrics were not precise while the forest stand inventory metrics and forest cover metrics, with some exceptions, were precise. The precision for many of the field and derived metrics compared favorably with the level of precision for similar metrics reported in the literature. Recommendations are made to improve the precision for some metrics and they include changing the way precision is calculated, re-defining the field protocol, or improving field training. PMID:15900665

  19. Succession-inducing disturbances and the old-growth forest mosaic of a Central Amazon landscape

    NASA Astrophysics Data System (ADS)

    Chambers, J. Q.; Negron Juarez, R. I.; Marra, D.; Roberts, D. A.; Di Vittorio, A. V.; Higuchi, N.; Trumbore, S.

    2011-12-01

    Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. Tropical forest studies commonly assume that plots covering only a small fraction of the landscape representatively sample this mosaic, and that departures from steady-state represent trends. Here a critical test of this equilibrium assumption for a Central Amazon old-growth forest landscape is carried out by combining extensive forest field plot data, remote sensing analysis to generate disturbance probability distribution functions, and simulation modeling to place plot-level results into a landscape context. Results show that succession-inducing disturbances had a return frequency of ~100 years, and that these episodic events have been poorly sampled by existing forest sample plots. Overall, key ecosystem attributes of small patches are expected to constantly change in the Central Amazon, and long significant trends can result from purely stochastic processes. The role of episodic disturbances will be discussed in terms of Amazon forest carbon balance, and regional tree diversity patterns.

  20. The dynamics of annual carbon allocation to wood in European forests is consistent with a combined source-sink limitation of growth.

    NASA Astrophysics Data System (ADS)

    Guillemot, Joannès; Martin-StPaul, Nicolas K.; Dufrêne, Eric; François, Christophe; Soudani, Kamel; Ourcival, Jean-Marc; Leadley, Paul; Delpierre, Nicolas

    2015-04-01

    The extent to which forest growth is limited by carbon (C) supply (source control) or by cambial activity (sink control) will strongly determines the responses of trees to global changes. However, the physiological processes responsible for the limitation of forest growth are still under debate. The aim of this study was i) to evaluate the key drivers of the annual carbon allocation to wood along large soil and climate regional gradients in four tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex and Picea abies) ii) to implement the identified key drivers in a new C allocation scheme within the CASTANEA terrestrial biosphere model (TBM). Combining field measurements and process-based simulations at 49 sites (931 site-years), our analyses revealed that the inter-site variability in C allocation to wood was predominantly driven by an age-related decline. The direct control of temperature or water stress on sink activity (i.e. independently from their effects on C supply) exerted a strong influence on the annual woody growth in all the species considered, including deciduous temperate species. The lagged effect of the past environment conditions was a significant driver of the annual C allocation to wood. Carbon supply appeared to strongly limit growth only in deciduous temperate species. Our study supports the premise that European forest growth is under a complex panel of source- and sink- limitations, contradicting the simple source control implemented in most TBMs. The implementation of these combined forest growth limitations in the CASTANEA model significantly improved its performance when evaluated against independent stand growth data at the regional scale (mainland France, >10000 plots). We finally discuss how the sink imitation affects the CASTANEA simulated projections of forest productivity along the 21th century, especially with respect to the expected fertilizing effect of increasing atmospheric

  1. Soil Carbon Storage and Turnover in an Old-Growth Coastal Redwood Forest and Adjacent Prairie

    NASA Astrophysics Data System (ADS)

    McFarlane, K. J.; Torn, M. S.; Mambelli, S.; Dawson, T. E.

    2010-12-01

    Coastal redwood (Sequoia sempervirens) forests store lots of carbon in aboveground tree biomass because redwoods are very long-lived and can grow very large. Redwood is known for its high resistance to decay, a result of high levels of aromatic compounds (tannins) in the tree’s tissues. We tested the hypothesis that because coastal redwoods are highly productive and produce organic matter that is chemically resistant to decay, old-growth redwood forests should store large amounts of stabilized soil carbon. We measured soil C storage to 110 cm depth in an old-growth coastal redwood forest and used physical soil fractionation combined with radiocarbon measurements to determine soil organic matter turnover time. In addition, we measured soil C storage and turnover at an adjacent prairie experiencing the same climate and with soils derived from the same parent material. We found larger soil C stocks to 110 cm at the prairie (350 Mg C ha-1) than the redwood forest (277 Mg C ha-1) even with O-horizons included for the forest. Larger N stocks were also observed at the prairie than the redwood and these differences in stocks were driven by higher C and N concentrations in mineral soils at the prairie. Differences between ecosystems in soil C and N concentrations, C:N ratios, and C and N stocks were observed for the top 50 cm only, suggesting that the influence of the different litter types did not extend to deeper soils. Contrary to what was expected, bulk soil and heavy density-fraction Δ14C values were higher, indicating shorter turnover times, for the redwood forest than the prairie. In summary, we did not observe greater C storage or 14C-based turnover times in old-growth redwood forest compared to adjacent prairie, suggesting chemical recalcitrance of litter inputs does not drive soil C stabilization at these ecosystems.

  2. Increased water deficit decreases Douglas fir growth throughout western US forests.

    PubMed

    Restaino, Christina M; Peterson, David L; Littell, Jeremy

    2016-08-23

    Changes in tree growth rates can affect tree mortality and forest feedbacks to the global carbon cycle. As air temperature increases, evaporative demand also increases, increasing effective drought in forest ecosystems. Using a spatially comprehensive network of Douglas fir (Pseudotsuga menziesii) chronologies from 122 locations that represent distinct climate environments in the western United States, we show that increased temperature decreases growth via vapor pressure deficit (VPD) across all latitudes. Using an ensemble of global circulation models, we project an increase in both the mean VPD associated with the lowest growth extremes and the probability of exceeding these VPD values. As temperature continues to increase in future decades, we can expect deficit-related stress to increase and consequently Douglas fir growth to decrease throughout its US range. PMID:27503880

  3. The effect of growth parameters on the height and density of carbon nanotube forests

    NASA Astrophysics Data System (ADS)

    Call, Robert W.

    Carbon nanotube forests (CNTFs) are grown using an injection chemical vapor deposition method. Images of CNTFs are taken using a scanning electron microscope and are used to measure their height and density. Growth parameters are systematically varied to determine their effect on the height and density of CNTFs. Investigations of CNTF density as a function of distance from the growth substrate reveal that diffusion can be a limiting factor on CNTF growth. Our findings indicate that height and density are related and that each growth parameter has multi-dimensional effects.

  4. Disturbance legacies and climate jointly drive tree growth and mortality in an intensively studied boreal forest.

    PubMed

    Bond-Lamberty, Ben; Rocha, Adrian V; Calvin, Katherine; Holmes, Bruce; Wang, Chuankuan; Goulden, Michael L

    2014-01-01

    Most North American forests are at some stage of post-disturbance regrowth, subject to a changing climate, and exhibit growth and mortality patterns that may not be closely coupled to annual environmental conditions. Distinguishing the possibly interacting effects of these processes is necessary to put short-term studies in a longer term context, and particularly important for the carbon-dense, fire-prone boreal forest. The goals of this study were to combine dendrochronological sampling, inventory records, and machine-learning algorithms to understand how tree growth and death have changed at one highly studied site (Northern Old Black Spruce, NOBS) in the central Canadian boreal forest. Over the 1999-2012 inventory period, mean tree diameter increased even as stand density and basal area declined significantly. Tree mortality averaged 1.4 ± 0.6% yr-(1), with most mortality occurring in medium-sized trees; new recruitment was minimal. There have been at least two, and probably three, significant influxes of new trees since stand initiation, but none in recent decades. A combined tree ring chronology constructed from sampling in 2001, 2004, and 2012 showed several periods of extreme growth depression, with increased mortality lagging depressed growth by ~5 years. Higher minimum and maximum air temperatures exerted a negative influence on tree growth, while precipitation and climate moisture index had a positive effect; both current- and previous-year data exerted significant effects. Models based on these variables explained 23-44% of the ring-width variability. We suggest that past climate extremes led to significant mortality still visible in the current forest structure, with decadal dynamics superimposed on slower patterns of fire and succession. These results have significant implications for our understanding of previous work at NOBS, the carbon sequestration capability of old-growth stands in a disturbance-prone landscape, and the sustainable management of

  5. Slow Growth Rates of Amazonian Trees: Consequences for Carbon Sequestration and Forest Management.

    NASA Astrophysics Data System (ADS)

    Vieira, S. A.; Camargo, P. B.; Selhorst, D.; Chambers, J.; Higuchi, N.; Martinelli, L. A.; Trumbore, S.

    2004-12-01

    Growth rates for tropical forest trees estimated from radiocarbon ages and dendrometer measurements illustrate differences in forest age and structure among three sites located in the eastern, central and western Amazon basin. Although growth rates vary dramatically among individual trees overall the slowest growing trees (averaging \\sim0.1mm yr-1 as opposed to 0.3mm yr-1 diameter increment) are found in the central Amazon. Small individuals (DBH \\<30cm) have slower growth rates than larger diameter trees, and trees in this size class with radiocarbon ages >500 yr are encountered at all sites. Only \\sim2MgC ha-1 year-1, or \\SIM7% of annual photosynthesis, is allocated to growth of living wood at the eastern and central Amazon sites. Rates of C allocation to stem growth are similar across the three sites we studied because slowest growth occurs at the central Amazon site that has highest stem density and greatest biomass. Extrapolating our growth increment data to forest stand, we estimate the mean age of individual trees is \\SIM350 years in the central Amazon but \\SIM200\\-250 years in the other two areas. The mean age of C making up the trees has a smaller range of \\SIM250\\-310 years, because of the greater fraction of biomass in larger individuals in the eastern and western Amazon sites. These residence times for C are longer than those of 100\\-180 years obtained by simply dividing the total biomass C by the rate of C allocation to new wood for the same reason. We estimate that >20% of trees at all sites should have ages >300 years, and that maximum tree ages of >1000 years, though not common, are in accord with the growth rates we find. The fact that many Amazon trees attain ages greater than several centuries should be accounted for in management practices in these forests.

  6. Establishment, survival, and growth of selected browse species in a ponderosa pine forest

    USGS Publications Warehouse

    Dietz, D.R.; Uresk, D.W.; Messner, H.E.; McEwen, L.C.

    1980-01-01

    Information is presented on establishment, survival, and growth of seven selected browse species in a ponderosa pine forest over a 10-year period. Methods of establishment included hand seeding and planting bare-root and containerized stock. Success of different methods differed with shrub species.

  7. PROCESS MODELING TREE AND FOREST GROWTH: CURRENT PERSPECTIVES AND FUTURE NEEDS

    EPA Science Inventory

    This volume demonstrates that the modeling of tree and forest growth based on physiological processes is emerging as an important discipline in forestry research. ome possible directions for future research include the development of overall carbon budgets with maintenance and gr...

  8. The Dynamic of Annual Carbon Allocation to Wood in European Forests Is Consistent with a Combined Source-Sink Limitation of Growth: Implications on Growth Simulations in a Terrestrial Biosphere Model

    NASA Astrophysics Data System (ADS)

    Guillemot, J.; Martin-StPaul, N. K.; Dufrêne, E.; François, C.; Soudani, K.; Ourcival, J. M.; Leadley, P.; Delpierre, N.

    2014-12-01

    The extent to which forest growth is limited by carbon (C) supply (source control) or by cambial activity (sink control) will strongly determines the responses of trees to global changes. However, the physiological processes responsible for the limitation of forest growth are still under debate. The aim of this study was i) to evaluate the key drivers of the annual carbon allocation to wood along large soil and climate regional gradients in four tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex and Picea abies) ii) to implement the identified key drivers in a new C allocation scheme within the CASTANEA terrestrial biosphere model (TBM). Combining field measurements and process-based simulations at 49 sites (931 site-years), our analyses revealed that the inter-site variability in C allocation to wood was predominantly driven by an age-related decline. The direct control of temperature or water stress on sink activity (i.e. independently from their effects on C supply) exerted a strong influence on the annual woody growth in all the species considered, including deciduous temperate species. The lagged effect of the past environment conditions was a significant driver of the annual C allocation to wood. Carbon supply appeared to strongly limit growth only in deciduous temperate species. Our study supports the premise that European forest growth is under a complex panel of source- and sink- limitations, contradicting the simple source control implemented in most TBMs. The implementation of these combined forest growth limitations in the CASTANEA model significantly improved its performance when evaluated against independent stand growth data at the regional scale (mainland France, >103 plots). We finally discuss how the sink imitation affects the CASTANEA simulated projections of forest productivity along the 21th century, especially with respect to the expected fertilizing effect of increasing atmospheric

  9. Fix success and accuracy of GPS radio collars in old-growth temperate coniferous forests

    USGS Publications Warehouse

    Sager-Fradkin, Kimberly A.; Jenkins, Kurt J.; Hoffman, Robert L.; Happe, P.; Beecham, J.; Wright, R.G.

    2007-01-01

    Global Positioning System (GPS) telemetry is used extensively to study animal distribution and resource selection patterns but is susceptible to biases resulting from data omission and spatial inaccuracies. These data errors may cause misinterpretation of wildlife habitat selection or spatial use patterns. We used both stationary test collars and collared free-ranging American black bears (Ursus americanus) to quantify systemic data loss and location error of GPS telemetry in mountainous, old-growth temperate forests of Olympic National Park, Washington, USA. We developed predictive models of environmental factors that influence the probability of obtaining GPS locations and evaluated the ability of weighting factors derived from these models to mitigate data omission biases from collared bears. We also examined the effects of microhabitat on collar fix success rate and examined collar accuracy as related to elevation changes between successive fixes. The probability of collars successfully obtaining location fixes was positively associated with elevation and unobstructed satellite view and was negatively affected by the interaction of overstory canopy and satellite view. Test collars were 33% more successful at acquiring fixes than those on bears. Fix success rates of collared bears varied seasonally and diurnally. Application of weighting factors to individual collared bear fixes recouped only 6% of lost data and failed to reduce seasonal or diurnal variation in fix success, suggesting that variables not included in our model contributed to data loss. Test collars placed to mimic bear bedding sites received 16% fewer fixes than randomly placed collars, indicating that microhabitat selection may contribute to data loss for wildlife equipped with GPS collars. Horizontal collar errors of >800 m occurred when elevation changes between successive fixes were >400 m. We conclude that significant limitations remain in accounting for data loss and error inherent in using

  10. A Hierarchical Analysis of Tree Growth and Environmental Drivers Across Eastern US Temperate Forests

    NASA Astrophysics Data System (ADS)

    Mantooth, J.; Dietze, M.

    2014-12-01

    Improving predictions of how forests in the eastern United States will respond to future global change requires a better understanding of the drivers of variability in tree growth rates. Current inventory data lack the temporal resolution to characterize interannual variability, while existing growth records lack the extent required to assess spatial scales of variability. Therefore, we established a network of forest inventory plots across ten sites across the eastern US, and measured growth in adult trees using increment cores. Sites were chosen to maximize climate space explored, while within sites, plots were spread across primary environmental gradients to explore landscape-level variability in growth. Using the annual growth record available from tree cores, we explored the responses of trees to multiple environmental covariates over multiple spatial and temporal scales. We hypothesized that within and across sites growth rates vary among species, and that intraspecific growth rates increase with temperature along a species' range. We also hypothesized that trees show synchrony in growth responses to landscape-scale climatic changes. Initial analyses of growth increments indicate that across sites, trees with intermediate shade tolerance, e.g. Red Oak (Quercus rubra), tend to have the highest growth rates. At the site level, there is evidence for synchrony in response to large-scale climatic events (e.g. prolonged drought and above average temperatures). However, growth responses to climate at the landscape scale have yet to be detected. Our current analysis utilizes hierarchical Bayesian state-space modeling to focus on growth responses of adult trees to environmental covariates at multiple spatial and temporal scales. This predictive model of tree growth currently incorporates observed effects at the individual, plot, site, and landscape scale. Current analysis using this model shows a potential slowing of growth in the past decade for two sites in the

  11. Habitat management for red tree voles in douglas-fir forests. Biology and management of old-growth forests. Forest Service general technical report

    SciTech Connect

    Huff, M.H.; Holthausen, R.S.; Aubry, K.B.

    1992-09-01

    The relations between arboreal rodents and trees causes the animals to be particularly sensitive to the effects of timber harvesting. Among arboreal rodents, the authors consider the red tree vole to be the most vulnerable to local extinctions resulting from the loss or fragmentation of old-growth Douglas-fir forests. Red tree voles are nocturnal, canopy dwelling, and difficult to study. The following habitat characteristics are potentially important for the species: tree species, stand development, tree size, moisture conditions, topographic positions, elevation, and stand size. Based on these characteristics, the authors developed interim management strategies to help sustain or expand existing populations of red tree voles.

  12. Windthrow and salvage logging in an old-growth hemlock-northern hardwoods forest

    USGS Publications Warehouse

    Lang, K.D.; Schulte, L.A.; Guntenspergen, G.R.

    2009-01-01

    Although the initial response to salvage (also known as, post-disturbance or sanitary) logging is known to vary among system components, little is known about longer term forest recovery. We examine forest overstory, understory, soil, and microtopographic response 25 years after a 1977 severe wind disturbance on the Flambeau River State Forest in Wisconsin, USA, a portion of which was salvage logged. Within this former old-growth hemlock-northern hardwoods forest, tree dominance has shifted from Eastern hemlock (Tsuga canadensis) to broad-leaf deciduous species (Ulmus americana, Acer saccharum, Tilia americana, Populus tremuloides, and Betula alleghaniensis) in both the salvaged and unsalvaged areas. While the biological legacies of pre-disturbance seedlings, saplings, and mature trees were initially more abundant in the unsalvaged area, regeneration through root suckers and stump sprouts was common in both areas. After 25 years, tree basal area, sapling density, shrub layer density, and seedling cover had converged between unsalvaged and salvaged areas. In contrast, understory herb communities differed between salvaged and unsalvaged forest, with salvaged forest containing significantly higher understory herb richness and cover, and greater dominance of species benefiting from disturbance, especially Solidago species. Soil bulk density, pH, organic carbon content, and organic nitrogen content were also significantly higher in the salvaged area. The structural legacy of tip-up microtopography remains more pronounced in the unsalvaged area, with significantly taller tip-up mounds and deeper pits. Mosses and some forest herbs, including Athyrium filix-femina and Hydrophyllum virginianum, showed strong positive responses to this tip-up microrelief, highlighting the importance of these structural legacies for understory biodiversity. In sum, although the pathways of recovery differed, this forest appeared to be as resilient to the compound disturbances of windthrow

  13. A high-resolution monitoring network investigating stem growth of tropical forest trees

    NASA Astrophysics Data System (ADS)

    Hofhansl, F.; De Araujo, A. C.; DeLucia, E. H.

    2015-12-01

    The proportion of carbon (C) allocated to tree stems is an important determinant of the C sink-strength of global forest ecosystems. Understanding the mechanisms controlling stem growth is essential for parameterization of global vegetation models and to accurately predict C sequestration of forest ecosystems. However, we still lack a thorough understanding of intra-annual variations in stem growth of tropical forest ecosystems, which could be especially prone to projected climatic changes. We here present high-resolution data (≤ 6 µm; ≥ 1 min) from a novel monitoring network of wireless devices for automated measurement of expansion and contraction in tree diameter using a membrane potentiometer, as well as point dendrometers on phloem and xylem to analyze diurnal changes in stem growth. Our results indicate that diurnal changes in stem diameter were associated with sap flow and related to seasonal variations in daytime temperature and water availability, such that daily maximum stem growth was positively related to temperature during the wet season but showed the opposite trend during the onset of the dry season. We show that high-resolution monitoring of stem growth of tropical trees is crucial to determine the response to intra-annual climate variation and therefore will be key to accurately predict future responses of tropical aboveground C storage, and should be of special interest for tropical ecosystem research and earth system science.

  14. Evaluation on the coefficient and exponent of runoff energy in MUSLE in forest watersed of Korea

    NASA Astrophysics Data System (ADS)

    Kim, Jaehoon; Choi, Hyung Tae; Lim, Hong-geun

    2016-04-01

    MUSLE is one of evaluation method of erosion and has been widely applied various areas. However, the coefficient and exponent of runoff energy in MUSLE was developed from US areas, especially Nebraska and Texas areas. Thus, when these values are applied in Korean forest watershed they should be modified due to the difference conditions such as topography, forest type and slope. This study was carried out to examine the coefficient and exponent of runoff energy in MUSLE for small forest watershed in Korea. Peak discharge, runoff volume and sediment yield were measured in forest watershed and the coefficient and exponent of runoff energy were calculated to 0.002 and 0.81 respectively. These values were based on undisturbed forest watershed and could be larger in disturbed forest including forest management or forest fires.

  15. The growth-defense trade-off and habitat specialization by plants in Amazonian forests.

    PubMed

    Fine, Paul V A; Miller, Zachariah J; Mesones, Italo; Irazuzta, Sebastian; Appel, Heidi M; Stevens, M Henry H; Sääksjärvi, Ilari; Schultz, Jack C; Coley, Phyllis D

    2006-07-01

    Tropical forests include a diversity of habitats, which has led to specialization in plants. Near Iquitos, in the Peruvian Amazon, nutrient-rich clay forests surround nutrient-poor white-sand forests, each harboring a unique composition of habitat specialist trees. We tested the hypothesis that the combination of impoverished soils and herbivory creates strong natural selection for plant defenses in white-sand forest, while rapid growth is favored in clay forests. Recently, we reported evidence from a reciprocal-transplant experiment that manipulated the presence of herbivores and involved 20 species from six genera, including phylogenetically independent pairs of closely related white-sand and clay specialists. When protected from herbivores, clay specialists exhibited faster growth rates than white-sand specialists in both habitats. But, when unprotected, white-sand specialists outperformed clay specialists in white-sand habitat, and clay specialists outperformed white-sand specialists in clay habitat. Here we test further the hypothesis that the growth defense trade-off contributes to habitat specialization by comparing patterns of growth, herbivory, and defensive traits in these same six genera of white-sand and clay specialists. While the probability of herbivore attack did not differ between the two habitats, an artificial defoliation experiment showed that the impact of herbivory on plant mortality was significantly greater in white-sand forests. We quantified the amount of terpenes, phenolics, leaf toughness, and available foliar protein for the plants in the experiment. Different genera invested in different defensive strategies, and we found strong evidence for phylogenetic constraint in defense type. Overall, however, we found significantly higher total defense investment for white-sand specialists, relative to their clay specialist congeners. Furthermore, herbivore resistance consistently exhibited a significant trade-off against growth rate in each of

  16. Optimal regeneration planning for old-growth forest: addressing scientific uncertainty in endangered species recovery through adaptive management

    USGS Publications Warehouse

    Moore, C.T.; Conroy, M.J.

    2006-01-01

    Stochastic and structural uncertainties about forest dynamics present challenges in the management of ephemeral habitat conditions for endangered forest species. Maintaining critical foraging and breeding habitat for the endangered red-cockaded woodpecker (Picoides borealis) requires an uninterrupted supply of old-growth forest. We constructed and optimized a dynamic forest growth model for the Piedmont National Wildlife Refuge (Georgia, USA) with the objective of perpetuating a maximum stream of old-growth forest habitat. Our model accommodates stochastic disturbances and hardwood succession rates, and uncertainty about model structure. We produced a regeneration policy that was indexed by current forest state and by current weight of evidence among alternative model forms. We used adaptive stochastic dynamic programming, which anticipates that model probabilities, as well as forest states, may change through time, with consequent evolution of the optimal decision for any given forest state. In light of considerable uncertainty about forest dynamics, we analyzed a set of competing models incorporating extreme, but plausible, parameter values. Under any of these models, forest silviculture practices currently recommended for the creation of woodpecker habitat are suboptimal. We endorse fully adaptive approaches to the management of endangered species habitats in which predictive modeling, monitoring, and assessment are tightly linked.

  17. The value of volume and growth measurements in timber sales management of the National Forests

    NASA Technical Reports Server (NTRS)

    Lietzke, K. R.

    1977-01-01

    This paper summarizes work performed in the estimation of gross social value of timber volume and growth rate information used in making regional harvest decisions in the National Forest System. A model was developed to permit parametric analysis. The problem is formulated as one of finding optimal inventory holding patterns. Public timber management differs from other inventory holding problems in that the inventory, itself, generates value over time in providing recreational, aesthetic and environmental goods. 'Nontimber' demand estimates are inferred from past Forest Service harvest and sales levels. The solution requires a description of the harvest rates which maintain the optimum inventory level. Gross benefits of the Landsat systems are estimated by comparison with Forest Service information gathering models. Gross annual benefits are estimated to be $5.9 million for the MSS system and $7.2 million for the TM system.

  18. Drought stress, growth and nonstructural carbohydrate dynamics of pine trees in a semi-arid forest.

    PubMed

    Klein, Tamir; Hoch, Günter; Yakir, Dan; Körner, Christian

    2014-09-01

    In trees exposed to prolonged drought, both carbon uptake (C source) and growth (C sink) typically decrease. This correlation raises two important questions: (i) to what degree is tree growth limited by C availability; and (ii) is growth limited by concurrent C storage (e.g., as nonstructural carbohydrates, NSC)? To test the relationships between drought, growth and C reserves, we monitored the changes in NSC levels and constructed stem growth chronologies of mature Pinus halepensis Miller trees of three drought stress levels growing in Yatir forest, Israel, at the dry distribution limit of forests. Moderately stressed and stressed trees showed 34 and 14% of the stem growth, 71 and 31% of the sap flux density, and 79 and 66% of the final needle length of healthy trees in 2012. In spite of these large reductions in growth and sap flow, both starch and soluble sugar concentrations in the branches of these trees were similar in all trees throughout the dry season (2-4% dry mass). At the same time, the root starch concentrations of moderately stressed and stressed trees were 47 and 58% of those of healthy trees, but never <2% dry mass. Our results show that all the studied trees maintain a fairly good coordination between C supply and demand, and even during prolonged drought there is more than one way for a tree to maintain a positive C balance. PMID:25187568

  19. Who is the new sheriff in town regulating boreal forest growth?

    NASA Astrophysics Data System (ADS)

    Park Williams, A.; Xu, Chonggang; McDowell, Nate G.

    2011-12-01

    Climate change appears to be altering boreal forests. One recently observed symptom of these changes has been an apparent weakening of the positive relationship between high-latitude boreal tree growth and temperature at some sites (D'Arrigo et al 2008). This phenomenon is referred to as the 'divergence problem' or 'divergence effect' and is thought to reflect a non-linear relationship between temperature and tree growth, where recent warming has allowed other factors besides growing-season temperature to emerge as dominant regulators of annual growth rates. Figure 1 demonstrates this divergence phenomenon with records of tree-ring widths collected from 59 populations of white spruce in Alaska 1. Key tendencies among these populations include: (1) growth is most sensitive to temperature during relatively cold growing seasons (figure 1(a)), (2) populations at colder sites are more sensitive to temperature than those at warmer sites are (figure 1(a)), and (3) growth at warmer sites may respond negatively to increased temperature beyond some optimal growing-season temperature (figure 1(b)). Since temperature is rising rapidly at high latitudes, one interpretation of figures 1(a) and (b) is that warming has promoted increased growth at colder sites, but caused growth to plateau or slow at warmer sites. Corroborating this interpretation, satellite imagery and tree-ring data indicate increasing vegetation productivity near the forest-tundra boundary but declining productivity in warmer regions within forest interiors (e.g., Bunn and Goetz 2006, Beck and Goetz 2011, Beck et al 2011, Berner et al 2011). Will continued warming cause a northward migration of boreal forests, with mortality in the warmer, southern locations and expansion into the colder tundra? This question is difficult to answer because many factors besides temperature influence boreal forest dynamics. Widespread productivity declines within interior boreal forests appear to be related to warming

  20. Credit Risk Evaluation of Power Market Players with Random Forest

    NASA Astrophysics Data System (ADS)

    Umezawa, Yasushi; Mori, Hiroyuki

    A new method is proposed for credit risk evaluation in a power market. The credit risk evaluation is to measure the bankruptcy risk of the company. The power system liberalization results in new environment that puts emphasis on the profit maximization and the risk minimization. There is a high probability that the electricity transaction causes a risk between companies. So, power market players are concerned with the risk minimization. As a management strategy, a risk index is requested to evaluate the worth of the business partner. This paper proposes a new method for evaluating the credit risk with Random Forest (RF) that makes ensemble learning for the decision tree. RF is one of efficient data mining technique in clustering data and extracting relationship between input and output data. In addition, the method of generating pseudo-measurements is proposed to improve the performance of RF. The proposed method is successfully applied to real financial data of energy utilities in the power market. A comparison is made between the proposed and the conventional methods.

  1. Effects of wood ash fertilization on forest floor greenhouse gas emissions and tree growth in nutrient poor drained peatland forests.

    PubMed

    Ernfors, M; Sikström, U; Nilsson, M; Klemedtsson, L

    2010-09-15

    Wood ash (3.1, 3.3 or 6.6 tonnes dry weight ha(-1)) was used to fertilize two drained and forested peatland sites in southern Sweden. The sites were chosen to represent the Swedish peatlands that are most suitable for ash fertilization, with respect to stand growth response. The fluxes of carbon dioxide (CO(2)), methane (CH(4)) and nitrous oxide (N(2)O) from the forest floor, measured using opaque static chambers, were monitored at both sites during 2004 and 2005 and at one of the sites during the period 1 October 2007-1 October 2008. No significant (p>0.05) changes in forest floor greenhouse gas exchange were detected. The annual emissions of CO(2) from the sites varied between 6.4 and 15.4 tonnes ha(-1), while the CH(4) fluxes varied between 1.9 and 12.5 kg ha(-1). The emissions of N(2)O were negligible. Ash fertilization increased soil pH at a depth of 0-0.05 m by up to 0.9 units (p<0.01) at one site, 5 years after application, and by 0.4 units (p<0.05) at the other site, 4 years after application. Over the first 5 years after fertilization, the mean annual tree stand basal area increment was significantly larger (p<0.05) at the highest ash dose plots compared with control plots (0.64 m(2) ha(-1) year(-1) and 0.52 m(2) ha(-1) year(-1), respectively). The stand biomass, which was calculated using tree biomass functions, was not significantly affected by the ash treatment. The groundwater levels during the 2008 growing season were lower in the high ash dose plots than in the corresponding control plots (p<0.05), indicating increased evapotranspiration as a result of increased tree growth. The larger basal area increment and the lowered groundwater levels in the high ash dose plots suggest that fertilization promoted tree growth, while not affecting greenhouse gas emissions. PMID:20667583

  2. Bat activity in thinned, unthinned, and old-growth forests in western Oregon

    USGS Publications Warehouse

    Humes, Marcia L.; Hayes, J.P.; Collopy, M.W.

    1999-01-01

    Many aspects of the influences of forest management activities on bats (Chiroptera) in the Pacific Northwest are poorly known. We compared thinned and unthinned forest stands of the same age and old-growth forest stands to determine potential differences in structure and amount of use by bats. We hypothesized that activity levels of bats would differ in stands differing in structure as a result of management history and that activity of bats would be similar in stands of similar structure. We used automated ultrasonic detectors (Anabat II) to record calls of bats in 50-100-year-old thinned and unthinned stands, and in old-growth (a?Y200 yr old) stands in the Oregon Coast Range during the summers of 1994 and 1995. Our median index of bat activity was higher in old-growth than in unthinned stands and higher in thinned than in unthinned stands. We were not able to detect a significant difference between the index of median bat activity for old-growth and thinned stands. More than 90% of identifiable passes were identified as calls from Myotis species. The 3 stand types we examined differed in certain structural characteristics such as density and size of trees, and amount of overstory and understory cover. We concluded that the structural changes caused by thinning may benefit bats by creating habitat structure in young stands that bats are able to use more effectively.

  3. Disturbance legacies and climate jointly drive tree growth and mortality in an intensively studied boreal forest

    SciTech Connect

    Bond-Lamberty, Benjamin; Rocha, Adrian; Calvin, Katherine V.; Holmes, Bruce; Wang, Chuankuan; Goulden, Michael L.

    2014-01-01

    How will regional growth and mortality change with even relatively small climate shifts, even independent of catastrophic disturbances? This question is particularly acute for the North American boreal forest, which is carbon-dense and subject The goals of this study were to combine dendrochronological sampling, inventory records, and machine-learning algorithms to understand how tree growth and death have changed at one highly studied site (Northern Old Black Spruce, NOBS) in the central Canadian boreal forest. Over the 1999-2012 inventory period, mean DBH increased even as stand density and basal area declined significantly from 41.3 to 37.5 m2 ha-1. Tree mortality averaged 1.4±0.6% yr-1, with most mortality occurring in medium-sized trees. A combined tree ring chronology constructed from 2001, 2004, and 2012 sampling showed several periods of extreme growth depression, with increased mortality lagging depressed growth by ~5 years. Minimum and maximum air temperatures exerted a negative influence on tree growth, while precipitation and climate moisture index had a positive effect; both current- and previous-year data exerted significant effects. Models based on these variables explained 23-44% of the ring-width variability. There have been at least one, and probably two, significant recruitment episodes since stand initiation, and we infer that past climate extremes led to significant NOBS mortality still visible in the current forest structure. These results imply that a combination of successional and demographic processes, along with mortality driven by abiotic factors, continue to affect the stand, with significant implications for our understanding of previous work at NOBS and the sustainable management of regional forests.

  4. Ground Layer Plant Species Turnover and Beta Diversity in Southern-European Old-Growth Forests

    PubMed Central

    Sabatini, Francesco Maria; Burrascano, Sabina; Tuomisto, Hanna; Blasi, Carlo

    2014-01-01

    Different assembly processes may simultaneously affect local-scale variation of species composition in temperate old-growth forests. Ground layer species diversity reflects chance colonization and persistence of low-dispersal species, as well as fine-scale environmental heterogeneity. The latter depends on both purely abiotic factors, such as soil properties and topography, and factors primarily determined by overstorey structure, such as light availability. Understanding the degree to which plant diversity in old-growth forests is associated with structural heterogeneity and/or to dispersal limitation will help assessing the effectiveness of silvicultural practices that recreate old-growth patterns and structures for the conservation or restoration of plant diversity. We used a nested sampling design to assess fine-scale species turnover, i.e. the proportion of species composition that changes among sampling units, across 11 beech-dominated old-growth forests in Southern Europe. For each stand, we also measured a wide range of environmental and structural variables that might explain ground layer species turnover. Our aim was to quantify the relative importance of dispersal limitation in comparison to that of stand structural heterogeneity while controlling for other sources of environmental heterogeneity. For this purpose, we used multiple regression on distance matrices at the within-stand extent, and mixed effect models at the extent of the whole dataset. Species turnover was best predicted by structural and environmental heterogeneity, especially by differences in light availability and in topsoil nutrient concentration and texture. Spatial distances were significant only in four out of eleven stands with a relatively low explanatory power. This suggests that structural heterogeneity is a more important driver of local-scale ground layer species turnover than dispersal limitation in southern European old-growth beech forests. PMID:24748155

  5. Evaluating climate variability and management impacts on carbon dynamics of a temperate forest using a variety of techniques

    NASA Astrophysics Data System (ADS)

    Arain, M. A.

    2015-12-01

    Climate variability, extreme weather events, forest age and management history impacts carbon sequestration in forest ecosystems. A variety of measurement techniques such as eddy covariance, dendrochronology, automatic soil CO2 chambers and remote sensing are employed fully understand forest carbon dynamics. Here, we present carbon flux measurements from 2003-2014 in a 76-year old managed temperate pine ((-Pinus strobus L.) forest, near Lake Erie in southern Ontario, Canada. Forest was partially thinned (30% tree harvested) in 1983 and 2012. The thinning in 2012 did not significantly impact carbon fluxes as post-thinning fluxes were within the range of inter-annual variability. Mean annual post-thinning (2012-2104) gross ecosystem productivity (GEP) measure by the eddy covariance technique was 1518 ± 78 g C m-2 year-1 as compared to pre-thinning (2003-2011) GEP of 1384 ± 121 g C m-2·year-1. Over the same period, mean post-thinning net ecosystem productivity (NEP) was 185 ± 75 g C m-2 year-1 as compared to post-thinning NEP of 180 ± 70 g C m-2 year-1, indicating that pre-thinning NEP was not significantly different than post-thinning NEP. Only post-thinning mean annual ecosystem respiration (Re; 1322 ± 54 g C m-2 year-1) was higher than pre-thinning Re (1195 ± 101 g C m-2 year-1). Soil CO2 efflux measurements showed similar trends. We also evaluated the impacts of climate variability and management regime on the full life cycle of the forest using annual radial tree-ring growths from 15 trees and compared them with historical climate (temperature and precipitation) data. While the annual growth rates displayed weak correlation with long-term climatic records, the growth was generally reduced during years with extreme drought (-36% of mean annual precipitation) and extreme temperature variability (±0.6 - 1.0°C). Overall, forest was more sensitive to management regime than climate variability. It showed higher growth stress during low light condition after

  6. Temperature and rainfall strongly drive temporal growth variation in Asian tropical forest trees.

    PubMed

    Vlam, Mart; Baker, Patrick J; Bunyavejchewin, Sarayudh; Zuidema, Pieter A

    2014-04-01

    Climate change effects on growth rates of tropical trees may lead to alterations in carbon cycling of carbon-rich tropical forests. However, climate sensitivity of broad-leaved lowland tropical trees is poorly understood. Dendrochronology (tree-ring analysis) provides a powerful tool to study the relationship between tropical tree growth and annual climate variability. We aimed to establish climate-growth relationships for five annual-ring forming tree species, using ring-width data from 459 canopy and understory trees from a seasonal tropical forest in western Thailand. Based on 183/459 trees, chronologies with total lengths between 29 and 62 years were produced for four out of five species. Bootstrapped correlation analysis revealed that climate-growth responses were similar among these four species. Growth was significantly negatively correlated with current-year maximum and minimum temperatures, and positively correlated with dry-season precipitation levels. Negative correlations between growth and temperature may be attributed to a positive relationship between temperature and autotrophic respiration rates. The positive relationship between growth and dry-season precipitation levels likely reflects the strong water demand during leaf flush. Mixed-effect models yielded results that were consistent across species: a negative effect of current wet-season maximum temperatures on growth, but also additive positive effects of, for example, prior dry-season maximum temperatures. Our analyses showed that annual growth variability in tropical trees is determined by a combination of both temperature and precipitation variability. With rising temperature, the predominantly negative relationship between temperature and growth may imply decreasing growth rates of tropical trees as a result of global warming. PMID:24352845

  7. Long-term growth trends and time series of elemental wood composition from two old-growth forests - natural versus anthropogenic influences

    NASA Astrophysics Data System (ADS)

    Scharnweber, Tobias; van der Maaten, Ernst; Heinrich, Ingo; Buras, Allan; van der Maaten Theunissen, Marieke; Wilmking, Martin

    2014-05-01

    In contrast to extreme environments with low human impact, where often one specific (climatic) factor is limiting tree growth, dendrochronological research in the temperate zone has to cope with a wide variety of climatic and non-climatic drivers. Sophisticated statistical tools, like various detrending and filtering techniques, allow for a rather precise analysis of high-frequency (annual) climate-growth relationships. However, as almost all forests in the temperate zone are to some degree influenced by human activities, it is difficult to separate anthropogenic from climatic influence on the lower time-frequencies of decades to centuries. Footprints of human activity in time series of tree-ring parameters might be caused directly through forest utilization (logging) or indirectly through environmental changes such as eutrophication or atmospheric pollution. The former can be elucidated by traditional dendrochronological techniques based on ring parameters; evaluation of the latter requires additional proxies such as dendrochemical data. For the interpretation of long-term trends and the calibration of tree-ring based reconstructions it is therefore necessary to study tree growth in as undisturbed forest environments as possible. Comparison with dendrochronological time series from managed forest might then allow separation of climatic- from anthropogenic signals. Here, we present long-term growth trends for the broadleaved tree species common beech, pedunculate oak and sycamore maple, from two protected old-growth forests in northern Germany (one with a documented last logging activity dating back to 1527), and compare those with well-replicated regional chronologies from other, mostly managed forests. Our results indicate that several low frequency trends that can be found in many regional chronologies are likely caused by synchronous periods of heavy loggings as for example during the years following World War II, and do not relate to climatic drivers. In

  8. Modeling Urban Dynamics Using Random Forest: Implementing Roc and Toc for Model Evaluation

    NASA Astrophysics Data System (ADS)

    Ahmadlou, M.; Delavar, M. R.; Shafizadeh-Moghadam, H.; Tayyebi, A.

    2016-06-01

    The importance of spatial accuracy of land use/cover change maps necessitates the use of high performance models. To reach this goal, calibrating machine learning (ML) approaches to model land use/cover conversions have received increasing interest among the scholars. This originates from the strength of these techniques as they powerfully account for the complex relationships underlying urban dynamics. Compared to other ML techniques, random forest has rarely been used for modeling urban growth. This paper, drawing on information from the multi-temporal Landsat satellite images of 1985, 2000 and 2015, calibrates a random forest regression (RFR) model to quantify the variable importance and simulation of urban change spatial patterns. The results and performance of RFR model were evaluated using two complementary tools, relative operating characteristics (ROC) and total operating characteristics (TOC), by overlaying the map of observed change and the modeled suitability map for land use change (error map). The suitability map produced by RFR model showed 82.48% area under curve for the ROC model which indicates a very good performance and highlights its appropriateness for simulating urban growth.

  9. [Characteristics of CO₂ flux in an old growth mixed forest in Tianmu Mountain, Zhejiang, China].

    PubMed

    Niu, Xiao-dong; Jiang, Hong; Zhang, Jin-meng; Fang, Cheng-yuan; Chen, Xiao-feng; Sun, Heng

    2016-01-01

    The old-growth, multiple ages, multispecies natural forest has played an important role in terrestrial ecosystem dynamics model and the global carbon budget. However, carbon fluxes of old forests in subtropical regions are rarely reported in China. In the present study, the CO₂ flux of an old-growth subtropical evergreen and deciduous broad-leaved mixed forest was observed using eddy covariance technique in Tianmu Mountain of Zhejiang Province. Based on the data sets which were observed from July 2013 to June 2014, the variations of net ecosystem exchange (NEE), eco-system respiration (Re), and gross ecosystem exchange (GEE) were analyzed. The results showed that during the study period, the monthly NEE all had a negative value (acted as a carbon sink) except for December and February (acted as a carbon source). The average monthly NEE was -61.52 g C · m⁻², the monthly carbon sequestration showed a double-peak curve and the maximum carbon sink was -149.40 g C · m⁻², which occurred in June while the maximum carbon source was 23.45 g C · m⁻², which occurred in February. The maximum of monthly mean CO₂ flux occurred in June with a value of -0.98 mg · m⁻² · s⁻¹, while the minimum value occurred in December with a value of -0.35 mg · m⁻² · s⁻¹. The NEE at the time point of positive and negative conversion had typical seasonal characteristics. The yearly NEE, Re, and GEE were -738.18, 931.05 and -1669.23 g C · m⁻², respectively. Compared with other forest ecosystems located at the similar latitude, the carbon fixation of the old-growth forest was larger, likely due to its complicated structure within the canopy and the presence of young-growth regeneration and successional stands. This showed that other than in carbon neutral, old-growth forests of Tianmu Mountain in subtropical China had a strong capability in carbon sequestration. PMID:27228586

  10. A New Model for Size-Dependent Tree Growth in Forests

    PubMed Central

    Konno, Yasuo; Umeki, Kiyoshi; Ohno, Yasuyuki

    2016-01-01

    Tree growth, especially diameter growth of tree stems, is an important issue for understanding the productivity and dynamics of forest stands. Metabolic scaling theory predicted that the 2/3 power of stem diameter at a certain time is a linear function of the 2/3 power of the initial diameter and that the diameter growth rate scales to the 1/3 power of the initial diameter. We tested these predictions of the metabolic scaling theory for 11 Japanese secondary forests at various growth stages. The predictions were not supported by the data, especially in younger stands. Alternatively, we proposed a new theoretical model for stem diameter growth on the basis of six assumptions. All these assumptions were supported by the data. The model produced a nearly linear to curvilinear relationship between the 2/3 power of stem diameters at two different times. It also fitted well to the curvilinear relationship between diameter growth rate and the initial diameter. Our model fitted better than the metabolic scaling theory, suggesting the importance of asymmetric competition among trees, which has not been incorporated in the metabolic scaling theory. PMID:27035709

  11. Survival and growth of seedlings of 19 native tree and shrub species planted in degraded forest as part of a forest restoration project in Madagascar’s highlands

    PubMed Central

    Birkinshaw, Chris; Andrianjafy, Mamisoa; Rasolofonirina, Jean-Jacques

    2011-01-01

    Percentage survival and mean percentage change in height were compared for 19 native tree and shrub species planted at Ankafobe Forest, a degraded fragment of highland forest, at ten months after planting. The species varied considerably in both, survival and growth. Best performers included Macaranga alnifolia (Euphorbiaceae), Harungana madagascariensis (Clusiaceae), Filicium decipiens (Sapindaceae) and Dodonaea madagascariensis (Sapindaceae). A comparison of survival between relatively short seedlings compared to relatively tall seedlings revealed no significant difference. This information will be used to increase the efficiency of forest restoration at this site. PMID:21892357

  12. High Latitude Forest Dynamics - CO2 EXCHANGE Measurements and Forest Growth at the Altitudinal Forest Line in High Subarctic Finnish Lapland

    NASA Astrophysics Data System (ADS)

    Dengel, S.; Siivola, E.; Aakala, T.; Kolari, P.; Hari, P.; Back, J. K.; Grace, J.; Vesala, T.

    2015-12-01

    Forests in high subarctic fell regions of Fennoscandia belong to the most northern forests in the world, a dynamic ecosystem vulnerable under a changing climate with treelines moving further north and also higher up slopes. An ecosystem is characterised by the interaction between micrometeorology, macroecology and the underlying terrain and topography. The current study is carried out at 68° North (Värriö strict nature reserve), the most sensitive zone of the high subarctic in Finnish Lapland. As the treeline is climbing up the slopes trees and eventually forests establish along the slopes leading to a greening of the area ("Greening of the Arctic" effect) and to an increase in CO2 uptake, also as a result of rising air temperatures and Nitrogen fertilization effects. Such developments and the little grazing (in this area) are leading to an increase in photosynthesising biomass. In order to fully understand the atmosphere - forest interaction in the fell region of Finnish Lapland, several important aspects are taken in consideration: its high latitudinal location, on-going climate change, polar day, its topographic characteristic and the dynamic of the progressing tree line. All these physiognomies cumulate in the capacity and efficiency of high latitude biomes in converting energy into photosynthate and contributing to removal of CO2 from the atmosphere. Carrying out CO2 and energy exchange measurements at ecosystem level in such extreme environments are challenging in particular when trying to follow and fulfil established assumptions set out by the application of the eddy covariance technique. Results from the first four consecutive snow free growing seasons show this site to act as a sink for atmospheric CO2. We are investigating the orographic effect on the observed fluxes and evaluate the performance of the flux setup determining if the topography has any systematic effects on fluxes or whether its external properties bias the carbon balance.

  13. Spatial models reveal the microclimatic buffering capacity of old-growth forests.

    PubMed

    Frey, Sarah J K; Hadley, Adam S; Johnson, Sherri L; Schulze, Mark; Jones, Julia A; Betts, Matthew G

    2016-04-01

    Climate change is predicted to cause widespread declines in biodiversity, but these predictions are derived from coarse-resolution climate models applied at global scales. Such models lack the capacity to incorporate microclimate variability, which is critical to biodiversity microrefugia. In forested montane regions, microclimate is thought to be influenced by combined effects of elevation, microtopography, and vegetation, but their relative effects at fine spatial scales are poorly known. We used boosted regression trees to model the spatial distribution of fine-scale, under-canopy air temperatures in mountainous terrain. Spatial models predicted observed independent test data well (r = 0.87). As expected, elevation strongly predicted temperatures, but vegetation and microtopography also exerted critical effects. Old-growth vegetation characteristics, measured using LiDAR (light detection and ranging), appeared to have an insulating effect; maximum spring monthly temperatures decreased by 2.5°C across the observed gradient in old-growth structure. These cooling effects across a gradient in forest structure are of similar magnitude to 50-year forecasts of the Intergovernmental Panel on Climate Change and therefore have the potential to mitigate climate warming at local scales. Management strategies to conserve old-growth characteristics and to curb current rates of primary forest loss could maintain microrefugia, enhancing biodiversity persistence in mountainous systems under climate warming. PMID:27152339

  14. Spatial models reveal the microclimatic buffering capacity of old-growth forests

    PubMed Central

    Frey, Sarah J. K.; Hadley, Adam S.; Johnson, Sherri L.; Schulze, Mark; Jones, Julia A.; Betts, Matthew G.

    2016-01-01

    Climate change is predicted to cause widespread declines in biodiversity, but these predictions are derived from coarse-resolution climate models applied at global scales. Such models lack the capacity to incorporate microclimate variability, which is critical to biodiversity microrefugia. In forested montane regions, microclimate is thought to be influenced by combined effects of elevation, microtopography, and vegetation, but their relative effects at fine spatial scales are poorly known. We used boosted regression trees to model the spatial distribution of fine-scale, under-canopy air temperatures in mountainous terrain. Spatial models predicted observed independent test data well (r = 0.87). As expected, elevation strongly predicted temperatures, but vegetation and microtopography also exerted critical effects. Old-growth vegetation characteristics, measured using LiDAR (light detection and ranging), appeared to have an insulating effect; maximum spring monthly temperatures decreased by 2.5°C across the observed gradient in old-growth structure. These cooling effects across a gradient in forest structure are of similar magnitude to 50-year forecasts of the Intergovernmental Panel on Climate Change and therefore have the potential to mitigate climate warming at local scales. Management strategies to conserve old-growth characteristics and to curb current rates of primary forest loss could maintain microrefugia, enhancing biodiversity persistence in mountainous systems under climate warming. PMID:27152339

  15. Positive effects of neighborhood complementarity on tree growth in a Neotropical forest.

    PubMed

    Chen, Yuxin; Wright, S Joseph; Muller-Landau, Helene C; Hubbell, Stephen P; Wang, Yongfan; Yu, Shixiao

    2016-03-01

    Numerous grassland experiments have found evidence for a complementarity effect, an increase in productivity with higher plant species richness due to niche partitioning. However, empirical tests of complementarity in natural forests are rare. We conducted a spatially explicit analysis of 518 433 growth records for 274 species from a 50-ha tropical forest plot to test neighborhood complementarity, the idea that a tree grows faster when it is surrounded by more dissimilar neighbors. We found evidence for complementarity: focal tree growth rates increased by 39.8% and 34.2% with a doubling of neighborhood multi-trait dissimilarity and phylogenetic dissimilarity, respectively. Dissimilarity from neighbors in maximum height had the most important effect on tree growth among the six traits examined, and indeed, its effect trended much larger than that of the multitrait dissimilarity index. Neighborhood complementarity effects were strongest for light-demanding species, and decreased in importance with increasing shade tolerance of the focal individuals. Simulations demonstrated that the observed neighborhood complementarities were sufficient to produce positive stand-level biodiversity-productivity relationships. We conclude that neighborhood complementarity is important for productivity in this tropical forest, and that scaling down to individual-level processes can advance our understanding of the mechanisms underlying stand-level biodiversity-productivity relationships. PMID:27197403

  16. Evaluation of the importance of nonlinear spectral mixing in coniferous forests

    NASA Astrophysics Data System (ADS)

    Caetano, Mario R.; Ni, Wenge; Cardoso Pereira, Jose M.; Huete, Alfredo R.

    1998-12-01

    We developed a simple technique to evaluate the importance of non-linear mixing in coniferous forests with different overstory structural characteristics and different backgrounds. The methodology consists on using a hybrid forest reflectance model for reflectance simulation, and on using factor analysis and target testing for unmixing the forest reflectance into three components: a forest canopy component (free of background effects), a background component (free of canopy effects) and a background-and-canopy dependent component. This third component is considered responsible for non-linearities since it depends simultaneously on the background reflectance and on the canopy transmittance. After running the model, the contribution of the third (non-linear) component to the total forest reflectance was evaluated and compared over different forest scenarios parameterized with data collected on maritime pine stands in Central Portugal.

  17. OAK FOREST CARBON AND WATER SIMULATIONS: MODEL INTERCOMPARISONS AND EVALUATIONS AGAINST INDEPENDENT DATA

    SciTech Connect

    Hanson, Paul J; Amthor, Jeffrey S; Wullschleger, Stan D; Wilson, K.; Grant, Robert F.; Hartley, Anne; Hui, D.; HuntJr., E. Raymond; Johnson, Dale W.; Kimball, John S.; King, Anthony Wayne; Luo, Yiqi; McNulty, Steven G.; Sun, G.; Thornton, Peter; Wang, S.; Williams, M.; Baldocchi, D. D.; Cushman, Robert Michael

    2004-01-01

    Models represent our primary method for integration of small-scale, processlevel phenomena into a comprehensive description of forest-stand or ecosystem function. They also represent a key method for testing hypotheses about the response of forest ecosystems to multiple changing environmental conditions. This paper describes the evaluation of 13 stand-level models varying in their spatial, mechanistic, and temporal complexity for their ability to capture intra- and interannual components of the water and carbon cycle for an upland, oak-dominated forest of eastern Tennessee. Comparisons between model simulations and observations were conducted for hourly, daily, and annual time steps. Data for the comparisons were obtained from a wide range of methods including: eddy covariance, sapflow, chamber-based soil respiration, biometric estimates of stand-level net primary production and growth, and soil water content by time or frequency domain reflectometry. Response surfaces of carbon and water flux as a function of environmental drivers, and a variety of goodness-of-fit statistics (bias, absolute bias, and model efficiency) were used to judge model performance. A single model did not consistently perform the best at all time steps or for all variables considered. Intermodel comparisons showed good agreement for water cycle fluxes, but considerable disagreement among models for predicted carbon fluxes. The mean of all model outputs, however, was nearly always the best fit to the observations. Not surprisingly, models missing key forest components or processes, such as roots or modeled soil water content, were unable to provide accurate predictions of ecosystem responses to short-term drought phenomenon. Nevertheless, an inability to correctly capture short-term physiological processes under drought was not necessarily an indicator of poor annual water and carbon budget simulations. This is possible because droughts in the subject ecosystem were of short duration and

  18. The contribution of competition to tree mortality in old-growth coniferous forests

    USGS Publications Warehouse

    Das, A.; Battles, J.; Stephenson, N.L.; van Mantgem, P.J.

    2011-01-01

    Competition is a well-documented contributor to tree mortality in temperate forests, with numerous studies documenting a relationship between tree death and the competitive environment. Models frequently rely on competition as the only non-random mechanism affecting tree mortality. However, for mature forests, competition may cease to be the primary driver of mortality.We use a large, long-term dataset to study the importance of competition in determining tree mortality in old-growth forests on the western slope of the Sierra Nevada of California, U.S.A. We make use of the comparative spatial configuration of dead and live trees, changes in tree spatial pattern through time, and field assessments of contributors to an individual tree's death to quantify competitive effects.Competition was apparently a significant contributor to tree mortality in these forests. Trees that died tended to be in more competitive environments than trees that survived, and suppression frequently appeared as a factor contributing to mortality. On the other hand, based on spatial pattern analyses, only three of 14 plots demonstrated compelling evidence that competition was dominating mortality. Most of the rest of the plots fell within the expectation for random mortality, and three fit neither the random nor the competition model. These results suggest that while competition is often playing a significant role in tree mortality processes in these forests it only infrequently governs those processes. In addition, the field assessments indicated a substantial presence of biotic mortality agents in trees that died.While competition is almost certainly important, demographics in these forests cannot accurately be characterized without a better grasp of other mortality processes. In particular, we likely need a better understanding of biotic agents and their interactions with one another and with competition. ?? 2011.

  19. Atmospheric CO sub 2 concentrations within a mixed forest: Implications for seedling growth

    SciTech Connect

    Bazzaz, F.A.; Williams, W.E. )

    1991-02-01

    The authors studied carbon dioxide concentrations in a mixed deciduous forest in New England, US by making continuous measurements at 0.05, 0.2, 3, and 12m above the soil surface. The measurements began in early March and continued until the end of November 1985; therefore, they spanned the growing season and parts of the dormant seasons both before and afterwards. The data were compared with those from Mauna Loa Hawaii, which represent global atmospheric CO{sub 2} levels in the Northern Hemisphere. The results show strong seasonal and daily variations in CO{sub 2} concentrations at all heights in the forest. On average, during the growing season, CO{sub 2} levels were generally higher in the forest than in bulk air at Mauna Loa. The highest level of CO{sub 2} was found near the forest floor and the lowest at the 12-m level. Daily levels of CO{sub 2} were constant throughout the day in the dormant season and were the same for all heights in the forest. However, during the growing season, the Co{sub 2} concentrations were lowest during the middle of the day, especially at the 12m height. Thus, this study shows that the CO{sub 2} concentrations in the forest may be quite different than those in bulk air and that seedlings, saplings, and mature trees may experience different CO{sub 2} environments for which they may show different responses in photosynthesis, growth, and water use. Moreover, a tree may experience different CO{sub 2} environments as it grows towards the canopy, and different modules of an individual may also be growing in different CO{sub 2} atmospheres.

  20. Pattern and dynamics of biomass stock in old growth forests: The role of habitat and tree size

    NASA Astrophysics Data System (ADS)

    Yuan, Zuoqiang; Gazol, Antonio; Wang, Xugao; Lin, Fei; Ye, Ji; Zhang, Zhaochen; Suo, YanYan; Kuang, Xu; Wang, Yunyun; Jia, Shihong; Hao, Zhanqing

    2016-08-01

    Forest ecosystems play a fundamental role in the global carbon cycle. However, how stand-level changes in tree age and structure influence biomass stock and dynamics in old-growth forests is a question that remains unclear. In this study, we quantified the aboveground biomass (AGB) standing stock, the coarse woody productivity (CWP), and the change in biomass over ten years (2004-2014) in a 25 ha unmanaged broad-leaved Korean pine mixed forest in northeastern China. In addition, we quantified how AGB stock and change (tree growth, recruitment and mortality) estimations are influenced by the variation in habitat heterogeneity, tree size structure and subplot size. Our analysis indicated that Changbai forest had AGB of 265.4 Mg ha-1 in 2004, and gained1.36 Mg ha-1 y-1 between 2004 and 2014. Despite recruitment having better performance in nutrient rich habitat, we found that there is a directional tree growth trend independent of habitat heterogeneity for available nutrients in this old growth forest. The observed increases in AGB stock (∼70%) are mainly attributed to the growth of intermediate size trees (30-70 cm DBH), indicating that this forest is still reaching its mature stage. Meanwhile, we indicated that biomass loss due to mortality reduces living biomass, not increment, may be the primary factor to affect forest biomass dynamics in this area. Also, spatial variation in forest dynamics is large for small sizes (i.e. coefficient of variation in 20 × 20 m subplots is 53.2%), and more than 90 percent of the inherent variability of these coefficients was predicted by a simple model including plot size. Our result provides a mean by which to estimate within-plot variability at a local scale before inferring any directional change in forest dynamics at a regional scale, and information about the variability of forest structure and dynamics are fundamental to design effective sampling strategies in future study.

  1. Contingent valuation study of the value of reducing fire hazards to old-growth forests in the Pacific northwest. Forest Service research paper

    SciTech Connect

    Loomis, J.B.; Gonzalez-Caban, A.; Gregory, R.

    1996-07-01

    A contingent valuation methodology was applied to old-growth forests and critical habitat units for the Northern Spotted Owl in Oregon to esimate the economic value to the public in knowing that rare and unique ecosystems will be protected from fire for current and future generations. Generalizing to the whole state, the total annual willingness-to-pay of Oregon residents ranges from $49.6 to $99 million. In terms of old-growth forests protected from fire, the value is $28 per acre.

  2. Tree growth rates in an Amazonian evergreen forest: seasonal patterns and correlations with leaf phenology

    NASA Astrophysics Data System (ADS)

    Wu, J.; Silva Campos, K.; Prohaska, N.; Ferreira, M. L.; Nelson, B. W.; Saleska, S. R.; da Silva, R.

    2014-12-01

    Metabolism and phenology of tropical forests significantly influence global dynamics of climate, carbon and water. However, there is still lack of mechanistic understanding of the controls on tropical forest metabolism, particularly at individual tree level. In this study, we are interested in investigating (1) what is the seasonal pattern of woody growth for tropical trees and (2) what is the mechanistic controls onwoody growth at individual level?To explore the above questions,we use two data sources from an evergreen tropical forest KM67 site (near Santarem, Brazil). They are: (1) image time series from a tower mounted RGB imaging system, with images recordedin10 minutes interval since October 2013.Images near local noon homogeneous diffuse lighting were selectedfor leaf phenologymonitoring; (2) ground based bi-weekly biometry survey (via dendrometry band technique) for 25 trees from random sampling since September 2013. 12 among 25 trees are within the tower mounted camera image view. Our preliminary resultsdemonstrate that 20 trees among 25 trees surveyed significantly increase woody growth (or "green up") in dry season. Our results also find thatamong those 20 trees, 12 trees reaches the maximum woody increment rate in late dry season with a mean DBH (Diameter at Breast Height) around 30 cm,while 8 trees reaching the maximum in the middle of wet season, with a mean DBH around 90 cm. This study,though limited in the sample size, mightprovide another line of evidence that Amazon rainforests "green up" in dry season. As for mechanistic controls on tropical tree woody control, we hypothesize both climate and leaf phenology control individual woody growth. We would like to link both camera based leaf phenology and climate data in the next to explorethe reason as to the pattern found in this study that bigger trees might have different seasonal growth pattern as smaller trees.

  3. Nitrogen limitation of growth and nutrient dynamics in a disturbed mangrove forest, Indian River Lagoon, Florida

    USGS Publications Warehouse

    Feller, Ilka C.; Whigham, D.F.; McKee, K.L.; Lovelock, C.E.

    2003-01-01

    The objectives of this study were to determine effects of nutrient enrichment on plant growth, nutrient dynamics, and photosynthesis in a disturbed mangrove forest in an abandoned mosquito impoundment in Florida. Impounding altered the hydrology and soil chemistry of the site. In 1997, we established a factorial experiment along a tree-height gradient with three zones, i.e., fringe, transition, dwarf, and three fertilizer treatment levels, i.e., nitrogen (N), phosphorus (P), control, in Mosquito Impoundment 23 on the eastern side of Indian River. Transects traversed the forest perpendicular to the shoreline, from a Rhizophora mangle-dominated fringe through an Avicennia germinans stand of intermediate height, and into a scrub or dwarf stand of A. germinans in the hinterland. Growth rates increased significantly in response to N fertilization. Our growth data indicated that this site is N-limited along the tree-height gradient. After 2 years of N addition, dwarf trees resembled vigorously growing saplings. Addition of N also affected internal dynamics of N and P and caused increases in rates of photosynthesis. These findings contrast with results for a R. mangle-dominated forest in Belize where the fringe is N-limited, but the dwarf zone is P-limited and the transition zone is co-limited by N and P. This study demonstrated that patterns of nutrient limitation in mangrove ecosystems are complex, that not all processes respond similarly to the same nutrient, and that similar habitats are not limited by the same nutrient when different mangrove forests are compared.

  4. Nitrogen limitation of growth and nutrient dynamics in a disturbed mangrove forest, Indian River Lagoon, Florida.

    PubMed

    Feller, Ilka C; Whigham, Dennis F; McKee, Karen L; Lovelock, Catherine E

    2003-02-01

    The objectives of this study were to determine effects of nutrient enrichment on plant growth, nutrient dynamics, and photosynthesis in a disturbed mangrove forest in an abandoned mosquito impoundment in Florida. Impounding altered the hydrology and soil chemistry of the site. In 1997, we established a factorial experiment along a tree-height gradient with three zones, i.e., fringe, transition, dwarf, and three fertilizer treatment levels, i.e., nitrogen (N), phosphorus (P), control, in Mosquito Impoundment 23 on the eastern side of Indian River. Transects traversed the forest perpendicular to the shoreline, from a Rhizophora mangle-dominated fringe through an Avicennia germinans stand of intermediate height, and into a scrub or dwarf stand of A. germinans in the hinterland. Growth rates increased significantly in response to N fertilization. Our growth data indicated that this site is N-limited along the tree-height gradient. After 2 years of N addition, dwarf trees resembled vigorously growing saplings. Addition of N also affected internal dynamics of N and P and caused increases in rates of photosynthesis. These findings contrast with results for a R. mangle-dominated forest in Belize where the fringe is N-limited, but the dwarf zone is P-limited and the transition zone is co-limited by N and P. This study demonstrated that patterns of nutrient limitation in mangrove ecosystems are complex, that not all processes respond similarly to the same nutrient, and that similar habitats are not limited by the same nutrient when different mangrove forests are compared. PMID:12647149

  5. Systematic Evaluation of the "Forests in Schools" (SIS) Project.

    ERIC Educational Resources Information Center

    School Research Newsletter, 1985

    1985-01-01

    The purpose of an inquiry was to study the feasibility, content, mediation, and results of the Swedish "Forests in Schools" (SIS) project, an example of a link between schools and working life (the latter represented by forest enterprise in general). It also sought to describe and, if possible, explain the effects of the activities conducted at…

  6. EVALUATION OF FOREST CANOPY MODELS FOR ESTIMATING ISOPRENE EMISSIONS

    EPA Science Inventory

    During the summer of 1992, isoprene emissions were measured in a mixed deciduous forest near Oak Ridge, Tennessee. Measurements were aimed at the experimental scale-up of emissions from the leaf level to the forest canopy to the mixed layer. Results from the scale-up study are co...

  7. Amazon old-growth forest wind disturbance and the regional carbon balance

    NASA Astrophysics Data System (ADS)

    Chambers, J. Q.; Negron Juarez, R. I.; Marra, D. M.; Roberts, D. A.; Hurtt, G. C.; Lima, A.; Higuchi, N.

    2010-12-01

    Estimating the carbon balance of a landscape is challenging. A key problem is determining whether or not measurements made in plots are representative of the carbon state of a larger region. A key parameter for calculating landscape carbon balance is the return frequency of episodic disturbances. If disturbances are clustered and occur more frequently than the time required for biomass recovery, a spatial mixture of patches in different stages of recovery occurs. Under these shifting steady-state mosaic conditions, quantifying the mean state of ecosystem attributes such as carbon balance or tree species diversity is difficult. In this study, satellite remote sensing (Landsat) was coupled with field investigations to create ~25 year landscape-scale disturbance chronosequence for old-growth forest in the Central Amazon. The detected disturbances were caused by strong storms which resulted in tree mortality events ranging from small clusters of 7-10 downed trees, to large contiguous blowdowns larger than 30 ha in size. Using the chronosequence, a cumulative probability distribution function was developed, which followed a power law, and was used to parameterize a forest carbon balance model. Results demonstrate that for power law exponents less than about 2.0, the spatial scale at which forest carbon balance establishes is much larger than generally expected. Ultimately, an increase in wind disturbance frequency and/or intensity with a warming climate has the potential to cause a net loss of carbon from Amazon forests to the atmosphere.

  8. Carbon stocks of an old-growth forest and an anthropogenic peatland in southern Chile

    NASA Astrophysics Data System (ADS)

    Perez-Quezada, Jorge; Brito, Carla; Cabezas, Julian; Salvo, Patricia; Lemunao, Pedro; Flores, Ernesto; Valdés, Ariel; Fuentes, Juan Pablo; Galleguillos, Mauricio; Pérez, Cecilia

    2015-04-01

    The distribution of carbon in the different ecosystem stocks may change with direct human perturbation or climate change. We present a detailed description of the carbon stocks of an old-growth forest and an anthropogenic peatland (i.e., created by flooding, as a consequence of forest fires or logging). The study area was located in a private reserve in the Chiloé Island, southern Chile (41° 52' S, 73° 40' W). Sampling was done on plots separated 60 m from each other, in areas of approximately 30 ha for each ecosystem type. Total C was 1523 ± 117 Mg ha-1 in the forest and 130 ± 13.8 Mg ha-1 in the peatland, with 69.7% and 91.7% of this found belowground, respectively. In the forest, the necromass stock composed by logs and snags was high (183 Mg C ha-1), compared with the live-tree stock (264 Mg C ha-1) and with the C stored in the understory vegetation (14 Mg C ha-1). In the peatland, most of the C was stored in the most decomposed layer of peat, deeper in the ground. Because the anthropogenic peatland is experiencing a secondary succession, there is great potential to sequester back the C lost due to the perturbation. However, in most of the area where these ecosystems are found, the moss is being harvested for horticultural purposes.

  9. The synergistic effect in the Fe-Co bimetallic catalyst system for the growth of carbon nanotube forests

    SciTech Connect

    Hardeman, D.; Esconjauregui, S. Cartwright, R.; D'Arsié, L.; Robertson, J.; Bhardwaj, S.; Cepek, C.; Oakes, D.; Clark, J.; Ducati, C.

    2015-01-28

    We report the growth of multi-walled carbon nanotube forests employing an active-active bimetallic Fe-Co catalyst. Using this catalyst system, we observe a synergistic effect by which—in comparison to pure Fe or Co—the height of the forests increases significantly. The homogeneity in the as-grown nanotubes is also improved. By both energy dispersive spectroscopy and in-situ x-ray photoelectron spectroscopy, we show that the catalyst particles consist of Fe and Co, and this dramatically increases the growth rate of the tubes. Bimetallic catalysts are thus potentially useful for synthesising nanotube forests more efficiently.

  10. Evaluation of satellite change detection methods for monitoring forest harvest and silvicultural activity in Maine industrial forests

    NASA Astrophysics Data System (ADS)

    Pangaribuan, Humala P.; Sader, Steven A.

    1997-09-01

    Change detection is a major application of satellite remote sensing. The idea is to analyze change in spectral patterns over a particular geographic area at different points of time. The information might be gathered by different satellite platforms (multi-sensor), in various wavebands (multi- spectral) and on several acquisition dates (multi-temporal). For forestry field applications, change detection might provide useful information for forest resources management, inventory, evaluation, planning, and monitoring. This study incorporated a multi-temporal approach for detecting forest change due to clearcut, partial cut, and release operation treatments in a Maine study area. Most forest change detection studies include only two dates of imagery. However, in this investigation, three date satellite images from 1983, 1988 and 1991 were examined simultaneously in a single step analysis approach. Two change detection methods, the Normalized Difference Vegetation Index (NDVI) and the Principal Components Analysis (PCA) were evaluated and a new method, Principal Factor Analysis (PFA) was introduced. A maximum likelihood classification algorithm was used to categorize change/no change events and the results were compared to a forest stand exam and history database. The Khat statistic was chosen as the criteria to evaluate the accuracy of each classification method while pairwise significance tests were constructed to compare results between methods. The Standardized variant of Principal Factor Analysis (SPFA) produced the best results followed by Principal Components Analysis and Normalized Difference Vegetation index.

  11. Fire regimes and tree growth in low rainfall jarrah forest of south-west Australia.

    PubMed

    Burrows, Neil; Ward, Bruce; Robinson, Alex

    2010-06-01

    Regular fuel reduction burning is an important management strategy for reducing the scale and intensity of wildfires in south-west Australian native forests, but the long term effects of this on tree and stand growth are not well understood. Five fire treatments, including application of frequent and infrequent low intensity burns, and 25 years of fire exclusion, were applied to small (4 ha) experimental plots in a low rainfall mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest to investigate the effects of these treatments on tree stem diameter growth, stand basal area increment and tree mortality. Mean tree stem growth measured over 20 years was lowest in the long unburnt treatment compared with the burn treatments, although surface soil nutrient levels were generally higher in the unburnt treatment, suggesting these sites may be moisture limited. There was no clear pattern of the effects of the burn treatments, including the number of fires and the interval between fires, on tree stem growth, stand basal area increment, crown health or mortality. These factors were strongly influenced by dominance condition, with dominant and co-dominant trees growing most and suppressed trees growing least and experiencing the highest mortality levels. There was no evidence of deteriorating tree or stand health that could be attributed to either regular low intensity burning or to a long period (25 years) of fire exclusion. PMID:20405126

  12. Growth and characterization of CNT Forests using Bimetallic Nanoparticles as Catalyst

    NASA Astrophysics Data System (ADS)

    Lee, Kyung-Hwan; Sra, A.; Jang, H.; Choi, B.; Overzet, L.; Lee, G.; Yang, D.

    2008-10-01

    We study the growth of Multiwall carbon nanotubes (MWCNT) using bimetallic nanoparticles (NP) as catalyst rather than zerovalent metal ions such as Fe, Ni, Co. One advantage of using bimetallic NP is that both the size and shape and composition (atomic ordering) can be controlled. We will describe a simple method of producing bimetallic Fe-Pt, Fe-Co alloy nanoparticles and compare MWCNT growth using them to Fe catalyst growth. The synthesis of Fe, Fe-Pt, Fe-Co NP was carried out using a bottom-up polyol process. Subsequent growth of MWCNT forests was accomplished by PECVD using acetylene as precursor. TEM and SEM analysis of the sample cross-section grown at substrate temperature of 680 ^oC indicates that the diameters of the CNTs are ˜ 10-20 nm while height of the forest varies from 30 μm for Fe to 5 μm for Fe-Pt and 80-100 μm for Fe-Co. The number of walls in the CNTs and the graphitization content could be manipulated by varying the temperature (increasing to 760 ^oC) or by pre-treatment of the nanoparticles with oxygen plasma.

  13. Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality

    USGS Publications Warehouse

    Foster, Jane R.; D'Amato, Anthony W.; Bradford, John B.

    2014-01-01

    Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20–30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25–30 % higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

  14. EVALUATION OF A MEASUREMENT METHOD FOR FOREST VEGETATION IN A LARGE-SCALE ECOLOGICAL SURVEY

    EPA Science Inventory

    We evaluate a field method for determining species richness and canopy cover of vascular plants for the Forest Health Monitoring Program (FHM), an ecological survey of U.S. forests. Measurements are taken within 12 1-m2 quadrats on 1/15 ha plots in FHM. Species richness and cover...

  15. Drought stress, growth, and nonstructural carbohydrate dynamics of pine trees in a semi-arid forest

    NASA Astrophysics Data System (ADS)

    Klein, Tamir; Yakir, Dan; Hoch, Günter

    2014-05-01

    • In trees under prolonged drought, both carbon uptake (C source) and growth (C sink) typically decrease. This correlation raises two important questions: (1) to what degree is tree growth limited by C availability; and (2) Is growth limited by concurrent C storage (e.g. as nonstructural carbohydrates, NSC). • To test the relationships between drought, growth, and C reserves, we monitored the changes in NSC levels and constructed stem growth chronologies of Pinus halepensis trees of three drought stress levels growing in Yatir forest, Israel, at the dry limit of forest existence. • Moderately stressed and stressed trees showed 37% and 21% of the stem growth of healthy trees in 2012; 71% and 31% of the sap flux density; and 79% and 66% of the final needle length. In spite of these large reductions, both starch and soluble sugars concentrations in branches of these trees were similar in all trees throughout the dry season (2-4% dry mass). At the same time the root starch concentrations of moderately stressed and stressed trees were 47% and 58% of that of healthy trees, but never below 2% d.m. • Our results suggest that the drought-induced growth reduction is associated with a general C shortage, rather than competition with concurrent C storage. The relatively small effect of drought stress level on NSC dynamics, the maintenance of a 2% d.m. starch, and the continued sap flow indicate that a whole-tree C starvation is not likely to occur in these trees growing at the edge of the desert. Special request: If the abstract is not accepted for presentation in this session, please consider for presentation in session BG2.11 Plant traits and biogeochemical cycles. Thank you.

  16. 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

  17. Growth periodicity, biomass and nutrient content of fine roots in a northern hardwood forest

    SciTech Connect

    Burke, M.K.; Raynal, D.J.

    1987-07-01

    Seasonal periodicity of growth, biomass and nutrient content of fine roots were estimated in a beech-birch-maple forest in the Adirondack Mountains. Root elongation rate was measured at regular intervals for one calendar using rhizotrons. Root growth was minimal from January to April and from September to December. Initiation of fine root growth occurred in mid-April, remained high throughout the summer months and declined sharply during August. Fine root biomass, necromass, length, and nutrient content (Ca, Mg, K, N, P and S) were estimated from soil core samples. Estimates for each parameter generally declined with depth in the profile. Fine root production is strongly seasonal, decreases with depth, and accounts for a significant portion of the soil nutrient capital.

  18. Evaluation and operationalization of a novel forest detrainment modeling approach for computational snow avalanche simulation

    NASA Astrophysics Data System (ADS)

    Teich, M.; Feistl, T.; Fischer, J.; Bartelt, P.; Bebi, P.; Christen, M.; Grêt-Regamey, A.

    2013-12-01

    Two-dimensional avalanche simulation software operating in three-dimensional terrain are widely used for hazard zoning and engineering to predict runout distances and impact pressures of snow avalanche events. Mountain forests are an effective biological protection measure; however, the protective capacity of forests to decelerate or even to stop avalanches that start within forested areas or directly above the treeline is seldom considered in this context. In particular, runout distances of small- to medium-scale avalanches are strongly influenced by the structural conditions of forests in the avalanche path. This varying decelerating effect has rarely been addressed or implemented in avalanche simulation. We present an evaluation and operationalization of a novel forest detrainment modeling approach implemented in the avalanche simulation software RAMMS. The new approach accounts for the effect of forests in the avalanche path by detraining mass, which leads to a deceleration and runout shortening of avalanches. The extracted avalanche mass caught behind trees stops immediately and, therefore, is instantly subtracted from the flow and the momentum of the stopped mass is removed from the total momentum of the avalanche flow. This relationship is parameterized by the empirical detrainment coefficient K [Pa] which accounts for the braking power of different forest types per unit area. To define K dependent on specific forest characteristics, we simulated 40 well-documented small- to medium-scale avalanches which released in and ran through forests with varying K-values. Comparing two-dimensional simulation results with one-dimensional field observations for a high number of avalanche events and simulations manually is however time consuming and rather subjective. In order to process simulation results in a comprehensive and standardized way, we used a recently developed automatic evaluation and comparison method defining runout distances based on a pressure

  19. [Carbon exchange of Chinese boreal forest during its growth season and related regulation mechanisms].

    PubMed

    Zhou, Li-yan; Jia, Bing-rui; Zhou, Guang-sheng; Zeng, Wei; Wang, Yu

    2010-10-01

    Based on the two-year continuous observation on the carbon exchange of Chinese boreal forest during its growth seasons in 2007 and 2008 by the method of open path eddy covariance, this paper analyzed the seasonal dynamics of the gross ecosystem productivity (GEP), ecosystem respiration (Re), and net ecosystem carbon exchange (NEE) of the forest, with related regulation mechanisms approached. The GEP, Re, and NEE of the forest reached to their maximum in the vigorous growth period from late June to mid August, but the dates of the maximum appeared differed. The mean daily GEP, Re, and NEE were 19.45, 15.15, and -1.45 g CO2 x m(-2) x d(-1) in 2007, and 17.67, 14.11, and -1.37 g CO2 x m(-2) x d(-1) in 2008, respectively. The intensity of the carbon exchange during growth season was obviously stronger in 2007 than in 2008, possibly due to the higher mean air temperature (12.46 degrees C in 2007 vs. 11.04 degrees C in 2008) and the higher mean photosynthetically active radiation (PAR) (697 micromol x m(-2) x s(-1) in 2007 vs. 639 micromol x m(-2) x s(-1) in 2008). The GEP had close linear relationships with air temperature and PAR, and the correlation coefficient of GEP and air temperature was around 0.55 (P<0.01). The Re was mainly controlled by air temperature, with the correlation coefficient being 0.66-0.72 (P<0.01), and the NEE was mainly controlled by PAR, with the correlation coefficient being 0.59-0.63 (P<0.01). PMID:21328928

  20. Lianas suppress seedling growth and survival of 14 tree species in a Panamanian tropical forest.

    PubMed

    Martínez-Izquierdo, Laura; García, María M; Powers, Jennifer S; Schnitzer, Stefan A

    2016-01-01

    Lianas are a common plant growth form in tropical forests, where they compete intensely with trees, decreasing tree recruitment, growth, and survival. If the detrimental effects of lianas vary significantly with tree species identity, as is often assumed, then lianas may influence tree species diversity and community composition. Furthermore, recent studies have shown that liana abundance and biomass are increasing relative to trees in neotropical forests, which will likely magnify the detrimental effects of lianas and may ultimately alter tree species diversity, relative abundances, and community composition. Few studies, however, have tested the responses of multiple tree species to the presence of lianas in robust, well-replicated experiments. We tested the hypotheses that lianas reduce tree seedling growth and survival, and that the effect of lianas varies with tree species identity. We used a large-scale liana removal experiment in Central Panama in which we planted 14 replicate seedlings of 14 different tree species that varied in shade tolerance in each of 16 80 x 80 m plots (eight liana-removal and eight unmanipulated controls; 3136 total seedlings). Over a nearly two-yr period, we found that tree seedlings survived 75% more, grew 300% taller, and had twice the aboveground biomass in liana-removal plots than seedlings in control plots, consistent with strong competition between lianas and tree seedlings. There were no significant differences in the response of tree species to liana competition (i.e., there was no species by treatment interaction), indicating that lianas had a similar negative effect on all 14 tree species. Furthermore, the effect of lianas did not vary with tree species shade tolerance classification, suggesting that the liana effect was not solely based on light. Based on these findings, recently observed increases in liana abundance in neotropical forests will substantially reduce tree regeneration, but will not significantly alter

  1. Long-term growth and succession in restored and natural mangrove forests in southwestern Florida

    USGS Publications Warehouse

    Proffitt, C.E.; Devlin, D.J.

    2005-01-01

    We compared colonization, growth and succession from 1989 to 2000 in a restored mangrove site and in gap and closed canopy sites in a natural mangrove forest. The restored site was created in 1982 and planted with Rhizophora mangle (???2 m-2) propagules. By 1989, Laguncularia racemosa, with densities up to 12.9 tree m-2, was a dominant in all plots, although densities were greater at edge plots relative to inner plots, and near open water (west plots) relative to further inland (east plots), and in tall mangrove plots relative to scrub plots. Rhizophora mangle (1989 tree densities about 2 m-2) was a codominant in inner and scrub plots, while Avicennia germinans had the lowest densities (<1 tree m-2) in all plots. From 1989 to 2000 L. racemosa experienced reduced recruitment and apparent density-dependent mortality of canopy individuals in plots with high initial densities. Scrub plots experienced high rates of colonization by R. mangle and L. racemosa, rapid growth in height of all species (1989-1996), followed by a dieoff of L. racemosa in later years (1997-2000) as the canopy came to resemble that of tall mangrove plots. Colonization and growth rates were lower in gap and closed canopy regions of the natural forest relative to rates in the restored site. After 11 years, densities of L. racemosa were 10-20x lower and R. mangle slightly less in the gap relative to densities in tall mangrove plots in the restored site at the same age. Although the restored stand had converged with the natural forest by 2000 in terms of some factors such as species richness, vegetation cover, litterfall, and light penetration, trees were still much smaller and stem densities much higher. Full development of mature structure and ecological function will likely require decades more development. ?? Springer 2005.

  2. Early spring leaf out enhances growth and survival of saplings in a temperate deciduous forest.

    PubMed

    Augspurger, Carol K

    2008-05-01

    Saplings of many canopy tree species in winter deciduous forests receive the major portion of their light budget for their growing season prior to canopy closure in the spring. This period of high light may be critical for achieving a positive carbon (C) gain, thus contributing strongly to their growth and survival. This study of saplings of Aesculus glabra and Acer saccharum in Trelease Woods, Illinois, USA, tested this hypothesis experimentally by placing tents of shade cloth over saplings during their spring period of high light prior to canopy closure in three consecutive years. Leaf senescence began 16 days (year 0) and 60 days (year 1) earlier for shaded A. glabra saplings than control saplings. No change in senescence occurred for A. saccharum. The annual absolute growth in stem diameter of both species was negligible or negative for shaded saplings, but positive for control saplings. Only 7% of the shaded A. glabra saplings were alive after 2 years, while all control saplings survived for 3 years; only 20% of the shaded A. saccharum saplings survived for 3 years, while 73% of control saplings were alive after the same period. Early spring leaf out is a critical mechanism that allows the long-term persistence of saplings of these species in this winter deciduous forest. Studies and models of C gain, growth, and survival of saplings in deciduous forests may need to take into account their spring phenology because saplings of many species are actually "sun" individuals in the spring prior to their longer period in the summer shade. PMID:18347817

  3. Evaluating Anthropogenic Risk of Grassland and Forest Habitat Degradation Using Land-Cover Data

    EPA Science Inventory

    The effects of landscape context on habitat quality are receiving increased attention in conservation biology. The objective of this research is to demonstrate an approach to mapping and evaluating the anthropogenic risks of grassland and forest habitat degradation by examining ...

  4. Development and use of bounding functions in a forest growth model. [Pinus lambertiana; Calocedrus decurrens; Pseudotsuga menziesii; Abies concolor

    SciTech Connect

    Dolph, K.L. ); Dixon, G.E. )

    1993-01-01

    Erroneous predictions of forest growth and yield may result when computer simulation models use extrapolated data in repeated or long-term projections or if the models are used outside the range of data on which they were built. Bounding functions that limit the predicted diameter and height growth of individual trees to maximum observed values were developed to constrain these erroneous predictions in a forest growth and yield simulator. Species studied included sugar pine, incense-cedar, Douglas-fir, and California white fir.

  5. Density, ages, and growth rates in old-growth and young-growth forests in coastal Oregon

    USGS Publications Warehouse

    Tappeiner, J. C., II; Huffman, D.; Spies, T.; Bailey, John D.

    1997-01-01

    We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) old-growth stands on 10 sites and compared them with young-growth stands (50-70 years old, regenerated after timber harvest) in the Coast Range of western Oregon. The diameters and diameter growth rates for the first 100 years of trees in the old-growth stands were significantly greater than those in the young-growth stands. Growth rates in the old stands were comparable with those from long-term studies of young stands in which density is about 100-120 trees/ha; often young-growth stand density is well over 500 trees/ha. Ages of large trees in the old stands ranged from 100 to 420 years; ages in young stands varied by only about 5 to 10 years. Apparently, regeneration of old-growth stands on these sites occurred over a prolonged period, and trees grew at low density with little self-thinning; in contrast, after timber harvest, young stands may develop with high density of trees with similar ages and considerable self-thinning. The results suggest that thinning may be needed in dense young stands where the management objective is to speed development of old-growth characteristics.

  6. Preliminary Survey on TRY Forest Traits and Growth Index Relations - New Challenges

    NASA Astrophysics Data System (ADS)

    Lyubenova, Mariyana; Kattge, Jens; van Bodegom, Peter; Chikalanov, Alexandre; Popova, Silvia; Zlateva, Plamena; Peteva, Simona

    2016-04-01

    Forest ecosystems provide critical ecosystem goods and services, including food, fodder, water, shelter, nutrient cycling, and cultural and recreational value. Forests also store carbon, provide habitat for a wide range of species and help alleviate land degradation and desertification. Thus they have a potentially significant role to play in climate change adaptation planning through maintaining ecosystem services and providing livelihood options. Therefore the study of forest traits is such an important issue not just for individual countries but for the planet as a whole. We need to know what functional relations between forest traits exactly can express TRY data base and haw it will be significant for the global modeling and IPBES. The study of the biodiversity characteristics at all levels and functional links between them is extremely important for the selection of key indicators for assessing biodiversity and ecosystem services for sustainable natural capital control. By comparing the available information in tree data bases: TRY, ITR (International Tree Ring) and SP-PAM the 42 tree species are selected for the traits analyses. The dependence between location characteristics (latitude, longitude, altitude, annual precipitation, annual temperature and soil type) and forest traits (specific leaf area, leaf weight ratio, wood density and growth index) is studied by by multiply regression analyses (RDA) using the statistical software package Canoco 4.5. The Pearson correlation coefficient (measure of linear correlation), Kendal rank correlation coefficient (non parametric measure of statistical dependence) and Spearman correlation coefficient (monotonic function relationship between two variables) are calculated for each pair of variables (indexes) and species. After analysis of above mentioned correlation coefficients the dimensional linear regression models, multidimensional linear and nonlinear regression models and multidimensional neural networks models are

  7. Long Tree-Ring Chronologies Provide Evidence of Recent Tree Growth Decrease in a Central African Tropical Forest

    PubMed Central

    Battipaglia, Giovanna; Zalloni, Enrica; Castaldi, Simona; Marzaioli, Fabio; Cazzolla- Gatti, Roberto; Lasserre, Bruno; Tognetti, Roberto; Marchetti, Marco; Valentini, Riccardo

    2015-01-01

    It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2. PMID:25806946

  8. Peatland simulator connecting drainage, nutrient cycling, forest growth, economy and GHG efflux in boreal and tropical peatlands

    NASA Astrophysics Data System (ADS)

    Lauren, Ari; Hökkä, Hannu; Launiainen, Samuli; Palviainen, Marjo; Lehtonen, Aleksi

    2016-04-01

    Forest growth in peatlands is nutrient limited; principal source of nutrients is the decomposition of organic matter. Excess water decreases O2 diffusion and slows down the nutrient release. Drainage increases organic matter decomposition, CO2 efflux, and nutrient supply, and enhances the growth of forest. Profitability depends on costs, gained extra yield and its allocation into timber assortments, and the rate of interest. We built peatland simulator Susi to define and parameterize these interrelations. We applied Susi-simulator to compute water and nutrient processes, forest growth, and CO2 efflux of forested drained peatland. The simulator computes daily water fluxes and storages in two dimensions for a peatland forest strip located between drainage ditches. The CO2 efflux is made proportional to peat bulk density, soil temperature and O2 availability. Nutrient (N, P, K) release depends on decomposition and peat nutrient content. Growth limiting nutrient is detected by comparing the need and supply of nutrients. Increased supply of growth limiting nutrient is used to quantify the forest growth response to improved drainage. The extra yield is allocated into pulpwood and sawlogs based on volume of growing stock. The net present values of ditch cleaning operation and the gained extra yield are computed under different rates of interest to assess the profitability of the ditch cleaning. The hydrological sub-models of Susi-simulator were first parameterized using daily water flux data from Hyytiälä SMEAR II-site, after which the predictions were tested against independent hydrologic data from two drained peatland forests in Southern Finland. After verification of the hydrologic model, the CO2 efflux, nutrient release and forest growth proportionality hypothesis was tested and model performance validated against long-term forest growth and groundwater level data from 69 forested peatland sample plots in Central Finland. The results showed a clear relation between

  9. Biomass and nutrient distributions in central Oregon second-growth ponderosa pine ecosystems. Forest Service research paper

    SciTech Connect

    Little, S.N.; Shainsky, L.J.

    1995-03-01

    We investigated the distributioin of biomass and nurtrients in second-growth ponderosa pine (Pinus ponderosa Dougl. ex Laws.) ecosystems in central Oregon. Destructive sampling of aboveground and belowground tree biomass was carried out at six sites in the Deschutes National Forest; three of these sites also were intensively sampled for biomass and nutrient concentrations of the soil, forest floor, residue, and shrub components. Tree biomass equations were developed that related component biomass to diameter at breast height and total tree height.

  10. Seedling Growth and Phosphorus Cycling in Northern Forest Soils Amended With Biochar and Wood Ash

    NASA Astrophysics Data System (ADS)

    Noyce, G. L.; Jones, T.; Fulthorpe, R.; Basiliko, N.

    2015-12-01

    Biochar may be a powerful soil amendment to reduce nutrient depletion in North American forests where long-term nitrogen deposition has led to phosphorus (P) limitation, but many effects of biochar in these ecosystems are still unknown. We performed a 12-week growth chamber experiment in which red pine (Pinus resinosa) and sugar maple (Acer saccharum) seedlings were grown in pots with soil from three Ontario forests and varying amounts of sugar maple biochar. Additionally, biochar effects were compared with the effects of wood ash, a forest biomass bioenergy by-product that may also be a beneficial soil amendment in these ecosystems. We assessed plant biomass, soil microbial biomass and phosphatase activity; additional chemical analyses of plant tissue and soils are ongoing. Biochar effects on seedling growth were not consistent across tree species, soil type, and addition rate. For sugar maple seedlings grown in sand and sandy-loam textured soils, biochar additions of 20 t ha-1 significantly (p = 0.03) decreased root biomass by 25 %, and the root-to-shoot ratio correspondingly declined, but this effect was not observed in a silty soil. For red pine seedlings, the same biochar addition rate slightly increased root biomass. Wood ash effects on biomass were similarly variable. For example, in the sandy soil, sugar maple root biomass was significantly lower after application of 16 t ash ha-1, but unchanged by rates of 4 or 40 t ash ha-1. Microbial biomass and soil phosphatase activity also varied by soil type. Phosphatase activity was significantly lower (p = 0.02) in soils with sugar maple compared to red pine, but there were no consistent biochar or ash effects across all soils and species. However, for red pine seedlings grown in silt, biochar significantly (p = 0.04) reduced the phosphatase activity compared to the control and ash soils. Overall, biochar may lessen P-limitation in forested ecosystems, but the suitability of biochar, and wood ash, for increasing P

  11. Effects of CO[sub 2] and climate change on forest trees: Shoot growth and gas flux responses

    SciTech Connect

    Olszyk, D.M.; Wise, C.M.; Tingey, D.T.; Rygiewicz, P.T. ); Waschmann, R.S. )

    1994-06-01

    Critical questions regarding effects of rising atmospheric CO[sub 2] and climate change on forested systems include: Will shoot growth change in response to elevated CO[sub 2] and temperature . Will net carbon and water fluxes change in response to elevated CO[sub 2] and temperature Initial shoot growth and gas flux data are presented for Pseudotsuga menziesii seedlings continuously exposed for one year to target environments of ambient or ambient +200 ppm CO[sub 2], and ambient or ambient + 4[degrees]C air temperature in closed chambers. Changes in stem diameter, height, terminal shoot and bud length, are reported. Whole canopy and single branch level gas flux data used to calculate photosynthetic, respiration, and transpiration rates also are reported. The experiment is continuing so that longer-term impacts of CO[sub 2] and temperature on the seedlings can be determined and data obtained for process-based modeling of tree growth. The aboveground effects will be related to belowground processes to evaluate whole system responses to atmospheric CO[sub 2] and climate change.

  12. Evaluation of Forest Canopy and Understory Gap Fraction Derived from Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Chen, K. C.; Wang, C. K.

    2016-06-01

    The quantification of forest carbon sequestration is helpful to understand the carbon storage on the Earth. The estimation of forest carbon sequestration can be achieved by the use of leaf area index (LAI), which is derived from forest gap fraction. The hemispherical image-based technique is the most popular non-destructive means for obtaining such information. However, only the gap fraction of the top canopy is derived due to the limitation of imaging technique. The gap fraction information of understory is thus neglected. In this study, we evaluate the use of a terrestrial laser scanner (TLS) to obtain the forest canopy and understory gap fraction. The forest TLS data were manually classified as the top canopy and understory layers to facilitate the estimation of top canopy and understory gap fraction, respectively.

  13. Using US Forest Inventory (FIA) Data to Test for Growth Enhancement

    NASA Astrophysics Data System (ADS)

    Masek, J. G.; Collatz, G. J.; Williams, C. A.

    2015-12-01

    It is recognized that land ecosystems sequester a significant fraction of anthropogenic carbon emissions, and that the magnitude of the "land sink" appears to be increasing through time. This observation has led to the hypothesis that forest ecosystems are experiencing more rapid growth than their historical norm, due to some combination of CO2 fertilization, longer growing seasons, nitrogen deposition, and more intensive management. Direct evidence for growth enhancment has been reported from experimental plots, where long-term (historical) rates of biomass accumulation appear lower than contemporary rates derived from remeasurement of individual trees. However, the approach has not been pursued at a national scale. Since the late 1990's the US Forest Inventory and Analysis (FIA) program has standardized plot locations across the United States, and has systematically remeasured tree and plot attributes on 5-year (east) or 10-year (west) cycles. In principle, these remeasured plots provide a robust dataset for comparing contemporary and historical growth rates. In this talk we review approaches for performing this comparison at both plot and tree scales. We find that recent plot-level biomass accumulation rates from the eastern US do show more rapid growth than would be expected from historical biomass-age curves, with enhancement factors of up 2x. However, the implicit inclusion of "cryptic" or older disturbances in the historical curves hinders a definitive interpretation. Stand-level age-biomass simulations confirm that disturbance events must be included in the remeasured data set in order to provide comparability with historical curves. Remeasured DBH measurements from individual trees may provide a more robust approach for examining the issue.

  14. Regeneration patterns of northern white cedar, an old-growth forest dominant

    USGS Publications Warehouse

    Scott, Michael L.; Murphy, Peter G.

    1987-01-01

    Regeneration of Thuja occidentalis L. was examined in an old-growth dune forest on South Manitou Island, Michigan. To estimate the current status of cedar regeneration, we determined size structure of seedlings and stems and analyzed present patterns of establishment and persistence relative to substrate type. There has been a shift in the pattern of cedar establishment from soil to log substrates. While 97% of all stems ≥15 cm dbh are associated with a soil substrate, 81% of stems ≥2.5cm-25 cm tall. There was no significant relationship between the state of log decay and the density of seedlings >25 cm in height, indicating that long-term survival is not dependent on the degree of log decomposition. However, survival on logs is associated with canopy openings. Seedlings >25 cm tall were associated with gaps, and 78% of cedar stems (≥2.5 cm dbh) on logs were associated with a single windthrow gap. Thus, current cedar regeneration in this old-growth forest depends on logs and the canopy openings associated with them.

  15. Growth and reproductive performance of sambar deer in Sabal Forest Reserve of Sarawak, Malaysia.

    PubMed

    Dahlan, Ismail; Dawend, Jiwan

    2013-10-01

    We examined the growth, reproduction, rutting behavior, and health status of sambar deer (Cervus unicolor brookei) in secondary Acacia mangium plantation. The data were collected over 11 years from a breeding herd of 21 stags and 33 hinds in Sabal Forest Reserve, Sarawak, Malaysia. Brody's growth model of the pooled data is Y t  = 148.56 (1 - 0.98e(-0.023t)), which estimates that maximum weights of adults are 184 and 115 kg for males and females respectively. Sambar deer are nonseasonal breeders with the breeding peak in February. Although the earliest age at which a female reached sexual maturity was 11 months, the mean age was 23 ± 7 months. Mean age of first fawning was 32 ± 8 months. Mean gestation period was 259 ± 12 days (n = 82). Stags shed antlers mostly between March and July. Velvet hardens at 103 ± 27 days (n = 23), and velvet harvesting is best at 7-9 weeks when antler length is 25-30 cm. Sambar deer are suitable as a farm species in forest plantations and have a vast potential to uplift rural living standards. PMID:23475732

  16. An Evaluation of Processes Critical to Predicting the Carbon Sink of Natural Tropical Forests in a Demographic Vegetation Model

    NASA Astrophysics Data System (ADS)

    Knox, R. G.; Holm, J. A.; Chambers, J. Q.; Longo, M.; Moorcroft, P. R.; Higuchi, N.; Riley, W. J.; Manzi, A. O.; Koven, C. D.

    2014-12-01

    The direct effects of rising atmospheric CO2 concentrations on tropical forests have been the focus of a large body of research including manipulative experiments, observational studies and model estimation. The work presented here seeks to evaluate the processes involved in modelling forest dynamics under changes in atmospheric CO2, and ascertain the strengths and deficiencies of these representations. To do this, the Ecosystem Demography Model 2 (ED2) and the Community Land Model (CLM 4.5-BGC) are used to simulate the vegetation dynamics of an old-growth Central Amazonian forest through the next century, and are compared with flux and inventory data. Using default calibrations (regional specificity), both models were found to overestimate mortality rate and biomass increment (by 1.4 and 0.8 Mg ha-1 yr-1 in ED2 and CLM respectively). This comparison has lead to a closer examination of mortality, the allocation of assimilated carbon and the phasing of plant competition. An analysis of model output and literature review corroborate that tree mortality in old growth tropical forests is complex and is driven by a variety of mechanisms. We find that mortality parameterizations used in earth system models may benefit from simplicity until a more comprehensive mechanistic understanding of mortality and its drivers becomes available. An analysis of field data also showed that a significant fraction of mature trees in the upper canopy were exhibiting no increment in growth. It is not immediately clear if these trees are exhibiting decreased net primary production, or alternatively, how these trees have shifted their resource usage strategy. Demographic ecosystem models such as ED2 provide a means to represent and test these alternative hypotheses as they emerge.

  17. Merits of random forests emerge in evaluation of chemometric classifiers by external validation.

    PubMed

    Scott, I M; Lin, W; Liakata, M; Wood, J E; Vermeer, C P; Allaway, D; Ward, J L; Draper, J; Beale, M H; Corol, D I; Baker, J M; King, R D

    2013-11-01

    Real-world applications will inevitably entail divergence between samples on which chemometric classifiers are trained and the unknowns requiring classification. This has long been recognized, but there is a shortage of empirical studies on which classifiers perform best in 'external validation' (EV), where the unknown samples are subject to sources of variation relative to the population used to train the classifier. Survey of 286 classification studies in analytical chemistry found only 6.6% that stated elements of variance between training and test samples. Instead, most tested classifiers using hold-outs or resampling (usually cross-validation) from the same population used in training. The present study evaluated a wide range of classifiers on NMR and mass spectra of plant and food materials, from four projects with different data properties (e.g., different numbers and prevalence of classes) and classification objectives. Use of cross-validation was found to be optimistic relative to EV on samples of different provenance to the training set (e.g., different genotypes, different growth conditions, different seasons of crop harvest). For classifier evaluations across the diverse tasks, we used ranks-based non-parametric comparisons, and permutation-based significance tests. Although latent variable methods (e.g., PLSDA) were used in 64% of the surveyed papers, they were among the less successful classifiers in EV, and orthogonal signal correction was counterproductive. Instead, the best EV performances were obtained with machine learning schemes that coped with the high dimensionality (914-1898 features). Random forests confirmed their resilience to high dimensionality, as best overall performers on the full data, despite being used in only 4.5% of the surveyed papers. Most other machine learning classifiers were improved by a feature selection filter (ReliefF), but still did not out-perform random forests. PMID:24139571

  18. Early positive effects of tree species richness on herbivory in a large-scale forest biodiversity experiment influence tree growth

    PubMed Central

    Schuldt, Andreas; Bruelheide, Helge; Härdtle, Werner; Assmann, Thorsten; Li, Ying; Ma, Keping; von Oheimb, Goddert; Zhang, Jiayong

    2015-01-01

    Despite the importance of herbivory for the structure and functioning of species-rich forests, little is known about how herbivory is affected by tree species richness, and more specifically by random vs. non-random species loss. We assessed herbivore damage and its effects on tree growth in the early stage of a large-scale forest biodiversity experiment in subtropical China that features random and non-random extinction scenarios of tree mixtures numbering between one and 24 species. In contrast to random species loss, the non-random extinction scenarios were based on the tree species’ local rarity and specific leaf area – traits that may strongly influence the way herbivory is affected by plant species richness. Herbivory increased with tree species richness across all scenarios and was unaffected by the different species compositions in the random and non-random extinction scenarios. Whereas tree growth rates were positively related to herbivory on plots with smaller trees, growth rates significantly declined with increasing herbivory on plots with larger trees. Our results suggest that the effects of herbivory on growth rates increase from monocultures to the most species-rich plant communities and that negative effects with increasing tree species richness become more pronounced with time as trees grow larger. Synthesis. Our results indicate that key trophic interactions can be quick to become established in forest plantations (i.e. already 2.5 years after tree planting). Stronger herbivory effects on tree growth with increasing tree species richness suggest a potentially important role of herbivory in regulating ecosystem functions and the structural development of species-rich forests from the very start of secondary forest succession. The lack of significant differences between the extinction scenarios, however, contrasts with findings from natural forests of higher successional age, where rarity had negative effects on herbivory. This indicates that

  19. Protecting rare, old-growth, forest-associated species under the Survey and Manage Program guidelines of the Northwest Forest Plan.

    PubMed

    Molina, Randy; Marcot, Bruce G; Lesher, Robin

    2006-04-01

    The Survey and Manage Program of the Northwest Forest Plan (NWFP) represents an unparalleled attempt to protect rare, little-known species associated with late-successional and old-growth forests on more than 9.7 million ha of federal lands. Approximately 400 species of amphibians, bryophytes, fungi, lichens, mollusks, vascular plants, arthropod functional groups, and one mammal were listed under this program because viability evaluations indicated the plan's network of reserve land allocations might not sustain the species over time. The program's standards and guidelines used an adaptive approach, protecting known sites and collecting new information to address concerns for species persistence and to develop management strategies. Since implementation in 1994, approximately 68,000 known sites have been recorded at an expense of several tens of millions of dollars. New knowledge from surveys reduced concern for nearly 100 species, and they were removed from the protection list. Although successful in protecting hundreds of rare species not typically considered in most conservation programs, some of the enacted conservation measures created conflicts in meeting other management objectives of the plan, particularly timber harvest. The program accrued important gains in knowledge, reduced uncertainty about conservation of a number of species, and developed new methods of species inventory that will be useful in future management planning and implementation at many scales. The program, however was not completed because of changes in land-management philosophy. Ongoing litigation regarding its termination and potential changes to the plan cast further uncertainty on how the original goal of maintaining persistence of late-successional and old-growth species will be met and measured. The outcomes, controversies, and management frustrations of the program exemplify the inherent difficulties in balancing broad, regional conservation goals with social and economic goals of

  20. Chemical evaluation of soil-solution in acid forest soils

    USGS Publications Warehouse

    Lawrence, G.B.; David, M.B.

    1996-01-01

    Soil-solution chemistry is commonly studied in forests through the use of soil lysimeters.This approach is impractical for regional survey studies, however, because lysimeter installation and operation is expensive and time consuming. To address these problems, a new technique was developed to compare soil-solution chemistry among red spruce stands in New York, Vermont, New Hampshire, Maine. Soil solutions were expelled by positive air pressure from soil that had been placed in a sealed cylinder. Before the air pressure was applied, a solution chemically similar to throughfall was added to the soil to bring it to approximate field capacity. After the solution sample was expelled, the soil was removed from the cylinder and chemically analyzed. The method was tested with homogenized Oa and Bs horizon soils collected from a red spruce stand in the Adirondack Mountains of New York, a red spruce stand in east-central Vermont, and a mixed hardwood stand in the Catskill Mountains of New York. Reproducibility, effects of varying the reaction time between adding throughfall and expelling soil solution (5-65 minutes) and effects of varying the chemical composition of added throughfall, were evaluated. In general, results showed that (i) the method was reproducible (coefficients of variation were generally < 15%), (ii) variations in the length of reaction-time did not affect expelled solution concentrations, and (iii) adding and expelling solution did not cause detectable changes in soil exchange chemistry. Concentrations of expelled solutions varied with the concentrations of added throughfall; the lower the CEC, the more sensitive expelled solution concentrations were to the chemical concentrations of added throughfall. Addition of a tracer (NaBr) showed that the expelled solution was a mixture of added solution and solution that preexisted in the soil. Comparisons of expelled solution concentrations with concentrations of soil solutions collected by zero-tension and

  1. Evaluation of Annual Modis Ptc Data for Deforestation and Forest Degradation Analysis

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Ghilardi, A.; Mas, J. F.; Paneque-Galvez, J.; Skutsch, M.

    2016-06-01

    Anthropogenic land-cover change, e.g. deforestation and forest degradation cause carbon emissions. To estimate deforestation and forest degradation, it is important to have reliable data on forest cover. In this analysis, we evaluated annual MODIS Percent Tree Cover (PTC) data for the detection of forest change including deforestation, forest degradation, reforestation and revegetation. The annual MODIS PTC data (2000 - 2010) were pre-processed by applying quality layer. Based on the PTC values of the annual MODIS data, forest change maps were produced and assessed by comparing with the data from visual interpretation of SPOT-5 images. The assessment was applied to two case-studies: Ayuquila Basin and Monarch Reserve. Results show that the detected deforestation patches by visual interpretation are roughly 4 times in quantity more than those by MODIS PTC data, which can be partially due to the much higher spatial resolution of SPOT-5, being able to pick up small deforestation patches. This analysis found poor spatial overlapping for both case-studies. Possible reasons for the discrepancy in quantity and spatial coincidence were provided. It is necessary to refine the methodology for forest change detection by PTC images; also to refine the validation data in terms of data periods and forest change categories to ensure a better assessment.

  2. Mating system, population growth, and management scenario for Kalanchoe pinnata in an invaded seasonally dry tropical forest.

    PubMed

    González de León, Salvador; Herrera, Ileana; Guevara, Roger

    2016-07-01

    Ecological invasions are a major issue worldwide, where successful invasion depends on traits that facilitate dispersion, establishment, and population growth. The nonnative succulent plant Kalanchoe pinnata, reported as invasive in some countries, is widespread in remnants of seasonally dry tropical forest on a volcanic outcrop with high conservation value in east-central Mexico where we assessed its mating system and demographic growth and identified management strategies. To understand its local mating system, we conducted hand-pollination treatments, germination, and survival experiments. Based on the experimental data, we constructed a life-stage population matrix, identified the key traits for population growth, weighted the contributions of vegetative and sexual reproduction, and evaluated management scenarios. Hand-pollination treatments had slight effects on fruit and seed setting, as well as on germination. With natural pollination treatment, the successful germination of seeds from only 2/39 fruit suggests occasional effective natural cross-pollination. The ratios of the metrics for self- and cross-pollinated flowers suggest that K. pinnata is partially self-compatible. Most of the pollinated flowers developed into fruit, but the seed germination and seedling survival rates were low. Thus, vegetative propagation and juvenile survival are the main drivers of population growth. Simulations of a virtual K. pinnata population suggest that an intense and sustained weeding campaign will reduce the population within at least 10 years. Synthesis and applications. The study population is partially self-compatible, but sexual reproduction by K. pinnata is limited at the study site, and population growth is supported by vegetative propagation and juvenile survival. Demographic modeling provides key insights and realistic forecasts on invasion process and therefore is useful to design management strategies. PMID:27386095

  3. Evaluating Developed Rule Sets Transferability For Extracting Forest Resources From Rapid Eye Data

    NASA Astrophysics Data System (ADS)

    Kindu, Mengistie; Elatawneh, Alata; Corti, Nicolas; Wallner, Adelheid; Felbermeier, Bernhard; Cabra, Ricardo A.; Schneider, Thomas; Knoke, Thomas

    2013-12-01

    This study examined transferability of developed rule sets in an Alpine test site of Germany (Oberammergau) on classifying forest/non-forest at level 1 and forest types (coniferous, deciduous and mixed) at level 2 from RapidEye satellite image. It was evaluated in test sites of three environmental settings; Ethiopia (Munessa), Ecuador (San Francisco) and China (Shangnan) with similar land use/cover types and topography. The same pre-processing steps were applied in each image of all test sites. Object-based image analysis was used to evaluate the rule sets transferability. Comparisons of direct transferability were conducted using accuracies of the classified images. The forest/non-forest classification at level 1 result reveals the direct transferability. However, accuracies decline steeply along with a disturbed nature of the forest resources. The results of forest type classification at level 2 also show the need of further refinement of the already developed rule sets. Adding more rules or adapting to each of the environmental setting is recommended for higher accuracy.

  4. Long-term Patterns of Climate, Tree Growth, and Tree Mortality in Permanent Forest Plots of Hawaii Island

    NASA Astrophysics Data System (ADS)

    Ostertag, R.; Buckley, W.; Cordell, S.; Giambelluca, T. W.; Giardina, C. P.; Inman-Narahari, F.; Litton, C. M.; Nullet, M.; Sack, L.; Sibley, A.; VanDeMark, J.

    2014-12-01

    Long-term permanent vegetation plots provide opportunities for in-depth examinations of forest dynamics and climate. We used Center for Tropical Forest Science (CTFS) methodology to establish 4-ha forest dynamics plots in two contrasting climates on Hawaii Island. We established a montane wet forest dynamics plot in a site with 1150 m elevation, mean annual temperature (MAT) of 16.0 C, and mean annual precipitation (MAP) of 3440 mm. A second plot was established in a lowland dry forest site at 240 m elevation, 20.0 C MAT, and 835 mm MAP. The lowland wet forest site averaged only one month per year with < 100 mm rainfall (considered a dry season month), while the lowland dry forest had 12 dry season months. All trees greater or equal to 1 cm diameter were tagged, mapped, and followed from 2008/2009 to 2013/2014 as part of a 5-year census, and a subset of trees were measured annually. Climate variables measured were shortwave and longwave radiation, air temperature, photosynthetically active radiation, relative humidity, windspeed, soil moisture, and rainfall. At both sites, rainfall was the best predictor of annual growth rates. Rainfall and soil moisture were the two variables that demonstrated the greatest interannual variation; coefficients of variation were 36.7% and 61.6% for rainfall at the montane wet forest and lowland dry forest sites, respectively, and 13.4% and 66.1% for soil moisture at the two sites. Preliminary results from the five-year resurvey demonstrate that Hawaiian trees grow slowly, averaging 0.05 cm/y among 19 species in the montane wet forest, at much slower rates for the 15 species in the lowland dry forest plot. Preliminary mortality rates are 11.8% in the montane wet forest and 14.5% in the lowland dry forest. Forest dynamics appear highly related to water availability, even in wet forests, and are likely to be sensitive to climate change, under which reduced rainfall is predicted for much of the Hawaiian Islands.

  5. Soil Organic Carbon and Total Nitrogen Gains in an Old Growth Deciduous Forest in Germany

    PubMed Central

    Schrumpf, Marion; Kaiser, Klaus; Schulze, Ernst-Detlef

    2014-01-01

    Temperate forests are assumed to be organic carbon (OC) sinks, either because of biomass increases upon elevated CO2 in the atmosphere and large nitrogen deposition, or due to their age structure. Respective changes in soil OC and total nitrogen (TN) storage have rarely been proven. We analysed OC, TN, and bulk densities of 100 soil cores sampled along a regular grid in an old-growth deciduous forest at the Hainich National Park, Germany, in 2004 and again in 2009. Concentrations of OC and TN increased significantly from 2004 to 2009, mostly in the upper 0–20 cm of the mineral soil. Changes in the fine earth masses per soil volume impeded the detection of OC changes based on fixed soil volumes. When calculated on average fine earth masses, OC stocks increased by 323±146 g m−2 and TN stocks by 39±10 g m−2 at 0–20 cm soil depth from 2004 to 2009, giving average annual accumulation rates of 65±29 g OC m−2 yr−1 and 7.8±2 g N m−2 yr−1. Accumulation rates were largest in the upper part of the B horizon. Regional increases in forest biomass, either due to recovery of forest biomass from previous forest management or to fertilization by elevated CO2 and N deposition, are likely causes for the gains in soil OC and TN. As TN increased stronger (1.3% yr−1 of existing stocks) than OC (0.9% yr−1), the OC-to-TN ratios declined significantly. Results of regression analyses between changes in OC and TN stocks suggest that at no change in OC, still 3.8 g TN m−2 yr−1 accumulated. Potential causes for the increase in TN in excess to OC are fixation of inorganic N by the clay-rich soil or changes in microbial communities. The increase in soil OC corresponded on average to 6–13% of the estimated increase in net biome productivity. PMID:24586720

  6. Soil organic carbon and total nitrogen gains in an old growth deciduous forest in Germany.

    PubMed

    Schrumpf, Marion; Kaiser, Klaus; Schulze, Ernst-Detlef

    2014-01-01

    Temperate forests are assumed to be organic carbon (OC) sinks, either because of biomass increases upon elevated CO2 in the atmosphere and large nitrogen deposition, or due to their age structure. Respective changes in soil OC and total nitrogen (TN) storage have rarely been proven. We analysed OC, TN, and bulk densities of 100 soil cores sampled along a regular grid in an old-growth deciduous forest at the Hainich National Park, Germany, in 2004 and again in 2009. Concentrations of OC and TN increased significantly from 2004 to 2009, mostly in the upper 0-20 cm of the mineral soil. Changes in the fine earth masses per soil volume impeded the detection of OC changes based on fixed soil volumes. When calculated on average fine earth masses, OC stocks increased by 323 ± 146 g m(-2) and TN stocks by 39 ± 10 g m(-2) at 0-20 cm soil depth from 2004 to 2009, giving average annual accumulation rates of 65 ± 29 g OC m(-2) yr(-1) and 7.8 ± 2 g N m(-2) yr(-1). Accumulation rates were largest in the upper part of the B horizon. Regional increases in forest biomass, either due to recovery of forest biomass from previous forest management or to fertilization by elevated CO2 and N deposition, are likely causes for the gains in soil OC and TN. As TN increased stronger (1.3% yr(-1) of existing stocks) than OC (0.9% yr(-1)), the OC-to-TN ratios declined significantly. Results of regression analyses between changes in OC and TN stocks suggest that at no change in OC, still 3.8 g TN m(-2) yr(-1) accumulated. Potential causes for the increase in TN in excess to OC are fixation of inorganic N by the clay-rich soil or changes in microbial communities. The increase in soil OC corresponded on average to 6-13% of the estimated increase in net biome productivity. PMID:24586720

  7. Age-dependent climate-growth relationships and regeneration of Picea abies in a drought-prone mixed coniferous forest in the Alps

    PubMed Central

    Schuster, Roman; Oberhuber, Walter

    2013-01-01

    Within dry inner Alpine environments climate warming is expected to affect the development of forest ecosystems by changing species composition and inducing shifts in forest distribution. By applying dendroecological techniques we evaluated climate sensitivity of radial growth and establishment of Picea abies in a drought-prone mixed-coniferous forest in the Austrian Alps. Time series of annual increments were developed from > 220 trees and assigned to four age classes. While radial growth of old P. abies trees (mean age 121 and 174 yr) responded highly significant to May-June precipitation, young trees (mean age 28 and 53 yr) were insensitive to precipitation in the current year. Because tree age was closely correlated to height and diameter (r2 = 0.709 and 0.784, respectively), we relate our findings to the increase in tree size rather than age per se. Synchronicity found among trend in basal area increment and tree establishment suggests that canopy openings increased light and water availability, which favoured growth and establishment of moderately shade-tolerant P. abies. We conclude that although P. abies is able to regenerate at this drought prone site, increasing inter-tree competition for water in dense stands gradually lowers competitive strength and restricts scattered occurrence to dry-mesic sites. PMID:24027351

  8. Effects of soil fertility and topography on tree growth in subtropical forest ecosystems

    NASA Astrophysics Data System (ADS)

    Seitz, Steffen; Goebes, Philipp; Kühn, Peter; Schmidt, Karsten; Song, Zhengshan; Scholten, Thomas

    2016-04-01

    This study investigates the effects of soil fertility and topography on tree growth in a forest biodiversity and ecosystem functioning experiment. The main objective was to examine whether topography controls small-scale differences of soil fertility expressed in soil texture, soil pH, soil organic carbon (SOC), N, cation exchange capacity (CEC), base saturation, Na, K, Mg, Ca, Fe and Mn in a hilly forest area in subtropical China. Geomorphometric terrain analyses were carried out at a spatial resolution of 5 m × 5 m. Soil samples of different depth increments and data on tree growth were collected from a total of 566 plots (667 m2 each). All plots were classified into geomorphological units. Analyses of variance and linear regressions were applied to all terrain, soil fertility and tree growth attributes. In general, limited soil formation and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment. This explains the concurrently increasing CEC and SOC stocks downslope, in hollows and in valleys. However, colluvial carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways. The results showed that soil fertility is mainly influenced by topography. Monte-Carlo flow accumulation (MCCA), curvature, slope and aspect significantly affected soil fertility. Furthermore, soil fertility attributes were affected by the different geomorphological positions of the experimental sites with ridge and spur positions showing lower exchangeable base cation contents due to leaching. This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50 cm depth. Few soil fertility attributes affect tree height after 1-2 years of growth, among which C stocks proved to be most important while pHKCl and CEC only played minor

  9. Pattern and dynamics of biomass stock in old growth forests: The role of habitat and tree size

    NASA Astrophysics Data System (ADS)

    Yuan, Zuoqiang; Gazol, Antonio; Wang, Xugao; Lin, Fei; Ye, Ji; Zhang, Zhaochen; Suo, YanYan; Kuang, Xu; Wang, Yunyun; Jia, Shihong; Hao, Zhanqing

    2016-08-01

    Forest ecosystems play a fundamental role in the global carbon cycle. However, how stand-level changes in tree age and structure influence biomass stock and dynamics in old-growth forests is a question that remains unclear. In this study, we quantified the aboveground biomass (AGB) standing stock, the coarse woody productivity (CWP), and the change in biomass over ten years (2004-2014) in a 25 ha unmanaged broad-leaved Korean pine mixed forest in northeastern China. In addition, we quantified how AGB stock and change (tree growth, recruitment and mortality) estimations are influenced by the variation in habitat heterogeneity, tree size structure and subplot size. Our analysis indicated that Changbai forest had AGB of 265.4 Mg ha-1 in 2004, and gained1.36 Mg ha-1 y-1 between 2004 and 2014. Despite recruitment having better performance in nutrient rich habitat, we found that there is a directional tree growth trend independent of habitat heterogeneity for available nutrients in this old growth forest. The observed increases in AGB stock (∼70%) are mainly attributed to the growth of intermediate size trees (30-70 cm DBH), indicating that this forest is still reaching its mature stage. Meanwhile, we indicated that biomass loss due to mortality reduces living biomass, not increment, may be the primary factor to affect forest biomass dynamics in this area. Also, spatial variation in forest dynamics is large for small sizes (i.e. coefficient of variation in 20 × 20 m subplots is 53.2%), and more than 90 percent of the inherent variability of these coefficients was predicted by a simple model including plot size. Our result provides a mean by which to estimate within-plot variability at a local scale before inferring any directional change in forest dynamics at a regional scale, and information about the variability of forest structure and dynamics are fundamental to design effective sampling strategies in future study.

  10. Response of Quercus velutina growth and water use efficiency to climate variability and nitrogen fertilization in a temperate deciduous forest in the northeastern USA.

    PubMed

    Jennings, Katie A; Guerrieri, Rossella; Vadeboncoeur, Matthew A; Asbjornsen, Heidi

    2016-04-01

    Nitrogen (N) deposition and changing climate patterns in the northeastern USA can influence forest productivity through effects on plant nutrient relations and water use. This study evaluates the combined effects of N fertilization, climate and rising atmospheric CO2on tree growth and ecophysiology in a temperate deciduous forest. Tree ring widths and stable carbon (δ(13)C) and oxygen (δ(18)O) isotopes were used to assess tree growth (basal area increment, BAI) and intrinsic water use efficiency (iWUE) ofQuercus velutinaLamb., the dominant tree species in a 20+ year N fertilization experiment at Harvard Forest (MA, USA). We found that fertilized trees exhibited a pronounced and sustained growth enhancement relative to control trees, with the low- and high-N treatments responding similarly. All treatments exhibited improved iWUE over the study period (1984-2011). Intrinsic water use efficiency trends in the control trees were primarily driven by changes in stomatal conductance, while a stimulation in photosynthesis, supported by an increase in foliar %N, contributed to enhancing iWUE in fertilized trees. All treatments were predominantly influenced by growing season vapor pressure deficit (VPD), with BAI responding most strongly to early season VPD and iWUE responding most strongly to late season VPD. Nitrogen fertilization increasedQ. velutinasensitivity to July temperature and precipitation. Combined, these results suggest that ambient N deposition in N-limited northeastern US forests has enhanced tree growth over the past 30 years, while rising ambient CO2has improved iWUE, with N fertilization and CO2having synergistic effects on iWUE. PMID:26917704

  11. Biology of amphibians and reptiles in old-growth forests in the Pacific northwest. Forest Service general technical report

    SciTech Connect

    Blaustein, A.R.; Beatty, J.J.; Olson, D.H.; Storm, R.M.

    1995-03-01

    The amphibian and reptile fauna of older forest ecosystems in the Pacific Northwest includes several endemic species, species with unique behavioral and ecological characteristics, and species whose populations have been in decline in recent years. The authors review the biology of these species and include information on their distinguishing characteristics, behavior, and ecology. Herpetofaunal associations with forest characteristic and the impact of habitat loss are addressed.

  12. Low-temperature catalyst activator: mechanism of dense carbon nanotube forest growth studied using synchrotron radiation

    PubMed Central

    Takashima, Akito; Izumi, Yudai; Ikenaga, Eiji; Ohkochi, Takuo; Kotsugi, Masato; Matsushita, Tomohiro; Muro, Takayuki; Kawabata, Akio; Murakami, Tomo; Nihei, Mizuhisa; Yokoyama, Naoki

    2014-01-01

    The mechanism of the one-order-of-magnitude increase in the density of vertically aligned carbon nanotubes (CNTs) achieved by a recently developed thermal chemical vapor deposition process was studied using synchrotron radiation spectroscopic techniques. In the developed process, a Ti film is used as the underlayer for an Fe catalyst film. A characteristic point of this process is that C2H2 feeding for the catalyst starts at a low temperature of 450°C, whereas conventional feeding temperatures are ∼800°C. Photoemission spectroscopy using soft and hard X-rays revealed that the Ti underlayer reduced the initially oxidized Fe layer at 450°C. A photoemission intensity analysis also suggested that the oxidized Ti layer at 450°C behaved as a support for nanoparticle formation of the reduced Fe, which is required for dense CNT growth. In fact, a CNT growth experiment, where the catalyst chemical state was monitored in situ by X-ray absorption spectroscopy, showed that the reduced Fe yielded a CNT forest at 450°C. Contrarily, an Fe layer without the Ti underlayer did not yield such a CNT forest at 450°C. Photoemission electron microscopy showed that catalyst annealing at the conventional feeding temperature of 800°C caused excess catalyst agglomeration, which should lead to sparse CNTs. In conclusion, in the developed growth process, the low-temperature catalyst activation by the Ti underlayer before the excess Fe agglomeration realised the CNT densification. PMID:25075343

  13. [Evaluation of soil microbial communities in two types of Siberian forest ecosystems].

    PubMed

    Grodnitskaia, I D; Sorokin, N D

    2007-01-01

    Microbial respiration and biomass were evaluated in soils of the Ermak Tree Nursery and Pogorel'skii Forest under different coniferous species. The degree of disturbance of each biocenosis was determined from the metabolic coefficient (qCO2). The microbial investigation demonstrated a lower resistance to ecological factors of the tree nursery biocenosis as compared to those of the Pogorel'skii Forest. PMID:19768961

  14. Regulatory and information support for evaluation of biological productivity of Ukrainian forests and climate change

    NASA Astrophysics Data System (ADS)

    Lakyda, Petro; Vasylyshyn, Roman; Lakyda, Ivan

    2013-04-01

    Stabilization and preservation of the planet's climate system today is regarded as one of the most important global political-economic, environmental and social problems of mankind. Rising concentration of carbon dioxide in the planet's atmosphere due to anthropogenic impact is the main reason leading to global climate change. Due to the above mentioned, social demands on forests are changing their biosphere role and function of natural sink of greenhouse gases becomes top priority. It is known that one of the most essential components of biological productivity of forests is their live biomass. Absorption, long-term sequestration of carbon and generation of oxygen are secured by its components. System research of its parametric structure and development of regulatory and reference information for assessment of aboveground live biomass components of trees and stands of the main forest-forming tree species in Ukraine began over twenty-five years ago at the department of forest mensuration and forest inventory of National University of Life and Environmental Sciences of Ukraine, involving staff from other research institutions. Today, regulatory and reference materials for evaluation of parametric structure of live biomass are developed for trees of the following major forest-forming tree species of Ukraine: Scots pine of natural and artificial origin, Crimean pine, Norway spruce, silver fir, pedunculate oak, European beech, hornbeam, ash, common birch, aspen and black alder (P.I. Lakyda et al., 2011). An ongoing process on development of similar regulatory and reference materials for forest stands of the abovementioned forest-forming tree species of Ukraine is secured by scientists of departments of forest management, and forest mensuration and forest inventory. The total experimental research base is 609 temporary sample plots, where 4880 model trees were processed, including 3195 model trees with estimates of live biomass components. Laboratory studies conducted

  15. Growth and Mycorrhizal Community Structure of Pinus sylvestris Seedlings following the Addition of Forest Litter▿

    PubMed Central

    Aučina, Algis; Rudawska, Maria; Leski, Tomasz; Skridaila, Audrius; Riepšas, Edvardas; Iwanski, Michal

    2007-01-01

    We report the effects of pine and oak litter on species composition and diversity of mycorrhizal fungi colonizing 2-year-old Pinus sylvestris L. seedlings grown in a bare-root nursery in Lithuania. A layer of pine or oak litter was placed on the surface of the nursery bed soil to mimic natural litter cover. Oak litter amendment appeared to be most favorable for seedling survival, with a 73% survival rate, in contrast to the untreated mineral bed soil (44%). The concentrations of total N, P, K, Ca, and Mg were higher in oak growth medium than in pine growth medium. Relative to the control (pH 6.1), the pH was lower in pine growth medium (5.8) and higher in oak growth medium (6.3). There were also twofold and threefold increases in the C content of growth medium with the addition of pine and oak litter, respectively. Among seven mycorrhizal morphotypes, eight different mycorrhizal taxa were identified: Suillus luteus, Suillus variegatus, Wilcoxina mikolae, a Tuber sp., a Tomentella sp., Cenococcum geophilum, Amphinema byssoides, and one unidentified ectomycorrhizal symbiont. Forest litter addition affected the relative abundance of mycorrhizal symbionts more than their overall representation. This was more pronounced for pine litter than for oak litter, with 40% and 25% increases in the abundance of suilloid mycorrhizae, respectively. Our findings provide preliminary evidence that changes in the supply of organic matter through litter manipulation may have far-reaching effects on the chemistry of soil, thus influencing the growth and survival of Scots pine seedlings and their mycorrhizal communities. PMID:17575001

  16. Carbon Flux Partitioning in an Old-Growth Forest: Study of Seasonal and Interannual Variation

    NASA Astrophysics Data System (ADS)

    Paw U, K.; Falk, M.

    2003-12-01

    We investigate the decompostion of eddy flux measurements of net ecosystem exchange (NEE) into gross primary productivity (GPP), ecosystem respiration (Reco) and the temporal dynamics of component fluxes for 4 « years of data from long-term measurements of carbon fluxes above and within Old-growth Forest at the Wind River Canopy Crane AMERIFLUX site. Trees at the site are up to 500 years old and 65 meters tall. The forest structure at the site is complex for a temperate conifer stand with seven gymnosperm and two angiosperm tree species in the 2.3 ha crane circle, large standing biomass and large amounts of woody debris on the forest floor. Soil respiration is a major contributor to the carbon budget at the site with roughly 75% of total respiration on average. The annual estimates of net ecosystem exchange (NEE) of carbon range from a strong sink (2.1 tC/ha per year) to a source (-0.5 tC/ha per year). Summers are usually warm and dry (1998, 2001) but relatively wet and cool ones have been observed (1999). Precipitation levels throughout the observation period varied from 1600 to 2600 mm with the latter close to the 25-year average. The main period of maximum carbon uptake is limited to the months March through May when ecosystem respiration and water stress are low. Stand-level light response functions show optima for low temperatures and diffuse light conditions. Reco also shows a clear seasonal pattern but lags significantly behind NEE with a maximum in late summer and has a range of 13 - 16 tC/ha per year. GPP shows a similar lag against NEE but is relatively invariant on an annual basis (16 tC/ha).

  17. Widespread negative correlations between black spruce growth and temperature across topographic moisture gradients in the boreal forest

    NASA Astrophysics Data System (ADS)

    Walker, Xanthe; Johnstone, Jill F.

    2014-05-01

    The responses of tree growth to recent climate warming may signal changes in the susceptibility of forest communities to compositional change and consequently impact a wide range of ecosystem processes and services. Previous research in the boreal forest has largely documented negative growth responses to climate in forest species and habitats characteristic of drier conditions, emphasizing the sensitivity of drier or warmer landscape positions to climate warming. In this study, we explored relationships between climate and tree-ring growth of black spruce, a dominant tree species typical of cool and moist habitats in the boreal forests of North America. We assessed how these responses varied with stand characteristics and landscape position across four different regions in Alaska and Yukon Territory. Approximately half of the trees measured across regions and topographic gradients exhibited reduced radial growth in response to warm temperatures in the previous growing season and current spring, which we interpret as a signal of drought stress. Although we found considerable variation in the growth responses of individual trees within sites, landscape position and stand characteristics were weak predictors of this variability, explaining ≦̸12% of the variation in any region. Our results indicate that future warming, particularly in spring, is likely to result in drought stress and a reduction of black spruce radial growth independent of region, landscape position, or stand characteristics. The occurrence of negative growth responses to temperature, even in cool and moist habitats, suggests that drought stress limitations may be more widespread in the northern boreal forest than previously anticipated, indicating broad sensitivity of ecosystem processes and services to climate change across a diverse range of habitat types.

  18. Environmental determinants of tropical forest and savanna distribution: A quantitative model evaluation and its implication

    NASA Astrophysics Data System (ADS)

    Zeng, Zhenzhong; Chen, Anping; Piao, Shilong; Rabin, Sam; Shen, Zehao

    2014-07-01

    The distributions of tropical ecosystems are rapidly being altered by climate change and anthropogenic activities. One possible trend—the loss of tropical forests and replacement by savannas—could result in significant shifts in ecosystem services and biodiversity loss. However, the influence and the relative importance of environmental factors in regulating the distribution of tropical forest and savanna biomes are still poorly understood, which makes it difficult to predict future tropical forest and savanna distributions in the context of climate change. Here we use boosted regression trees to quantitatively evaluate the importance of environmental predictors—mainly climatic, edaphic, and fire factors—for the tropical forest-savanna distribution at a mesoscale across the tropics (between 15°N and 35°S). Our results demonstrate that climate alone can explain most of the distribution of tropical forest and savanna at the scale considered; dry season average precipitation is the single most important determinant across tropical Asia-Australia, Africa, and South America. Given the strong tendency of increased seasonality and decreased dry season precipitation predicted by global climate models, we estimate that about 28% of what is now tropical forest would likely be lost to savanna by the late 21st century under the future scenario considered. This study highlights the importance of climate seasonality and interannual variability in predicting the distribution of tropical forest and savanna, supporting the climate as the primary driver in the savanna biogeography.

  19. An evaluation of resource inventory and monitoring program used in national forest planning

    NASA Astrophysics Data System (ADS)

    Morrison, Michael L.; Marcot, Bruce G.

    1995-01-01

    The National Forest Management Act (1976) specifies that multiresource inventories be conducted to provide baseline data for development and, later, monitoring of national forest management plans. This mandate entails the most ambitious and complex resource planning effort ever attempted. In this paper we evaluate the structure and use of current inventory-monitoring programs and recommend a framework for gathering data to improve national forest planning. Current national guidelines are general and provide only basic directions to forest-level planners. Forest inventories have traditionally concentrated on timber. Although these inventories are often well designed, the questions we are now asking about forest resources have outgrown these methods. Forest management is impeded by general confusion over definitions of resources and the interactions among them. We outline a simple classification scheme that centers on identification of basic ecosystem elements that can be readily measured. Furthermore, spatial and temporal scales must be considered in the design of inventory-monitoring programs. The concept of ecological indicators is reviewed, and caution is advised in their use. Inventory-monitoring programs should be goal-directed and based on as rigorous a statistical design as possible. We also review fundamental issues of variable selection, validation, and sampling bias. We conclude by developing a flexible inventory-monitoring program that is designed to provide information on individual characteristics of the environment, rather than being based on fixed definitions of resources.

  20. Epicormic Branches: a Growth Indicator for the Tropical Forest Tree, Dicorynia guianensis Amshoff (Caesalpiniaceae)

    PubMed Central

    NICOLINI, ERIC; CARAGLIO, YVES; PÉLISSIER, RAPHAËL; LEROY, CELINE; ROGGY, JEAN‐CHRISTOPHE

    2003-01-01

    Architectural analyses of temperate tree species using a chronological approach suggest that the expression of epicormic branches is closely related to low growth rates in the axes that make up the branching system. Therefore, sole consideration of epicormic criteria may be sufficient to identify trees with low secondary growth levels or with both low primary and secondary growth levels. In a tropical tree such as Dicorynia guianensis (basralocus), where chronological studies are difficult, this relationship could be very useful as an easily accessible indicator of growth potentials. A simple method of architectural tree description was used to characterize the global structure of more than 1650 basralocus trees and to evaluate their growth level. Measurements of simple growth characters [height, basal diameter, internode length of submittal part (top of the main axis of the tree)] and the observation of four structural binary descriptors on the main stem (presence of sequential branches and young epicormic branches, state of the submittal part, global orientation), indicated that epicormic branch formation is clearly related to a decrease in length of the successive growth units of the main stem. Analysis of height vs. diameter ratios among different tree subgroups, with and without epicormic branching, suggested that trees with epicormic branches generally have a low level of secondary growth compared with primary growth. PMID:12824071

  1. Spatial Characteristics of Tree Diameter Distributions in a Temperate Old-Growth Forest

    PubMed Central

    Zhao, Xiuhai; von Gadow, Klaus

    2013-01-01

    This contribution identifies spatial characteristics of tree diameter in a temperate forest in north-eastern China, based on a fully censused observational study area covering 500×600 m. Mark correlation analysis with three null hypothesis models was used to determine departure from expectations at different neighborhood distances. Tree positions are clumped at all investigated scales in all 37 studied species, while the diameters of most species are spatially negatively correlated, especially at short distances. Interestingly, all three cases showing short-distance attraction of dbh marks are associated with light-demanding shrub species. The short-distance attraction of dbh marks indicates spatially aggregated cohorts of stems of similar size. The percentage of species showing significant dbh suppression peaked at a 4 m distance under the heterogeneous Poisson model. At scales exceeding the peak distance, the percentage of species showing significant dbh suppression decreases sharply with increasing distances. The evidence from this large observational study shows that some of the variation of the spatial characteristics of tree diameters is related variations of topography and soil chemistry. However, an obvious interpretation of this result is still lacking. Thus, removing competitors surrounding the target trees is an effective way to avoid neighboring competition effects reducing the growth of valuable target trees in forest management practice. PMID:23527066

  2. [Effects of artificial tending on Pinus tabulaeformis forest growth and its structural characteristics].

    PubMed

    Cao, Yun; Yang, Yie; Song, Bingyu; Huang, Heping; Yang, Mingbo; Zheng, Min

    2005-03-01

    The investigation on the growth status, community composition, and structural characteristics of Pinus tabulaeformis forest artificially tended for six years showed that there were significant differences in the average DBH, height, and crown size of the forest among the treatments DA (trimming without intermediate cutting), FA (trimming and intermediate cutting) and CK (without trending). Treatment FA had the highest values of average DBH (7.8 +/- 0.29 cm), height (5.5 +/- 0.09 m) and crown size (249 +/- 7.24 cm), while the CK had the lowest ones. The average biomass of new leaf (1-year-old), old leaf (2 or more-year-old), and branch per tree increased significantly (P<0.01) with enhancing tending treatments. The aboveground biomass of treatment FA was the biggest (44.0 t x hm(-2)), and that of CK was the smallest (14.9 t x hm(-2)). The leaf length and SLA at the early and terminal stages of development (May, June and September) had significant difference among the treatments, and the amount of community composition and the cover degree of undergrowth plants increased evidently under artificial tending treatments. PMID:15943345

  3. Spatial characteristics of tree diameter distributions in a temperate old-growth forest.

    PubMed

    Zhang, Chunyu; Wei, Yanbo; Zhao, Xiuhai; von Gadow, Klaus

    2013-01-01

    This contribution identifies spatial characteristics of tree diameter in a temperate forest in north-eastern China, based on a fully censused observational study area covering 500×600 m. Mark correlation analysis with three null hypothesis models was used to determine departure from expectations at different neighborhood distances. Tree positions are clumped at all investigated scales in all 37 studied species, while the diameters of most species are spatially negatively correlated, especially at short distances. Interestingly, all three cases showing short-distance attraction of dbh marks are associated with light-demanding shrub species. The short-distance attraction of dbh marks indicates spatially aggregated cohorts of stems of similar size. The percentage of species showing significant dbh suppression peaked at a 4 m distance under the heterogeneous Poisson model. At scales exceeding the peak distance, the percentage of species showing significant dbh suppression decreases sharply with increasing distances. The evidence from this large observational study shows that some of the variation of the spatial characteristics of tree diameters is related variations of topography and soil chemistry. However, an obvious interpretation of this result is still lacking. Thus, removing competitors surrounding the target trees is an effective way to avoid neighboring competition effects reducing the growth of valuable target trees in forest management practice. PMID:23527066

  4. Simulating stand climate, phenology, and photosynthesis of a forest stand with a process-based growth model

    NASA Astrophysics Data System (ADS)

    Rötzer, Thomas; Leuchner, Michael; Nunn, Angela J.

    2010-07-01

    In the face of climate change and accompanying risks, forest management in Europe is becoming increasingly important. Model simulations can help to understand the reactions and feedbacks of a changing environment on tree growth. In order to simulate forest growth based on future climate change scenarios, we tested the basic processes underlying the growth model BALANCE, simulating stand climate (air temperature, photosynthetically active radiation (PAR) and precipitation), tree phenology, and photosynthesis. A mixed stand of 53- to 60-year-old Norway spruce ( Picea abies) and European beech ( Fagus sylvatica) in Southern Germany was used as a reference. The results show that BALANCE is able to realistically simulate air temperature gradients in a forest stand using air temperature measurements above the canopy and PAR regimes at different heights for single trees inside the canopy. Interception as a central variable for water balance of a forest stand was also estimated. Tree phenology, i.e. bud burst and leaf coloring, could be reproduced convincingly. Simulated photosynthesis rates were in accordance with measured values for beech both in the sun and the shade crown. For spruce, however, some discrepancies in the rates were obvious, probably due to changed environmental conditions after bud break. Overall, BALANCE has shown to respond to scenario simulations of a changing environment (e.g., climate change, change of forest stand structure).

  5. Simulating stand climate, phenology, and photosynthesis of a forest stand with a process-based growth model.

    PubMed

    Rötzer, Thomas; Leuchner, Michael; Nunn, Angela J

    2010-07-01

    In the face of climate change and accompanying risks, forest management in Europe is becoming increasingly important. Model simulations can help to understand the reactions and feedbacks of a changing environment on tree growth. In order to simulate forest growth based on future climate change scenarios, we tested the basic processes underlying the growth model BALANCE, simulating stand climate (air temperature, photosynthetically active radiation (PAR) and precipitation), tree phenology, and photosynthesis. A mixed stand of 53- to 60-year-old Norway spruce (Picea abies) and European beech (Fagus sylvatica) in Southern Germany was used as a reference. The results show that BALANCE is able to realistically simulate air temperature gradients in a forest stand using air temperature measurements above the canopy and PAR regimes at different heights for single trees inside the canopy. Interception as a central variable for water balance of a forest stand was also estimated. Tree phenology, i.e. bud burst and leaf coloring, could be reproduced convincingly. Simulated photosynthesis rates were in accordance with measured values for beech both in the sun and the shade crown. For spruce, however, some discrepancies in the rates were obvious, probably due to changed environmental conditions after bud break. Overall, BALANCE has shown to respond to scenario simulations of a changing environment (e.g., climate change, change of forest stand structure). PMID:20084520

  6. Stimulating seedling growth in early stages of secondary forest succession: a modeling approach to guide tree liberation.

    PubMed

    van Kuijk, Marijke; Anten, Niels P R; Oomen, Roelof J; Schieving, Feike

    2014-01-01

    Excessive growth of non-woody plants and shrubs on degraded lands can strongly hamper tree growth and thus secondary forest succession. A common method to accelerate succession, called liberation, involves opening up the vegetation canopy around young target trees. This can increase growth of target trees by reducing competition for light with neighboring plants. However, liberation has not always had the desired effect, likely due to differences in light requirement between tree species. Here we present a 3D-model, which calculates photosynthetic rate of individual trees in a vegetation stand. It enables us to examine how stature, crown structure, and physiological traits of target trees and characteristics of the surrounding vegetation together determine effects of light on tree growth. The model was applied to a liberation experiment conducted with three pioneer species in a young secondary forest in Vietnam. Species responded differently to the treatment depending on their height, crown structure and their shade-tolerance level. Model simulations revealed practical thresholds over which the tree growth response is heavily influenced by the height and density of surrounding vegetation and gap radius. There were strong correlations between calculated photosynthetic rates and observed growth: the model was well able to predict growth of trees in young forests and the effects of liberation there upon. Thus, our model serves as a useful tool to analyze light competition between young trees and surrounding vegetation and may help assess the potential effect of tree liberation. PMID:25101100

  7. Stimulating seedling growth in early stages of secondary forest succession: a modeling approach to guide tree liberation

    PubMed Central

    van Kuijk, Marijke; Anten, Niels P. R.; Oomen, Roelof J.; Schieving, Feike

    2014-01-01

    Excessive growth of non-woody plants and shrubs on degraded lands can strongly hamper tree growth and thus secondary forest succession. A common method to accelerate succession, called liberation, involves opening up the vegetation canopy around young target trees. This can increase growth of target trees by reducing competition for light with neighboring plants. However, liberation has not always had the desired effect, likely due to differences in light requirement between tree species. Here we present a 3D-model, which calculates photosynthetic rate of individual trees in a vegetation stand. It enables us to examine how stature, crown structure, and physiological traits of target trees and characteristics of the surrounding vegetation together determine effects of light on tree growth. The model was applied to a liberation experiment conducted with three pioneer species in a young secondary forest in Vietnam. Species responded differently to the treatment depending on their height, crown structure and their shade-tolerance level. Model simulations revealed practical thresholds over which the tree growth response is heavily influenced by the height and density of surrounding vegetation and gap radius. There were strong correlations between calculated photosynthetic rates and observed growth: the model was well able to predict growth of trees in young forests and the effects of liberation there upon. Thus, our model serves as a useful tool to analyze light competition between young trees and surrounding vegetation and may help assess the potential effect of tree liberation. PMID:25101100

  8. Tree growth and forest ecosystem functioning in Eurasia under extreme climate conditions

    NASA Astrophysics Data System (ADS)

    Saurer, Matthias; Kirdyanov, Alexander; Prokushkin, Anatoly; Bryukhanova, Marina; Knorre, Anastasia; Nasyrov, Muhtor; Frank, David; Treydte, Kerstin; Sidorova, Olga; Siegwolf, Rolf

    2013-04-01

    The main goal of this study is to improve our understanding of the influence of a changing climate on trees in extreme conditions by a detailed analysis of the factors controlling tree-ring growth. We investigated forest ecosystems in regions that are very sensitive to climatic changes and where rapid and dramatic environmental and climatic changes are on-going, namely, the high latitude permafrost region in Central Siberia (Russia), the semi-arid dry areas in Central Asia (Uzbekistan) and high-altitude sites in the Alps (Switzerland). Tree-ring parameters studied were ring-width, density, cell number and structure and the ratio of carbon and oxygen isotopes. An important aspect of the work was the characterization of seasonal growth and water supply of trees. Intra-seasonal dynamics of tree-ring formation was correlated with monitored environmental factors, such as air and soil temperature and moisture, permafrost depth and the isotope composition of soil water, of precipitation, and of stream water. Intra-annual and long-term variability of the main tree-ring parameters were compared for the different regions. The results obtained help us to understand better tree-physiological processes valid under contrasting environmental conditions. For instance, the relationship between the onset of cell division in the cambium and the thermo-hydrological soil regime was used to determine the period of the year with the highest influence on the start of tree-ring formation. Seasonally resolved oxygen isotope depth profiles of soil water and concurrent xylem and leaf water measurements show the importance of time-lags between precipitation, leaf processes and growth. The data obtained are important for improving tree-ring growth models and estimating future tree growth under climate change. Funding: SNF SCOPES IZ73Z0_128035

  9. Growth duration is a better predictor of stem increment than carbon supply in a Mediterranean oak forest: implications for assessing forest productivity under climate change.

    PubMed

    Lempereur, Morine; Martin-StPaul, Nicolas K; Damesin, Claire; Joffre, Richard; Ourcival, Jean-Marc; Rocheteau, Alain; Rambal, Serge

    2015-08-01

    Understanding whether tree growth is limited by carbon gain (source limitation) or by the direct effect of environmental factors such as water deficit or temperature (sink limitation) is crucial for improving projections of the effects of climate change on forest productivity. We studied the relationships between tree basal area (BA) variations, eddy covariance carbon fluxes, predawn water potential (Ψpd ) and temperature at different timescales using an 8-yr dataset and a rainfall exclusion experiment in a Quercus ilex Mediterranean coppice. At the daily timescale, during periods of low temperature (< 5°C) and high water deficit (< -1.1 MPa), gross primary productivity and net ecosystem productivity remained positive whereas the stem increment was nil. Thus, stem increment appeared limited by drought and temperature rather than by carbon input. Annual growth was accurately predicted by the duration of BA increment during spring (Δtt0-t1 ). The onset of growth (t0 ) was related to winter temperatures and the summer interruption of growth (t1 ) to a threshold Ψpd value of -1.1 MPa. We suggest that using environmental drivers (i.e. drought and temperature) to predict stem growth phenology can contribute to an improvement in vegetation models and may change the current projections of Mediterranean forest productivity under climate change scenarios. PMID:25913661

  10. Unusual forest growth decline in boreal North America covaries with the retreat of Arctic sea ice.

    PubMed

    Girardin, Martin P; Guo, Xiao Jing; De Jong, Rogier; Kinnard, Christophe; Bernier, Pierre; Raulier, Frédéric

    2014-03-01

    The 20th century was a pivotal period at high northern latitudes as it marked the onset of rapid climatic warming brought on by major anthropogenic changes in global atmospheric composition. In parallel, Arctic sea ice extent has been decreasing over the period of available satellite data records. Here, we document how these changes influenced vegetation productivity in adjacent eastern boreal North America. To do this, we used normalized difference vegetation index (NDVI) data, model simulations of net primary productivity (NPP) and tree-ring width measurements covering the last 300 years. Climatic and proxy-climatic data sets were used to explore the relationships between vegetation productivity and Arctic sea ice concentration and extent, and temperatures. Results indicate that an unusually large number of black spruce (Picea mariana) trees entered into a period of growth decline during the late-20th century (62% of sampled trees; n = 724 cross sections of age >70 years). This finding is coherent with evidence encoded in NDVI and simulated NPP data. Analyses of climatic and vegetation productivity relationships indicate that the influence of recent climatic changes in the studied forests has been via the enhanced moisture stress (i.e. greater water demands) and autotrophic respiration amplified by the declining sea ice concentration in Hudson Bay and Hudson Strait. The recent decline strongly contrasts with other growth reduction events that occurred during the 19th century, which were associated with cooling and high sea ice severity. The recent decline of vegetation productivity is the first one to occur under circumstances related to excess heat in a 300-year period, and further culminates with an intensifying wildfire regime in the region. Our results concur with observations from other forest ecosystems about intensifying temperature-driven drought stress and tree mortality with ongoing climatic changes. PMID:24115302

  11. Evaluating Landscape Connectivity for Puma concolor and Panthera onca Among Atlantic Forest Protected Areas

    NASA Astrophysics Data System (ADS)

    Castilho, Camila S.; Hackbart, Vivian C. S.; Pivello, Vânia R.; dos Santos, Rozely F.

    2015-06-01

    Strictly Protected Areas and riparian forests in Brazil are rarely large enough or connected enough to maintain viable populations of carnivores and animal movement over time, but these characteristics are fundamental for species conservation as they prevent the extinction of isolated animal populations. Therefore, the need to maintain connectivity for these species in human-dominated Atlantic landscapes is critical. In this study, we evaluated the landscape connectivity for large carnivores (cougar and jaguar) among the Strictly Protected Areas in the Atlantic Forest, evaluated the efficiency of the Mosaics of Protected Areas linked to land uses in promoting landscape connectivity, identified the critical habitat connections, and predicted the landscape connectivity status under the implementation of legislation for protecting riparian forests. The method was based on expert opinion translated into land use and land cover maps. The results show that the Protected Areas are still connected by a narrow band of landscape that is permeable to both species and that the Mosaics of Protected Areas increase the amount of protected area but fail to increase the connectivity between the forested mountain ranges (Serra do Mar and Serra da Mantiqueira). Riparian forests greatly increase connectivity, more than tripling the cougars' priority areas. We note that the selection of Brazilian protected areas still fails to create connectivity among the legally protected forest remnants. We recommend the immediate protection of the priority areas identified that would increase the structural landscape connectivity for these large carnivores, especially paths in the SE/NW direction between the two mountain ranges.

  12. Evaluating Landscape Connectivity for Puma concolor and Panthera onca Among Atlantic Forest Protected Areas.

    PubMed

    Castilho, Camila S; Hackbart, Vivian C S; Pivello, Vânia R; dos Santos, Rozely F

    2015-06-01

    Strictly Protected Areas and riparian forests in Brazil are rarely large enough or connected enough to maintain viable populations of carnivores and animal movement over time, but these characteristics are fundamental for species conservation as they prevent the extinction of isolated animal populations. Therefore, the need to maintain connectivity for these species in human-dominated Atlantic landscapes is critical. In this study, we evaluated the landscape connectivity for large carnivores (cougar and jaguar) among the Strictly Protected Areas in the Atlantic Forest, evaluated the efficiency of the Mosaics of Protected Areas linked to land uses in promoting landscape connectivity, identified the critical habitat connections, and predicted the landscape connectivity status under the implementation of legislation for protecting riparian forests. The method was based on expert opinion translated into land use and land cover maps. The results show that the Protected Areas are still connected by a narrow band of landscape that is permeable to both species and that the Mosaics of Protected Areas increase the amount of protected area but fail to increase the connectivity between the forested mountain ranges (Serra do Mar and Serra da Mantiqueira). Riparian forests greatly increase connectivity, more than tripling the cougars' priority areas. We note that the selection of Brazilian protected areas still fails to create connectivity among the legally protected forest remnants. We recommend the immediate protection of the priority areas identified that would increase the structural landscape connectivity for these large carnivores, especially paths in the SE/NW direction between the two mountain ranges. PMID:25860593

  13. Growth dynamics and biodiversity of larch forest after wildfire at the north of central Siberia

    SciTech Connect

    Danilin, I.

    1996-12-31

    Investigations of qualitative and quantitative changes occurring in disturbed forest communities in Siberia are now recognized as important issues, since anthropogenic stress is increasingly affecting forests from year to year and often results in irreversible decomposition of forest ecosystems over large areas. In forests of central Siberia, fire accounts for the greatest disturbance. The level of fire-caused forest destruction is noticeably high. Space imagery analysis has revealed that, from 1980 throughout 1995, the average annual forest area covered by fires was more than 500,000 ha. In as much as this is a country with permafrost soils, fires promote swamping and treeless areas. However, forests regenerate naturally on some burned areas. Forest regeneration can occur either with stand replacement (through secondary birch) or without replacement when new forests are formed by the pre-fire edificators. The second way of succession is ecologically more preferable, because the larch population is more resistant to external influences and keeps its native biodiversity.

  14. Evaluating regional differences in macroinvertebrate communities from forested depressional wetlands across eastern and central North America.

    SciTech Connect

    Batzer, Darold, P.; Dietz-Brantley, Susan E.; Taylor, Barbera E.; DeBiase, Adrienne E.

    2005-02-12

    Batzer, Darold, P., Susan E. Dietz-Brantley, Barbera E. Taylor, and Adrienne E. DeBiase. 2005. Evaluating regional differences in macroinvertebrate communities from forested depressional wetlands across eastern and central North America. J. N. Am. Benthol. Soc. 24(2):403-414. Abstract. Forested depressional wetlands are an important seasonal wetland type across eastern and central North America. Macroinvertebrates are crucial ecosystem components of most forested depressional wetlands, but community compositions can vary widely across the region. We evaluated variation in macroinvertebrate faunas across eastern and central North America using 5 published taxa lists from forested depressional wetlands in Michigan, Ontario, Wisconsin, Florida, and Georgia. We supplemented those data with quantitative community descriptions generated from 17 forested depressional wetlands in South Carolina and 74 of these wetlands in Minnesota. Cluster analysis of presence/absence data from these 7 locations indicated that distinct macroinvertebrate communities existed in northern and southern areas. Taxa characteristic of northern forested depressionalwetlands included Sphaeriidae, Lumbriculidae, Lymnaeidae, Physidae, Limnephilidae, Chirocephalidae, and Hirudinea (Glossophoniidae and/or Erpodbellidae) and taxa characteristic of southern sites included Asellidae, Crangonyctidae, Noteridae, and Cambaridae. Quantitative sampling in South Carolina and Minnesota indicated that regionally characteristic taxa included some of the most abundant organisms, with Sphaeriidae being the 2nd most abundant macroinvertebrate in Minnesota wetlands and Asellidae being the 2nd most abundant macroinvertebrate in South Carolina wetlands. Mollusks, in general, were restricted to forested depressional wetlands of northern latitudes, a pattern that may reflect a lack of Ca needed for shell formation in acidic southern sites. Differences in community composition probably translate into region

  15. Limited Growth Recovery after Drought-Induced Forest Dieback in Very Defoliated Trees of Two Pine Species.

    PubMed

    Guada, Guillermo; Camarero, J Julio; Sánchez-Salguero, Raúl; Cerrillo, Rafael M Navarro

    2016-01-01

    Mediterranean pine forests display high resilience after extreme climatic events such as severe droughts. However, recent dry spells causing growth decline and triggering forest dieback challenge the capacity of some forests to recover following major disturbances. To describe how resilient the responses of forests to drought can be, we quantified growth dynamics in plantations of two pine species (Scots pine, black pine) located in south-eastern Spain and showing drought-triggered dieback. Radial growth was characterized at inter- (tree-ring width) and intra-annual (xylogenesis) scales in three defoliation levels. It was assumed that the higher defoliation the more negative the impact of drought on tree growth. Tree-ring width chronologies were built and xylogenesis was characterized 3 years after the last severe drought occurred. Annual growth data and the number of tracheids produced in different stages of xylem formation were related to climate data at several time scales. Drought negatively impacted growth of the most defoliated trees in both pine species. In Scots pine, xylem formation started earlier in the non-defoliated than in the most defoliated trees. Defoliated trees presented the shortest duration of the radial-enlargement phase in both species. On average the most defoliated trees formed 60% of the number of mature tracheids formed by the non-defoliated trees in both species. Since radial enlargement is the xylogenesis phase most tightly related to final growth, this explains why the most defoliated trees grew the least due to their altered xylogenesis phases. Our findings indicate a very limited resilience capacity of drought-defoliated Scots and black pines. Moreover, droughts produce legacy effects on xylogenesis of highly defoliated trees which could not recover previous growth rates and are thus more prone to die. PMID:27066053

  16. Limited Growth Recovery after Drought-Induced Forest Dieback in Very Defoliated Trees of Two Pine Species

    PubMed Central

    Guada, Guillermo; Camarero, J. Julio; Sánchez-Salguero, Raúl; Cerrillo, Rafael M. Navarro

    2016-01-01

    Mediterranean pine forests display high resilience after extreme climatic events such as severe droughts. However, recent dry spells causing growth decline and triggering forest dieback challenge the capacity of some forests to recover following major disturbances. To describe how resilient the responses of forests to drought can be, we quantified growth dynamics in plantations of two pine species (Scots pine, black pine) located in south-eastern Spain and showing drought-triggered dieback. Radial growth was characterized at inter- (tree-ring width) and intra-annual (xylogenesis) scales in three defoliation levels. It was assumed that the higher defoliation the more negative the impact of drought on tree growth. Tree-ring width chronologies were built and xylogenesis was characterized 3 years after the last severe drought occurred. Annual growth data and the number of tracheids produced in different stages of xylem formation were related to climate data at several time scales. Drought negatively impacted growth of the most defoliated trees in both pine species. In Scots pine, xylem formation started earlier in the non-defoliated than in the most defoliated trees. Defoliated trees presented the shortest duration of the radial-enlargement phase in both species. On average the most defoliated trees formed 60% of the number of mature tracheids formed by the non-defoliated trees in both species. Since radial enlargement is the xylogenesis phase most tightly related to final growth, this explains why the most defoliated trees grew the least due to their altered xylogenesis phases. Our findings indicate a very limited resilience capacity of drought-defoliated Scots and black pines. Moreover, droughts produce legacy effects on xylogenesis of highly defoliated trees which could not recover previous growth rates and are thus more prone to die. PMID:27066053

  17. PATTERNS OF NITROGEN AND CARBON STABLE ISOTOPE RATIOS IN MACROFUNGI, PLANTS AND SOILS IN TWO OLD-GROWTH CONIFER FORESTS

    EPA Science Inventory

    Natural abundance stable isotope ratios represent a potentially valuable tool for studying fungal ecology. We measured 15N and 13C in ectomycorrhizal and saprotrophic macrofungi from two old-growth conifer forests, and in plants, woody debris, and soils. Fungi, plants, and so...

  18. Carbon flows and economic evaluation of mitigation options in Tanzani's forest sector

    SciTech Connect

    Makundi, W.R.; Okinting'Ati, Aku

    1995-02-02

    This paper presents estimates of the rate of forest use, deforestation and forest degradation, as well as the corresponding carbon flows, in the Tanzanian forest sector. It is estimated that the country lost 525,000 ha of forests in 1990, with associated committed emissions of 31.5 Mt. Carbon (MtC), and 7.05 MtC of committed carbon sequestration. The paper then describes the possible response options in the forest sector to mitigate GHG emissions, and evaluates the most stable subset of these-i.e. forest conservation, woodfuel plantations and agroforestry. The conservation options were found to cost an average of U.S. $1.27 per tonne of carbon (tC) conserved. Five options for fuelwood plantations and agroforestry, with two different ownership regimes were evaluated. Each one of the options gives a positive net present value at low rates of discount, ranging from U.S. $1.06 to 3.4/1C of avoided emissions at 0 percent discount rate. At 10 percent discount, the eucalyptus and maize option has a highest PNV of U.S. $1.73 tC, and the government plantation gives a negative PNV (loss) of U.S. $0.13 tC sequestered. The options with a private/community type of ownership scheme fared better than government run options. This conclusion also held true when ranking the options by the BRAC indicator, with the government fuelwood plantation ranked the lowest, and the private agroforestry option of eucalyptus and corn performing best. The mitigation options evaluated here show that the forest sector in Tanzania has one of the most cost-effective GHG mitigation opportunities in the world, and they are within the developmental aspirations of the country.

  19. Evaluating the risk of air pollution to forests in central and Eastern Europe

    SciTech Connect

    Ellsworth, D.S.; Oleksyn, J.

    1996-09-01

    Foliar damage to trees by air pollution in Central and Eastern Europe has been a major scientific and political issue. Emissions of toxic gases such as sulfur dioxide and nitrogen oxides can have wide-ranging effects on local and regional vegetation that can be compounded by other environmental stresses to plant growth. Since uptake and physiological effects of these gases on tree leaves we largely, mediated by stomata, surrogate methods for estimating pollutant conductances into leaves and forest canopies may lead to risk assessments for major vegetation types that can then be used in regional planning. Management options to ameliorate or mitigate air pollutant damage to forests and losses in productivity are likely to be more difficult to widely implement than on-the-stack emissions abatement. Informed management and policy decisions regarding Central and Eastern European forests are dependent on the development of quantitative tools and models for risk assessment of the effects of atmospheric pollutants on ecosystem health and productivity.

  20. Interactive effects of ozone and climate on tree growth and water use in a southern Appalachian forest in the USA

    SciTech Connect

    McLaughlin, Samuel B.; Nosal, M.; Wullschleger, Stan D; Sun, G.

    2007-01-01

    Summary: {sm_bullet}Documentation of the degree and direction of effects of ozone on transpiration of canopies of mature forest trees is critically needed to model ozone effects on forest water use and growth in a warmer future climate. {sm_bullet}Patterns of sap flow in stems and soil moisture in the rooting zones of mature trees, coupled with late-season streamflow in three forested watersheds in east Tennessee, USA, were analyzed to determine relative influences of ozone and other climatic variables on canopy physiology and streamflow patterns.{sm_bullet}Statistically significant increases in whole-tree canopy conductance, depletion of soil moisture in the rooting zone, and reduced late-season streamflow in forested watersheds were detected in response to increasing ambient ozone levels. {sm_bullet}Short-term changes in canopy water use and empirically modeled streamflow patterns over a 23-yr observation period suggest that current ambient ozone exposures may exacerbate the frequency and level of negative effects of drought on forest growth and stream health.

  1. Characterizing Growth Patterns of Early-successional Forests Using Phenological Parameters Derived from Near-daily Satellite Data

    NASA Astrophysics Data System (ADS)

    Briggs, K. M.; Cohen, W. B.; Gao, F.

    2011-12-01

    Satellite-based remote sensing data has proven to be useful for monitoring regrowth trajectories of early-successional forest stands after disturbance. Traditionally, forest recovery has been monitored with annual images acquired during the peak of the growing season. Our research will expand upon these previous research efforts through the use of near-daily imagery to track regrowth trajectories in young stands (disturbed between 1985 and 1990) in the Blue River watershed in Oregon's western Cascade mountains. To monitor forest regrowth with high temporal frequency at the fine scales required of the fragmented and heterogeneous landscape of the study region, the STARFM fusion algorithm will be used to blend frequent, coarse-scale MODIS images (near-daily at 500m) with infrequent, fine-scale Landsat images (16-day interval at 30m) to produce near-daily, 30m resolution images. Our goal is to determine how the additional information provided by high frequency synthetic Landsat data can improve the monitoring of changes in vegetation type and forest structure during forest regrowth. The changes in the annual spectral signatures of forest stands, due to phenology, will provide a basis for which variability in vegetation type and structure will be analyzed. Furthermore, this research will also allow us to evaluate the effectiveness of using STARFM in the heterogeneous forests and complex topography of Oregon's western Cascades.

  2. Effectiveness of Nature Reserve System for Conserving Tropical Forests: A Statistical Evaluation of Hainan Island, China

    PubMed Central

    Wang, Wei; Pechacek, Peter; Zhang, Mingxia; Xiao, Nengwen; Zhu, Jianguo; Li, Junsheng

    2013-01-01

    Evaluating the effectiveness of existing nature reserve systems for the conservation of tropical forests is an urgent task to save the remaining biodiversity. Here, we tested the effectiveness of the reserve system on Hainan Island by conducting a three-way comparison of changes in forest area in locations within the reserves, adjacent to the reserves, and far outside of the reserves. We used a general linear model to control for the effects of covariates (historical forest area, elevation, slope, and distance to nearest roads), which may also be correlated with the changes in forest area, to better explain the effectiveness of the reserve system. From 2000 to 2010, the forest area inside Hainan’s nature reserve system showed an increase while adjacent unprotected areas and the wider, unprotected landscape both experienced deforestation. However, the simple inside-outside comparisons may overestimate the protective effect of the reserve system. Most nature reserves (>60%) showed increasing fragmentation. And the risk of rapid deforestation remained high at low elevations, where remaining forests tend to be easily logged and converted to commercial plantations. Future conservation efforts should pay more attention to those sites with less challenging environmental conditions. PMID:23469024

  3. Effectiveness of nature reserve system for conserving tropical forests: a statistical evaluation of Hainan Island, China.

    PubMed

    Wang, Wei; Pechacek, Peter; Zhang, Mingxia; Xiao, Nengwen; Zhu, Jianguo; Li, Junsheng

    2013-01-01

    Evaluating the effectiveness of existing nature reserve systems for the conservation of tropical forests is an urgent task to save the remaining biodiversity. Here, we tested the effectiveness of the reserve system on Hainan Island by conducting a three-way comparison of changes in forest area in locations within the reserves, adjacent to the reserves, and far outside of the reserves. We used a general linear model to control for the effects of covariates (historical forest area, elevation, slope, and distance to nearest roads), which may also be correlated with the changes in forest area, to better explain the effectiveness of the reserve system. From 2000 to 2010, the forest area inside Hainan's nature reserve system showed an increase while adjacent unprotected areas and the wider, unprotected landscape both experienced deforestation. However, the simple inside-outside comparisons may overestimate the protective effect of the reserve system. Most nature reserves (>60%) showed increasing fragmentation. And the risk of rapid deforestation remained high at low elevations, where remaining forests tend to be easily logged and converted to commercial plantations. Future conservation efforts should pay more attention to those sites with less challenging environmental conditions. PMID:23469024

  4. Induced precipitation recycling (IPR) strategy to increase forest growth and regional rainfall

    NASA Astrophysics Data System (ADS)

    Layton, K. M.; Ellison, D.

    2013-12-01

    This presentation describes a project designed to capitalize on observed natural interactions between forest cover and the hydrologic cycle in order to increase available water supplies in arid regions, and to purify degraded water resources. An approach is presented to transition observed precipitation recycling effects into practical applications. Higher regional precipitation can be induced by promoting favorable conditions through afforestation and the irrigation of afforested land (IPR). Waste-water streams processed by the forest can increase local precipitation through the by-product evapotranspiration (ET). The proposed project illustrates how increased runoff from induced precipitation can help mitigate chronic regional water shortages in Southern California, using available degraded water resources. Each day, several hundred million gallons of treated sewage and excess storm water from the Los Angeles basin are channeled to the ocean for disposal. A portion of this can irrigate afforested land, initiating the IPR process. The afforested site likewise produces additional beneficial ecosystem services including nutrient management (of the sewage stream), carbon sequestration (from new growth), cooling of urban 'heat islands', and flood control. Research will explore interactions between ET plumes and local geography to aid the selection of afforestation sites and ensure increased precipitation over land, supporting the regional water supply. The IPR project is designed to manage risk and complexity through phased implementation. While no unproven technologies are used, there are uncertainties in applying theories from scientific research. During the 'pilot phase', initial afforestation site(s) will support research to examine the interactions of irrigated forest cover and IPR. As a proof of concept, this will develop the analytical basis for large-scale expansion. Once the theoretical foundation has been established, the project can expand to more irrigated

  5. Evaluation of Algorithms for Calculating Forest Micrometeorological Variables Using an Extensive Dataset of Paired Station Recordings

    NASA Astrophysics Data System (ADS)

    Garvelmann, J.; Pohl, S.; Warscher, M.; Mair, E.; Marke, T.; Strasser, U.; Kunstmann, H.

    2015-12-01

    Forests represent significant areas of subalpine environments and their influence is crucial for the snow cover dynamics on the ground. Since measurements of major micrometeorological variables are usually lacking for forested sites, physically based or empirical parameterizations are usually applied to calculate the beneath-canopy micrometeorological conditions for snow hydrological modeling. Most of these parameterizations have been developed from observations at selected long-term climate stations. Consequently, the high spatial variability of the micrometeorological variables is usually not taken into account. The goal of this study is to evaluate existing approaches using an extensive dataset collected during five winter seasons using a stratified sampling design with pairs of snow monitoring stations (SnoMoS) at open/forested sites in three study areas (Black Forest region of SW Germany, Brixenbach catchment in the Austrian Alps and the Berchtesgadener Ache catchment in the Berchtesgaden Alps of SE Germany). In total, recordings from 110 station pairs were available for analysis. The measurements of air temperature, relative humidity, wind speed and global radiation from the open field sites were used to calculate the adjacent inside forest conditions. Calculation results are compared to the respective beneath-canopy measurements in order to evaluate the applied model algorithms. The results reveal that the algorithms surprisingly well reproduced the inside canopy conditions for wind speed and global radiation. However, air temperature and relative humidity are not well reproduced. Our study comes up with a modification of the two respective parameterizations developed from the paired measurements.

  6. Seed predation by insects in tropical mangrove forests: extent and effects on seed viability and the growth of seedlings.

    PubMed

    Robertson, A I; Giddins, R; Smith, T J

    1990-06-01

    Although insects are known to be important seed predators in most terrestrial forests, their role in marine tidal (mangrove) forests has not been examined. Surveys at 12 sites in tropical Australia showed that between 3.1 and 92.7 percent of the seeds or propagules of 12 mangrove tree species had been attacked by insects. Seeds/propagules of six species (Avicennia marina, Bruguiera gymnorrhiza, B. parviflora, Heritiera littoralis, Xylocarpus australasicus and X. granatum) showed consistently high (>40%) levels of insect damage. Greater than 99% of H. littoralis seeds were attacked by insect predators. The survival and subsequent growth in height and biomass of insect-damaged and non-damaged control seeds/propagules of eight mangrove species were compared in shadehouse experiments. Mangrove species fell into 4 groups with regard to the effect of insect predators on their seeds and seedlings. Xylocarpus australasicus and X. granatum had significantly decreased survival (X 48 and 70%) and growth in height (X 61 and 96%) and biomass (X 66 and 85%). Bruguiera parviflora showed decreased survival (X 59%), but there was no effect of insects on the growth of surviving propagules. In contrast, there was no effect of insect damage on the survival of seedlings of Avicennia marina and Bruguiera exaristata, but decreased growth in height (X 22 and 25%) and biomass (X 22 and 26%). Survival and growth of seedlings of Rhizophora stylosa and Bruguiera gymnorrhiza were not affected. The influence of insect seed predators on the survival and growth of seeds of mangrove species in forests will depend on the relative abundance of seed-eating crabs and intertidal position in mangrove forests. PMID:22160114

  7. Evaluation: Rx for Counseling Program Growth.

    ERIC Educational Resources Information Center

    Keene, Kathleen MacIntosh; Stewart, Norman R.

    1989-01-01

    Addresses the basic issues faced, methods used, and problems encountered in evaluating school counseling services. Gives examples and suggestions to assist in learning about evaluation. Contends that counselors have the requisite skills and should be involved in evaluation of the services they provide. (NB)

  8. A Comprehensive Evaluation of the Supreme Court's "Forest Grove" Decision?

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2013-01-01

    The article by Dixon, Eusebio, Turton, Wright, and Hale is entitled "Forest Grove School District v. T.A. Supreme Court Case: Implications for School Psychology Practice." Its implications are that a "comprehensive evaluation" under the Individuals with Disabilities Education Act (IDEA) requires assessment of the child's…

  9. Statewide Strategic Forest Resource Planning Programs: Evaluation Based on Context, Process, Outputs, and Performance.

    ERIC Educational Resources Information Center

    Gray, Gerald J.; Ellefson, Paul V.

    1991-01-01

    Evaluation of strategic planning programs is illustrated using the examples of statewide forest resource planning programs implemented by state governments in 1986. Client-based perspectives were studied via a survey of 216 officials affected by the forestry planning program. Considering planning's context, process, outputs, and performance helped…

  10. Wood phenology, not carbon input, controls the interannual variability of wood growth in a temperate oak forest.

    PubMed

    Delpierre, Nicolas; Berveiller, Daniel; Granda, Elena; Dufrêne, Eric

    2016-04-01

    Although the analysis of flux data has increased our understanding of the interannual variability of carbon inputs into forest ecosystems, we still know little about the determinants of wood growth. Here, we aimed to identify which drivers control the interannual variability of wood growth in a mesic temperate deciduous forest. We analysed a 9-yr time series of carbon fluxes and aboveground wood growth (AWG), reconstructed at a weekly time-scale through the combination of dendrometer and wood density data. Carbon inputs and AWG anomalies appeared to be uncorrelated from the seasonal to interannual scales. More than 90% of the interannual variability of AWG was explained by a combination of the growth intensity during a first 'critical period' of the wood growing season, occurring close to the seasonal maximum, and the timing of the first summer growth halt. Both atmospheric and soil water stress exerted a strong control on the interannual variability of AWG at the study site, despite its mesic conditions, whilst not affecting carbon inputs. Carbon sink activity, not carbon inputs, determined the interannual variations in wood growth at the study site. Our results provide a functional understanding of the dependence of radial growth on precipitation observed in dendrological studies. PMID:26619197

  11. Motivating and Evaluating Growth in Ballet Technique

    ERIC Educational Resources Information Center

    White, Julie Hammond

    2012-01-01

    In teaching young dancers ballet, the utilization of effective assessments in partnership with supportive and creative teaching strategies can transform not only the learning experience, but the dancer as well. In this article, the author shares a "growth grade rubric" that specifically addresses three areas in ballet training: (1) skills and…

  12. Disparate effects of global-change drivers on mountain conifer forests: warming-induced growth enhancement in young trees vs. CO2 fertilization in old trees from wet sites.

    PubMed

    Camarero, J Julio; Gazol, Antonio; Galván, Juan Diego; Sangüesa-Barreda, Gabriel; Gutiérrez, Emilia

    2015-02-01

    Theory predicts that the postindustrial rise in the concentration of CO2 in the atmosphere (c(a)) should enhance tree growth either through a direct fertilization effect or indirectly by improving water use efficiency in dry areas. However, this hypothesis has received little support in cold-limited and subalpine forests where positive growth responses to either rising ca or warmer temperatures are still under debate. In this study, we address this issue by analyzing an extensive dendrochronological network of high-elevation Pinus uncinata forests in Spain (28 sites, 544 trees) encompassing the whole biogeographical extent of the species. We determine if the basal area increment (BAI) trends are linked to climate warming and increased c(a) by focusing on region- and age-dependent responses. The largest improvement in BAI over the past six centuries occurred during the last 150 years affecting young trees and being driven by recent warming. Indeed, most studied regions and age classes presented BAI patterns mainly controlled by temperature trends, while growing-season precipitation was only relevant in the driest sites. Growth enhancement was linked to rising ca in mature (151-300 year-old trees) and old-mature trees (301-450 year-old trees) from the wettest sites only. This finding implies that any potential fertilization effect of elevated c(a) on forest growth is contingent on tree features that vary with ontogeny and it depends on site conditions (for instance water availability). Furthermore, we found widespread growth decline in drought-prone sites probably indicating that the rise in ca did not compensate for the reduction in water availability. Thus, warming-triggered drought stress may become a more important direct driver of growth than rising ca in similar subalpine forests. We argue that broad approaches in biogeographical and temporal terms are required to adequately evaluate any effect of rising c(a) on forest growth. PMID:25362899

  13. Facilitative-competitive interactions in an old-growth forest: the importance of large-diameter trees as benefactors and stimulators for forest community assembly.

    PubMed

    Fichtner, Andreas; Forrester, David I; Härdtle, Werner; Sturm, Knut; von Oheimb, Goddert

    2015-01-01

    The role of competition in tree communities is increasingly well understood, while little is known about the patterns and mechanisms of the interplay between above- and belowground competition in tree communities. This knowledge, however, is crucial for a better understanding of community dynamics and developing adaptive near-natural management strategies. We assessed neighbourhood interactions in an unmanaged old-growth European beech (Fagus sylvatica) forest by quantifying variation in the intensity of above- (shading) and belowground competition (crowding) among dominant and co-dominant canopy beech trees during tree maturation. Shading had on average a much larger impact on radial growth than crowding and the sensitivity to changes in competitive conditions was lowest for crowding effects. We found that each mode of competition reduced the effect of the other. Increasing crowding reduced the negative effect of shading, and at high levels of shading, crowding actually had a facilitative effect and increased growth. Our study demonstrates that complementarity in above- and belowground processes enable F. sylvatica to alter resource acquisition strategies, thus optimising tree radial growth. As a result, competition seemed to become less important in stands with a high growing stock and tree communities with a long continuity of anthropogenic undisturbed population dynamics. We suggest that growth rates do not exclusively depend on the density of potential competitors at the intraspecific level, but on the conspecific aggregation of large-diameter trees and their functional role for regulating biotic filtering processes. This finding highlights the potential importance of the rarely examined relationship between the spatial aggregation pattern of large-diameter trees and the outcome of neighbourhood interactions, which may be central to community dynamics and the related forest ecosystem services. PMID:25803035

  14. Tropical rain forest tree growth and atmospheric carbon dynamics linked to interannual temperature variation during 1984-2000.

    PubMed

    Clark, D A; Piper, S C; Keeling, C D; Clark, D B

    2003-05-13

    During 1984-2000, canopy tree growth in old-growth tropical rain forest at La Selva, Costa Rica, varied >2-fold among years. The trees' annual diameter increments in this 16-yr period were negatively correlated with annual means of daily minimum temperatures. The tree growth variations also negatively covaried with the net carbon exchange of the terrestrial tropics as a whole, as inferred from nearly pole-to-pole measurements of atmospheric carbon dioxide (CO(2)) interpreted by an inverse tracer-transport model. Strong reductions in tree growth and large inferred tropical releases of CO(2) to the atmosphere occurred during the record-hot 1997-1998 El Niño. These and other recent findings are consistent with decreased net primary production in tropical forests in the warmer years of the last two decades. As has been projected by recent process model studies, such a sensitivity of tropical forest productivity to on-going climate change would accelerate the rate of atmospheric CO(2) accumulation. PMID:12719545

  15. Contrasting Spatial Patterns in Active-Fire and Fire-Suppressed Mediterranean Climate Old-Growth Mixed Conifer Forests

    PubMed Central

    Fry, Danny L.; Stephens, Scott L.; Collins, Brandon M.; North, Malcolm P.; Franco-Vizcaíno, Ernesto; Gill, Samantha J.

    2014-01-01

    In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha−1, and occupied 27–46% of the study areas. Average canopy gap sizes (0.04 ha) covering 11–20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥56%) in large patches (≥10 trees), and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types. PMID:24586472

  16. Evaluating the Potential of Satellite Hyperspectral Resurs-P Data for Forest Species Classification

    NASA Astrophysics Data System (ADS)

    Brovkina, O.; Hanuš, J.; Zemek, F.; Mochalov, V.; Grigorieva, O.; Pikla, M.

    2016-06-01

    Satellite-based hyperspectral sensors provide spectroscopic information in relatively narrow contiguous spectral bands over a large area which can be useful in forestry applications. This study evaluates the potential of satellite hyperspectral Resurs-P data for forest species mapping. Firstly, a comparative study between top of canopy reflectance obtained from the Resurs-P, from the airborne hyperspectral scanner CASI and from field measurement (FieldSpec ASD 4) on selected vegetation cover types is conducted. Secondly, Resurs-P data is tested in classification and verification of different forest species compartments. The results demonstrate that satellite hyperspectral Resurs-P sensor can produce useful informational and show good performance for forest species classification comparable both with forestry map and classification from airborne CASI data, but also indicate that developments in pre-processing steps are still required to improve the mapping level.

  17. Rapid Structural and Compositional Change in an Old-Growth Subtropical Forest: Using Plant Traits to Identify Probable Drivers

    PubMed Central

    Malizia, Agustina; Easdale, Tomás A.; Grau, H. Ricardo

    2013-01-01

    Recent studies have shown directional changes in old-growth tropical forests, but changes are complex and diverse, and their drivers unclear. Here, we report rapid net structural and compositional changes in an old-growth subtropical forest and we assess the functional nature of these changes to test hypothetical drivers including recovery from past disturbances, reduction in ungulate browsing, CO2 fertilization, and increases in rainfall and temperature. The study relies on 15 years of demographic monitoring within 8 ha of subtropical montane forest in Argentina. Between 1992 and 2007, stem density markedly increased by 50% (12 stems ha−1 y−1) and basal area by 6% (0.13 m2 ha−1 y−1). Increased stem density resulted from enhanced recruitment of understory treelets (Piper tucumanum, Eugenia uniflora, Allophylus edulis) into small size classes. Among 27 common tree species, net population growth was negatively correlated with maximum tree size and longevity, and positively correlated with leaf size and leaf nutrient content, especially so when initial population size was controlled for. Changes were inconsistent with predictions derived from past disturbances (no increase in shade-tolerant or long-lived late-succesional species), rainfall or temperature increase (no increase in evergreen or deciduous species, respectively). However, the increase in nutrient-rich soft-leaved species was consistent with exclusion of large herbivores two decades before monitoring started; and CO2 fertilization could help explain the disproportionate increase in small stems. Reductions in populations of large vertebrates have been observed in many otherwise undisturbed tropical forests, and our results suggest they can have important structural and functional repercussions in these forests. PMID:24069204

  18. Rapid structural and compositional change in an old-growth subtropical forest: using plant traits to identify probable drivers.

    PubMed

    Malizia, Agustina; Easdale, Tomás A; Grau, H Ricardo

    2013-01-01

    Recent studies have shown directional changes in old-growth tropical forests, but changes are complex and diverse, and their drivers unclear. Here, we report rapid net structural and compositional changes in an old-growth subtropical forest and we assess the functional nature of these changes to test hypothetical drivers including recovery from past disturbances, reduction in ungulate browsing, CO2 fertilization, and increases in rainfall and temperature. The study relies on 15 years of demographic monitoring within 8 ha of subtropical montane forest in Argentina. Between 1992 and 2007, stem density markedly increased by 50% (12 stems ha(-1) y(-1)) and basal area by 6% (0.13 m(2) ha(-1) y(-1)). Increased stem density resulted from enhanced recruitment of understory treelets (Piper tucumanum, Eugenia uniflora, Allophylus edulis) into small size classes. Among 27 common tree species, net population growth was negatively correlated with maximum tree size and longevity, and positively correlated with leaf size and leaf nutrient content, especially so when initial population size was controlled for. Changes were inconsistent with predictions derived from past disturbances (no increase in shade-tolerant or long-lived late-succesional species), rainfall or temperature increase (no increase in evergreen or deciduous species, respectively). However, the increase in nutrient-rich soft-leaved species was consistent with exclusion of large herbivores two decades before monitoring started; and CO2 fertilization could help explain the disproportionate increase in small stems. Reductions in populations of large vertebrates have been observed in many otherwise undisturbed tropical forests, and our results suggest they can have important structural and functional repercussions in these forests. PMID:24069204

  19. Relationship between types of urban forest and PM2.5 capture at three growth stages of leaves.

    PubMed

    Nguyen, Thithanhthao; Yu, Xinxiao; Zhang, Zhenming; Liu, Mengmeng; Liu, Xuhui

    2015-01-01

    Particulate matter diameter ≤ 2.5 μm (PM2.5) causes direct harm to human health. Finding forms of urban forest systems that with the ability to reduce the amount of particulate matter in air effectively is the aim of this study. Five commonly cultivated kinds of urban forest types were studied in Beijing city at three stages of leaf growth. Results show that the urban forest system is capable of storing and capturing dust from the air. The types of shrubs and broadleaf trees that have the ability to capture PM2.5 from the air are most effective when leaves have fully developed. In the leafless season, the conifer and mixed tree types are the most effective in removing dust from the air. For all kinds of forest types and stages of leaf growth, the PM2.5 concentration is highest in the morning but lower in the afternoon and evening. Grassland cannot control particles suspended in the air, but can reduce dust pollution caused by dust from the ground blown by the wind back into the air. PMID:25597660

  20. Effects of forest management on density, survival, and population growth of wood thrushes

    USGS Publications Warehouse

    Powell, L.A.; Lang, J.D.; Conroy, M.J.; Krementz, D.G.

    2000-01-01

    Loss and alteration of breeding habitat have been proposed as causes of declines in several Neotropical migrant bird populations. We conducted a 4-year study to determine the effects of winter prescribed burning and forest thinning on breeding wood thrush (Hylocichla mustelina) populations at the Piedmont National Wildlife Refuge (PNWR) in Georgia. We estimated density, adult and juvenile survival rates, and apparent annual survival using transect surveys, radiotelemetry, and mist netting. Burning and thinning did not cause lower densities (P = 0.25); wood thrush density ranged from 0.15 to 1.30 pairs/10 ha. No radiomarked male wood thrushes (n = 68) died during the 4 years, but female (n = 63) weekly survival was 0.981 ? 0.014 (SE) for females (n = 63) and 0.976 ? 0.010 for juveniles (n = 38). Apparent annual adult survival was 0.579 (SE = 0.173). Thinning and prescribed burning did not reduce adult or juvenile survival during the breeding season or apparent annual adult survival. Annual population growth (lambda) at PNWR was 1.00 (95% confidence interval = 0.32--1.63), and the considerable uncertainty in this prediction underscores the need for long term monitoring to effectively manage Neotropical migrants. Population growth increased on experimental compartments after the burn and thin (95% CI before = 0.91--0.97, after = 0.98--1.05), while control compartment declined (before = 0.98--1.05, after = 0.87--0.92). We found no evidence that the current management regime at PNWR, designed to improve red-cockaded woodpecker (Picoides borealis) habitat, negatively affected wood thrushes.

  1. Hydraulic redistribution of soil water in two old-growth coniferous forests: quantifying patterns and controls.

    PubMed

    Warren, Jeffrey M; Meinzer, Frederick C; Brooks, J Renée; Domec, Jean-Christophe; Coulombe, Rob

    2007-01-01

    Although hydraulic redistribution of soil water (HR) by roots is a widespread phenomenon, the processes governing spatial and temporal patterns of HR are not well understood. We incorporated soil/plant biophysical properties into a simple model based on Darcy's law to predict seasonal trajectories of HR. We investigated the spatial and temporal variability of HR across multiple years in two old-growth coniferous forest ecosystems with contrasting species and moisture regimes by measurement of soil water content (theta) and water potential (Psi) throughout the upper soil profile, root distribution and conductivity, and relevant climate variables. Large HR variability within sites (0-0.5 mm d(-1)) was attributed to spatial patterns of roots, soil moisture and depletion. HR accounted for 3-9% of estimated total site water depletion seasonally, peaking at 0.16 mm d(-1) (ponderosa pine; Pinus ponderosa) or 0.30 mm d(-1) (Douglas-fir; Pseudotsuga menziesii), then declining as modeled pathway conductance dropped with increasing root cavitation. While HR can vary tremendously within a site, among years and among ecosystems, this variability can be explained by natural variability in Psi gradients and seasonal courses of root conductivity. PMID:17286824

  2. Remote Sensing and GIS Based Risk Index Map For Predicting Forest Fire Danger - Evaluation From Forestry Datasets, India

    NASA Astrophysics Data System (ADS)

    Prasad, V. K.; Badarinath, K. V. S.

    Forest fires constitute one of the most serious ecological as well as environmental problems affecting most vegetation zones across the world, including India. In this study, we evaluated forest fire risk for sixteen different forest and vegetation types of India. Data from Normalized Difference Vegetation Index (NDVI) from NOAA AVHRR data has been integrated with bioclimatic data and fuel value index to quantify the forest fire risk. Biomass data for different forest types in different pools has been used as ancillary data. In using the fuel value index, calorific value of wood content for 60 species has been collected and aggregated, for specific species. Results from NDVI and precipitation correlations were found to be highly significant for tropical dry deciduous and moist deciduous forests. Spatial patterns in NDVI closely followed seasonal trends in precipitation for most of the forests. An integrated GIS framework with biophysical, biomass, thermo chemical and bioclimatic parameters allowed the calculation of risk indices for the different forest types. The methodology followed in the study and the maps produced are found to be useful for evaluating forest fire risk and for predicting forest fire danger in different vegetation zones in India.

  3. Root systems of successional and old-growth forest species and its role on nutrient dynamics within a tropical rainforest in Indonesia

    SciTech Connect

    Soedjito, H.

    1990-01-01

    Most studies of nutrient dynamics in tropical rainforest have focused on the above ground portion of forest trees. However, the aim of this dissertation is to demonstrate the root systems also play an important role in nutrient dynamics. Nutrient dynamics, in general, are likely to differ between successional forest and old-growth forest. To test for differences in nutrient uptake between trees of successional and old-growth forests, the author experimentally compared seedlings of six different species by measuring biomass allocation and nutrient concentrations as well as determining spatial patterns of root distribution and the absorption ability of the root systems by usign the [sup 32]P radiotracer technique. Young saplings of ten species from natural habitats were also examined for the same parameters, and the results to determine whether results of the laboratory experiments were consistent with field results. It was found that as seedlings, roots of successional forest species penetrate deeper into the soil and have longer lateral roots than old-growth forest species. Successional forest species also had greater biomass accumulation rates, higher ability to absorb [sup 32]P, and contained higher levels of nutrients than species of old-growth forest. Mycorrhizal associations are suspected to be responsible for the high nutrient concentrations, primarily of P and N, within successional species. Successional forest tree species had more cases of infection by vesicular arbuscular mycorrhizas (VAM), while old-growth forest species were infected by both VAM and ectomycorrhizas. Therefore, successional seedlings can play an important role in conserving released nutrients after disturbance. At the landscape level, successional species together with old-growth species can maintain sustainable nutrient cycling within tropical rainforests.

  4. Building a Culture of Growth and Evaluation in Schools

    ERIC Educational Resources Information Center

    Hall, Catherine J.

    2013-01-01

    This author contends that there are four key ingredients to a growth mindset in schools: observation, dialog, feedback, and investment. In addition, teachers and supervisors need to be jointly invested in the growth mindset of the school. The author suggests that if a school is considering a new faculty evaluation system, it is crucial that…

  5. Evaluating the Predictive Value of Growth Prediction Models

    ERIC Educational Resources Information Center

    Murphy, Daniel L.; Gaertner, Matthew N.

    2014-01-01

    This study evaluates four growth prediction models--projection, student growth percentile, trajectory, and transition table--commonly used to forecast (and give schools credit for) middle school students' future proficiency. Analyses focused on vertically scaled summative mathematics assessments, and two performance standards conditions (high…

  6. Longevity of Wood-Forced Pools in an Old-Growth Forest

    NASA Astrophysics Data System (ADS)

    Buffington, J. M.; Woodsmith, R. D.; Johnson, A. C.

    2009-12-01

    Wood debris plays an important role in scouring pools in forest channels and providing resultant habitat for aquatic organisms. We investigated the longevity of such pools in a gravel-bed river flowing through old-growth forest in southeastern Alaska by aging trees and “bear’s bread” fungi (Ganoderma applanatum, Fomitopsis pinicola) growing on pool-forming wood debris. Ages were determined by counting annual growth rings from cores and cross sections of trees and fungi growing on the wood debris. These ages are minimum values because they do not account for lag time between debris recruitment and seedling/spore establishment on the debris, nor do they account for flood scour that may periodically reset tree and fungi growth on the debris. The study stream has a gradient of about 1%, bankfull width and depth of 13.3 and 0.78 m, respectively, median grain size of 18 mm, a high wood loading (0.8 pieces/m), and a correspondingly low pool spacing (0.3 bankfull widths/pool), with 81% of the pools forced by wood debris. The size of wood debris in the study stream is large relative to the channel (average log length of 7.6 m and diameter of 0.35 m), rendering most debris immobile. Eighty-one pool-forming pieces of wood were dated over 1.2 km of stream length, with 28% of these pieces causing scour of more than one pool. In all, 122 wood-forced pools were dated, accounting for 38% of all pools at the site and 47% of the wood-forced pools. Fifty-three percent of the wood-forced pools lacked datable wood because these pieces either: were newly recruited; had been scoured by floods; or were contained below the active channel elevation, prohibiting vegetation establishment on the wood debris (the most common cause). The debris age distribution declined exponentially from 2 to 113 yrs., with a median value of 18 yrs. Similar exponential residence time distributions have been reported in other studies, but our analysis focused specifically on the ages of pool-forming wood

  7. Forest tree growth response to hydroclimate variability in the southern Appalachians.

    PubMed

    Elliott, Katherine J; Miniat, Chelcy F; Pederson, Neil; Laseter, Stephanie H

    2015-12-01

    Climate change will affect tree species growth and distribution; however, under the same climatic conditions species may differ in their response according to site conditions. We evaluated the climate-driven patterns of growth for six dominant deciduous tree species in the southern Appalachians. We categorized species into two functional groups based on their stomatal regulation and xylem architecture: isohydric, diffuse porous and anisohydric, ring porous. We hypothesized that within the same climatic regime: (i) species-specific differences in growth will be conditional on topographically mediated soil moisture availability; (ii) in extreme drought years, functional groups will have markedly different growth responses; and (iii) multiple hydroclimate variables will have direct and indirect effects on growth for each functional group. We used standardized tree-ring chronologies to examine growth of diffuse-porous (Acer, Liriodendron, and Betula) and ring-porous (Quercus) species vs. on-site climatic data from 1935 to 2003. Quercus species growing on upslope sites had higher basal area increment (BAI) than Quercus species growing on mesic, cove sites; whereas, Acer and Liriodendron had lower BAI on upslope compared to cove sites. Diffuse-porous species were more sensitive to climate than ring porous, especially during extreme drought years. Across functional groups, radial growth was more sensitive to precipitation distribution, such as small storms and dry spell length (DSL), rather than the total amount of precipitation. Based on structural equation modeling, diffuse-porous species on upslope sites were the most sensitive to multiple hydroclimate variables (r(2)  = 0.46), while ring-porous species on upslope sites were the least sensitive (r(2)  = 0.32). Spring precipitation, vapor pressure deficit, and summer storms had direct effects on summer AET/P, and summer AET/P, growing season small storms and DSL partially explained growth. Decreasing numbers of

  8. New foliage growth is a significant, unaccounted source for volatiles in boreal evergreen forests

    NASA Astrophysics Data System (ADS)

    Aalto, J.; Kolari, P.; Hari, P.; Kerminen, V.-M.; Schiestl-Aalto, P.; Aaltonen, H.; Levula, J.; Siivola, E.; Kulmala, M.; Bäck, J.

    2014-03-01

    Estimates of volatile organic compound (VOC) emissions from forests are based on the assumption that foliage has a steady emission potential over its lifetime, and that emissions are mainly modified by short-term variations in light and temperature. However, in many field studies this has been challenged, and high emissions and atmospheric concentrations have been measured during periods of low biological activity, such as in springtime. We conducted measurements during three years, using an online gas-exchange monitoring system to observe volatile organic emissions from a mature (1 year-old) and a growing Scots pine shoot. The emission rates of organic vapors from vegetative buds of Scots pine during the dehardening and rapid shoot growth stages were one to two orders of magnitude higher than those from mature foliage; this difference decreased and finally disappeared when the new shoot was maturing in late summer. On average, the springtime monoterpene emission rate of the bud was about 500 times higher than that of the mature needles; during the most intensive needle elongation period, the monoterpene emission rate of the growing needles was 3.5 higher than that of the mature needles, and in September the monoterpene emission rate of the same years' needles was even lower (50%) than that of the previous years' needles. For other measured compounds (methanol, acetone and methylbutenol) the values were of the same order of magnitude, except before bud break in spring, when the emission rates of buds for those compounds were on average about 20-30 times higher than that of mature needles. During spring and early summer the buds and growing shoots are a strong source of several VOCs, and if they are not accounted for in emission modeling a significant proportion of the emissions - from a few percent to even half of the annual cumulative emissions - will remain concealed. The diurnal emission pattern of growing shoots differed from the diurnal cycle in temperature as

  9. Long-term growth-increment chronologies reveal diverse influences of climate forcing on freshwater and forest biota in the Pacific Northwest

    USGS Publications Warehouse

    Black, Bryan A.; Dunham, Jason B.; Blundon, Brett W.; Brim-Box, Jayne; Tepley, Alan J.

    2015-01-01

    Analyses of how organisms are likely to respond to a changing climate have focused largely on the direct effects of warming temperatures, though changes in other variables may also be important, particularly the amount and timing of precipitation. Here, we develop a network of eight growth-increment width chronologies for freshwater mussel species in the Pacific Northwest, United States and integrate them with tree-ring data to evaluate how terrestrial and aquatic indicators respond to hydroclimatic variability, including river discharge and precipitation. Annual discharge averaged across water years (October 1–September 30) was highly synchronous among river systems and imparted a coherent pattern among mussel chronologies. The leading principal component of the five longest mussel chronologies (1982–2003; PC1mussel) accounted for 47% of the dataset variability and negatively correlated with the leading principal component of river discharge (PC1discharge; r = −0.88; P < 0.0001). PC1mussel and PC1discharge were closely linked to regional wintertime precipitation patterns across the Pacific Northwest, the season in which the vast majority of annual precipitation arrives. Mussel growth was also indirectly related to tree radial growth, though the nature of the relationships varied across the landscape. Negative correlations occurred in forests where tree growth tends to be limited by drought while positive correlations occurred in forests where tree growth tends to be limited by deep or lingering snowpack. Overall, this diverse assemblage of chronologies illustrates the importance of winter precipitation to terrestrial and freshwater ecosystems and suggests that a complexity of climate responses must be considered when estimating the biological impacts of climate variability and change.

  10. Long-term growth-increment chronologies reveal diverse influences of climate forcing on freshwater and forest biota in the Pacific Northwest.

    PubMed

    Black, Bryan A; Dunham, Jason B; Blundon, Brett W; Brim-Box, Jayne; Tepley, Alan J

    2015-02-01

    Analyses of how organisms are likely to respond to a changing climate have focused largely on the direct effects of warming temperatures, though changes in other variables may also be important, particularly the amount and timing of precipitation. Here, we develop a network of eight growth-increment width chronologies for freshwater mussel species in the Pacific Northwest, United States and integrate them with tree-ring data to evaluate how terrestrial and aquatic indicators respond to hydroclimatic variability, including river discharge and precipitation. Annual discharge averaged across water years (October 1-September 30) was highly synchronous among river systems and imparted a coherent pattern among mussel chronologies. The leading principal component of the five longest mussel chronologies (1982-2003; PC1(mussel)) accounted for 47% of the dataset variability and negatively correlated with the leading principal component of river discharge (PC1(discharge); r = -0.88; P < 0.0001). PC1(mussel) and PC1(discharge) were closely linked to regional wintertime precipitation patterns across the Pacific Northwest, the season in which the vast majority of annual precipitation arrives. Mussel growth was also indirectly related to tree radial growth, though the nature of the relationships varied across the landscape. Negative correlations occurred in forests where tree growth tends to be limited by drought while positive correlations occurred in forests where tree growth tends to be limited by deep or lingering snowpack. Overall, this diverse assemblage of chronologies illustrates the importance of winter precipitation to terrestrial and freshwater ecosystems and suggests that a complexity of climate responses must be considered when estimating the biological impacts of climate variability and change. PMID:25258169

  11. Evaluation of a 3-D rockfall module within a forest patch model

    NASA Astrophysics Data System (ADS)

    Rammer, W.; Brauner, M.; Dorren, L. K. A.; Berger, F.; Lexer, M. J.

    2010-04-01

    Many slopes in the Alps are prone to rockfall and forests play a vital role in protecting objects such as (rail) roads and infrastructure against rockfall. Decision support tools are required to assess rockfall processes and to quantify the rockfall protection effect of forest stands. This paper presents results of an iterative sequence of tests and improvements of a coupled rockfall and forest dynamics model with focus on the rockfall module. As evaluation data a real-size rockfall experiment in the French Alps and two 2-D rockfall trajectories from Austria and Switzerland were used. Modification of the rebound algorithm and the inclusion of an algorithm accounting for the sudden halt of falling rocks due to surface roughness greatly improved the correspondence between simulated and observed key rockfall variables like run-out distances, rebound heights and jump lengths for the real-size rockfall experiment. Moreover, the observed jump lengths and run-out distances of the 2-D trajectories were well within the stochastic range of variation yielded by the simulations. Based on evaluation results it is concluded that the rockfall model can be employed to assess the protective effect of forest vegetation.

  12. Accelerating forest growth enhancement due to climate and atmospheric changes in British Colombia, Canada over 1956-2001.

    PubMed

    Wu, Chaoyang; Hember, Robbie A; Chen, Jing M; Kurz, Werner A; Price, David T; Boisvenue, Céline; Gonsamo, Alemu; Ju, Weimin

    2014-01-01

    Changes in climate and atmospheric CO2 and nitrogen (N) over the last several decades have induced significant effects on forest carbon (C) cycling. However, contributions of individual factors are largely unknown because of the lack of long observational data and the undifferentiating between intrinsic factors and external forces in current ecosystem models. Using over four decades (1956-2001) of forest inventory data at 3432 permanent samples in maritime and boreal regions of British Columbia (B.C.), Canada, growth enhancements were reconstructed and partitioned into contributions of climate, CO2 and N after removal of age effects. We found that climate change contributed a particularly large amount (over 70%) of the accumulated growth enhancement, while the remaining was attributed to CO2 and N, respectively. We suggest that climate warming is contributing a widespread growth enhancement in B.C.'s forests, but ecosystem models should consider CO2 and N fertilization effects to fully explain inventory-based observations. PMID:24844560

  13. Differential Growth Responses to Water Balance of Coexisting Deciduous Tree Species Are Linked to Wood Density in a Bolivian Tropical Dry Forest

    PubMed Central

    Mendivelso, Hooz A.; Camarero, J. Julio; Royo Obregón, Oriol; Gutiérrez, Emilia; Toledo, Marisol

    2013-01-01

    A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability. PMID:24116001

  14. Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest.

    PubMed

    Mendivelso, Hooz A; Camarero, J Julio; Royo Obregón, Oriol; Gutiérrez, Emilia; Toledo, Marisol

    2013-01-01

    A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability. PMID:24116001

  15. Forest health monitoring: 1991 Georgia indicator evaluation and field study

    SciTech Connect

    Alexander, S.A.; Baldwin, M.; Bechtold, W.A.; Cassell, D.L.; Cline, S.

    1994-03-01

    The pilot study was designed to test methods for quantifying vegetation structure, photosynthetically active radiation (PAR), dendrochronology, and selected root fungi. Testing the methods included comparing different data collection procedures for individual indicators, estimating sampling efficiency (both of the sampling design and the sampling unit design), and evaluating spatial variability. In addition, the accuracy and precision of tree height instruments were determined as part of the pilot study.

  16. Population differentiation in tree-ring growth response of white fir (Abies concolor) to climate: Implications for predicting forest responses to climate change

    SciTech Connect

    Jensen, D.B.

    1993-10-01

    Forest succession models and correlative models have predicted 200--650 kilometer shifts in the geographic range of temperate forests and forest species as one response to global climate change. Few studies have investigated whether population differences may effect the response of forest species to climate change. This study examines differences in tree-ring growth, and in the phenotypic plasticity of tree-ring growth in 16-year old white fir, Abies concolor, from ten populations grown in four common gardens in the Sierra Nevada of California. For each population, tree-ring growth was modelled as a function of precipitation and degree-day sums. Tree-ring growth under three scenarios of doubled C0{sub 2} climates was estimated.

  17. Negative impacts of high temperatures on growth of black spruce forests intensify with the anticipated climate warming.

    PubMed

    Girardin, Martin P; Hogg, Edward H; Bernier, Pierre Y; Kurz, Werner A; Guo, Xiao Jing; Cyr, Guillaume

    2016-02-01

    An increasing number of studies conclude that water limitations and heat stress may hinder the capacity of black spruce (Picea mariana (Mill.) B.S.P.) trees, a dominant species of Canada's boreal forests, to grow and assimilate atmospheric carbon. However, there is currently no scientific consensus on the future of these forests over the next century in the context of widespread climate warming. The large spatial extent of black spruce forests across the Canadian boreal forest and associated variability in climate, demography, and site conditions pose challenges for projecting future climate change responses. Here we provide an evaluation of the impacts of climate warming and drying, as well as increasing [CO2 ], on the aboveground productivity of black spruce forests across Canada south of 60°N for the period 1971 to 2100. We use a new extensive network of tree-ring data obtained from Canada's National Forest Inventory, spatially explicit simulations of net primary productivity (NPP) and its drivers, and multivariate statistical modeling. We found that soil water availability is a significant driver of black spruce interannual variability in productivity across broad areas of the western to eastern Canadian boreal forest. Interannual variability in productivity was also found to be driven by autotrophic respiration in the warmest regions. In most regions, the impacts of soil water availability and respiration on interannual variability in productivity occurred during the phase of carbohydrate accumulation the year preceding tree-ring formation. Results from projections suggest an increase in the importance of soil water availability and respiration as limiting factors on NPP over the next century due to warming, but this response may vary to the extent that other factors such as carbon dioxide fertilization, and respiration acclimation to high temperature, contribute to dampening these limitations. PMID:26507106

  18. Negative impacts of high temperatures on growth of black spruce forests intensify with the anticipated climate warming

    NASA Astrophysics Data System (ADS)

    Girardin, M. P.; Hogg, T.; Kurz, W.; Bernier, P. Y.; Guo, X. J.; Cyr, G.

    2015-12-01

    An increasing number of studies conclude that water limitations and heat stress may hinder the capacity of black spruce (Picea mariana (Mill.) B.S.P.) trees, a dominant species of Canada's boreal forests, to grow and assimilate atmospheric carbon. However, there is currently no scientific consensus on the future of these forests over the next century in the context of widespread climate warming. The large spatial extent of black spruce forests across the Canadian boreal forest and associated variability in climate, demography and site conditions pose challenges for projecting future climate change responses. Here we provide an evaluation of the impacts of climate warming and drying, as well as increasing [CO2], on the aboveground productivity of black spruce forests across Canada south of 60ºN for the period 1971 to 2100. We use a new extensive network of tree-ring data obtained from Canada's National Forest Inventory, spatially-explicit simulations of Net Primary Productivity (NPP) and its drivers, and multivariate statistical modelling. We found that soil water availability is a significant driver of black spruce inter-annual variability in productivity across broad areas of the western to eastern Canadian boreal forest. Inter-annual variability in productivity was also found to be driven by autotrophic respiration in the warmest regions. In most regions, the impacts of soil water availability and respiration on inter-annual variability in productivity occurred during the phase of carbohydrate accumulation the year preceding tree ring formation. Results from projections suggest an increase in the importance of soil water availability and respiration as limiting factors on NPP over the next century due to warming, but this response may vary to the extent that other factors such as carbon dioxide fertilization, and respiration acclimation to high temperature, contribute to dampening these limitations.

  19. Nutrient Limitation on Ecosystem Productivity and Processes of Mature and Old-Growth Subtropical Forests in China

    PubMed Central

    Hou, Enqing; Chen, Chengrong; McGroddy, Megan E.; Wen, Dazhi

    2012-01-01

    Nitrogen (N) is considered the dominant limiting nutrient in temperate regions, while phosphorus (P) limitation frequently occurs in tropical regions, but in subtropical regions nutrient limitation is poorly understood. In this study, we investigated N and P contents and N:P ratios of foliage, forest floors, fine roots and mineral soils, and their relationships with community biomass, litterfall C, N and P productions, forest floor turnover rate, and microbial processes in eight mature and old-growth subtropical forests (stand age >80 yr) at Dinghushan Biosphere Reserve, China. Average N:P ratios (mass based) in foliage, litter (L) layer and mixture of fermentation and humus (F/H) layer, and fine roots were 28.3, 42.3, 32.0 and 32.7, respectively. These values are higher than the critical N:P ratios for P limitation proposed (16–20 for foliage, ca. 25 for forest floors). The markedly high N:P ratios were mainly attributed to the high N concentrations of these plant materials. Community biomass, litterfall C, N and P productions, forest floor turnover rate and microbial properties were more strongly related to measures of P than N and frequently negatively related to the N:P ratios, suggesting a significant role of P availability in determining ecosystem production and productivity and nutrient cycling at all the study sites except for one prescribed disturbed site where N availability may also be important. We propose that N enrichment is probably a significant driver of the potential P limitation in the study area. Low P parent material may also contribute to the potential P limitation. In general, our results provided strong evidence supporting a significant role for P availability, rather than N availability, in determining ecosystem primary productivity and ecosystem processes in subtropical forests of China. PMID:23284873

  20. Fiber 3.0: An ecological growth model for northeastern forest types. Forest Service general technical report (Final)

    SciTech Connect

    Solomon, D.S.; Herman, D.A.; Leak, W.B.

    1995-05-22

    Fiber, a stand projection growth model, simulates the growth and structural development of stands in the Northeast. The internal structure of the model is specified and constructed by the ecological type classifications of sugar maple--ash, beech--red maple, oad--white pine, spruce--fir, hemlock--spruce, and cedar--black spruce. Guidelines are provided on operational procedures for the major commercial species growing on these different ecologic land classifications for a range of even-aged and uneven-aged silvicultural treatments and harvesting schedules.

  1. Linking Topographic, Hydrologic, Climatic, and Ecologic Processes in Semi-arid Forests: an investigation of aboveground growth dynamics

    NASA Astrophysics Data System (ADS)

    Adams, H. R.; Loomis, A. K.; Barnard, H. R.

    2013-12-01

    Topography and climate play an integral role in the spatial variability and annual dynamics of aboveground carbon sequestration. Topographic, climatic, and hydrologic dynamics of a catchment interact to drive vegetation spatial distribution, growth patterns, and physiological processes in the catchment. Despite previous knowledge concerning gradient-theory influences on vegetation spatial distribution, little is known about the specific influence of complex terrain coupled with hydrologic and topo-climatic variation on aboveground biomass, especially in semi-arid forests of the Rocky Mountains. Climate change predictions for the semi-arid west, however, include increased temperatures, more frequent and extreme drought events, and decreases in snow pack all of which put forests at risk of altered species ranges and physiological processes, and susceptibility to disturbance events. In this study, we determine how species-specific tree growth patterns and water use efficiency respond to interannual variability in moisture availability (drought) through the use of dendrochronology techniques and carbon isotopes as a measure of water use efficiency with regard to topography and climate through data collection at 75 forest plots. Preliminary results suggest that tree growth and physiological processes respond directly to topographic and climatic parameters including aspect, elevation, and drought events (p < .05) and species vary in their response to these parameters (p < .05). Carbon isotope analyses indicate no significant difference appears in the water use efficiency of ponderosa pine between a drought year and a non-drought year while lodgepole pine water use efficiency increases significantly in a drought year. Both species, however, experience decreases in growth in drought years (p < .05) and, while aspect is a significant predictor of lodgepole pine tree growth in a wet year (p < .05), it becomes insignificant in a dry year. Varying responses from different

  2. Tree species and size structure of old-growth Douglas-fir forests in central western Oregon, USA

    USGS Publications Warehouse

    Poage, Nathan; Tappeiner, J. C., II

    2005-01-01

    We characterized the structure of 91 old-growth forests dominated by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), using inventory data from recent (1985a??1991) old-growth timber sales in western Oregon. The data were complete counts (i.e., censuses) of all live trees >20 cm diameter at breast height (dbh, measured at 1.4 m above the ground) over a mean area of 17.1 ha at each site. Across all sites, Douglas-fir accounted for 79% of the total basal area (m2/ha) of all species. The average density of trees >100 cm dbh was 19 trees/ha and 90% of these trees were Douglas-fir. Species other than Douglas-fir constituted only about 20% of the total basal area at each old-growth site, on average, but largely accounted for the structural variation between sites. We used multivariate techniques such as cluster analysis, indicator species analysis, and ordination with non-metric multidimensional scaling (NMS) to identify and characterize six structural groups in terms of basal area in different speciesa??diameter classes. Almost 97% of the structural information was captured by the first (r2 = 0.841) and second (r2 = 0.128) NMS ordination axis. Geographic information systems (GIS) analysis and NMS indicated that the structural differences among groups of sites were associated with moisture, temperature, and elevation gradients within the study area. This type of analysis can be used to help define differences among old-growth forests and to set local structural goals for growing forests with old-growth characteristics.

  3. Tropical rain forest structure, tree growth and dynamics along a 2700-m elevational transect in Costa Rica.

    PubMed

    Clark, David B; Hurtado, Johanna; Saatchi, Sassan S

    2015-01-01

    Rapid biological changes are expected to occur on tropical elevational gradients as species migrate upslope or go extinct in the face of global warming. We established a series of 9 1-ha plots in old-growth tropical rainforest in Costa Rica along a 2700 m relief elevational gradient to carry out long-term monitoring of tropical rain forest structure, dynamics and tree growth. Within each plot we mapped, identified, and annually measured diameter for all woody individuals with stem diameters >10 cm for periods of 3-10 years. Wood species diversity peaked at 400-600 m and decreased substantially at higher elevations. Basal area and stem number varied by less than two-fold, with the exception of the 2800 m cloud forest summit, where basal area and stem number were approximately double that of lower sites. Canopy gaps extending to the forest floor accounted for <3% of microsites at all elevations. Height of highest crowns and the coefficient of variation of crown height both decreased with increasing elevation. Rates of turnover of individuals and of stand basal area decreased with elevation, but rates of diameter growth and stand basal area showed no simple relation to elevation. We discuss issues encountered in the design and implementation of this network of plots, including biased sampling, missing key meteorological and biomass data, and strategies for improving species-level research. Taking full advantage of the major research potential of tropical forest elevational transects will require sustaining and extending ground based studies, incorporation of new remotely-sensed data and data-acquisition platforms, and new funding models to support decadal research on these rapidly-changing systems. PMID:25856163

  4. Tropical Rain Forest Structure, Tree Growth and Dynamics along a 2700-m Elevational Transect in Costa Rica

    PubMed Central

    Clark, David B.; Hurtado, Johanna; Saatchi, Sassan S.

    2015-01-01

    Rapid biological changes are expected to occur on tropical elevational gradients as species migrate upslope or go extinct in the face of global warming. We established a series of 9 1-ha plots in old-growth tropical rainforest in Costa Rica along a 2700 m relief elevational gradient to carry out long-term monitoring of tropical rain forest structure, dynamics and tree growth. Within each plot we mapped, identified, and annually measured diameter for all woody individuals with stem diameters >10 cm for periods of 3-10 years. Wood species diversity peaked at 400-600 m and decreased substantially at higher elevations. Basal area and stem number varied by less than two-fold, with the exception of the 2800 m cloud forest summit, where basal area and stem number were approximately double that of lower sites. Canopy gaps extending to the forest floor accounted for <3% of microsites at all elevations. Height of highest crowns and the coefficient of variation of crown height both decreased with increasing elevation. Rates of turnover of individuals and of stand basal area decreased with elevation, but rates of diameter growth and stand basal area showed no simple relation to elevation. We discuss issues encountered in the design and implementation of this network of plots, including biased sampling, missing key meteorological and biomass data, and strategies for improving species-level research. Taking full advantage of the major research potential of tropical forest elevational transects will require sustaining and extending ground based studies, incorporation of new remotely-sensed data and data-acquisition platforms, and new funding models to support decadal research on these rapidly-changing systems. PMID:25856163

  5. Beneath the veil: Plant growth form influences the strength of species richness-productivity relationships in forests

    USGS Publications Warehouse

    Oberle, B.; Grace, J.B.; Chase, J.M.

    2009-01-01

    Aim: Species richness has been observed to increase with productivity at large spatial scales, though the strength of this relationship varies among functional groups. In forests, canopy trees shade understorey plants, and for this reason we hypothesize that species richness of canopy trees will depend on macroclimate, while species richness of shorter growth forms will additionally be affected by shading from the canopy. In this study we test for differences in species richness-productivity relationships (SRPRs) among growth forms (canopy trees, shrubs, herbaceous species) in small forest plots. Location: We analysed 231 plots ranging from 34.0?? to 48.3?? N latitude and from 75.0?? to 124.2?? W longitude in the United States. Methods: We analysed data collected by the USDA Forest Inventory and Analysis program for plant species richness partitioned into different growth forms, in small plots. We used actual evapotranspiration as a macroclimatic estimate of regional productivity and calculated the area of light-blocking tissue in the immediate area surrounding plots for an estimate of the intensity of local shading. We estimated and compared SRPRs for different partitions of the species richness dataset using generalized linear models and we incorporated the possible indirect effects of shading using a structural equation model. Results: Canopy tree species richness increased strongly with regional productivity, while local shading primarily explained the variation in herbaceous plant richness. Shrub species richness was related to both regional productivity and local shading. Main conclusions: The relationship between total forest plant species richness and productivity at large scales belies strong effects of local interactions. Counter to the pattern for overall richness, we found that understorey herbaceous plant species richness does not respond to regional productivity gradients, and instead is strongly influenced by canopy density, while shrub species

  6. Lessons about parks and poverty from a decade of forest loss and economic growth around Kibale National Park, Uganda.

    PubMed

    Naughton-Treves, Lisa; Alix-Garcia, Jennifer; Chapman, Colin A

    2011-08-23

    We use field data linked to satellite image analysis to examine the relationship between biodiversity loss, deforestation, and poverty around Kibale National Park (KNP) in western Uganda, 1996-2006. Over this decade, KNP generally maintained forest cover, tree species, and primate populations, whereas neighboring communal forest patches were reduced by half and showed substantial declines in tree species and primate populations. However, a bad decade for forest outside the park proved a prosperous one for most local residents. Panel data for 252 households show substantial improvement in welfare indicators (e.g., safer water, more durable roof material), with the greatest increases found among those with highest initial assets. A combination of regression analysis and matching estimators shows that although the poor tend to be located on the park perimeter, proximity to the park has no measureable effect on growth of productive assets. The risk for land loss among the poor was inversely correlated with proximity to the park, initial farm size, and decline in adjacent communal forests. We conclude the current disproportionate presence of poor households at the edge of the park does not signal that the park is a poverty trap. Rather, Kibale appears to provide protection against desperation sales and farm loss among those most vulnerable. PMID:21873178

  7. [Evaluation of ecosystem service values of the forests of Shennongjia Nature Reserve].

    PubMed

    Liu, Yong-Jie; Wang, Shi-Chang; Peng, Hao; Li, Zhen-Qing

    2014-05-01

    As an ecological protected area for rare animals and plants in a subtropical forest zone, Shennongjia National Reserve plays an important role in the study of biodiversity in China. By using the market value, shade-price and opportunity-cost methods, the forest ecosystem service values of Shennongjia National Nature Reserve were evaluated, including forest production, recreation and culture, water conservation, soil conservation, gas regulation, environment purification, nutrient circulation and biodiversity conservation. The total value of the Shennongjia Nature Reserve was approximately 204.33 x 10(8) yuan RMB x a(-1). The values of the different functions were in order of biodiversity conservation (68.5%) > soil conservation (12.7%) > recreation and culture (4.9%) > gas regulation (4.8%) > forest production (4.2%) > water conservation (3.9%) > environment purification (0.7%) > nutrient circulation (0.3%). The values with respect to utility were in sequence of unused value (68.5%) > indirect value in use (22.4% ) > direct value in use (9.1%). PMID:25129946

  8. Coordination between growth, phenology and carbon storage in three coexisting deciduous tree species in a temperate forest.

    PubMed

    Klein, Tamir; Vitasse, Yann; Hoch, Günter

    2016-07-01

    In deciduous trees growing in temperate forests, bud break and growth in spring must rely on intrinsic carbon (C) reserves. Yet it is unclear whether growth and C storage occur simultaneously, and whether starch C in branches is sufficient for refoliation. To test in situ the relationships between growth, phenology and C utilization, we monitored stem growth, leaf phenology and stem and branch nonstructural carbohydrate (NSC) dynamics in three deciduous species: Carpinus betulus L., Fagus sylvatica L. and Quercus petraea (Matt.) Liebl. To quantify the role of NSC in C investment into growth, a C balance approach was applied. Across the three species, >95% of branchlet starch was consumed during bud break, confirming the importance of C reserves for refoliation in spring. The C balance calculation showed that 90% of the C investment in foliage (7.0-10.5 kg tree(-1) and 5-17 times the C needed for annual stem growth) was explained by simultaneous branchlet starch degradation. Carbon reserves were recovered sooner than expected, after leaf expansion, in parallel with stem growth. Carpinus had earlier leaf phenology (by ∼25 days) but delayed cambial growth (by ∼15 days) than Fagus and Quercus, the result of a competitive strategy to flush early, while having lower NSC levels. PMID:27126226

  9. Nutrient limitation restricts growth and reproductive output in a tropical montane cloud forest bromeliad: findings from a long-term forest fertilization experiment.

    PubMed

    Lasso, Eloisa; Ackerman, James D

    2013-01-01

    From studies in seasonal lowland tropical forests, bromeliad epiphytes appear to be limited mainly by water, and to a lesser extent by nutrient supply, especially phosphorous. Less is understood about the mineral nutrition of tropical montane cloud forest (TMCF) epiphytes, even though their highest diversity is in this habitat. Nutrient limitation is known to be a key factor restricting forest productivity in TMCF, and if epiphytes are nutritionally linked to their host trees, as has been suggested, we would expect that they are also nutrient limited. We studied the effect of a higher nutrient input on reproduction and growth of the tank bromeliad Werauhia sintenisii in experimental plots located in a TMCF in Puerto Rico, where all macro- and micronutrients had been added quarterly starting in 1989 and continuing throughout the duration of this study. We found that bromeliads growing in fertilized plots were receiving litterfall with higher concentrations of N, P, and Zn and had higher concentrations of P, Zn, Fe, Al, and Na in their vegetative body. The N:P ratios found (fertilized = 27.5 and non-fertilized = 33.8) suggest that W. sintenisii may also be phosphorous limited as are lowland epiphytes. Fertilized plants had slightly longer inflorescences, and more flowers per inflorescence, than non-fertilized plants, but their flowers produced nectar in similar concentrations and quantities. Fertilized plants produced more seeds per fruit and per plant. Frequency of flowering in two consecutive years was higher for fertilized plants than for controls, suggesting that fertilized plants overcome the cost of reproduction more readily than non-fertilized plants. These results provide evidence that TMCF epiphytic bromeliads are nutrient limited like their lowland counterparts. PMID:22767363

  10. Multi-decade biomass dynamics in an old-growth hemlock-northern hardwood forest, Michigan, USA

    PubMed Central

    2014-01-01

    Trends in living aboveground biomass and inputs to the pool of coarse woody debris (CWD) in an undisturbed, old-growth hemlock-northern hardwood forest in northern MI were estimated from multi-decade observations of permanent plots. Growth and demographic data from seven plot censuses over 47 years (1962–2009), combined with one-time measurement of CWD pools, help assess biomass/carbon status of this landscape. Are trends consistent with traditional notions of late-successional forests as equilibrial ecosystems? Specifically, do biomass pools and CWD inputs show consistent long-term trends and relationships, and can living and dead biomass pools and trends be related to forest composition and history? Aboveground living biomass densities, estimated using standard allometric relationships, range from 360–450 Mg/ha among sampled stands and types; these values are among the highest recorded for northeastern North American forests. Biomass densities showed significant decade-scale variation, but no consistent trends over the full study period (one stand, originating following an 1830 fire, showed an aggrading trend during the first 25 years of the study). Even though total above-ground biomass pools are neither increasing nor decreasing, they have been increasingly dominated, over the full study period, by very large (>70 cm dbh) stems and by the most shade-tolerant species (Acer saccharum and Tsuga canadensis). CWD pools measured in 2007 averaged 151 m3/ha, with highest values in Acer-dominated stands. Snag densities averaged 27/ha, but varied nearly ten-fold with canopy composition (highest in Tsuga-dominated stands, lowest in Acer-dominated); snags constituted 10–50% of CWD biomass. Annualized CWD inputs from tree mortality over the full study period averaged 1.9–3.2 Mg/ha/yr, depending on stand and species composition. CWD input rates tended to increase over the course of the study. Input rates may be expected to increase over longer-term observations

  11. Multi-decade biomass dynamics in an old-growth hemlock-northern hardwood forest, Michigan, USA.

    PubMed

    Woods, Kerry D

    2014-01-01

    Trends in living aboveground biomass and inputs to the pool of coarse woody debris (CWD) in an undisturbed, old-growth hemlock-northern hardwood forest in northern MI were estimated from multi-decade observations of permanent plots. Growth and demographic data from seven plot censuses over 47 years (1962-2009), combined with one-time measurement of CWD pools, help assess biomass/carbon status of this landscape. Are trends consistent with traditional notions of late-successional forests as equilibrial ecosystems? Specifically, do biomass pools and CWD inputs show consistent long-term trends and relationships, and can living and dead biomass pools and trends be related to forest composition and history? Aboveground living biomass densities, estimated using standard allometric relationships, range from 360-450 Mg/ha among sampled stands and types; these values are among the highest recorded for northeastern North American forests. Biomass densities showed significant decade-scale variation, but no consistent trends over the full study period (one stand, originating following an 1830 fire, showed an aggrading trend during the first 25 years of the study). Even though total above-ground biomass pools are neither increasing nor decreasing, they have been increasingly dominated, over the full study period, by very large (>70 cm dbh) stems and by the most shade-tolerant species (Acer saccharum and Tsuga canadensis). CWD pools measured in 2007 averaged 151 m(3)/ha, with highest values in Acer-dominated stands. Snag densities averaged 27/ha, but varied nearly ten-fold with canopy composition (highest in Tsuga-dominated stands, lowest in Acer-dominated); snags constituted 10-50% of CWD biomass. Annualized CWD inputs from tree mortality over the full study period averaged 1.9-3.2 Mg/ha/yr, depending on stand and species composition. CWD input rates tended to increase over the course of the study. Input rates may be expected to increase over longer-term observations because, (a

  12. Simulating Carbon cycle and phenology in complex forests using a multi-layer process based ecosystem model; evaluation and use of 3D-CMCC-Forest Ecosystem Model in a deciduous and an evergreen neighboring forests, within the area of Brasschaat (Be)

    NASA Astrophysics Data System (ADS)

    Marconi, S.; Collalti, A.; Santini, M.; Valentini, R.

    2013-12-01

    3D-CMCC-Forest Ecosystem Model is a process based model formerly developed for complex forest ecosystems to estimate growth, water and carbon cycles, phenology and competition processes on a daily/monthly time scale. The Model integrates some characteristics of the functional-structural tree models with the robustness of the light use efficiency approach. It treats different heights, ages and species as discrete classes, in competition for light (vertical structure) and space (horizontal structure). The present work evaluates the results of the recently developed daily version of 3D-CMCC-FEM for two neighboring different even aged and mono specific study cases. The former is a heterogeneous Pedunculate oak forest (Quercus robur L. ), the latter a more homogeneous Scot pine forest (Pinus sylvestris L.). The multi-layer approach has been evaluated against a series of simplified versions to determine whether the improved model complexity in canopy structure definition increases its predictive ability. Results show that a more complex structure (three height layers) should be preferable to simulate heterogeneous scenarios (Pedunculate oak stand), where heights distribution within the canopy justify the distinction in dominant, dominated and sub-dominated layers. On the contrary, it seems that using a multi-layer approach for more homogeneous stands (Scot pine stand) may be disadvantageous. Forcing the structure of an homogeneous stand to a multi-layer approach may in fact increase sources of uncertainty. On the other hand forcing complex forests to a mono layer simplified model, may cause an increase in mortality and a reduction in average DBH and Height. Compared with measured CO2 flux data, model results show good ability in estimating carbon sequestration trends, on both a monthly/seasonal and daily time scales. Moreover the model simulates quite well leaf phenology and the combined effects of the two different forest stands on CO2 fluxes.

  13. Evaluation of a regional monitoring program's statistical power to detect temporal trends in forest health indicators

    USGS Publications Warehouse

    Perles, Stephanie J.; Wagner, Tyler; Irwin, Brian J.; Manning, Douglas R.; Callahan, Kristina K.; Marshall, Matthew R.

    2014-01-01

    Forests are socioeconomically and ecologically important ecosystems that are exposed to a variety of natural and anthropogenic stressors. As such, monitoring forest condition and detecting temporal changes therein remain critical to sound public and private forestland management. The National Parks Service’s Vital Signs monitoring program collects information on many forest health indicators, including species richness, cover by exotics, browse pressure, and forest regeneration. We applied a mixed-model approach to partition variability in data for 30 forest health indicators collected from several national parks in the eastern United States. We then used the estimated variance components in a simulation model to evaluate trend detection capabilities for each indicator. We investigated the extent to which the following factors affected ability to detect trends: (a) sample design: using simple panel versus connected panel design, (b) effect size: increasing trend magnitude, (c) sample size: varying the number of plots sampled each year, and (d) stratified sampling: post-stratifying plots into vegetation domains. Statistical power varied among indicators; however, indicators that measured the proportion of a total yielded higher power when compared to indicators that measured absolute or average values. In addition, the total variability for an indicator appeared to influence power to detect temporal trends more than how total variance was partitioned among spatial and temporal sources. Based on these analyses and the monitoring objectives of theVital Signs program, the current sampling design is likely overly intensive for detecting a 5 % trend·year−1 for all indicators and is appropriate for detecting a 1 % trend·year−1 in most indicators.

  14. Evaluation of a Regional Monitoring Program's Statistical Power to Detect Temporal Trends in Forest Health Indicators

    NASA Astrophysics Data System (ADS)

    Perles, Stephanie J.; Wagner, Tyler; Irwin, Brian J.; Manning, Douglas R.; Callahan, Kristina K.; Marshall, Matthew R.

    2014-09-01

    Forests are socioeconomically and ecologically important ecosystems that are exposed to a variety of natural and anthropogenic stressors. As such, monitoring forest condition and detecting temporal changes therein remain critical to sound public and private forestland management. The National Parks Service's Vital Signs monitoring program collects information on many forest health indicators, including species richness, cover by exotics, browse pressure, and forest regeneration. We applied a mixed-model approach to partition variability in data for 30 forest health indicators collected from several national parks in the eastern United States. We then used the estimated variance components in a simulation model to evaluate trend detection capabilities for each indicator. We investigated the extent to which the following factors affected ability to detect trends: (a) sample design: using simple panel versus connected panel design, (b) effect size: increasing trend magnitude, (c) sample size: varying the number of plots sampled each year, and (d) stratified sampling: post-stratifying plots into vegetation domains. Statistical power varied among indicators; however, indicators that measured the proportion of a total yielded higher power when compared to indicators that measured absolute or average values. In addition, the total variability for an indicator appeared to influence power to detect temporal trends more than how total variance was partitioned among spatial and temporal sources. Based on these analyses and the monitoring objectives of the Vital Signs program, the current sampling design is likely overly intensive for detecting a 5 % trend·year-1 for all indicators and is appropriate for detecting a 1 % trend·year-1 in most indicators.

  15. A multivariate model of plant species richness in forested systems: Old-growth montane forests with a long history of fire

    USGS Publications Warehouse

    Laughlin, D.C.; Grace, J.B.

    2006-01-01

    Recently, efforts to develop multivariate models of plant species richness have been extended to include systems where trees play important roles as overstory elements mediating the influences of environment and disturbance on understory richness. We used structural equation modeling to examine the relationship of understory vascular plant species richness to understory abundance, forest structure, topographic slope, and surface fire history in lower montane forests on the North Rim of Grand Canyon National Park, USA based on data from eighty-two 0.1 ha plots. The questions of primary interest in this analysis were: (1) to what degree are influences of trees on understory richness mediated by effects on understory abundance? (2) To what degree are influences of fire history on richness mediated by effects on trees and/or understory abundance? (3) Can the influences of fire history on this system be related simply to time-since-fire or are there unique influences associated with long-term fire frequency? The results we obtained are consistent with the following inferences. First, it appears that pine trees had a strong inhibitory effect on the abundance of understory plants, which in turn led to lower understory species richness. Second, richness declined over time since the last fire. This pattern appears to result from several processes, including (1) a post-fire stimulation of germination, (2) a decline in understory abundance, and (3) an increase over time in pine abundance (which indirectly leads to reduced richness). Finally, once time-since-fire was statistically controlled, it was seen that areas with higher fire frequency have lower richness than expected, which appears to result from negative effects on understory abundance, possibly by depletions of soil nutrients from repeated surface fire. Overall, it appears that at large temporal and spatial scales, surface fire plays an important and complex role in structuring understory plant communities in old-growth

  16. Characterizing ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS-2011

    NASA Astrophysics Data System (ADS)

    Cui, Y.; Hodzic, A.; Smith, J. N.; Ortega, J. V.; de Foy, B.

    2013-12-01

    Representing the formation and growth of ultrafine particles in chemistry and climate models is challenging due to the complexity of processes involved, which leads to uncertainties in aerosol size distributions and their effects on Cloud Condensation Nuclei (CCN). The Rocky Mountain Biogenic Aerosol Study (RoMBAS) was an intensive measurement campaign as part of the broader BEACHON (Bio-hydro-atmosphere interactions of Energy Aerosols, Carbon, H2O, Organics and Nitrogen) project. This took place during July - August 2011 at the Manitou Experimental Forest Observatory. The location is situated in the rural-urban interface along the Colorado Front Range and allows us to study the effects of aerosol formation and other atmospheric chemistry phenomenon in a forested region with periodic urban influences. Surface measurements of gases, aerosols and meteorological parameters from this campaign were used to examine the formation and growth processes leading to observed Aiken-mode Particle burst Events (APEs), and to quantify their effects on aerosol properties and cloud condensation nuclei CCN concentrations. Results suggest that APEs were observed at the forest site in the early afternoon associated with the arrival of anthropogenic plumes from Denver and Colorado Springs. Mean number concentrations of ultrafine particles (4-30nm) typically exceeded 5000 cm-3 during APEs and these elevated concentrations were correlated with elevated SO2. The Weather Research and Forecasting model with on-line Chemistry (WRF-Chem) was used to model APEs during BEACHON-RoMBAS. The model was updated to include an activation nucleation (AN) scheme with an empirical representation of aerosol nucleation rate, and subsequent growth due to the condensation of organic and inorganic vapors. Comparisons with ground measurements show that the updated model reasonably captures aerosol number concentrations and size distribution during APEs, as well as CN and CCN concentrations. Model results

  17. Evaluation and parameterization of ATCOR3 topographic correction method for forest cover mapping in mountain areas

    NASA Astrophysics Data System (ADS)

    Balthazar, Vincent; Vanacker, Veerle; Lambin, Eric F.

    2012-08-01

    A topographic correction of optical remote sensing data is necessary to improve the quality of quantitative forest cover change analyses in mountainous terrain. The implementation of semi-empirical correction methods requires the calibration of model parameters that are empirically defined. This study develops a method to improve the performance of topographic corrections for forest cover change detection in mountainous terrain through an iterative tuning method of model parameters based on a systematic evaluation of the performance of the correction. The latter was based on: (i) the general matching of reflectances between sunlit and shaded slopes and (ii) the occurrence of abnormal reflectance values, qualified as statistical outliers, in very low illuminated areas. The method was tested on Landsat ETM+ data for rough (Ecuadorian Andes) and very rough mountainous terrain (Bhutan Himalayas). Compared to a reference level (no topographic correction), the ATCOR3 semi-empirical correction method resulted in a considerable reduction of dissimilarities between reflectance values of forested sites in different topographic orientations. Our results indicate that optimal parameter combinations are depending on the site, sun elevation and azimuth and spectral conditions. We demonstrate that the results of relatively simple topographic correction methods can be greatly improved through a feedback loop between parameter tuning and evaluation of the performance of the correction model.

  18. Evaluation and improvement of the Community Land Model (CLM 4.0) in Oregon forests

    NASA Astrophysics Data System (ADS)

    Hudiburg, T. W.; Law, B. E.; Thornton, P. E.

    2012-09-01

    Ecosystem process models are important tools for determining the interactive effects of global change and disturbance on forest carbon dynamics. Here we evaluated and improved terrestrial carbon cycling simulated by the Community Land Model (CLM4), the land model portion of the Community Earth System Model (CESM1.0.4). Our analysis was conducted primarily in Oregon forests using FLUXNET and forest inventory data for the period 2001-2006. We go beyond prior modeling studies in the region by incorporating regional variation in physiological parameters from >100 independent field sites in the region. We also compare spatial patterns of simulated forest carbon stocks and net primary production (NPP) at 15 km resolution using data collected from federal forest inventory plots (FIA) from >3000 plots in the study region. Finally, we evaluate simulated gross primary production (GPP) with FLUXNET eddy-covariance tower data at wet and dry sites in the region. We improved model estimates by making modifications to CLM4 to allow physiological parameters (e.g. foliage carbon to nitrogen ratios and specific leaf area), mortality rate, biological nitrogen fixation, and wood allocation to vary spatially by plant functional type (PFT) within an ecoregion based on field plot data in the region. Prior to modifications, default parameters resulted in underestimation of stem biomass in all forested ecoregions except the Blue Mountains and annual NPP was both over and underestimated. After modifications, model estimates of mean NPP fell within the observed range of uncertainty in all ecoregions (two-sided p-value = 0.8) and the underestimation of stem biomass was reduced. This was an improvement from the default configuration by 50% for stem biomass and 30% for NPP. At the tower sites, modeled monthly GPP fell within the observed range of uncertainty at both sites for the majority of the year, however summer GPP was underestimated at the Metolius semi-arid pine site and spring GPP was

  19. Evaluation and improvement of the Community Land Model (CLM4) in Oregon forests

    NASA Astrophysics Data System (ADS)

    Hudiburg, T. W.; Law, B. E.; Thornton, P. E.

    2013-01-01

    Ecosystem process models are important tools for determining the interactive effects of global change and disturbance on forest carbon dynamics. Here we evaluated and improved terrestrial carbon cycling simulated by the Community Land Model (CLM4), the land model portion of the Community Earth System Model (CESM1.0.4). Our analysis was conducted primarily in Oregon forests using FLUXNET and forest inventory data for the period 2001-2006. We go beyond prior modeling studies in the region by incorporating regional variation in physiological parameters from >100 independent field sites in the region. We also compare spatial patterns of simulated forest carbon stocks and net primary production (NPP) at 15 km resolution using data collected from federal forest inventory plots (FIA) from >3000 plots in the study region. Finally, we evaluate simulated gross primary production (GPP) with FLUXNET eddy covariance tower data at wet and dry sites in the region. We improved model estimates by making modifications to CLM4 to allow physiological parameters (e.g., foliage carbon to nitrogen ratios and specific leaf area), mortality rate, biological nitrogen fixation, and wood allocation to vary spatially by plant functional type (PFT) within an ecoregion based on field plot data in the region. Prior to modifications, default parameters resulted in underestimation of stem biomass in all forested ecoregions except the Blue Mountains and annual NPP was both over- and underestimated. After modifications, model estimates of mean NPP fell within the observed range of uncertainty in all ecoregions (two-sided P value = 0.8), and the underestimation of stem biomass was reduced. This was an improvement from the default configuration by 50% for stem biomass and 30% for NPP. At the tower sites, modeled monthly GPP fell within the observed range of uncertainty at both sites for the majority of the year, however summer GPP was underestimated at the Metolius semi-arid pine site and spring GPP

  20. Evaluation of the Impact of the Natural Forest Protection Program on Rural Household Livelihoods

    NASA Astrophysics Data System (ADS)

    Mullan, Katrina; Kontoleon, Andreas; Swanson, Timothy M.; Zhang, Shiqiu

    2010-03-01

    In this study, we estimated the impact on local household livelihoods of the Natural Forest Protection Program (NFPP), which is the largest logging-ban program in the world, which aims to protect watersheds and conserve natural forests. In doing so, we used a series of microeconometric policy-evaluation techniques to assess the impacts of the NFPP on two interrelated facets of household livelihoods: income and off-farm labor supply. We found that the NFPP has had a negative impact on incomes from timber harvesting but has actually had a positive impact on total household incomes from all sources. Furthermore, we found that off-farm labor supply outside the village has increased more rapidly in NFPP than in non-NFPP areas. Based on these results, policy implications for household livelihoods were drawn and are presented herein.

  1. Evaluation of the impact of the natural forest protection program on rural household livelihoods.

    PubMed

    Mullan, Katrina; Kontoleon, Andreas; Swanson, Timothy M; Zhang, Shiqiu

    2010-03-01

    In this study, we estimated the impact on local household livelihoods of the Natural Forest Protection Program (NFPP), which is the largest logging-ban program in the world, which aims to protect watersheds and conserve natural forests. In doing so, we used a series of microeconometric policy-evaluation techniques to assess the impacts of the NFPP on two interrelated facets of household livelihoods: income and off-farm labor supply. We found that the NFPP has had a negative impact on incomes from timber harvesting but has actually had a positive impact on total household incomes from all sources. Furthermore, we found that off-farm labor supply outside the village has increased more rapidly in NFPP than in non-NFPP areas. Based on these results, policy implications for household livelihoods were drawn and are presented herein. PMID:19387724

  2. Form Follows Function: can Tropical Mountain Forest Competition Drive the Growth of Topography?

    NASA Astrophysics Data System (ADS)

    Brocard, G. Y.; Willenbring, J. K.; Scatena, F. N.

    2014-12-01

    Forest succession theory maintains that trees drape existing landscapes as passive niche optimizers. Here, we explore the opposite view - that tree type can control the landscape morphology through canopy and soil structure differences between tree types. Using field observations combined with the analysis of a 1 m-resolution LiDAR DEM and cosmogenic nuclide geochemical techniques, we report links between topographic position, erosion rates, and tree distribution above 600 m in elevation in the pristine, tropical rainforest of the Luquillo Critical Zone Observatory, Puerto Rico. Above 600 m, flat ridges connect a subdued topographic surface and cap a relict landscape composed of 10s-of-meters-thick saprolite derived from a quartz dioritic bedrock. Erosion in the form of concave coves dissects this landscape, exposing the underlying corestones and bedrock and progressively creating a new landscape of greater local relief and higher erosion. To understand the origin of the increase in local relief we measured the respective contributions of ridges and coves to the stream signal by analyzing 10Be in soils and stream sediments. We find that, in the coves, erosion is systematically higher than on the ridges, confirming the increase in landscape dissection. Because the overall forest structure has not been altered by anthropogenic disturbances, the tree type represents a long-term feature of the landscape. We analyzed the distribution of tree associations over the LiDAR topography by classifying high-resolution multispectral images of the forest. Vegetation in the study area is dominated by Palm and Palo Colorado forests. We found an almost systematic association of the Palm forest with the coves and of the Palo Colorado with the ridges. These forest types vary in their potential to prevent or enhance soil erosion. The Palo Colorado generates greater soil coverage and rain interception rates. Therefore, we propose that soils are more vulnerable to erosion under the Palm

  3. The steady-state mosaic of disturbance and succession across an old-growth Central Amazon forest landscape

    PubMed Central

    Chambers, Jeffrey Q.; Negron-Juarez, Robinson I.; Marra, Daniel Magnabosco; Di Vittorio, Alan; Tews, Joerg; Roberts, Dar; Ribeiro, Gabriel H. P. M.; Trumbore, Susan E.; Higuchi, Niro

    2013-01-01

    Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. The size distribution and return frequency of disturbance events, and subsequent recovery processes, determine to a large extent the spatial scale over which this old-growth steady state develops. Here, we characterize this mosaic for a Central Amazon forest by integrating field plot data, remote sensing disturbance probability distribution functions, and individual-based simulation modeling. Results demonstrate that a steady state of patches of varying successional age occurs over a relatively large spatial scale, with important implications for detecting temporal trends on plots that sample a small fraction of the landscape. Long highly significant stochastic runs averaging 1.0 Mg biomass⋅ha−1⋅y−1 were often punctuated by episodic disturbance events, resulting in a sawtooth time series of hectare-scale tree biomass. To maximize the detection of temporal trends for this Central Amazon site (e.g., driven by CO2 fertilization), plots larger than 10 ha would provide the greatest sensitivity. A model-based analysis of fractional mortality across all gap sizes demonstrated that 9.1–16.9% of tree mortality was missing from plot-based approaches, underscoring the need to combine plot and remote-sensing methods for estimating net landscape carbon balance. Old-growth tropical forests can exhibit complex large-scale structure driven by disturbance and recovery cycles, with ecosystem and community attributes of hectare-scale plots exhibiting continuous dynamic departures from a steady-state condition. PMID:23359707

  4. Multi-stemmed trees of Nothofagus pumilio second-growth forest in Patagonia are formed by highly related individuals

    PubMed Central

    Till-Bottraud, Irène; Fajardo, Alex; Rioux, Delphine

    2012-01-01

    Background and Aims Multi-stemmed trees (tree clusters) in Nothofagus pumilio, a dominant tree species in Patagonia, are very uncommon and are restricted to the edge of second-growth forests following human-provoked fires. No vegetative reproduction has been reported so far. The genetic structure of multi-stemmed trees of this species was investigated and it was hypothesized that genets within a cluster were more closely related than average in the population. Methods Fifteen clusters (composed of at least three purported stems) and 15 single trees were sampled at the edge of a second-growth forest and genotyped using two amplified fragment length polymorphism (AFLP) primer pairs. We obtained 119 polymorphic markers that allowed clonality to be determined, together with sibship structure and relatedness among samples. Key Results Clonality was detected in seven clusters but all clusters had at least two different genotypes. Full sibs were found exclusively within clusters and in all clusters. Within a cluster, stems that were not identified as full sibs were often half sibs. Relatedness values for the full sibs and half sibs were higher than the theoretical values of 0·5 and 0·25 but the relatedness between clusters was very low. Conclusions Tree clusters that are merged at the edge of the second-growth forest of N. pumilio are composed of stems of the same genotype and of other genotypes that are highly related (but not always). It is suggested that this peculiar genetic structure results from a combination of several causes, including selection for merging of related individuals. PMID:22782238

  5. Predicting ecosystem dynamics at regional scales: an evaluation of a terrestrial biosphere model for the forests of northeastern North America

    PubMed Central

    Medvigy, David; Moorcroft, Paul R.

    2012-01-01

    Terrestrial biosphere models are important tools for diagnosing both the current state of the terrestrial carbon cycle and forecasting terrestrial ecosystem responses to global change. While there are a number of ongoing assessments of the short-term predictive capabilities of terrestrial biosphere models using flux-tower measurements, to date there have been relatively few assessments of their ability to predict longer term, decadal-scale biomass dynamics. Here, we present the results of a regional-scale evaluation of the Ecosystem Demography version 2 (ED2)-structured terrestrial biosphere model, evaluating the model's predictions against forest inventory measurements for the northeast USA and Quebec from 1985 to 1995. Simulations were conducted using a default parametrization, which used parameter values from the literature, and a constrained model parametrization, which had been developed by constraining the model's predictions against 2 years of measurements from a single site, Harvard Forest (42.5° N, 72.1° W). The analysis shows that the constrained model parametrization offered marked improvements over the default model formulation, capturing large-scale variation in patterns of biomass dynamics despite marked differences in climate forcing, land-use history and species-composition across the region. These results imply that data-constrained parametrizations of structured biosphere models such as ED2 can be successfully used for regional-scale ecosystem prediction and forecasting. We also assess the model's ability to capture sub-grid scale heterogeneity in the dynamics of biomass growth and mortality of different sizes and types of trees, and then discuss the implications of these analyses for further reducing the remaining biases in the model's predictions. PMID:22144385

  6. Influence of soil conditions on dissolved organic matter leached from forest and wetland soils: a controlled growth chamber study.

    PubMed

    Kim, Eun-Ah; Nguyen, Hang Vo-Minh; Oh, Hae Sung; Hur, Jin; Choi, Jung Hyun

    2016-03-01

    This study investigated the effects of various soil conditions, including drying-rewetting, nitrogen deposition, and temperature rise, on the quantities and the composition of dissolved organic matter leached from forest and wetland soils. A set of forest and wetland soils with and without the nitrogen deposition were incubated in the growth chambers under three different temperatures. The moisture contents were kept constant, except for two-week drying intervals. Comparisons between the original and the treated samples revealed that drying-rewetting was a crucial environmental factor driving changes in the amount of dissolved organic carbon (DOC). The DOC was also notably increased by the nitrogen deposition to the dry forest soil and was affected by the temperature of the dry wetland soil. A parallel factor (PARAFAC) analysis identified three sub-fractions of the fluorescent dissolved organic matter (FDOM) from the fluorescence excitation-emission matrices (EEMs), and their compositions depended on drying-rewetting. The data as a whole, including the DOC and PARAFAC components and other optical indices, were possibly explained by the two main variables, which were closely related with the PARAFAC components and DOC based on principal component analysis (PCA). Our results suggested that the DOC and PARAFAC component information could provide a comprehensive interpretation of the changes in the soil-leached DOM in response to the different environmental conditions. PMID:26561321

  7. Composition for Personal Growth: Program Design and Evaluation.

    ERIC Educational Resources Information Center

    Hawley, Robert Coit

    This thesis describes the design and evaluation of the "Composition for Personal Growth" program developed by Sidney B. Simon, Robert C. Hawley, and David D. Britton. In developing the program, the designers sought to remedy what they considered to be the four major faults of many traditional composition programs: lack of meaningful subject…

  8. U.S. Forest Disturbance Evaluated using Landsat Observations and FIA Measurements: Initial Results and Ongoing Research in the North American Forest Dynamics (NAFD) Project

    NASA Astrophysics Data System (ADS)

    Thomas, N.; Goward, S. N.; Masek, J.; Cohen, W. B.; Moisen, G. G.; Huang, C.; Kennedy, R. E.; Healey, S. P.; Powell, S. L.; Schleeweis, K.; Hinds, A.; Rishmawi, K.

    2009-12-01

    The importance of forests as carbon sources or sinks depends, in part, upon stand age, which in turn is generally dependent on time since last disturbance. Uncertainties in North American carbon fluxes originate from poor understanding of forest dynamics, specifically disturbance and regeneration. The North American Forest Dynamics (NAFD) study, which supports North American Carbon Program (NACP) science goals, is improving understanding of North American forest dynamics through integration of U.S. Department of Agriculture (USDA) Forest Service (USFS) Forest Inventory and Analysis (FIA) field observations and biennial Landsat imagery to evaluate disturbance and regrowth patterns over the last ~ 35 years. NAFD Phase I (2005-2008) detailed forest disturbance history from Landsat time series stacks (LTSS) for 23 sample locations across the United States. Results of Phase I NAFD disturbance mapping reveal generally high rates of forest disturbance (0.5 - 3.0% per year across the U.S). These rates vary both spatially and temporally. Ongoing Phase II (2008-2011) work is refining the Phase I approach. Additional sample locations in the conterminous U.S are being added to reduce error in nationwide disturbance estimates. Detection of partial disturbances is being improved by moving toward annual rather then biennial LTSS. This is being accomplished with cloud clearing through image merging to provide within-growing season clear surface views. Additional elements of the NAFD Phase II work include partnering with Canada and Mexico to better understand North American continent-wide forest dynamics. We are also extending our effort to consider regrowth dynamics using the FIA data to support both radiative transfer modeling and synthesis of FIA and the remote sensing data to estimate biomass accumulation trends. We are also collaborating with other NACP- investigators where the NAFD products inform their alternate approaches (modeling and/ or accounting) for carbon assessment

  9. Cost-effectiveness of dryland forest restoration evaluated by spatial analysis of ecosystem services

    PubMed Central

    Birch, Jennifer C.; Newton, Adrian C.; Aquino, Claudia Alvarez; Cantarello, Elena; Echeverría, Cristian; Kitzberger, Thomas; Schiappacasse, Ignacio; Garavito, Natalia Tejedor

    2010-01-01

    Although ecological restoration is widely used to combat environmental degradation, very few studies have evaluated the cost-effectiveness of this approach. We examine the potential impact of forest restoration on the value of multiple ecosystem services across four dryland areas in Latin America, by estimating the net value of ecosystem service benefits under different reforestation scenarios. The values of selected ecosystem services were mapped under each scenario, supported by the use of a spatially explicit model of forest dynamics. We explored the economic potential of a change in land use from livestock grazing to restored native forest using different discount rates and performed a cost–benefit analysis of three restoration scenarios. Results show that passive restoration is cost-effective for all study areas on the basis of the services analyzed, whereas the benefits from active restoration are generally outweighed by the relatively high costs involved. These findings were found to be relatively insensitive to discount rate but were sensitive to the market value of carbon. Substantial variation in values was recorded between study areas, demonstrating that ecosystem service values are strongly context specific. However, spatial analysis enabled localized areas of net benefits to be identified, indicating the value of this approach for identifying the relative costs and benefits of restoration interventions across a landscape. PMID:21106761

  10. Evaluation drought response of tropical dry forests using advanced wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Sanchez-Azofeifa, G. A.

    2015-12-01

    Understanding of the effects of persistent drought in tropical dry forests has not been fully studied until today. In this presentation we will discuss one of the first results on the response of tropical dry forests to drought using advanced wireless sensor networks and canopy phenology towers, that provide hyper-temporal information on micro-meteorological variables such Temperature, relative humidity, and Vapor Pressure Deficit (VPD). In addition, we will evaluate drought response to as function of the Fraction of the Photosynthetic Active Radiation (FPAR), and the Normalized Difference Vegetation Index (NDVI). Our work is conducted at the Santa Rosa Environmental Monitoring Super Site (NR-EMSS) located at the Guancaste Province, Costa Rica, Central America. Our results indicate significant changes in terms of FPAR, VPD manifested via strong changes on NDVI. Our results pose questions about the resilience of these understudied tropical ecosystems and their long-term survival under severe and persistent drought conditions. This results provide a reference framework for the need of more integrated research on the Central American Dry Forest corridor where just between Costa Rica and Nicaragua over 100,000 families are facing strong drought conditions.

  11. Evaluation of the Environmentalist Dimension of Ecotourism at the Dadia Forest Reserve (Greece)

    NASA Astrophysics Data System (ADS)

    Hovardas, Tasos; Poirazidis, Kostas

    2006-11-01

    Environmental education and financial support of nature conservation are considered among the primary components of the environmentalist dimension of ecotourism. The potential of environmental education calls for enhancing visitor environmental knowledge and prompting change of visitor behavior. The present study addressed the evaluation of the environmentalist dimension of ecotourism in the Dadia Forest Reserve. The first objective of the research was to study the influence of variables determined prior to the visit, namely, visitor and visit characteristics, visitor environmental information sources, visitor pro-environmental behavior, and visitation goals, on variables determined during the visit, that is, visitor participation in and satisfaction from ecotourism activities. The second objective was to study the effect of selected variables on visitor knowledge and behavior intentions. Visitor participation in and satisfaction from ecotourism activities were primarily controlled by visit characteristics. Levels of visitor knowledge were quite satisfactory; however, coherence among knowledge items was rather loose. On the other hand, behavior intention items revealed the highest possible degree of coherence, which should be attributed to the pervasive influence of visitor satisfaction from watching birds at the Bird Observatory within the Dadia Forest Reserve. Ecotourism activities, during which the main part of environmental knowledge was offered, exerted no effect on visitor knowledge; all the same, they significantly influenced visitor behavior intentions. Overall, visitor behavior intentions revealed a considerable potential of financing environmental protection and providing voluntary work in the frame of the environmental management of the Dadia Forest Reserve.

  12. Energy evaluation of forest residues originated from Eucalyptus globulus Labill in Galicia.

    PubMed

    Núñez-Regueira, L; Proupín-Castiñeiras, J; Rodríguez-Añón, J A

    2002-03-01

    The possibility of retrieving the energy contained in forest residues originating from wood exploitation in Galicia (Spain) is evaluated. This study was made on Eucalyptus globulus Labill occupying a forest surface of 240000 ha. This species plays an important role in the economical development of Galicia, as it is the main forest species for production of pulp. Sampling was made over 1999 in seven different zones, three main stations plus four selected for comparison, situated in Galicia. The residues originating from cutting were sorted into three different groups and their calorific values were measured by static bomb calorimetry. These calorific values, close to 7200 kJ kg(-1), make possible the use of this residual biomass as an energy source. Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters, elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined. PMID:11848377

  13. Cost-effectiveness of dryland forest restoration evaluated by spatial analysis of ecosystem services.

    PubMed

    Birch, Jennifer C; Newton, Adrian C; Aquino, Claudia Alvarez; Cantarello, Elena; Echeverría, Cristian; Kitzberger, Thomas; Schiappacasse, Ignacio; Garavito, Natalia Tejedor

    2010-12-14

    Although ecological restoration is widely used to combat environmental degradation, very few studies have evaluated the cost-effectiveness of this approach. We examine the potential impact of forest restoration on the value of multiple ecosystem services across four dryland areas in Latin America, by estimating the net value of ecosystem service benefits under different reforestation scenarios. The values of selected ecosystem services were mapped under each scenario, supported by the use of a spatially explicit model of forest dynamics. We explored the economic potential of a change in land use from livestock grazing to restored native forest using different discount rates and performed a cost-benefit analysis of three restoration scenarios. Results show that passive restoration is cost-effective for all study areas on the basis of the services analyzed, whereas the benefits from active restoration are generally outweighed by the relatively high costs involved. These findings were found to be relatively insensitive to discount rate but were sensitive to the market value of carbon. Substantial variation in values was recorded between study areas, demonstrating that ecosystem service values are strongly context specific. However, spatial analysis enabled localized areas of net benefits to be identified, indicating the value of this approach for identifying the relative costs and benefits of restoration interventions across a landscape. PMID:21106761

  14. Nutrients and light limit biomass growth of N2-fixing but not non-fixing trees in tropical forests after 15 years of fertilization

    NASA Astrophysics Data System (ADS)

    Trierweiler, Annette; Wright, Joseph; Winter, Klaus; Hedin, Lars

    2015-04-01

    Tropical forests contribute a major fraction to the land C sink but the role of soil nutrients in limiting tree biomass growth in response to rising atmospheric CO2 is poorly known. Recent findings suggest that, following disturbance, successionally young forests may be deficient in nitrogen (N) and/or phosphorus (P), however nutrient manipulations of mature forests have revealed surprisingly weak effects of nutrients on the stem growth of mature individual trees. It is unclear how such weak experimental nutrient effects are reconciled with the existence of broad geographical correlations between soil nutrients and forest biomass growth. While tree growth is a complex function of nutrients, light, and canopy status, it is plausible that responses differ across different plant functional types. Here we use data from the longest running tropical fertilization experiment to ask first whether different functional groups have different nutrient needs, second, whether a differential nutrient limitation response will affect biomass accretion, and third, whether there is an interactive light-nutrient effect. Finally we examined how nutrient responses changed over time. We show that, in an intact and biodiverse mature tropical forest in Panama, N2-fixing trees more than double their basal area growth rate when exposed to increased soil P and N in the first 11 years of fertilization, for an overall 60% increase over 15 years. In contrast, there was no effect of nutrient treatment on the growth of non-fixing trees. We found a strong interactive effect of soil nutrients and light on fixer tree growth as the greatest growth response was in mature canopy-level trees with full access to light and potentially new nitrogen through fixation. In addition, the positive nutrient effect declined over the 15 years, rather than the expected increase. Our findings suggest that N2-fixing tree species may play a disproportionately important role in governing tropical forest response to

  15. Artificial recharge of groundwater through sprinkling infiltration: impacts on forest soil and the nutrient status and growth of Scots pine.

    PubMed

    Nöjd, Pekka; Lindroos, Antti-Jussi; Smolander, Aino; Derome, John; Lumme, Ilari; Helmisaari, Heljä-Sisko

    2009-05-01

    We studied the chemical changes in forest soil and the effects on Scots pine trees caused by continuous sprinkling infiltration over a period of two years, followed by a recovery period of two years. Infiltration increased the water input onto the forest soil by a factor of approximately 1000. After one year of infiltration, the pH of the organic layer had risen from about 4.0 to 6.7. The NH(4)-N concentration in the organic layer increased, most probably due to the NH(4) ions in the infiltration water, as the net N mineralization rate did not increase. Sprinkling infiltration initiated nitrification in the mineral soil. Macronutrient concentrations generally increased in the organic layer and mineral soil. An exception, however, was the concentration of extractable phosphorus, which decreased strongly during the infiltration period and did not show a recovery within two years. The NO(3)-N and K concentrations had reverted back to their initial level during the two-year recovery period, while the concentrations of Ca, Mg and NH(4)-N were still elevated. Nutrient concentrations in the pine needles increased on the infiltrated plots. However, the needle P concentration increased, despite the decrease in plant-available P in the soil. Despite the increase in the nutrient status, there were some visible signs of chlorosis in the current-year needles after two years of infiltration. The radial growth of the pines more than doubled on the infiltrated plots, which suggests that the very large increase in the water input onto the forest floor had no adverse effect on the functioning of the trees. However, a monitoring period of four years is not sufficient for detecting potential long term detrimental effects on forest trees. PMID:19269680

  16. Spatial Variability of Carbon Fluxes and Soil Respiration Within the Understory of a Pacific Northwest Old-Growth Forest

    NASA Astrophysics Data System (ADS)

    Falk, M.; Paw U, K.; Schroeder, M.

    2002-12-01

    We present data and analysis on the spatial heterogeneity of carbon fluxes measured by 2 additional eddy covariance systems in the forest understory at the Wind River Canopy Crane AMERIFLUX site. The Crane is located in a Pacific Northwest Old-growth Forest with trees up to 500 years old and 65 meters tall. A permanent eddy covariance station consisting of a Gill-Solent HS Research sonic anemometer and a LiCor LI6262 closed-path InfraRed Gas Analyzer (IRGA) has been operated for over 4 years at a height of 2.5 meters to complement an identical system measuring total ecosystem exchange at a height of 70 meters. Two additional eddy covariance systems, consisting of Campbell CSAT-3 sonic anemometers and open-path IRGA's (LiCor 7500 and NOAA probe) were located in the understory along a 200 m transect for a period of 13 months. The forest structure is complex with seven gymnosperm and two angiosperm tree species in the 2.3 ha crane circle, large amounts of woody debris on the forest floor, and a diverse understory. Soil respiration is a major contributor to the carbon budget at the site. The long-term understory Eddy-covariance data indicate the release of carbon from the soil to be as large as 11 tC ha-1 yr-1 with maximum values of 6 to 8 \\mu mol m-1 s-1. The Net ecosystem carbon exchange (NEE) estimated by eddy-covariance ranges from a sink of 1.9 tC ha-1 yr-1 to a source of 0.5 tC ha-1 yr-1. In this study we investigate the spatial and temporal dynamics of carbon fluxes within the canopy understory.

  17. Oregon Eastside Forests Restoration, Old Growth Protection, and Jobs Act of 2011

    THOMAS, 112th Congress

    Sen. Wyden, Ron [D-OR

    2011-01-27

    05/18/2011 Committee on Energy and Natural Resources Subcommittee on Public Lands and Forests. Hearings held. With printed Hearing: S.Hrg. 112-39. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  18. Early subtropical forest growth is driven by community mean trait values and functional diversity rather than the abiotic environment

    PubMed Central

    Kröber, Wenzel; Li, Ying; Härdtle, Werner; Ma, Keping; Schmid, Bernhard; Schmidt, Karsten; Scholten, Thomas; Seidler, Gunnar; von Oheimb, Goddert; Welk, Erik; Wirth, Christian; Bruelheide, Helge

    2015-01-01

    While functional diversity (FD) has been shown to be positively related to a number of ecosystem functions including biomass production, it may have a much less pronounced effect than that of environmental factors or species-specific properties. Leaf and wood traits can be considered particularly relevant to tree growth, as they reflect a trade-off between resources invested into growth and persistence. Our study focussed on the degree to which early forest growth was driven by FD, the environment (11 variables characterizing abiotic habitat conditions), and community-weighted mean (CWM) values of species traits in the context of a large-scale tree diversity experiment (BEF-China). Growth rates of trees with respect to crown diameter were aggregated across 231 plots (hosting between one and 23 tree species) and related to environmental variables, FD, and CWM, the latter two of which were based on 41 plant functional traits. The effects of each of the three predictor groups were analyzed separately by mixed model optimization and jointly by variance partitioning. Numerous single traits predicted plot-level tree growth, both in the models based on CWMs and FD, but none of the environmental variables was able to predict tree growth. In the best models, environment and FD explained only 4 and 31% of variation in crown growth rates, respectively, while CWM trait values explained 42%. In total, the best models accounted for 51% of crown growth. The marginal role of the selected environmental variables was unexpected, given the high topographic heterogeneity and large size of the experiment, as was the significant impact of FD, demonstrating that positive diversity effects already occur during the early stages in tree plantations. PMID:26380685

  19. Intra-annual response of tree growth to climate in temperate forests: larger implications of fine-scale responses

    NASA Astrophysics Data System (ADS)

    McMahon, S.; Parker, G. G.

    2013-12-01

    Tree growth is a key component in the movement of carbon through terrestrial ecosystems. Although correlating annual growth rates to temperature an precipitation averages is the most common approach to extrapolating climate sensitivities, individual trees respond to weather at a much finer temporal scale. This response, further, is sensitive to many environmental factors and that sensitivity can depend on species, individual location in the species range, or size of the individual among other factors. Using weekly and bi-weekly measurements of dendrometer bands on 100 trees in three sites in the eastern US (Massachusetts, Virginia, and Maryland) over four years, we fit functional forms to intra-annual growth and compared patterns in productivity response to daily temperature and water balance information. We also determined phenological patterns in growth initiation, cessation, and maximum rate. We found that across size classes and species, trees respond to high temperatures and minor droughts by pausing in diameter increase. Although water retention may contribute some to this pattern, large differences in end-of-year biomass gain demonstrate a clear relationship between these pauses and overall annual carbon gain. Species did show some distinct patterns in this sensitivity and the overall phenology of growth. Further, the growing season as defined by when the majority of biomass increase actually occurred was much smaller than the leaf-out season indicating that droughts and heat-waves in a key subset of the green season can have a disproportionate effect on tree carbon uptake and forest carbon balance.

  20. Modelling the climatic drivers determining secondary growth in Mediterranean forests using a process-based model and multiproxy data

    NASA Astrophysics Data System (ADS)

    Gea-Izquierdo, Guillermo; Guibal, Frederic; Joffre, Richard; Ourcival, Jean-Marc; Simioni, Guillaume; Guiot, Joel

    2015-04-01

    Different physiological processes determine gross primary productivity (GPP) and carbon allocation in relation to environmental forcing. Climatic variability limits these two processes differently and this needs to be properly addressed in process-based forest models. Generally, empirical models have been preferentially used in dendrochronological studies. However, it is necessary to better address the interaction between climate and other factors such as CO2 to properly assess the instability in the climate-growth response expressed by trees and increase the accuracy of the modelled relationships both in forward and inverse models. In this study we evolved an existing mechanistic model originally developed with dendrochronological data. The model was calibrated to fit a combination of eddy covariance CO2 flux data, dendrochronological time series of secondary growth and forest inventory data at two Mediterranean evergreen forests. Among other differences with the original formulation, the model was modified to be climate explicit in the key processes addressing acclimation of photosynthesis and allocation. It succeeded to fit both the high- and the low-frequency response of stand GPP and carbon allocation to the stem as calculated from tree-rings. Simulations suggest a decrease in mean stomatal conductance in response to environmental changes and an increase in mean annual intrinsic water use efficiency in both species during the last 50 years. However, this was not translated on a parallel simulated increase in ecosystem water use efficiency. A long-term decrease in annual GPP matched the local trend in precipitation since the 1970s observed in one site. In contrast, GPP did not show a negative trend and the trees buffered the climatic variability observed at the site where long-term precipitation remained stable. Long-term trends in GPP did not match those in growth, in agreement with the C-sink hypothesis. There is a great potential to use the model with

  1. Chronic nitrogen addition causes a reduction in soil carbon dioxide efflux during the high stem-growth period in a tropical montane forest but no response from a tropical lowland forest on a decadal time scale

    NASA Astrophysics Data System (ADS)

    Koehler, B.; Corre, M. D.; Veldkamp, E.; Sueta, J. P.

    2009-12-01

    Atmospheric nitrogen (N) deposition is rapidly increasing in tropical regions. We studied the response of soil carbon dioxide (CO2) efflux to long-term experimental N addition (125 kg N ha-1 yr-1) in mature lowland and montane forests in Panama. In the lowland forest, on soils with high nutrient-supplying and buffering capacity, fine litterfall and stem-growth were neither N- nor phosphorus-limited. In the montane forest, on soils with low nutrient supplying capacity and an organic layer, fine litterfall and stem-growth were N-limited. Our objectives were to 1) explore the influence of soil temperature and moisture on the dynamics of soil CO2 efflux and 2) determine the responses of soil CO2 efflux from an N-rich and N-limited forest to elevated N input. Annual soil CO2-C efflux was larger in the lowland (15.44 ± 1.02 Mg C ha-1) than in the montane forest (9.37 ± 0.28 Mg C ha-1). In the lowland forest, soil moisture explained the largest fraction of the variance in soil CO2 efflux while soil temperature was the main explanatory variable in the montane forest. Soil CO2 efflux in the lowland forest did not differ between the control and 9-11 yr N-addition plots, suggesting that chronic N input to nutrient-rich tropical lowland forests on well-buffered soils may not change their C balance on a decadal time scale. In the montane forest, first year N addition did not affect soil CO2 efflux but annual CO2 efflux was reduced by 14% and 8% in the 2nd and 3rd year N-addition plots, respectively, compared to the control. This reduction was caused by a decrease in soil CO2 efflux during the high stem-growth period of the year, suggesting a shift in carbon partitioning from below- to aboveground in the N-addition plots in which stem diameter growth was promoted.

  2. Chronic nitrogen addition causes a reduction in soil carbon dioxide efflux during the high stem-growth period in a tropical montane forest but no response from a tropical lowland forest in decadal scale

    NASA Astrophysics Data System (ADS)

    Koehler, B.; Corre, M. D.; Veldkamp, E.; Sueta, J. P.

    2009-09-01

    Atmospheric nitrogen (N) deposition is rapidly increasing in tropical regions. We studied the response of soil carbon dioxide CO2 efflux to long-term experimental N-addition (125 kg N ha-1 yr-1) in mature lowland and montane forests in Panamá. In the lowland forest, on soils with high nutrient-supplying and buffering capacity, fine litterfall and stem-growth were neither N- nor phosphorus-limited. In the montane forest, on soils with low nutrient supplying capacity and an organic layer, fine litterfall and stem-growth were N-limited. Our objectives were to 1) explore the influence of soil temperature and moisture on the dynamics of soil CO2 efflux and 2) determine the responses of soil CO2 efflux from an N-rich and N-limited forest to elevated N input. Annual soil CO2-C efflux was larger from the lowland (15.20±1.25 Mg C ha-1) than the montane forest (9.36±0.29 Mg C ha-1). In the lowland forest, soil moisture explained the largest fraction of the variance in soil CO2 efflux while soil temperature was the main explanatory variable in the montane forest. Soil CO2 efflux in the lowland forest did not differ between the control and 9-11 yr N-addition plots, suggesting that chronic N input to nutrient-rich tropical lowland forests on well-buffered soils may not change their C balance in decadal scale. In the montane forest, first year N addition did not affect soil CO2 efflux but annual CO2 efflux was reduced by 14% and 8% in the 2- and 3 yr N-addition plots, respectively, compared to the control. This reduction was caused by a decrease in soil CO2 efflux during the high stem-growth period of the year, suggesting a shift in carbon partitioning from below- to aboveground in the N-addition plots where stem diameter growth was promoted.

  3. Carbon exchange of an old-growth eastern hemlock (Tsuga canadensis) forest in central New England.

    PubMed

    Hadley, Julian L; Schedlbauer, Jessica L

    2002-11-01

    Carbon (C) exchange of an approximately 200-year-old eastern hemlock (Tsuga canadensis L.) forest in central Massachusetts, USA, was estimated from mid-October 2000 through October 2001 based on eddy covariance measurements and statistical modeling from microclimatic data. Measurements were made in 68% of the hours during the year of study, with > 50% coverage in all months except December and August. Data were filtered by wind direction and atmospheric turbulence to remove invalid measurements. Analysis of filtered data showed that photosynthetically active radiation (PAR) was significant in predicting C exchange, except during the winter. Daily minimum air temperature affected C exchange in autumn and winter, whereas time of day, water vapor pressure deficit and air temperature had significant effects on C storage in spring, summer and fall. Most C storage in the stand occurred in April through July and in October 2001, with maximum rates in April and May. Persistent cold weather prevented C storage in December through March. In early spring 2001, C uptake was sensitive to nocturnal frost: daily minimum air temperatures below 0 degrees C reduced C fixation, and minima below -5 degrees C caused its virtual cessation. Soil temperature was a poor predictor of C balance during this period. In August, high soil and air temperatures (averaging 16.7 and 21.1 degrees C, respectively) drove high ecosystem respiration, which approximately balanced C uptake. These patterns show potential for stimulated C storage in hemlock forests in a warmer climate with fewer spring and autumn frosts, but reduced C storage during warmer summers. Estimated annual C storage was 3.0 Mg ha(-1), which is higher than for younger coniferous and deciduous forests during earlier years in the northeastern USA. Long-term data are needed to determine if the estimated high C storage in this hemlock forest is a result of interannual climate variation or an effect of forest composition. PMID:12414368

  4. Neighborhood matters: Patterns and controls on wood distribution in old-growth forest streams of the Colorado Front Range, USA

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen; Cadol, Daniel

    2011-01-01

    We surveyed wood characteristics along four headwater channel segments of the Colorado Front Range with drainage areas of 8-82 km 2. Stream lengths surveyed range from 3025 to 8980 m and together include a total of 15,706 pieces of wood. Time since last disturbance in the form of a stand-killing fire varied from 31 to > 500 years. Individual pieces of wood were highly aggregated at length scales of 1 to 150 m. Trends among jams were more weakly developed, but jams tended to be more segregated at lengths < 10 m, slightly more aggregated at lengths ~ 100-300 m, and to have diverging patterns at lengths > 300 m, with jams along individual channels being aggregated, segregated, or random. Multiple linear regressions failed to produce highly predictive models to explain the response variables of wood load, piece dimensions, or characteristics of jams other than jam volume (which correlated with drainage area and wood load); but examination of downstream patterns suggests that local valley and channel geometry (valley-bottom width, gradient, and sequence of longitudinal channel changes) exert a stronger influence on patterns of wood distribution than either time since last forest disturbance or progressive downstream trends associated with increasing drainage area. The longitudinal sequences of wood recruitment sources, forest stand age, and channel geometry together exert an important control on reach-scale wood load and aggregation. Wood loads in streams draining old-growth (> 250 years) forests of the Colorado Front Range are low compared to old-growth sites in other regions of the world, which we interpret to reflect decreased retention of wood recruited to the streams.

  5. Effects of Experimental Nitrogen and Phosphorus Addition on Litter Decomposition in an Old-Growth Tropical Forest

    PubMed Central

    Chen, Hao; Dong, Shaofeng; Liu, Lei; Ma, Chuan; Zhang, Tao; Zhu, Xiaomin; Mo, Jiangming

    2013-01-01

    The responses of litter decomposition to nitrogen (N) and phosphorus (P) additions were examined in an old-growth tropical forest in southern China to test the following hypotheses: (1) N addition would decrease litter decomposition; (2) P addition would increase litter decomposition, and (3) P addition would mitigate the inhibitive effect of N addition. Two kinds of leaf litter, Schima superba Chardn. & Champ. (S.S.) and Castanopsis chinensis Hance (C.C.), were studied using the litterbag technique. Four treatments were conducted at the following levels: control, N-addition (150 kg N ha−1 yr−1), P-addition (150 kg P ha−1 yr−1) and NP-addition (150 kg N ha−1 yr−1 plus 150 kg P ha−1 yr−1). While N addition significantly decreased the decomposition of both litters, P addition significantly inhibited decomposition of C.C., but did not affect the decomposition of S.S. The negative effect of N addition on litter decomposition might be related to the high N-saturation in this old-growth tropical forest; however, the negative effect of P addition might be due to the suppression of “microbial P mining”. Significant interaction between N and P addition was found on litter decomposition, which was reflected by the less negative effect in NP-addition plots than those in N-addition plots. Our results suggest that P addition may also have negative effect on litter decomposition and that P addition would mitigate the negative effect of N deposition on litter decomposition in tropical forests. PMID:24391895

  6. Evaluation of Vertical Lacunarity Profiles in Forested Areas Using Airborne Laser Scanning Point Clouds

    NASA Astrophysics Data System (ADS)

    Székely, B.; Kania, A.; Standovár, T.; Heilmeier, H.

    2016-06-01

    The horizontal variation and vertical layering of the vegetation are important properties of the canopy structure determining the habitat; three-dimensional (3D) distribution of objects (shrub layers, understory vegetation, etc.) is related to the environmental factors (e.g., illumination, visibility). It has been shown that gaps in forests, mosaic-like structures are essential to biodiversity; various methods have been introduced to quantify this property. As the distribution of gaps in the vegetation is a multi-scale phenomenon, in order to capture it in its entirety, scale-independent methods are preferred; one of these is the calculation of lacunarity. We used Airborne Laser Scanning point clouds measured over a forest plantation situated in a former floodplain. The flat topographic relief ensured that the tree growth is independent of the topographic effects. The tree pattern in the plantation crops provided various quasi-regular and irregular patterns, as well as various ages of the stands. The point clouds were voxelized and layers of voxels were considered as images for two-dimensional input. These images calculated for a certain vicinity of reference points were taken as images for the computation of lacunarity curves, providing a stack of lacunarity curves for each reference points. These sets of curves have been compared to reveal spatial changes of this property. As the dynamic range of the lacunarity values is very large, the natural logarithms of the values were considered. Logarithms of lacunarity functions show canopy-related variations, we analysed these variations along transects. The spatial variation can be related to forest properties and ecology-specific aspects.

  7. A BiomeBGC-based Evaluation of Dryness Stress of Central European Forests

    NASA Astrophysics Data System (ADS)

    Buddenbaum, H.; Hientgen, J.; Dotzler, S.; Werner, W.; Hill, J.

    2015-04-01

    Dryness stress is expected to become a more common problem in central European forests due to the predicted regional climate change. Forest management has to adapt to climate change in time and think ahead several decades in decisions on which tree species to plant at which locations. The summer of 2003 was the most severe dryness event in recent time, but more periods like this are expected. Since forests on different sites react quite differently to drought conditions, we used the process-based growth model BiomeBGC and climate time series from sites all over Germany to simulate the reaction of deciduous and coniferous tree stands in different characteristics of drought stress. Times with exceptionally high values of water vapour pressure deficit coincided with negative modelled values of net primary production (NPP). In addition, in these warmest periods the usually positive relationship between temperature and NPP was inversed, i.e., under stress conditions, more sunlight does not lead to more photosynthesis but to stomatal closure and reduced productivity. Thus we took negative NPP as an indicator for drought stress. In most regions, 2003 was the year with the most intense stress, but the results were quite variable regionally. We used the Modis MOD17 gross and net primary production product time series and MOD12 land cover classification to validate the spatial patterns observed in the model runs and found good agreement between modelled and observed behaviour. Thus, BiomeBGC simulations with realistic site parameterization and climate data in combination with species- and variety-specific ecophysiological constants can be used to assist in decisions on which trees to plant on a given site.

  8. Use of MODIS products to simplify and evaluate a forest fire plume dispersion model for PM 10 exposure assessment

    NASA Astrophysics Data System (ADS)

    Henderson, Sarah B.; Burkholder, Benjamin; Jackson, Peter L.; Brauer, Michael; Ichoku, Charles

    Plume dispersion models may improve assessment of the health effects associated with forest fire smoke, but they require considerable expertise in atmospheric and fire sciences to initialize and evaluate. Products from MODIS (Moderate Resolution Imaging Spectroradiometer) sensors can simplify the process by providing (1) estimates of fire location, size and emission rates, and (2) data useful for assessing model output. By grouping individual MODIS fire pixels into discrete events we simulated the growth and decay of large fires and estimated their total burned area. Radiative power measurements for each fire pixel were multiplied against a fuel-specific coefficient to estimate particle emission rates. Using the CALMET/CALPUFF package we modeled the dispersion of these particles throughout a 325,000 km 2 area with complex terrain. Moderate agreement (mean r = 0.61) between estimated and measured PM 10 concentrations was observed at five of six sites. Because surface measurements are only made at a limited number of locations, we used aerosol optical thickness (AOT) and color imagery product from MODIS for further evaluation. Strong trend association was observed between surface concentrations, model estimates and the AOT measurements. When CALPUFF plume contours were compared to smoke outlines traced from MODIS images we found an average overlap of 50% with better performance under high wind conditions. We conclude that this relatively simple and globally applicable approach can provide a strong foundation for enhanced smoke exposure modeling and public health risk assessment.

  9. Evaluation of the Liu model for predicting rainfall interception in forests world-wide

    USGS Publications Warehouse

    Liu, Shu-Guang

    2001-01-01

    Simple but effective models are needed for the prediction of rainfall interception under a full range of environmental and management conditions. The Liu model was validated using data published in the literature and was compared with two leading models in the literature: the Rutter and the Gash models. The Liu model was tested against the Rutter model on a single-storm basis with interception measurements observed from an old-growth Douglas fir (Pseudotsuga menziesii) forest in Oregon, USA. Simulated results by the Liu model were close to the measurements and comparable to those predicted by the Rutter model. The Liu model was further tested against the Gash model on a multistorm basis. The Gash and Liu models successfully predicted long-term interception losses from a broad range of 20 forests around the world. Results also indicated that both the Gash and the Liu models could be used to predict rainfall interception using daily rainfall data, although it was assumed in both models that there is only one storm per rain day. The sensitivity of the Liu model to stand storage capacity, canopy gap fraction and evaporation rate from wet canopy surface during rainfall was investigated. Results indicate that the Liu model has the simplest form, least data requirements and comparable accuracy for predicting rainfall interception as compared with the Rutter and the Gash models.

  10. An evaluation of ISOCLS and CLASSY clustering algorithms for forest classification in northern Idaho. [Elk River quadrange of the Clearwater National Forest

    NASA Technical Reports Server (NTRS)

    Werth, L. F. (Principal Investigator)

    1981-01-01

    Both the iterative self-organizing clustering system (ISOCLS) and the CLASSY algorithms were applied to forest and nonforest classes for one 1:24,000 quadrangle map of northern Idaho and the classification and mapping accuracies were evaluated with 1:30,000 color infrared aerial photography. Confusion matrices for the two clustering algorithms were generated and studied to determine which is most applicable to forest and rangeland inventories in future projects. In an unsupervised mode, ISOCLS requires many trial-and-error runs to find the proper parameters to separate desired information classes. CLASSY tells more in a single run concerning the classes that can be separated, shows more promise for forest stratification than ISOCLS, and shows more promise for consistency. One major drawback to CLASSY is that important forest and range classes that are smaller than a minimum cluster size will be combined with other classes. The algorithm requires so much computer storage that only data sets as small as a quadrangle can be used at one time.

  11. Charting the Impacts of Disturbance on Biomass Accumulation in Old-Growth Amazon Forests

    NASA Astrophysics Data System (ADS)

    Chambers, J.; Fisher, J.; Hurtt, G.; Baker, T.; Camargo, P.; Campanella, R.; Dos Santos, J.; Higuchi, N.; Malhi, Y.; Phillips, O.; Plourde, L.; Smith, M.; Trumbore, S.

    2006-12-01

    Observed increases in intact Amazon forest biomass, averaging ~0.6 Mg C ha-1 yr-1, have led to suggestions that a forest sink may be of a magnitude large enough to substantially offset Amazonian land- use sources. The mechanism which explains the biomass increase remains unclear. Here we use a synthetic approach, combining remote sensing, intensive field observations, and simulation modeling to elucidate the impact of disturbance on forest structure and changes in biomass. EO-1 Hyperion data and existing field data will be analyzed to generate broad scale disturbance maps. These maps will integrate information from field and remote sensing investigations, spanning a gradient from individual trees to landscape-scale events. Intensive field work will quantify the mortality from these disturbance events. Mapped data will be used to parameterize the height-structured Ecosystem Demography model (ED). ED offers a general method of scaling stochastic individual-based models of ecosystem dynamics to regional scales. Model runs of ED with synthetic mortality rates brackets the range of potential carbon flux attributable to disturbance, mortality, and recovery. The parameterization of the model with generated disturbance maps will provide a best estimate biomass gain due to disturbance patterns across the Amazon.

  12. Relating tree growth to rainfall in Bolivian rain forests: a test for six species using tree ring analysis.

    PubMed

    Brienen, Roel J W; Zuidema, Pieter A

    2005-11-01

    Many tropical regions show one distinct dry season. Often, this seasonality induces cambial dormancy of trees, particularly if these belong to deciduous species. This will often lead to the formation of annual rings. The aim of this study was to determine whether tree species in the Bolivian Amazon region form annual rings and to study the influence of the total amount and seasonal distribution of rainfall on diameter growth. Ring widths were measured on stem discs of a total of 154 trees belonging to six rain forest species. By correlating ring width and monthly rainfall data we proved the annual character of the tree rings for four of our study species. For two other species the annual character was proved by counting rings on trees of known age and by radiocarbon dating. The results of the climate-growth analysis show a positive relationship between tree growth and rainfall in certain periods of the year, indicating that rainfall plays a major role in tree growth. Three species showed a strong relationship with rainfall at the beginning of the rainy season, while one species is most sensitive to the rainfall at the end of the previous growing season. These results clearly demonstrate that tree ring analysis can be successfully applied in the tropics and that it is a promising method for various research disciplines. PMID:16012820

  13. Insights from an Evaluability Assessment of the U.S. Forest Service "More Kids in the Woods" Initiative

    ERIC Educational Resources Information Center

    Zint, Michaela T.; Covitt, Beth A.; Dowd, Patrick F.

    2011-01-01

    We conducted an evaluability assessment of the U.S. Forest Service's "More Kids in the Woods" internal grant initiative based on a review of 26 funded proposals, the creation of logic models, and a survey of project leaders. Evaluations of the initiative are warranted because it has clear outcome objectives, is implemented as intended, and results…

  14. Evaluation of space station ATCS evolution growth paths

    NASA Technical Reports Server (NTRS)

    Ames, Brian E.; Petete, Patricia A.

    1993-01-01

    This paper determines the feasibility of potential Active Thermal Control System (ATCS) growth paths by assessing thermal, integration, and implementation impacts. Thermal Radiation Analysis System/Infrared Radiation Transfer (TRASYS/IRTRAN) models were used to evaluate the effects of increased radiator temperature, increased radiator area, and radiator wing addition on Space Station Freedom (SSF) elements, including energy reflected back to the ATCS. Systems Improved Numerical Differencing Analyzer/Fluid Integrator (SINDA/FLUINT) models were used to determine the heat rejection capability of an ATCS loop with an integrated heat pump that operates with Electric Power System (EPS) peak power. The effects of upgrading the ATCS by advanced technology Orbital Replacement Unit (ORU) implementation during maintenance replacements was also evaluated. The study results presented lead to conclusions on which paths are best suited for different growth scenarios.

  15. Effects of calcium on seed germination, seedling growth and photosynthesis of six forest tree species under simulated acid rain.

    PubMed

    Liu, Ting-Wu; Wu, Fei-Hua; Wang, Wen-Hua; Chen, Juan; Li, Zhen-Ji; Dong, Xue-Jun; Patton, Janet; Pei, Zhen-Ming; Zheng, Hai-Lei

    2011-04-01

    We selected six tree species, Pinus massoniana Lamb., Cryptomeria fortunei Hooibr. ex Otto et Dietr., Cunninghamia lanceolata (Lamb.) Hook., Liquidambar formosana Hance, Pinus armandii Franch. and Castanopsis chinensis Hance, which are widely distributed as dominant species in the forest of southern China where acid deposition is becoming more and more serious in recent years. We investigated the effects and potential interactions between simulated acid rain (SiAR) and three calcium (Ca) levels on seed germination, radicle length, seedling growth, chlorophyll content, photosynthesis and Ca content in leaves of these six species. We found that the six species showed different responses to SiAR and different Ca levels. Pinus armandii and C. chinensis were very tolerant to SiAR, whereas the others were more sensitive. The results of significant SiAR × Ca interactions on different physiological parameters of the six species demonstrate that additional Ca had a dramatic rescue effect on the seed germination and seedling growth for the sensitive species under SiAR. Altogether, we conclude that the negative effects of SiAR on seed germination, seedling growth and photosynthesis of the four sensitive species could be ameliorated by Ca addition. In contrast, the physiological processes of the two tolerant species were much less affected by both SiAR and Ca treatments. This conclusion implies that the degree of forest decline caused by long-term acid deposition may be attributed not only to the sensitivity of tree species to acid deposition, but also to the Ca level in the soil. PMID:21470980

  16. 3-D Volumetric Evaluation of Human Mandibular Growth

    PubMed Central

    Reynolds, Mathew; Reynolds, Michael; Adeeb, Samer; El-Bialy, Tarek

    2011-01-01

    Bone growth is a complex process that is controlled by a multitude of mechanisms that are not fully understood.Most of the current methods employed to measure the growth of bones focus on either studying cadaveric bones from different individuals of different ages, or successive two-dimensional (2D) radiographs. Both techniques have their known limitations. The purpose of this study was to explore a technique for quantifying the three dimensional (3D) growth of an adolescent human mandible over the period of one year utilizing cone beam computed tomography (CBCT) scans taken for regular orthodontic records. Three -dimensional virtual models were created from the CBCT data using mainstream medical imaging software. A comparison between computer-generated surface meshes of successive 3-D virtual models illustrates the magnitude of relative mandible growth. The results of this work are in agreement with previously reported data from human cadaveric studies and implantable marker studies. The presented method provides a new relatively simple basis (utilizing commercially available software) to visualize and evaluate individualized 3D (mandibular) growth in vivo. PMID:22046201

  17. Teacher Evaluation: Five Keys to Growth. "A Training Program for Effective Evaluation."

    ERIC Educational Resources Information Center

    Rose, Mary; And Others

    This manual describes a training program for teacher evaluation. The purpose of the program is to provide educators who evaluate classroom instruction with the tools that result in professional growth for the teachers and improvement of classroom instruction. Joint participation by teachers and administrators is encouraged in all phases of the…

  18. A sweet spot for highly efficient growth of vertically aligned single-walled carbon nanotube forests enabling their unique structures and properties

    NASA Astrophysics Data System (ADS)

    Chen, Guohai; Davis, Robert C.; Futaba, Don N.; Sakurai, Shunsuke; Kobashi, Kazufumi; Yumura, Motoo; Hata, Kenji

    2015-12-01

    We investigated the correlation between growth efficiency and structural parameters of single-walled carbon nanotube (SWCNT) forests and report the existence of a SWCNT ``sweet spot'' in the CNT diameter and spacing domain for highly efficient synthesis. Only within this region could SWCNTs be grown efficiently. Through the investigation of the growth rates for ~340 CNT forests spanning diameters from 1.3 to 8.0 nm and average spacing from 5 to 80 nm, this ``sweet spot'' was found to exist because highly efficient growth was constrained by several mechanistic boundaries that either hindered the formation or reduced the growth rate of SWCNT forests. Specifically, with increased diameter SWCNTs transitioned to multiwalled CNTs (multiwall border), small diameter SWCNTs could only be grown at low growth rates (low efficiency border), sparse SWCNTs lacked the requirements to vertically align (lateral growth border), and high density catalysts could not be prepared (high catalyst density border). As a result, the SWCNTs synthesized within this ``sweet spot'' possessed a unique set of characteristics vital for the development applications, such as large diameter, long, aligned, defective, and high specific surface area.We investigated the correlation between growth efficiency and structural parameters of single-walled carbon nanotube (SWCNT) forests and report the existence of a SWCNT ``sweet spot'' in the CNT diameter and spacing domain for highly efficient synthesis. Only within this region could SWCNTs be grown efficiently. Through the investigation of the growth rates for ~340 CNT forests spanning diameters from 1.3 to 8.0 nm and average spacing from 5 to 80 nm, this ``sweet spot'' was found to exist because highly efficient growth was constrained by several mechanistic boundaries that either hindered the formation or reduced the growth rate of SWCNT forests. Specifically, with increased diameter SWCNTs transitioned to multiwalled CNTs (multiwall border), small

  19. Growth of Fagus in transition zones of forest and soil on the western slope of Mt. Chokai, northern Japan

    NASA Astrophysics Data System (ADS)

    Kato, S.; Watanabe, M.

    2012-04-01

    A wide transition zone for forest structure is expected to distribute on the gentle slope of western side of Mt. Chokai ,Yamagata prefecture, northern Japan (N39° 05'57", E140°02'55"). The annual mean temperature and total precipitation at summit (2,059 m asl.) are 0.5° C and 3,285mm, respectively. The parent materials of the soils are weathered Andesite associated with non-tephric loess deposits transported from continental China. Representative sites were selected in forests of Quercus mongolica and Fagus crenata to examine characteristics of transition zones of vegetation and soil in the western slope of Mt. Chokai with concern on the growth of Fagus in transition zones. Surveys on vegetation profile and projection diagram of canopy for each site (10-10m plots) were carried out in 7 sites selected along altitudinal sequence on the western slope of Mt. Chokai; Ch1-7: 550-1,100m asl.. Growth rate of Fagus was estimated by the measurement of tree rings from increment core samples. Timber volume of Fagus at each point was calculated based on diameter of breast height; DBH as an indicator of tree biomass. Soil profiles were observed at the above 7 sites and soil samples were collected from each horizon. As for soil analyses, soil pH (H2O, KCl, NaF) values were measured by the glass electrode method in the suspension mixture of soil with a 2.5 times volume of H2O or 1N KCl and 50 times volume of 4% NaF. Pyrophosphate, acid oxalate and dithionite-citrate extractable Al (Alp, Alo, Ald), Fe (Feo, Fed) and Si (Sio, Sid) were measured by ICP-AES. The content of exchangeable Al (AlEX) was obtained by titration of extract with 1N KCl. Sclerotia formed by species of Cenococcum, ectomycorrhizal fungi, were collected for grains of diameter larger than 0.5mm from wet samples. Sclerotia content was obtained by weight (mg g-1 soil). Due to intensive base leaching under extremely high precipitation and the mineralogical properties, Ah and Ae horizons of all profiles had low soil

  20. An expert-based approach to forest road network planning by combining Delphi and spatial multi-criteria evaluation.

    PubMed

    Hayati, Elyas; Majnounian, Baris; Abdi, Ehsan; Sessions, John; Makhdoum, Majid

    2013-02-01

    Changes in forest landscapes resulting from road construction have increased remarkably in the last few years. On the other hand, the sustainable management of forest resources can only be achieved through a well-organized road network. In order to minimize the environmental impacts of forest roads, forest road managers must design the road network efficiently and environmentally as well. Efficient planning methodologies can assist forest road managers in considering the technical, economic, and environmental factors that affect forest road planning. This paper describes a three-stage methodology using the Delphi method for selecting the important criteria, the Analytic Hierarchy Process for obtaining the relative importance of the criteria, and finally, a spatial multi-criteria evaluation in a geographic information system (GIS) environment for identifying the lowest-impact road network alternative. Results of the Delphi method revealed that ground slope, lithology, distance from stream network, distance from faults, landslide susceptibility, erosion susceptibility, geology, and soil texture are the most important criteria for forest road planning in the study area. The suitability map for road planning was then obtained by combining the fuzzy map layers of these criteria with respect to their weights. Nine road network alternatives were designed using PEGGER, an ArcView GIS extension, and finally, their values were extracted from the suitability map. Results showed that the methodology was useful for identifying road that met environmental and cost considerations. Based on this work, we suggest future work in forest road planning using multi-criteria evaluation and decision making be considered in other regions and that the road planning criteria identified in this study may be useful. PMID:22565600

  1. Wood growth patterns of Macrolobium acaciifolium (Benth.) Benth. (Fabaceae) in Amazonian black-water and white-water floodplain forests.

    PubMed

    Schöngart, Jochen; Piedade, Maria Teresa F; Wittmann, Florian; Junk, Wolfgang J; Worbes, Martin

    2005-09-01

    Macrolobium acaciifolium (Benth.) Benth. (Fabaceae) is a dominant legume tree species occurring at low elevations of nutrient-poor black-water (igapó) and nutrient-rich white-water floodplain forests (várzea) of Amazonia. As a consequence of the annual long-term flooding this species forms distinct annual tree rings allowing dendrochronological analyses. From both floodplain types in Central Amazonia we sampled cores from 20 large canopy trees growing at identical elevations with a flood-height up to 7 m. We determined tree age, wood density (WD) and mean radial increment (MRI) and synchronized ring-width patterns of single trees to construct tree-ring chronologies for every study site. Maximum tree age found in the igapó was more than 500 years, contrary to the várzea with ages not older than 200 years. MRI and WD were significantly lower in the igapó (MRI=1.52+/-0.38 mm year(-1), WD=0.39+/-0.05 g cm(-3)) than in the várzea (MRI=2.66+/-0.67 mm year(-1), WD=0.45+/-0.03 g cm(-3)). In both floodplain forests we developed tree-ring chronologies comprising the period 1857-2003 (n=7 trees) in the várzea and 1606-2003 (n=13 trees) in the igapó. The ring-width in both floodplain forests was significantly correlated with the length of the terrestrial phase (vegetation period) derived from the daily recorded water level in the port of Manaus since 1903. In both chronologies we found increased wood growth during El Niño events causing negative precipitation anomalies and a lower water discharge in Amazonian rivers, which leads to an extension of the terrestrial phase. The climate signal of La Niña was not evident in the dendroclimatic proxies. PMID:16025354

  2. Allometry in global models: an important reality check on the growth and biomass of forests

    NASA Astrophysics Data System (ADS)

    Wolf, A.; Berry, J. A.

    2009-12-01

    Data assimilation incorporates information into a model of nature, and regardless of the algorithm employed the success of DA rests heavily on the quality of both the data and the model. Here we ask the question: if would could assimilate biomass from remote sensing or direct observation, could the models accommodate this information? We find that the state variables that are simulated by land surface models, such as biomass per unit area, are not amenable to developing an "observation operator" necessary for comparison with data. That is, lidar, radar, and multi-angle observations are sensitive to the size and shape of individual trees, whereas most land surface models have no representation of an individual. In addition, most land surface models make no distinction between aboveground and belowground woody biomass. We used the Cannell (1982) forest inventory database to individuate the biomass simulated in land surface models and found that the scaling of biomass pools - leaves, stem, coarse and fine roots - do not obey widely observed empirical and theoretical allometric constraints that are observed for individual trees (Enquist and Niklas, 2002), suggesting that the fractional allocation to these pools and their characteristic turnover times are in error. This discrepancy represents a gap in the translation of research on individual-based allocation to the stand level, where self-pruning and competition are manifest in the observed fluxes and biomass pools per unit area. We develop an approach to synthesize individual-based allocation with area-based flux models using a recent database of component flux and biomass compiled from Fluxnet sites (Luyssaert et al., 2008). We present the size-dependent pattern of allocation and turnover time for forest biomass pools at the spatial scale appropriate for land surface models. We discuss the implications of these results at the global scale for forests with changing size and age structure.

  3. INFLUENCES OF CLIMATE CHANGE ON FOREST GROWTH RESPONSE TO NUTRIENT AMENDMENTS

    EPA Science Inventory

    This paper examines the influence of precipitation and temperature deviations on regional volume growth rates in even-aged, second-growth Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands, some of which received N fertilizer treatments. etween 1969 and 1986, average volum...

  4. Effects of Intensive Forest Management Practices on Insect Infestation Levels and Loblolly Pine Growth

    SciTech Connect

    Nowak, J.T.; Berisford, C.W.

    2000-04-01

    This study investigates the relationship between intensive management practices and insect infestation, maximum growth potential studies of loblolly pine over four years using different levels of cultural treatments. Results indicate tree fertilization can increase coneworm infestation and demonstrated that tip moth management can improve initial tree growth.

  5. GROWTH-TREND DECLINES OF SPRUCE AND FIR IN MID-APPALACHIAN SUBALPINE FORESTS

    EPA Science Inventory

    Dendroecological analysis of 258 increment growth cores collected from red spruce, balsam fir, and Fraser fir in central West Virginia and western Virginia indicates marked declines in growth-trend during the past 20 years similar to that reported for spruce and fir in high-eleva...

  6. Montana's forest resources. Forest Service resource bulletin

    SciTech Connect

    Conner, R.C.; O'Brien, R.A.

    1993-09-01

    The report includes highlights of the forest resource in Montana as of 1989. Also the study describes the extent, condition, and location of the State's forests with particular emphasis on timberland. Includes statistical tables, area by land classes, ownership, and forest type, growing stock and sawtimber volumes, growth, mortality, and removals for timberland.

  7. Water balances of old-growth and regenerating montane cloud forests in central Veracruz, Mexico

    NASA Astrophysics Data System (ADS)

    Muñoz-Villers, L. E.; Holwerda, F.; Gómez-Cárdenas, M.; Equihua, M.; Asbjornsen, H.; Bruijnzeel, L. A.; Marín-Castro, B. E.; Tobón, C.

    2012-09-01

    SummaryThis paper compares the water budgets of two adjacent micro-catchments covered by mature (MAT) and 20-year-old secondary (SEC) lower montane cloud forests, respectively, in central Veracruz, Mexico over a 2-year period. Rainfall (P) and streamflow (Q) were measured continuously, whereas dry canopy evaporation (transpiration Et), wet canopy evaporation (rainfall interception I), and cloud water interception (CWI) were quantified using a combination of field measurements and modeling. Mean annual P was 3467 mm, of which typically 80% fell during the wet season (May-October). Fog interception occurred exclusively during the dry season (November-April), and was ⩽2% of annual P for both forests. Rainfall interception loss was dominated by post-event evaporation of intercepted water rather than by within-event evaporation. Therefore, the higher overall I (i.e. including CWI) by the MAT (16% of P vs. 8% for the SEC) reflects a higher canopy storage capacity, related in turn to higher leaf area index and greater epiphyte biomass. Annual Et totals derived from sapflow measurements were nearly equal for the MAT and SEC (˜790 mm each). Total annual water yield calculated as P minus (Et + I) was somewhat higher for the SEC (2441 mm) than for the MAT (2077 mm), and mainly reflects the difference in I. Mean annual Q was also higher for the SEC (1527 mm) than for the MAT (1338 mm), and consisted mostly of baseflow (˜90%). Baseflow recession rates were nearly equal between the two forests, as were stormflow coefficients (4% and 5% for MAT and SEC, respectively). The very low runoff response to rainfall is attributed to the high infiltration and water retention capacities of the volcanic soils throughout the ˜2 m deep profile. The water budget results indicate that ˜875 and 700 mm year-1 leave the SEC and MAT as deep groundwater leakage, which is considered plausible given the fractured geology in the study area. It is concluded that 20 years of natural regeneration

  8. Seed reserve composition in 19 tree species of a tropical deciduous forest in Mexico and its relationship to seed germination and seedling growth

    PubMed Central

    Soriano, Diana; Orozco-Segovia, Alma; Márquez-Guzmán, Judith; Kitajima, Kaoru; Gamboa-de Buen, Alicia; Huante, Pilar

    2011-01-01

    Background and Aims The size and composition of seed reserves may reflect the ecological strategy and evolutionary history of a species and also temporal variation in resource availability. The seed mass and composition of seed reserves of 19 co-existing tree species were studied, and we examined how they varied among species in relation to germination and seedling growth rates, as well as between two years with contrasting precipitation (652 and 384 mm). Methods Seeds were collected from a tropical deciduous forest in the northwest of Mexico (Chamela Biological Station). The seed dry mass, with and without the seed coat, and the concentrations of lipids, nitrogen and non-structural carbohydrates for the seed minus seed coat were determined. The anatomical localization of these reserves was examined using histochemical analysis. The germination capacity, rate and lag time were determined. The correlations among these variables, and their relationship to previously reported seedling relative growth rates, were evaluated with and without phylogenetic consideration. Key Results There were interannual differences in seed mass and reserve composition. Seed was significantly heavier after the drier year in five species. Nitrogen concentration was positively correlated with seed coat fraction, and was significantly higher after the drier year in 12 species. The rate and lag time of germination were negatively correlated with each other. These trait correlations were also supported for phylogenetic independent contrasts. Principal component analysis supported these correlations, and indicated a negative association of seedling relative growth rate with seed size, and a positive association of germination rate with nitrogen and lipid concentrations. Conclusions Nitrogen concentration tended to be higher after the drier year and, while interannual variations in seed size and reserve composition were not sufficient to affect interspecific correlations among seed and seedling

  9. Effects of annual and interannual environmental variability on soil fungi associated with an old-growth, temperate hardwood forest.

    PubMed

    Burke, David J

    2015-06-01

    Seasonal and interannual variability in temperature, precipitation and chemical resources may regulate fungal community structure in forests but the effect of such variability is still poorly understood. In this study, I examined changes in fungal communities over two years and how these changes were correlated to natural variation in soil conditions. Soil cores were collected every month for three years from permanent plots established in an old-growth hardwood forest, and molecular methods were used to detect fungal species. Species richness and diversity were not consistent between years with richness and diversity significantly affected by season in one year but significantly affected by depth in the other year. These differences were associated with variation in late winter snow cover. Fungal communities significantly varied by plot location, season and depth and differences were consistent between years but fungal species within the community were not consistent in their seasonality or in their preference for certain soil depths. Some fungal species, however, were found to be consistently correlated with soil chemistry across sampled years. These results suggest that fungal community changes reflect the behavior of the individual species within the community pool and how those species respond to local resource availability. PMID:25979478

  10. Influence of logjam-formed hard points on the formation of valley-bottom landforms in an old-growth forest valley, Queets River, Washington, USA

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.; Abbe, Tim B.

    2006-01-01

    Field surveys and radiocarbon dating of buried logjams in the floodplain of an old-growth forest river demonstrate the formation of erosion-resistant "hard points" on the floodplain of the Queets River, Washington. These hard points provide refugia for development of old-growth forest patches in frequently disturbed riparian environments dominated by immature forest. Our surveys show that local bed aggradation associated with logjams not only influences channel patterns and profiles but leads to development of a patchwork of elevated landforms that can coalesce to form portions of the valley bottom with substantial (i.e., 1 to >4 m) relief above the bankfull elevation. In addition, logjam-formed hard points promote channel avulsion, anastomosing morphology, and growth of mature patches of floodplain forest that, in turn, provide large logs needed to form more logjam-formed hard points. Hence, our findings substantiate the potential for a feedback mechanism through which hard points sustain complex channel morphology and a patchwork floodplain composed of variable-elevation surfaces. Conversely, such a feedback further implies that major changes in riparian forest characteristics associated with land use can lead to dramatic simplification in channel and floodplain morphology.

  11. Morphologic and molecular evaluation of Chlamydia trachomatis growth in human endocervix reveals distinct growth patterns

    PubMed Central

    Lewis, Maria E.; Belland, Robert J.; AbdelRahman, Yasser M.; Beatty, Wandy L.; Aiyar, Ashok A.; Zea, Arnold H.; Greene, Sheila J.; Marrero, Luis; Buckner, Lyndsey R.; Tate, David J.; McGowin, Chris L.; Kozlowski, Pamela A.; O'Brien, Michelle; Lillis, Rebecca A.; Martin, David H.; Quayle, Alison J.

    2014-01-01

    In vitro models of Chlamydia trachomatis growth have long been studied to predict growth in vivo. Alternative or persistent growth modes in vitro have been shown to occur under the influence of numerous stressors but have not been studied in vivo. Here, we report the development of methods for sampling human infections from the endocervix in a manner that permits a multifaceted analysis of the bacteria, host and the endocervical environment. Our approach permits evaluating total bacterial load, transcriptional patterns, morphology by immunofluorescence and electron microscopy, and levels of cytokines and nutrients in the infection microenvironment. By applying this approach to two pilot patients with disparate infections, we have determined that their contrasting growth patterns correlate with strikingly distinct transcriptional biomarkers, and are associated with differences in local levels of IFNγ. Our multifaceted approach will be useful to dissect infections in the human host and be useful in identifying patients at risk for chronic disease. Importantly, the molecular and morphological analyses described here indicate that persistent growth forms can be isolated from the human endocervix when the infection microenvironment resembles the in vitro model of IFNγ-induced persistence. PMID:24959423

  12. Evaluation of hair growth promoting activity of Phyllanthus niruri

    PubMed Central

    Patel, Satish; Sharma, Vikas; S. Chauhan, Nagendra; Thakur, Mayank; Dixit, Vinod Kumar

    2015-01-01

    Objective: This study was designed to investigate the potential Phyllanthus niruri (P. niruri ) extracts in promotion of hair growth. Materials and Methods: Here, we studied the hair growth promoting activity of petroleum ether extract of P. niruri following its topical administration. Alopecia was induced in albino rats by subcutaneous administration of testosterone for 21 days. Evaluation of hair loss inhibition was done by concurrent administration of extract and monitoring parameters like follicular density, anagen/telogen (A/T) ratio and histological observation of animal skin sections. Finasteride solution was applied topically as standard. In vitro experiments were also performed to study the effect of extract on the activity of 5α-reductase enzyme Results: Groups treated with petroleum ether extract of plant showed hair re-growth as reflected by follicular density, A/T ratio and skin sections. Histopathology and morphologic observations of hair re-growth at shaved sites showed active follicular proliferation. In vitro experiments results showed inhibitory activity of petroleum ether extract on type-2 5α-reductase enzyme and an increase in the amount of testosterone with increasing concentrations. Conclusion: It could be concluded that petroleum ether extracts of P. niruri might be useful in the treatment of testosterone-induced alopecia in the experimental animal by inhibiting 5α-reductase enzyme. PMID:26693408

  13. Evaluating and optimizing horticultural regimes in space plant growth facilities

    NASA Technical Reports Server (NTRS)

    Berkovich, Y. A.; Chetirkin, P. V.; Wheeler, R. M.; Sager, J. C.

    2004-01-01

    In designing innovative space plant growth facilities (SPGF) for long duration space flight, various limitations must be addressed including onboard resources: volume, energy consumption, heat transfer and crew labor expenditure. The required accuracy in evaluating on board resources by using the equivalent mass methodology and applying it to the design of such facilities is not precise. This is due to the uncertainty of the structure and not completely understanding the properties of all associated hardware, including the technology in these systems. We present a simple criteria of optimization for horticultural regimes in SPGF: Qmax = max [M x (EBI)2/(V x E x T], where M is the crop harvest in terms of total dry biomass in the plant growth system; EBI is the edible biomass index (harvest index), V is volume occupied by the crop; E is the crop light energy supply during growth; T is the crop growth duration. The criterion reflects directly on the consumption of onboard resources for crop production. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  14. Restoration of Degraded Soil in the Nanmangalam Reserve Forest with Native Tree Species: Effect of Indigenous Plant Growth-Promoting Bacteria

    PubMed Central

    Ramachandran, Andimuthu; Radhapriya, Parthasarathy

    2016-01-01

    Restoration of a highly degraded forest, which had lost its natural capacity for regeneration, was attempted in the Nanmangalam Reserve Forest in Eastern Ghats of India. In field experiment, 12 native tree species were planted. The restoration included inoculation with a consortium of 5 native plant growth-promoting bacteria (PGPB), with the addition of small amounts of compost and a chemical fertilizer (NPK). The experimental fields were maintained for 1080 days. The growth and biomass varied depending on the plant species. All native plants responded well to the supplementation with the native PGPB. The plants such as Pongamia pinnata, Tamarindus indica, Gmelina arborea, Wrightia tinctoria, Syzygium cumini, Albizia lebbeck, Terminalia bellirica, and Azadirachta indica performed well in the native soil. This study demonstrated, by using native trees and PGPB, a possibility to restore the degraded forest. PMID:27195310

  15. Restoration of Degraded Soil in the Nanmangalam Reserve Forest with Native Tree Species: Effect of Indigenous Plant Growth-Promoting Bacteria.

    PubMed

    Ramachandran, Andimuthu; Radhapriya, Parthasarathy

    2016-01-01

    Restoration of a highly degraded forest, which had lost its natural capacity for regeneration, was attempted in the Nanmangalam Reserve Forest in Eastern Ghats of India. In field experiment, 12 native tree species were planted. The restoration included inoculation with a consortium of 5 native plant growth-promoting bacteria (PGPB), with the addition of small amounts of compost and a chemical fertilizer (NPK). The experimental fields were maintained for 1080 days. The growth and biomass varied depending on the plant species. All native plants responded well to the supplementation with the native PGPB. The plants such as Pongamia pinnata, Tamarindus indica, Gmelina arborea, Wrightia tinctoria, Syzygium cumini, Albizia lebbeck, Terminalia bellirica, and Azadirachta indica performed well in the native soil. This study demonstrated, by using native trees and PGPB, a possibility to restore the degraded forest. PMID:27195310

  16. Carbon balance and response to seasonal and long- term forcing at Tapaj¢s Forest old- growth site, Km 67

    NASA Astrophysics Data System (ADS)

    Wofsy, S. C.; Saleska, S. R.; Hutyra, L.; Matross, D. M.; Rice, A. H.; Pyle, E. H.; Daube, B.; Budney, J. W.; Bright, A.; Kirchhoff, V.; Camargo, P. D.; Crill, P.; Keller, M.; Martens, C.; Shay, T.

    2002-12-01

    We report > 2 years of data defining the carbon budget for this old-growth Equatorial evergreen forest, using comprehensive biometric methods and independent eddy covariance flux methods, and analyze the data in the context of extensive environmental ecological and demographic observations. Validation of the carbon budget is shown using independent ecosystem- scale data from continuous soil flux chambers (Crill and Keller) and continuous atmospheric Rn measurements (Martens and Shay) and comparisons are shown with eddy flux and biometric data from Km 83 control period (Goulden, de Rocha). Net Ecosystem Exchange shows uptake in the dry season and loss in the wet season, opposite to tree growth rates due to the dominance of decomposition processes. Trees are growing rapidly, but high mortality and decay of the large pool of CWD more than offsets growth. This result may be the legacy of ENSO events of the 1990's. Thus the Tapaj¢s old growth forest is losing carbon to the atmosphere.

  17. Tree Growth and Competition in a Betula platyphylla–Larix cajanderi Post-fire Forest in Central Kamchatka

    PubMed Central

    DOLEŽAL, JIŘÍ; ISHII, HIROAKI; VETROVA, VALENTINA P.; SUMIDA, AKIHIRO; HARA, TOSHIHIKO

    2004-01-01

    • Background and Aims Fire is the dominant disturbance in central Kamchatka boreal forests, yet patterns and mechanisms of stand recovery have not been investigated. • Methods Measurements were made of 1433 stems ≥1·3 m height and annual radial increments of 225 randomly selected trees in a 0·4-ha plot of a 53-year-old fire-origin mixed-species stand to examine the spatio-temporal variation in establishment, growth, size inequality and the mode of competition among individual trees. Growth variations were related to tree size, age and local interference with neighbours. • Key Results Betula platyphylla formed the main canopy following a fire in 1947, with Larix cajanderi and Pinus pumila progressively reinvading the lower tree and shrub stratum. Most B. platyphylla originated from sprouts in small patches (polycormons) during the first 15 post-fire years. Betula platyphylla had normal distributions of diameter and age classes, but negatively skewed height distribution, as expected from shade-intolerant, pioneer species. Larix cajanderi had fewer tall and many short individuals. The smaller and younger B. platyphylla grew disproportionately more in diameter than larger trees from 1950 to 1975, and hence stem size inequalities decreased. The reverse trend was observed from 1995 to 2000: larger trees grew more, indicating an increasing asymmetry of competition for light. Betula platyphylla had steady diameter growth in the first 25 post-fire years, after which the growth declined in smaller trees. Neighbourhood analysis showed that the decline resulted from increased competition from taller neighbours. • Conclusions The observed growth patterns suggest that mode of interactions altered during stand development from early stages of weak competition for soil resources released by fire to later stages of asymmetric competition for light. Asymmetric crown competition started later than reported in other studies, which can be attributed to the lower stem

  18. Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011

    NASA Astrophysics Data System (ADS)

    Cui, Y. Y.; Hodzic, A.; Smith, J. N.; Ortega, J.; Brioude, J.; Matsui, H.; Turnipseed, A.; Winkler, P.; de Foy, B.

    2014-03-01

    Formation and growth of ultrafine particles is crudely represented in chemistry-climate models, which contributes to uncertainties in aerosol composition, size distribution, and aerosol effects on cloud condensation nuclei (CCN) concentrations. Measurements of ultrafine particles, their precursor gases, and meteorological parameters were performed in a ponderosa pine forest in the Colorado Front Range in July-August 2011, and were analyzed to study processes leading to Aitken-mode Particle burst Events (APEs). These measurements suggest that APEs were associated with the arrival at the site of anthropogenic pollution plumes around noon or in the early afternoon. Number concentrations of ultrafine (4 to 30 nm diameter) particles typically exceeded 10 000 cm-3 during APEs, and these elevated concentrations coincided with increased SO2 and monoterpene concentrations, and led to a factor of two increase in CCN concentrations at 0.5% supersaturation. The APEs were simulated using the regional WRF-Chem model, which was extended to account for ultrafine particle sizes starting at 1 nm in diameter, to include an empirical activation nucleation scheme in the planetary boundary layer, and to explicitly simulate the subsequent growth of Aitken particles by condensation of organic and inorganic vapors. Comparisons with aerosol size distribution measurements showed that simulations using the activation nucleation parameterization reasonably captured aerosol number concentrations and size distribution during APEs, as well as ground level CCN concentrations. Results suggest that sulfuric acid from anthropogenic SO2 triggers APEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles drives their growth. The simulated growth rate of 3.4 nm h-1 for small particles (4-30 nm in diameter) was comparable to the measured average value of 2.3 nm h-1. Model results also suggest that the presence of APEs tends to modify the composition of sub-100 nm

  19. Recent variations in NDVI-based plant growth and their relationship with climate in boreal intact forest landscapes

    NASA Astrophysics Data System (ADS)

    Jin, J.; Jiang, H.; Lu, X.; Zhang, X.

    2015-12-01

    Intact Forest Landscapes (IFLs), defined as large unbroken expanses of forest landscape without signs of significant human activity, have significant ecological values. Previous studies suggest a reversal in the greening of boreal plants was exhibited in the late 1990s. In this study, we focus on variations in plant growth of boreal IFLs from 2000 to 2014 and their correlation with local climatic factors between 45°N and 70°N. The average Normalized Difference Vegetation Index (NDVI) during the growing season (GS, which is from April to October) derived from MOD13C2, is used as a proxy of plant growth. Compared to a significant increase in GS NDVI of boreal plants during the 1980s and early 1990s, GS NDVI of ca. 85.7% of total IFLs in the study area exhibited insignificant change after 2000. About 10.2% of total boreal IFLs exhibited significant greening (an increase in GS NDVI), and only 4.1% of the total showed significant browning (a decrease in GS NDVI) during the study period. For greening boreal IFLs, ca. 46.0% of these showed a significant correlation between GS temperature and NDVI. For browning IFLs, an increase in precipitation during the non-growing season (NGS, which is from previous November to current March) and cooling in GS and NGS were the main climatic causes for decreases of GS NDVI. However, over 65% of browning boreal IFLs did not correlate with any climatic factor, and the browning may be associated with artificial activities. About 49.4% of no-change boreal IFLs showed significant correlation between GS NDVI and climatic factors, and 72.5% of these sensitive plants exhibited a significant positive correlation between GS temperature and NDVI. On the whole, an increase in GS and NGS temperature could promote plant growth of boreal IFLs, while an increase of NGS precipitation mainly inhibited plant growth. However, nearly half of total boreal IFLs displayed no sensitivity to any climatic factors chosen in our present work.

  20. CTFS/ForestGEO: A global network to monitor forest interactions with a changing climate

    NASA Astrophysics Data System (ADS)

    Anderson-Teixeira, K. J.; Muller-Landau, H.; McMahon, S.; Davies, S. J.

    2013-12-01

    Forests are an influential component of the global carbon cycle and strongly influence Earth's climate. Climate change is altering the dynamics of forests globally, which may result in significant climate feedbacks. Forest responses to climate change entail both short-term ecophysiological responses and longer-term directional shifts in community composition. These short- and long-term responses of forest communities to climate change may be better understood through long-term monitoring of large forest plots globally using standardized methodology. Here, we describe a global network of forest research plots (CTFS/ForestGEO) of utility for understanding forest responses to climate change and consequent feedbacks to the climate system. CTFS/ForestGEO is an international network consisting of 51 sites ranging in size from 2-150 ha (median size: 25 ha) and spanning from 25°S to 52°N latitude. At each site, every individual > 1cm DBH is mapped and identified, and recruitment, growth, and mortality are monitored every 5 years. Additional measurements include aboveground productivity, carbon stocks, soil nutrients, plant functional traits, arthropod and vertebrates monitoring, DNA barcoding, airborne and ground-based LiDAR, micrometeorology, and weather monitoring. Data from this network are useful for understanding how forest ecosystem structure and function respond to spatial and temporal variation in abiotic drivers, parameterizing and evaluating ecosystem and earth system models, aligning airborne and ground-based measurements, and identifying directional changes in forest productivity and composition. For instance, CTFS/ForestGEO data have revealed that solar radiation and night-time temperature are important drivers of aboveground productivity in moist tropical forests; that tropical forests are mixed in terms of productivity and biomass trends over the past couple decades; and that the composition of Panamanian forests has shifted towards more drought

  1. Evaluation of DNA polymorphisms involving growth hormone relative to growth and carcass characteristics in Brahman steers.

    PubMed

    Beauchemin, V R; Thomas, M G; Franke, D E; Silver, G A

    2006-01-01

    Associations of DNA polymorphisms in growth hormone (GH) relative to growth and carcass characteristics in growing Brahman steers (N = 324 from 68 sires) were evaluated. Polymorphisms were an Msp-I RFLP and a leucine/valine SNP in the GH gene as well as a Hinf-I RFLP and a histidine/arginine SNP in transcriptional regulators of the GH gene, Pit-1 and Prop-1. Genotypic frequencies of the GH SNP, Pit-1 RFLP, and Prop-1 SNP were greater than 88% for one of the bi-allelic homozygous genotypes. Genotypic frequencies for the GH Msp-I RFLP genotypes were more evenly distributed with frequencies of 0.43, 0.42, and 0.15 for the genotypes of +/+, +/-, and -/-, respectively. Mixed model analyses of growth and carcass traits with genotype and contemporary group serving as fixed effects and sire fitted as a random effect suggested that sire was a significant source of variation (P < 0.05) in average daily gain, carcass yield, and marbling score. However, measures of growth and carcass traits were similar across GH Msp-I genotypes as steers were slaughtered when fat thickness was estimated to be approximately 1.0 cm. These polymorphisms within the GH gene and/or its transcriptional regulators do not appear to be informative predictors of growth and carcass characteristics in Brahman steers. This is partly due to the high level of homozygosity of genotypes. These findings do not eliminate the potential importance of these polymorphisms as predictors of growth and carcass traits in Bos taurus or Bos taurus x Bos indicus composite cattle. PMID:17117358

  2. Comparing NDVI and observed stem growth and wood density in forests of Northern Eurasia

    NASA Astrophysics Data System (ADS)

    Hughes, M. K.; Bunn, A. G.; Kirdyanov, A. V.; Shishov, V.; Losleben, M. V.; Oltchev, A.; Kuznetsova, E.; Novenko, E.

    2012-12-01

    To what extent does NDVI (Normalized Difference Vegetation Index) observed from space co-vary with directly observed stem radial increment and latewood density? To address this question we made correlation analyses between NDVI and paired tree-ring width (TRW) and maximum latewood density (MXD) records from 19 locations North of 54 degrees in the Russian Federation. The period of temporal overlap between the three sets of records started in 1981 and ended between 18 and 28 years later. We compared monthly NDVI at 8 km resolution for a region 24X24 km around each of the 19 locations with well-replicated TRW and MXD time series. Maximum correlation most often occurred in July of the current year, and was similar for both TRW (mean 0.34, minimum 0.04, maximum 0.63) and MXD (mean 0.31, min 0.09, max 0.61). There was a tendency for July correlations to be greatest with larch TRW and lower for spruce and pine TRW, with MXD following a similar pattern. Also, the greater the mean correlation ('rbar') between the component samples making up a location's mean tree ring time series, the greater that series' correlation with NDVI tended to be. We conclude that at the locations studied, which we believe to represent quite a large portion of the boreal forest, NDVI does co-vary with directly observed stem radial increment and latewood density, but to a rather modest degree. We will discuss the implications of our findings for the use of both data types, NDVI and tree rings, in tracking forest productivity on large spatial scales.

  3. An integrated model of environmental effects on growth, carbohydrate balance, and mortality of Pinus ponderosa forests in the southern Rocky Mountains

    USGS Publications Warehouse

    Tague, Christina L.; McDowell, Nathan G.; Allen, Craig D.

    2013-01-01

    Climate-induced tree mortality is an increasing concern for forest managers around the world. We used a coupled hydrologic and ecosystem carbon cycling model to assess temperature and precipitation impacts on productivity and survival of ponderosa pine (Pinus ponderosa). Model predictions were evaluated using observations of productivity and survival for three ponderosa pine stands located across an 800 m elevation gradient in the southern Rocky Mountains, USA, during a 10-year period that ended in a severe drought and extensive tree mortality at the lowest elevation site. We demonstrate the utility of a relatively simple representation of declines in non-structural carbohydrate (NSC) as an approach for estimating patterns of ponderosa pine vulnerability to drought and the likelihood of survival along an elevation gradient. We assess the sensitivity of simulated net primary production, NSC storage dynamics, and mortality to site climate and soil characteristics as well as uncertainty in the allocation of carbon to the NSC pool. For a fairly wide set of assumptions, the model estimates captured elevational gradients and temporal patterns in growth and biomass. Model results that best predict mortality risk also yield productivity, leaf area, and biomass estimates that are qualitatively consistent with observations across the sites. Using this constrained set of parameters, we found that productivity and likelihood of survival were equally dependent on elevation-driven variation in temperature and precipitation. Our results demonstrate the potential for a coupled hydrology-ecosystem carbon cycling model that includes a simple model of NSC dynamics to predict drought-related mortality. Given that increases in temperature and in the frequency and severity of drought are predicted for a broad range of ponderosa pine and other western North America conifer forest habitats, the model potentially has broad utility for assessing ecosystem vulnerabilities.

  4. An Integrated Model of Environmental Effects on Growth, Carbohydrate Balance, and Mortality of Pinus ponderosa Forests in the Southern Rocky Mountains

    PubMed Central

    Tague, Christina L.; McDowell, Nathan G.; Allen, Craig D.

    2013-01-01

    Climate-induced tree mortality is an increasing concern for forest managers around the world. We used a coupled hydrologic and ecosystem carbon cycling model to assess temperature and precipitation impacts on productivity and survival of ponderosa pine (Pinus ponderosa). Model predictions were evaluated using observations of productivity and survival for three ponderosa pine stands located across an 800 m elevation gradient in the southern Rocky Mountains, USA, during a 10-year period that ended in a severe drought and extensive tree mortality at the lowest elevation site. We demonstrate the utility of a relatively simple representation of declines in non-structural carbohydrate (NSC) as an approach for estimating patterns of ponderosa pine vulnerability to drought and the likelihood of survival along an elevation gradient. We assess the sensitivity of simulated net primary production, NSC storage dynamics, and mortality to site climate and soil characteristics as well as uncertainty in the allocation of carbon to the NSC pool. For a fairly wide set of assumptions, the model estimates captured elevational gradients and temporal patterns in growth and biomass. Model results that best predict mortality risk also yield productivity, leaf area, and biomass estimates that are qualitatively consistent with observations across the sites. Using this constrained set of parameters, we found that productivity and likelihood of survival were equally dependent on elevation-driven variation in temperature and precipitation. Our results demonstrate the potential for a coupled hydrology-ecosystem carbon cycling model that includes a simple model of NSC dynamics to predict drought-related mortality. Given that increases in temperature and in the frequency and severity of drought are predicted for a broad range of ponderosa pine and other western North America conifer forest habitats, the model potentially has broad utility for assessing ecosystem vulnerabilities. PMID:24282532

  5. Formation and growth of atmospheric particles at a forest site in the southeast US

    NASA Astrophysics Data System (ADS)

    Pillai, Priya; Walker, John; Khlystov, Andrey; Aneja, Viney

    2013-05-01

    Atmospheric particle size distribution measurements (10 ≤ aerodynamic diameter, Dp ≤ 250 nm), which took place above a loblolly pine plantation in the Southeast U.S. from November 2005 to September 2007, were made using Scanning Mobility Particle Sizer (SMPS). The size distributions were investigated to identify new particle formation and to classify the new particle formation episodes into different event classes based on the behavior of particle size distribution and particle growth pattern. About 69% of the observation days had nucleation. The event frequency was highest in spring and lowest in winter. The particle growth rate was highest in May (5.0 ± 3.6 nm hr-1) and lowest in February (1.2 ± 2.2 nm hr-1) with an annual average particle growth rate of 2.5 ± 0.3 nm hr-1. Nucleation frequency and event types are examined along with associated meteorological and chemical conditions.

  6. Proteomic Analyses Provide Novel Insights into Plant Growth and Ginsenoside Biosynthesis in Forest Cultivated Panax ginseng (F. Ginseng)

    PubMed Central

    Ma, Rui; Sun, Liwei; Chen, Xuenan; Mei, Bing; Chang, Guijuan; Wang, Manying; Zhao, Daqing

    2016-01-01

    F. Ginseng (Panax ginseng) is planted in the forest to enhance the natural ginseng resources, which have an immense medicinal and economic value. The morphology of the cultivated plants becomes similar to that of wild growing ginseng (W. Ginseng) over the years. So far, there have been no studies highlighting the physiological or functional changes in F. Ginseng and its wild counterparts. In the present study, we used proteomic technologies (2DE and iTRAQ) coupled to mass spectrometry to compare W. Ginseng and F. Ginseng at various growth stages. Hierarchical cluster analysis based on protein abundance revealed that the protein expression profile of 25-year-old F. Ginseng was more like W. Ginseng than less 20-year-old F. Ginseng. We identified 192 differentially expressed protein spots in F. Ginseng. These protein spots increased with increase in growth years of F. Ginseng and were associated with proteins involved in energy metabolism, ginsenosides biosynthesis, and stress response. The mRNA, physiological, and metabolic analysis showed that the external morphology, protein expression profile, and ginsenoside synthesis ability of the F. Ginseng increased just like that of W. Ginseng with the increase in age. Our study represents the first characterization of the proteome of F. Ginseng during development and provides new insights into the metabolism and accumulation of ginsenosides. PMID:26858731

  7. Effect of release herbicide on mortality, avoidance response, and growth of amphibian larvae in two forest wetlands.

    PubMed

    Wojtaszek, Barbara F; Buscarini, Teresa M; Chartrand, Derek T; Stephenson, Gerald R; Thompson, Dean G

    2005-10-01

    Effects of Release herbicide (triclopyr butoxyethyl ester, [TBEE]) on mortality, avoidance response, and growth of larval amphibians (Rana clamitans, Rana pipiens) were investigated using in situ enclosures deployed in two forest wetlands in northern Ontario, Canada. Release was applied at nominal concentrations ranging from 0.26 to 7.68 mg TBEE acid equivalents (AE)/L. No significant deleterious effects of this herbicide on larval growth were detected. However, concentration-dependent mortality and abnormal avoidance response were observed. Most mortality occurred within 96 h following treatment. Median lethal concentration (LC50) values for each species and experimental site ranged from 2.79 to 3.29 mg AE/L, while median effective concentration (EC50) values (abnormal avoidance response) ranged from 1.67 to 3.84 mg AE/L. The LC10 and EC10 endpoints approximated aqueous concentrations (0.59 mg AE/L) expected under direct aerial overspray scenarios, indicating a potential risk of impacts for a small proportion of native amphibian larvae. However, given the low frequency and limited use of this herbicide formulation in Canadian forestry, these risks are considered negligible. Changes in usage patterns would require concurrent chemical and biological monitoring of operational spray programs to accurately quantify the probability and magnitude of real-world exposures and to relate these exposure levels to concentration-response relationships including those described in this study. PMID:16268155

  8. AVAILABILITY AND UPTAKE OF INORGANIC NITROGEN IN A MIXED OLD-GROWTH CONIFEROUS FOREST

    EPA Science Inventory

    Rates of nitrogen mineralization, nitrification and an index of ammonium and nitrate uptake were monitored in a mixed old-growth stand of Douglas-fir (Pseudotsuga menziesii) western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata) over a two year period. uried ba...

  9. Evaluation of Terrestrial Laser Scanning for Rice Growth Monitoring

    NASA Astrophysics Data System (ADS)

    Tilly, N.; Hoffmeister, D.; Liang, H.; Cao, Q.; Liu, Y.; Lenz-Wiedemann, V.; Miao, Y.; Bareth, G.

    2012-08-01

    The rapidly growing world population and the resulting pressure on the efficiency of agriculture require a sustainable development of intensive field management with regard to natural resources. In this context, the use of non-destructive remote sensing technologies to monitor status and change detection of plant growth is in the focus of research and application. In this contribution, we evaluate the applicability of multitemporal terrestrial laser scanning (TLS) for rice growth monitoring. The test sites are located around Jiansanjiang in Heilongjiang Province in the far northeast of China. The focus of the field experiment was on different nitrogen fertilizer inputs during the growing period in 2011. To realize the monitoring approach, three campaigns were carried out during the vegetative stage of rice plants. For all campaigns the terrestrial laser scanner Riegl VZ-1000 was used. The achieved knowledge can be described in two parts. First, for each date the variability of plant height and biomass is detectable for the whole experiment field and - more important - between the plots. Furthermore, differences in height and biomass related to edge effects can be investigated for every single plot. The spatial distribution is visualized by Crop Surface Models (CSM), which are digital surface models with a high resolution and accuracy achieved by the interpolation of the 3D point clouds. Secondly, the multitemporal surveying approach enables the monitoring of the growth rate of the rice plants. Additionally, it is possible to detect and analyze as well the spatial distribution of the changes by comparing the CSMs. Our results show that TLS is a suitable and promising method for rice growth monitoring. Furthermore, the contemporaneous surveying with other sensors enables us to validate our measurements and bares opportunities for further enhancements.

  10. Temporal change in soil carbon stability at a paired old-growth douglas-fir forest/clear-cut site

    EPA Science Inventory

    Forest ecosystems are estimated to contain one-half of the total terrestrial carbon (C) pool (1146 Pg), with two-thirds of this C (787 Pg) residing in forest soils. Given the magnitude of this C pool, it is critical to understand the effects of forest management practices on soil...

  11. [Evaluation of ecological services of Populus simonii forest on Heerqin sandy land].

    PubMed

    Zhang, Hua; Li, Fengrui; Zhang, Tonghui; Zhao, Liya; Yasuhito, Shirato

    2003-10-01

    The main ecological services of the sand-fixed forest are windbreak, soil erosion control, and atmospheric dust retention. In this paper, the ecological services of Populus simonii forest were assessed by simultaneous measurements of wind speeds, daily amount of soil surface wind erosion, and amount of atmospheric dust deposition at different observation sites located within and outside the forestland. The results showed that compared with the control site (mobile sand dune), the daily mean wind velocity at 2 m height was reduced by 18.3, 31.6, 66.1, 66.0, 62.3 and 45.2% for the observation sites over the distances of 6 and 3 H (H meant average tree height) from forest edge of the windward side, forest center, and observation sites over the distances of 0, 6 and 8 H from forest edge of the leeward side, respectively. The greatest reduction in daily mean wind velocity was occurred in both forest center and forest edge of the leeward side. There was a significant positive relationship between leaf area index of the forest and monthly declining index of mean wind speed. The monthly declining index of mean wind speed increased with increasing the forest leaf area index by a cubic function. The daily wind erosion rates of soil surface in observation sites at 6 and 3 H from forest edge of the windward side, forest center, and at 0, 6 and 8 H from forest edge of the leeward side were reduced by as much as 85.2%-99.9%, in comparison with the control site. The greatest reduction in daily wind erosion rate of soil surface occurred in forest edge of the leeward side, followed in decreasing order by forest center, 6 and 8 H from forest edge of the leeward side, 3 and 6 H from forest edge of the windward side. During the observation period, the daily mean dust deposition within the forestland was 13.2 kg.hm-2, compared with 9.9 kg.hm-2 outside the forestland, with a 33% increase. All these results suggested that the poplar forest played an important role in reducing damaging

  12. Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests

    PubMed Central

    Kondraskov, Paulina; Schütz, Nicole; Schüßler, Christina; de Sequeira, Miguel Menezes; Guerra, Arnoldo Santos; Caujapé-Castells, Juli; Jaén-Molina, Ruth; Marrero-Rodríguez, Águedo; Koch, Marcus A.; Linder, Peter; Kovar-Eder, Johanna; Thiv, Mike

    2015-01-01

    The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data. PMID:26173113

  13. Biogenic isoprene emission: Model evaluation in a southeastern United States bottomland deciduous forest

    NASA Astrophysics Data System (ADS)

    Geron, Christopher D.; Nie, Dalin; Arnts, Robert R.; Sharkey, Thomas D.; Singsaas, Eric L.; Vanderveer, Peter J.; Guenther, Alex; Sickles, Joe E.; Kleindienst, Tad E.

    1997-08-01

    Isoprene is usually the dominant natural volatile organic compound emission from forest ecosystems, especially those with a major broadleaf deciduous component. Here we report isoprene emission model performance versus leaf and canopy level isoprene emission measurements made at the Duke University Research Forest near Chapel Hill, North Carolina. Emission factors, light and temperature response, canopy environment models, foliar mass, leaf area, and canopy level isoprene emission were evaluated in the field and compared with model estimates. Model components performed reasonably well and generally yielded estimates within 20% of values measured at the site. However, measured emission factors were much higher in early summer following an unusually dry spring. These decreased later in the summer but remained higher than values currently used in emission models. There was also a pronounced decline in basal emission rates in lower portions of the canopy which could not be entirely explained by decreasing specific leaf weight. Foliar biomass estimates by genera using basal area ratios adjusted for crown form were in excellent agreement with values measured by litterfall. Overall, the stand level isoprene emissions determined by relaxed eddy accumulation techniques agreed reasonably well with those predicted by the model, although there is some evidence for underprediction at ambient temperatures approaching 30°C, and overprediction during October as the canopy foliage senesced. A "Big Leaf" model considers the canopy as a single multispecies layer and expresses isoprene emission as a function of leaf area rather than mass. This simple model performs nearly as well as the other biomass-based models. We speculate that seasonal water balance may impact isoprene emission. Possible improvements to the canopy environment model and other components are discussed.

  14. Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests.

    PubMed

    Kondraskov, Paulina; Schütz, Nicole; Schüßler, Christina; de Sequeira, Miguel Menezes; Guerra, Arnoldo Santos; Caujapé-Castells, Juli; Jaén-Molina, Ruth; Marrero-Rodríguez, Águedo; Koch, Marcus A; Linder, Peter; Kovar-Eder, Johanna; Thiv, Mike

    2015-01-01

    The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data. PMID:26173113

  15. Dendrochronology-based stand growth estimation of Larix olgensis forest in relation with climate on the eastern slope of Changbai Mountain, NE China

    NASA Astrophysics Data System (ADS)

    Lin, Bo; Xu, Qianqian; Liu, Wenhui; Zhang, Guochun; Xu, Qiongyao; Liu, Qijing

    2013-12-01

    The eastern slope of Changbai Mountain is characterized by pure larch forest ( Larix olgensis) with little human disturbance. Response of tree growth to climate in this area remains unknown. Meanwhile, little is known about how climate variations affect the biomass increase which could be recognized as a three-dimensional tree growth index. The objective of this study is to investigate the climate effects on the radial and biomass growth of larch on eastern slope of Changbai Mountain. Tree-ring width chronologies and mean annual biomass increment were established using tree-ring data. We used correlation analysis and multiple regression analysis to explore the relationship between larch growth and climatic factors from 1957 to 2009. Results show that tree-ring growth and mean annual biomass increment were primarily and significantly affected by previous year climatic variables with slight difference among months. Temperatures were more consistently and strongly correlated to the chronologies and mean annual biomass increment than was precipitation. Temperature is the main factor limiting larch growth on Changbai Mountain and the ongoing climate warming may accelerate the growth of the species. The current stand biomass of the area was 240.72 Mg·ha-1 and the annual stand biomass increment in 2009 was 2.91 Mg·ha-1. In conclusion, the old-growth forest in the study area is still accumulating carbon efficiently.

  16. Comparing Forests across Climates and Biomes: Qualitative Assessments, Reference Forests and Regional Intercomparisons

    PubMed Central

    Salk, Carl F.; Frey, Ulrich; Rusch, Hannes

    2014-01-01

    Communities, policy actors and conservationists benefit from understanding what institutions and land management regimes promote ecosystem services like carbon sequestration and biodiversity conservation. However, the definition of success depends on local conditions. Forests' potential carbon stock, biodiversity and rate of recovery following disturbance are known to vary with a broad suite of factors including temperature, precipitation, seasonality, species' traits and land use history. Methods like tracking over-time changes within forests, or comparison with “pristine” reference forests have been proposed as means to compare the structure and biodiversity of forests in the face of underlying differences. However, data from previous visits or reference forests may be unavailable or costly to obtain. Here, we introduce a new metric of locally weighted forest intercomparison to mitigate the above shortcomings. This method is applied to an international database of nearly 300 community forests and compared with previously published techniques. It is particularly suited to large databases where forests may be compared among one another. Further, it avoids problematic comparisons with old-growth forests which may not resemble the goal of forest management. In most cases, the different methods produce broadly congruent results, suggesting that researchers have the flexibility to compare forest conditions using whatever type of data is available. Forest structure and biodiversity are shown to be independently measurable axes of forest condition, although users' and foresters' estimations of seemingly unrelated attributes are highly correlated, perhaps reflecting an underlying sentiment about forest condition. These findings contribute new tools for large-scale analysis of ecosystem condition and natural resource policy assessment. Although applied here to forestry, these techniques have broader applications to classification and evaluation problems using

  17. Comparing forests across climates and biomes: qualitative assessments, reference forests and regional intercomparisons.

    PubMed

    Salk, Carl F; Frey, Ulrich; Rusch, Hannes

    2014-01-01

    Communities, policy actors and conservationists benefit from understanding what institutions and land management regimes promote ecosystem services like carbon sequestration and biodiversity conservation. However, the definition of success depends on local conditions. Forests' potential carbon stock, biodiversity and rate of recovery following disturbance are known to vary with a broad suite of factors including temperature, precipitation, seasonality, species' traits and land use history. Methods like tracking over-time changes within forests, or comparison with "pristine" reference forests have been proposed as means to compare the structure and biodiversity of forests in the face of underlying differences. However, data from previous visits or reference forests may be unavailable or costly to obtain. Here, we introduce a new metric of locally weighted forest intercomparison to mitigate the above shortcomings. This method is applied to an international database of nearly 300 community forests and compared with previously published techniques. It is particularly suited to large databases where forests may be compared among one another. Further, it avoids problematic comparisons with old-growth forests which may not resemble the goal of forest management. In most cases, the different methods produce broadly congruent results, suggesting that researchers have the flexibility to compare forest conditions using whatever type of data is available. Forest structure and biodiversity are shown to be independently measurable axes of forest condition, although users' and foresters' estimations of seemingly unrelated attributes are highly correlated, perhaps reflecting an underlying sentiment about forest condition. These findings contribute new tools for large-scale analysis of ecosystem condition and natural resource policy assessment. Although applied here to forestry, these techniques have broader applications to classification and evaluation problems using crowdsourced

  18. Impact of Forest Management on Future Forest Carbon Storage in Alaska Coastal Forests

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Kushch, S. A.

    2014-12-01

    The forest in Coastal Alaska are unique in many ways. Two groups of forest types occur in the Alaska region: boreal and temperate rain forests. About eighty-eight percent of these forests are in public ownership. High proportations of reserved forests and old-growth forests make the forests in coastal Alaska differ from that in other coastal regions. This study is focused on how forest management actions may impact the future carbon stocks and flux in coastal Alaska forests. The Forest Inventory and Analysis (FIA) data collected by US Forest Service are the primary data used for estimation of current carbon storage and projections of future forest carbon storage for all forest carbon pools in Alaska coastal forests under different management scenarios and climate change effect.

  19. Improving survival and growth of planted Austrocedrus chilensis seedlings in disturbed patagonian forests of Argentina by managing understory vegetation.

    PubMed

    Pafundi, Leticia; Urretavizcaya, M Florencia; Defossé, Guillermo E

    2014-12-01

    This study was aimed at determining, under field conditions, early interactions between planted cypress seedlings and their associated shrubs in a mesic area of Andean Patagonia and, in a nursery, the effects of increasing light availability on cypress performance when soil water was not a limiting factor. The field experiment was performed in a former cypress-coihue mixed forest (42°02'S, 71°33'W), which was replaced in the 1970s by a plantation of radiata pine. In 2005, 800 cypress seedlings were planted under maqui shrubs in a clear-cut area of the pine stand. In 2007, two treatments were set: no-competition treatment ([NCT] i.e., the surrounding aboveground biomass was removed) and competition treatment ([CT] i.e., without disturbance). The nursery experiment (42°55'S, 71°21'W) consisted of two groups: "shade" (grown under shade cloth) and "sun" (grown at full sun) cypress seedlings. After one growing season, seedling survival and stem growth (in height and diameter) were determined at both sites. Furthermore, the growth rate of leaves, stems, and roots was determined in the nursery. In the field experiment, height growth and survival in NCT were significantly greater than in CT, and a competition process occurred between cypress and surrounding shrubs. In the nursery, sun plants grew more in diameter and increased root weight more than shade plants. Results also showed that in mesic areas of Patagonia, decreasing competition and increasing light levels produced stouter seedlings better adapted to support harsh environmental conditions. Therefore, the removal of protecting shrubs could be a good management practice to improve seedling establishment. PMID:25216990

  20. Improving Survival and Growth of Planted Austrocedrus chilensis Seedlings in Disturbed Patagonian Forests of Argentina by Managing Understory Vegetation

    NASA Astrophysics Data System (ADS)

    Pafundi, Leticia; Urretavizcaya, M. Florencia; Defossé, Guillermo E.

    2014-12-01

    This study was aimed at determining, under field conditions, early interactions between planted cypress seedlings and their associated shrubs in a mesic area of Andean Patagonia and, in a nursery, the effects of increasing light availability on cypress performance when soil water was not a limiting factor. The field experiment was performed in a former cypress-coihue mixed forest (42°02'S, 71°33'W), which was replaced in the 1970s by a plantation of radiata pine. In 2005, 800 cypress seedlings were planted under maqui shrubs in a clear-cut area of the pine stand. In 2007, two treatments were set: no-competition treatment ([NCT] i.e., the surrounding aboveground biomass was removed) and competition treatment ([CT] i.e., without disturbance). The nursery experiment (42°55'S, 71°21'W) consisted of two groups: "shade" (grown under shade cloth) and "sun" (grown at full sun) cypress seedlings. After one growing season, seedling survival and stem growth (in height and diameter) were determined at both sites. Furthermore, the growth rate of leaves, stems, and roots was determined in the nursery. In the field experiment, height growth and survival in NCT were significantly greater than in CT, and a competition process occurred between cypress and surrounding shrubs. In the nursery, sun plants grew more in diameter and increased root weight more than shade plants. Results also showed that in mesic areas of Patagonia, decreasing competition and increasing light levels produced stouter seedlings better adapted to support harsh environmental conditions. Therefore, the removal of protecting shrubs could be a good management practice to improve seedling establishment.

  1. Effects of Vision herbicide on mortality, avoidance response, and growth of amphibian larvae in two forest wetlands.

    PubMed

    Wojtaszek, Barbara F; Staznik, Bozena; Chartrand, Derek T; Stephenson, Gerald R; Thompson, Dean G

    2004-04-01

    The effects of Vision (glyphosate, 356 mg acid equivalents (a.e.)/L) on mortality, avoidance response, and growth of larval amphibians (Rana clamitans and Rana pipiens) were investigated using in situ enclosures deployed in two forest wetlands of northern Ontario, Canada. In addition to untreated controls, Vision was applied to yield initial concentrations ranging from 0.29 to 14.3 mg a.e./L (0.94-46.1 mg/L of Vision). Resultant 96-h median lethal concentration (LC50) values ranged from 2.70 to 11.5 mg a.e./L (8.71-37.1 mg/L of Vision) depending on the species or site involved. Substantial mortality and incidences of abnormal avoidance response occurred only at concentrations exceeding the expected environmental concentrations (EEC) (1.43 mg a.e./L, or 4.61 mg/L of Vision) as calculated by Canadian regulatory authorities. The concentration dependence of larval growth rate and maximum size varied depending on site and species. Mean growth rates and maximum sizes exposed to 1.43 mg a.e./L (EEC) treatments were the same or greater than controls. Experimental site and biotic/abiotic factors therein, such as pH and suspended sediments, substantially affected the expression of Vision herbicide toxicity in the amphibian larvae tested. Overall, results suggest that the silvicultural use of Vision herbicide in accordance with the product label and standard Canadian environmental regulations should have negligible adverse effects on sensitive larval life stages of native amphibians. PMID:15095877

  2. The future of tropical forests.

    PubMed

    Wright, S Joseph

    2010-05-01

    Five anthropogenic drivers--land use change, wood extraction, hunting, atmospheric change, climate change--will largely determine the future of tropical forests. The geographic scope and intensity of these five drivers are in flux. Contemporary land use change includes deforestation (approximately 64,000 km(2) yr(-1) for the entire tropical forest biome) and natural forests regenerating on abandoned land (approximately 21,500 km(2) yr(-1) with just 29% of the biome evaluated). Commercial logging is shifting rapidly from Southeast Asia to Africa and South America, but local fuelwood consumption continues to constitute 71% of all wood production. Pantropical rates of net deforestation are declining even as secondary and logged forests increasingly replace old-growth forests. Hunters reduce frugivore, granivore and browser abundances in most forests. This alters seed dispersal, seed and seedling survival, and hence the species composition and spatial template of plant regeneration. Tropical governments have responded to these local threats by protecting 7% of all land for the strict conservation of nature--a commitment that is only matched poleward of 40 degrees S and 70 degrees N. Protected status often fails to stop hunters and is impotent against atmospheric and climate change. There are increasing reports of stark changes in the structure and dynamics of protected tropical forests. Four broad classes of mechanisms might contribute to these changes. Predictions are developed to distinguish among these mechanisms. PMID:20536814

  3. Mountain pine beetle selectivity in old-growth ponderosa pine forests, Montana, USA

    PubMed Central

    Knapp, Paul A; Soulé, Peter T; Maxwell, Justin T

    2013-01-01

    A historically unprecedented mountain pine beetle (MPB) outbreak affected western Montana during the past decade. We examined radial growth rates (AD 1860–2007/8) of co-occurring mature healthy and MPB-infected ponderosa pine trees collected at two sites (Cabin Gulch and Kitchen Gulch) in western Montana and: (1) compared basal area increment (BAI) values within populations and between sites; (2) used carbon isotope analysis to calculate intrinsic water-use efficiency (iWUE) at Cabin Gulch; and (3) compared climate-growth responses using a suite of monthly climatic variables. BAI values within populations and between sites were similar until the last 20–30 years, at which point the visually healthy populations had consistently higher BAI values (22–34%) than the MPB-infected trees. These results suggest that growth rates two–three decades prior to the current outbreak diverged between our selected populations, with the slower-growing trees being more vulnerable to beetle infestation. Both samples from Cabin Gulch experienced upward trends in iWUE, with significant regime shifts toward higher iWUE beginning in 1955–59 for the visually healthy trees and 1960–64 for the MPB-infected trees. Drought tolerance also varied between the two populations with the visually healthy trees having higher growth rates than MPB-infected trees prior to infection during a multi-decadal period of drying summertime conditions. Intrinsic water-use efficiency significantly increased for both populations during the past 150 years, but there were no significant differences between the visually healthy and MPB-infected chronologies. PMID:23762502

  4. Evaluation of Remotely Sensed Vegetation and Elevation Products in a Tropical Forest

    NASA Astrophysics Data System (ADS)

    Leigh, H. W.; Neuenschwander, A. L.; Magruder, L. A.

    2014-12-01

    Space-based methods of remote sensing have enabled the generation of global or near-global elevation and vegetation products that have been applied to a wide spectrum of earth sciences, while airborne remote sensing platforms have enabled the collection of high resolution data products with regional coverage. In order to use small-footprint airborne data together with space-based products in future applications, it is necessary to understand how the data products are related, particularly in regards to accuracy and systematic biases. This work addresses the need for a better understanding of the quality of existing global elevation and vegetation products by validating a radar-derived, void-filled digital elevation model and a lidar-derived global canopy height model against ICESat waveforms and a small-footprint airborne lidar survey over tropical forests in the country of Gabon. The bare-earth digital terrain model and canopy height model obtained from the airborne lidar survey are validated against ICESat waveforms, and are then used to evaluate errors and biases in SRTMv3 and the 1km global canopy height model developed by Simard, et al. across the extent of the survey region near the city of Libreville, Gabon. ICESat waveforms are subsequently used to evaluate SRTMv3 and Simard, et al.'s canopy height model for the entire country of Gabon.

  5. Modelling Growth-Competition Relationships in Trembling Aspen and White Spruce Mixed Boreal Forests of Western Canada

    PubMed Central

    Huang, Jian-Guo; Stadt, Kenneth J.; Dawson, Andria; Comeau, Philip G.

    2013-01-01

    We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at breast height (SDBH), and density (N) for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR), were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10–25 years for aspen and ≥25 for spruce. Our model demonstrated a remarkable capability (adjusted R2>0.67) to represent this complex variation in growth as a function of site, size and competition. PMID:24204891

  6. Modelling growth-competition relationships in trembling aspen and white spruce mixed boreal forests of Western Canada.

    PubMed

    Huang, Jian-Guo; Stadt, Kenneth J; Dawson, Andria; Comeau, Philip G

    2013-01-01

    We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at breast height (SDBH), and density (N) for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR), were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10-25 years for aspen and ≥ 25 for spruce. Our model demonstrated a remarkable capability (adjusted R(2)>0.67) to represent this complex variation in growth as a function of site, size and competition. PMID:24204891

  7. Vegetation Feature Extraction from ALSM Measurements for Evaluation of GPS Signal Strength in Forested Area

    NASA Astrophysics Data System (ADS)

    Liu, P.; Lee, H.; Slatton, K. C.

    2009-12-01

    Evaluation of GPS signal strength before data collection in forested area is of particular interest to surveyors and forestry researchers. However, it is difficult to predict performance of GPS positioning because the signal propagated within vegetation may suffer attenuation and furthermore exacerbate the signal reception and positioning accuracy. The conventional wisdom is that the forest is like a uniformly horizontal slab, as shown in traditional slab models, so the signal attenuation is dependent on elevation angle (θ). In fact, elevation dominates the global scale signal attenuation, but still large differences of signal attenuation can be observed from varied azimuths (φ) at the same elevation angle while considering on local scale. 2D skyward photography methods were exploited to compute the relative canopy closure and attempted to relate the GPS signal strength to the open sky fraction. Although it could consider the directional elements (θ, φ), a lack of 3D profile forest information is inefficient to estimate the real vegetative interference within the signal transmitted path. ALSM system is capable of collecting high resolution 3D spatial information from a region of interest with high laser pulse and scan rates. Due to its multiple return characteristic with dense horizontal coverage, the vegetation structure is relatively well captured. This study presents a development of directional 3D structuring elements to segment ALSM points and relate to signal attenuation. The attenuation of GPS signals is determined by mapping between signal-to-noise ratio (SNR) of received GPS signals under canopies and the directional canopy features derived from ALSM observations. Firstly, a directional cylindrical scope function is constructed to segment the obstructions which interfere with the signal propagation between the satellite vehicle and the receiver, and a vegetation feature, called the directional vegetation path length (DVPL), is computed by measuring the

  8. Evaluating Historic Carbon Budget in Temperate Pacific Northwestern Conifer Forest Landscape Using CN-CLASS Model

    NASA Astrophysics Data System (ADS)

    Chen, B.; Arain, M. A.; Black, T. A.

    2009-05-01

    We used carbon and nitrogen coupled Canadian Land Surface Scheme (CN-CLASS), a process-based model, to simulate the historic carbon stocks and fluxes in a 2500 ha temperate Pacific Northwest conifer forest landscape from 1920 to 2004. Hourly meteorological data was provided from historic climate records. Site maps of soils, topography, vegetation and disturbance type (logging, fire events) were provided by the historic carbon modeling project of the Canadian Carbon Program (CCP). The initial aboveground tree biomass in 1920 and the disturbance matrices were produced by the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3). Over the study period from 1920-2004, CN-CLASS simulated 188 Mg C ha-1 loss of ecosystem carbon as compared to 200 Mg C ha-1 loss suggested by CBM-CFS3. From 1928 to 1944, burning, historic harvest and slash burning resulted in large losses of carbon to the atmosphere. In this period, the study area was a large carbon source with simulated net carbon loss of 282 Mg C ha-1. From 1945 to 1989, there were very few disturbance events and the study area started to recover with simulated net carbon uptake of 87 Mg C ha-1. During this period, CN-CLASS modeled annual Net Biome Productivity (NBP) ranged from 27 g C m-2 y-1 in 1945 to 590 g C m-2 y-1 in 1964. CN-CLASS simulated summer (July-September) NEP deviations during the undisturbed period (1945-1989), showed a negative relationship with the daily maximum air temperature and precipitation. As harvest of second-growth stands began in 1990s, disturbance again had significant impact on the landscape's carbon budget, and this effect was partially offset by ongoing C uptake in recovering young stands. CN-CLASS underestimated NEP as compared to observed eddy covariance flux measurements because of high temperature sensitivity of its soil respiration algorithm. Simulated mean annual NEP from 1998 to 2004 was 190 g C m-2 y-1 as compared to observed eddy covariance value of 352 g C m-2 y-1. This

  9. Remote sensing based detection of forested wetlands: An evaluation of LiDAR, aerial imagery, and their data fusion

    NASA Astrophysics Data System (ADS)

    Suiter, Ashley Elizabeth

    Multi-spectral imagery provides a robust and low-cost dataset for assessing wetland extent and quality over broad regions and is frequently used for wetland inventories. However in forested wetlands, hydrology is obscured by tree canopy making it difficult to detect with multi-spectral imagery alone. Because of this, classification of forested wetlands often includes greater errors than that of other wetlands types. Elevation and terrain derivatives have been shown to be useful for modelling wetland hydrology. But, few studies have addressed the use of LiDAR intensity data detecting hydrology in forested wetlands. Due the tendency of LiDAR signal to be attenuated by water, this research proposed the fusion of LiDAR intensity data with LiDAR elevation, terrain data, and aerial imagery, for the detection of forested wetland hydrology. We examined the utility of LiDAR intensity data and determined whether the fusion of Lidar derived data with multispectral imagery increased the accuracy of forested wetland classification compared with a classification performed with only multi-spectral image. Four classifications were performed: Classification A -- All Imagery, Classification B -- All LiDAR, Classification C -- LiDAR without Intensity, and Classification D -- Fusion of All Data. These classifications were performed using random forest and each resulted in a 3-foot resolution thematic raster of forested upland and forested wetland locations in Vermilion County, Illinois. The accuracies of these classifications were compared using Kappa Coefficient of Agreement. Importance statistics produced within the random forest classifier were evaluated in order to understand the contribution of individual datasets. Classification D, which used the fusion of LiDAR and multi-spectral imagery as input variables, had moderate to strong agreement between reference data and classification results. It was found that Classification A performed using all the LiDAR data and its derivatives

  10. Preparation and evaluation of mercuric iodide for crystal growth

    NASA Astrophysics Data System (ADS)

    Skinner, N. L.; Ortale, C.; Schieber, M. M.; van den Berg, L.

    1989-11-01

    Large quantities (on the order of several hundred kilograms) of consistent, high-quality mercuric iodide (HgI2) for crystal growth have not been commercially available. The hydrocarbon, anion and cation impurity levels varied considerably, occasionally preventing crystal growth. This occurred even though the starting material was from the same vendor and was subjected to the same purification treatment. This paper will describe an aqueous precipitation process of HgI2 preparation in batches of 3 kg using Hg(NO3)2, or HgCl2 and KI. Since these salts are produced in much larger quantities than HgI2, more consistent quality is available. The impurity content of these batches and single crystals grown from them have been evaluated. These results and those from several commercially available starting materials and their grown single crystals are compared. Some of the single crystals grown using the in-house prepared HgI2 have yielded a large number of spectroscopy-grade nuclear detectors. The influence of the major impurities will be discussed.

  11. Evaluation of growth in very low birth weight preterm babies

    PubMed Central

    Yeşinel, Serdar; Aldemir, Esin Yıldız; Kavuncuoğlu, Sultan; Yeşinel, Seda; Yıldız, Hayrettin

    2014-01-01

    Aim: The aim of this study was to evaluate physical growth of very low birth weight (VLBW) preterm babies at a mean age of three years and to investigate the factors which affected growth. Material and Methods: The factors including maternal problems, prenatal problems, early neonatal problems, nutrition, familial socioeconomical status and presence of chronic disease which affected catch-up growth in terms of height and weight in VLBW infants followed up in the neonatal intensive care unit (NICU) of our hospital were examined. The target height formula was used in assessment of growht in height and the contribution of genetic properties was investigated. The points of the subjects on the growth curve were plotted according to the Percentile Curve of the Turkish Children prepared by Neyzi et al. The states of the subjects with and without intrauterine growth retardation (were compared. The study was intitiated after obtaining approval from the ethics committeee of our hospital (100/25.10.2005). Results: One hundred and seventeen preterm babies (57 females and 60 males) with a mean adjusted age of 35.8±2.39 80 of whom were appropriate for gestational age (AGA), 28 of whom were symmetrical (small gestational age) SGA and 9 of whom were asymmetrical SGA were included in the study. The mean gestational age (GA) was found to be 31±2.16 weeks and the mean birth weight (BW) was found to be 1271±226 g. The mean current height was found to be 92.06±4.90 cm. The mean weight was found to be 12.98±1.94 kg. The mean target height was calculated to be 163.66±8.1 cm (157.20 cm for the girls and 170.20 cm for the boys). It was found that 15 preterm babies (12.8%) could not achieve the target height (girls: 6%, boys: 6.8%). The risk factors related with failure to achieve target height were found to include ventilator treatment, presence of chronic disease, advanced stage intracranial bleeding (ICB), posthemorrhagic hydrocephalus, absence of breastfeeding, failure to sit at

  12. An Evaluation of "Forests of the World," a Project Learning Tree Secondary Module

    ERIC Educational Resources Information Center

    Ghent, Cynthia; Parmer, Giavanna; Haines, Sarah

    2013-01-01

    This study sought to determine whether a secondary level curricular model based on enhancing knowledge and awareness of global forest issues would have an effect on students' self-perceived knowledge of forest issues, actual content knowledge of these issues, and pro-environmental attitudes. The study instrument is the secondary module…

  13. Evaluating the Impact of Forest Schools: A Collaboration between a University and a Primary School

    ERIC Educational Resources Information Center

    Slade, Melanie; Lowery, Claire; Bland, Ken

    2013-01-01

    The Forest School movement, an important part of education in Scandinavia, has gained momentum in the UK in recent years. Within the context of declining access to, and engagement with, the natural environment Forest Schools can provide invaluable life experiences for our children. In 2012 the University of Northampton investigated opportunities…

  14. Impact of spatial resolution on correlation between segmentation evaluation metrics and forest classification accuracy

    NASA Astrophysics Data System (ADS)

    Švab Lenarčič, Andreja; Ritlop, Klemen; Äńurić, Nataša.; Čotar, Klemen; Oštir, Krištof

    2015-10-01

    Slovenia is one of the most forested countries in Europe. Its forest management authorities need information about the forest extent and state, as their responsibility lies in forest observation and preservation. Together with appropriate geographic information system mapping methods the remotely sensed data represent essential tool for an effective and sustainable forest management. Despite the large data availability, suitable mapping methods still present big challenge in terms of their speed which is often affected by the huge amount of data. The speed of the classification method could be maximised, if each of the steps in object-based classification was automated. However, automation is hard to achieve, since segmentation requires choosing optimum parameter values for optimal classification results. This paper focuses on the analysis of segmentation and classification performance and their correlation in a range of segmentation parameter values applied in the segmentation step. In order to find out which spatial resolution is still suitable for forest classification, forest classification accuracies obtained by using four images with different spatial resolutions were compared. Results of this study indicate that all high or very high spatial resolutions are suitable for optimal forest segmentation and classification, as long as appropriate scale and merge parameters combinations are used in the object-based classification. If computation interval includes all segmentation parameter combinations, all segmentation-classification correlations are spatial resolution independent and are generally high. If computation interval includes over- or optimal-segmentation parameter combinations, most segmentation-classification correlations are spatial resolution dependent.

  15. OZONE AND SULFUR DIOXIDE DRY DEPOSITION TO FORESTS: OBSERVATIONS AND MODEL EVALUATION

    EPA Science Inventory

    Fluxes and deposition velocities of O3 and SO2 were measured over both a deciduous and a mixed coniferous-deciduous forest for full growing seasons. Fluxes and deposition velocities of O3 were measured over a coniferous forest for a month. Mean deposition velocities of 0.35 t...

  16. EVALUATING CHANGES IN FOREST CONDITION POTENTIALLY RELATED TO ACIDIC DEPOSITION: AN EXAMPLE USING RED SPRUCE

    EPA Science Inventory

    As a result of concern about forest decline in Europe and the USA, research has been conducted to investigate changes in forest condition that might be associated with acidic deposition and related pollutants (principally ozone). ymptoms of tree decline observed in the field typi...

  17. EVALUATION OF EFFECTS OF FOREST-FIRE SMOKE/HAZE ON BASIN-WIDE STREAM TEMPERATURES

    EPA Science Inventory

    The effects of forest fires on ecological resources in the area experiencing the burn are well documented in the literature. What is not well known is the effect of smoke and haze generated from forest fires on ecological resources adjacent to or at great distances from the burn ...

  18. Model-based analysis on the relationship between production and tree-ring growth in Japanese conifer-hardwood mixed forests

    NASA Astrophysics Data System (ADS)

    Koide, D.; Ito, A.

    2015-12-01

    Forest productivity is a basic and important component of terrestrial material flow and its importance increases according to recent climate warming and the increase in atmospheric-CO2 concentrations. Forest productivity study progresses through measurement by eddy-covariance data from flux tower and prediction by terrestrial ecosystem models. However, flux tower observation has spatiotemporal bias and limitation. On the other hand, tree-ring data have a close connection with forest ecosystem productivity. Compared to flux tower observation, we can collect tree-ring data from a larger number of sites and longer time scales. Comparisons between tree-ring observation and model-estimated productivity is important to reveal underlying mechanisms of forest ecosystem productivity and growth in wide spatiotemporal scale. This study aimed at revealing the relationship between temporal changes in tree-ring data and estimated forest ecosystem productivity in Japanese conifer-hardwood mixed forest. We also addressed climatic bias in the relationship by comparing between sites at different climatic conditions. Tree-ring data of Sakhalin spruce (Picea glehnii) were obtained from the International Tree Ring Data Bank. Six sites on the Hokkaido island (northern island of Japan) were selected for the present analysis. The Vegetation Integrated SImulator for Trace gasses (VISIT) model was validated by comparing with carbon flux data from Asia flux network sites. Past climatic parameters were obtained from ERA-20C reanalysis data from the European Center for Medium-range Weather Forecasts. Correlation between basal area increment and net ecosystem productivity was highest in the coldest site but this correlation weakened in warmer sites. This result implies that long-term growth trend was mainly restricted by cold stress associated with productivity reduction in colder sites but this factor is less important and other factors exert influence in warmer sites.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  20. Turnover of Species and Guilds in Shrub Spider Communities in a 100-Year Postlogging Forest Chronosequence.

    PubMed

    Haraguchi, Takashi F; Tayasu, Ichiro

    2016-02-01

    Disturbance of forests by logging and subsequent forest succession causes marked changes in arthropod communities. Although vegetation cover provides important habitat for arthropods, studies of the changes in their community structure associated with forest succession have been conducted mostly at ground level. To evaluate how forests of different ages contribute to arthropod biodiversity in shrub habitat, spiders were collected from shrubs in 12 forests ranging in age from 1 to 107 yr after logging. We found marked changes in spider community structure about 10 yr after logging: the number of species and individuals declined rapidly after this time. These changes were likely caused by a decrease in shrub cover in association with forest succession. Changes in spider species composition associated with stand age were small in forests at least 11 yr old and were not clustered by forest age. After the exclusion of species of which we sampled only one or two individuals incidentally, just 0.9 ± 0.5 (mean ± SD) species were unique to these older forests. The other 41.2 ± 4.3 species found in these forests were common to both older and young forests, although some of these species in common were found mainly in forests at least 11 yr old. These results suggest that preservation of old-growth forests contributes to the abundance of these common species, although old-growth forests contribute little to species diversity. PMID:26374757

  1. The combination of Forest Site Maps, Site specific Growth Models and Nutrient Balance Models as a Basis for Sustainable Management in the Northern Limestone Alps

    NASA Astrophysics Data System (ADS)

    Ettmayer, C.; Katzensteiner, K.; Eckmüllner, O.

    2012-04-01

    The demand for biomass from forests is rising continuously. Decision support tools for managers and forest authorities should help to avoid negative consequences of increased biomass extraction on ecosystem processes and the sustainable supply of forest services. Those tools have to be site and stand specific. In Alpine regions shallow soils with high organic matter content are widespread on calcareous bedrock. There is increasing evidence that those soils are particularly vulnerable and intensive harvest leads to rapid humus and nutrient losses and a decline of water storage capacity. Such soils may rely on the existence of a continuous forest cover and/or a minimum input of coarse woody debris. For a test region in Tyrol management scenarios will be modelled to predict management effects on sites with calcareous bedrock. Site specific growth and yield models for biomass fractions are developed based on existing inventory data, site maps and high resolution digital surface and terrain models, complemented by stratified biomass and nutrient inventories, and are used for the calculation of different production scenarios. Nutrient balance models taking into account nutrient extraction via harvest, leaching losses as well as gains via atmospheric deposition, and fertilization are used to calculate the potential sustainable harvest intensity. In addition humus dynamics of the frequently shallow rendzic Leptosols is taken into account. Concepts for long term carbon and nutrient management experiments as a basis for adaptive forest management in the Calacareous Alps are developed.

  2. Soil processes and tree growth at shooting ranges in a boreal forest reflect contamination history and lead-induced changes in soil food webs.

    PubMed

    Selonen, Salla; Setälä, Heikki

    2015-06-15

    The effects of shooting-derived lead (Pb) on the structure and functioning of a forest ecosystem, and the recovery of the ecosystem after range abandonment were studied at an active shotgun shooting range, an abandoned shooting range where shooting ceased 20 years earlier and an uncontaminated control site. Despite numerous lead-induced changes in the soil food web, soil processes were only weakly related to soil food web composition. However, decomposition of Scots pine (Pinus sylvestris) needle litter was retarded at the active shooting range, and microbial activity, microbial biomass and the rate of decomposition of Pb-contaminated grass litter decreased with increasing soil Pb concentrations. Tree (P. sylvestris) radial growth was suppressed at the active shooting range right after shooting activities started. In contrast, the growth of pines improved at the abandoned shooting range after the cessation of shooting, despite reduced nitrogen and phosphorus contents of the needles. Higher litter degradation rates and lower Pb concentrations in the topmost soil layer at the abandoned shooting range suggest gradual recovery after range abandonment. Our findings suggest that functions in lead-contaminated coniferous forest ecosystems depend on the successional stage of the forest as well as the time since the contamination source has been eliminated, which affects, e.g., the vertical distribution of the contaminant in the soil. However, despite multiple lead-induced changes throughout the ecosystem, the effects were rather weak, indicating high resistance of coniferous forest ecosystems to this type of stress. PMID:25770944

  3. Evaluating the relative impact of climate and economic changes on forest and agricultural ecosystem services in mountain regions.

    PubMed

    Briner, Simon; Elkin, Ché; Huber, Robert

    2013-11-15

    Provisioning of ecosystem services (ES) in mountainous regions is predicted to be influenced by i) the direct biophysical impacts of climate change, ii) climate mediated land use change, and iii) socioeconomic driven changes in land use. The relative importance and the spatial distribution of these factors on forest and agricultural derived ES, however, is unclear, making the implementation of ES management schemes difficult. Using an integrated economic-ecological modeling framework, we evaluated the impact of these driving forces on the provision of forest and agricultural ES in a mountain region of southern Switzerland. Results imply that forest ES will be strongly influenced by the direct impact of climate change, but that changes in land use will have a comparatively small impact. The simulation of direct impacts of climate change affects forest ES at all elevations, while land use changes can only be found at high elevations. In contrast, changes to agricultural ES were found to be primarily due to shifts in economic conditions that alter land use and land management. The direct influence of climate change on agriculture is only predicted to be substantial at high elevations, while socioeconomic driven shifts in land use are projected to affect agricultural ES at all elevations. Our simulation results suggest that policy schemes designed to mitigate the negative impact of climate change on forests should focus on suitable adaptive management plans, accelerating adaptation processes for currently forested areas. To maintain provision of agricultural ES policy needs to focus on economic conditions rather than on supporting adaptation to new climate. PMID:23995509

  4. A community classification system for forest evaluation: Development, validation, and extrapolation.

    PubMed

    Clatterbuck, W K

    1996-01-01

    A community classification system integrating vegetation and landforms was developed for the 8,054-ha Cheatham Wildlife Management Area (CWMA), located on the Western Highland Rim of Tennessee, USA, to obtain information on which to base multiresource land management decisions. A subjective procedure (synthesis tables) and several objective techniques (factor analysis, cluster analysis, and canonical discrimination) were used to evaluate importance values of overstory and midstory species, coverage values of understory species, and topographic parameters. These procedures were used collectively to guide and to provide evidence for interpretation of vegetational patterns on the landscape. The eight discrete communities identified on a 482-ha compartment within the CWMA were: northern red oak (Quercus rubra L.), chestnut oak (Q. prinus L.), scarlet oak (Q. coccinea Muenchh.), yellow-poplar (Liriodendron tulipifera L.), sycamore-sweetgum (Platanus occidentalis L.-Liquidambar styraciflua L.), black oak-hickory (Q. velutina Lam.-Carya spp.), post oak (Q. stellata Wangenh.), and American beech (Fagus grandifolia Ehrh.) communities. The classification system was validated with an independent data set. The eight communities were successfully extrapolated to an unsampled portion of the CWMA. Clearly, community analysis can become an important facet in forest management and may play a major role where a holistic understanding of vegetative relationships is essential. PMID:24198012

  5. Predicting acidification recovery at the Hubbard Brook Experimental Forest, New Hampshire: evaluation of four models.

    PubMed

    Tominaga, Koji; Aherne, Julian; Watmough, Shaun A; Alveteg, Mattias; Cosby, Bernard J; Driscoll, Charles T; Posch, Maximilian; Pourmokhtarian, Afshin

    2010-12-01

    The performance and prediction uncertainty (owing to parameter and structural uncertainties) of four dynamic watershed acidification models (MAGIC, PnET-BGC, SAFE, and VSD) were assessed by systematically applying them to data from the Hubbard Brook Experimental Forest (HBEF), New Hampshire, where long-term records of precipitation and stream chemistry were available. In order to facilitate systematic evaluation, Monte Carlo simulation was used to randomly generate common model input data sets (n = 10,000) from parameter distributions; input data were subsequently translated among models to retain consistency. The model simulations were objectively calibrated against observed data (streamwater: 1963-2004, soil: 1983). The ensemble of calibrated models was used to assess future response of soil and stream chemistry to reduced sulfur deposition at the HBEF. Although both hindcast (1850-1962) and forecast (2005-2100) predictions were qualitatively similar across the four models, the temporal pattern of key indicators of acidification recovery (stream acid neutralizing capacity and soil base saturation) differed substantially. The range in predictions resulted from differences in model structure and their associated posterior parameter distributions. These differences can be accommodated by employing multiple models (ensemble analysis) but have implications for individual model applications. PMID:21028800

  6. Evaluating effects of climate variability, extreme weather events and thinning on carbon and water exchanges in managed temperate forests in eastern Canada

    NASA Astrophysics Data System (ADS)

    Arain, M.; Brodeur, J. J.; Trant, J.; Thorne, R.; Peichl, M.; Kula, M.; Parsaud, A.; Khader, R.

    2013-12-01

    In this study the impact of climate variability and extreme weather events on gross ecosystem productivity (GEP), ecosystem respiration (RE), net ecosystem productivity (NEP) and evapotranspiration (E) is evaluated in an age-sequence (74-, 39- and 11-years old) of temperate pine (Pinus strobus L.) forests, north of Lake Erie in southern Ontario, Canada using ten years (2003-2012) of eddy covariance flux and meteorological data. Fluxes from conifer stands are also compared with measurements made in an 80-year-old deciduous (Carolinian) forest, established in 2012. All four sites are managed forests and part of the Turkey Point Flux Station and global Fluxnet. Ten-year mean NEP values were 169 (75 to 312), 371 (305 to 456, over 2008-2012) and 141 (-10 to 420) g C/m2/year in the 74-, 39-, and 11-year-old stand, respectively, while mean NEP in the 80-year-old deciduous stand was 286 g C/m2/year in 2012. This region is affected by low frequency climate oscillations, such as El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). The study period experienced four distinct extreme weather patterns: warm and dry springs in 2005 and 2012, extremely wet and warm summer in 2006, a summer drought in 2007 and warm summers in 2010 and 2012. In February-March 2012, the 74-year-old stand was selectively thinned and approximately 30% of trees were removed to improve light and water availability and stimulate growth of remaining trees. Thinning and warm/dry spring reduced NEP in the first post-thinning year, with mean annual NEP of 75 g C/m2/year in 2012. Increased supply of dead organic matter and warm temperatures in 2012 increased RE much more than GEP, resulting in lower annual NEP. Heat stress and drought in spring of 2005 reduced NEP of the 74-year stand to 78 g C/m2/year. The impact of this extreme weather event on NEP was similar to that observed in 2012 when stand experienced a drastic structural change, dry spring and warm temperatures throughout the

  7. North American Forest Dynamics Evaluated Using Landsat Observations and FIA Measurements: Science Goals within NACP

    NASA Astrophysics Data System (ADS)

    Huang, C.; Goward, S. N.; Masek, J. G.; Cohen, W. B.; Moisen, G. G.; Healey, S.; Kennedy, R. E.; Powell, S.; Thomas, N.; Schleeweis, K.; Hinds, A.; Rishmawi, K.

    2008-12-01

    One of the major goals of the North American Carbon Program is to understand the sources and sinks of atmospheric carbon. The first State of the Carbon Cycle Report (SOCCR) with a focus on North America identified forest as one of the largest sinks on this continent. This report attributed much of this carbon uptake to forest regeneration on abandoned agricultural lands based on carbon accounting procedures. Forest disturbance was not fully addressed. While forest disturbance and regrowth are recognized as significant forces modulating North American carbon balance, examining the carbon fluxes arising from these processes is hindered by a lack of understanding of continental-scale forest dynamics. The North American Forest Dynamics (NAFD) project has been developed to address this fundamental question using historical Landsat observations in combination with comprehensive field measurements collected through the USDA Forest Inventory and Analysis (FIA) program. This presentation will provide an overview of the science objectives of the NAFD project and the approaches for achieving these goals.

  8. Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

    USGS Publications Warehouse

    Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

    2006-01-01

    Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

  9. Use of branch and whole tree exposure systems to evaluate ozone impacts on forest trees

    SciTech Connect

    Schaap, W.

    1992-01-01

    An integrated research program was carried out to study the effects of ozone on physiological processes and growth of field-grown Douglas-fir saplings over a two year period (1989-1990). The main objective was to evaluate the use of branches as a means of scaling in air pollution research with a test of the hypothesis that branches can be treated as functionally independent units. This program was unique for a number of reasons, including (a) using >3.5 m tall saplings as opposed to seedlings and (b) experimentally separating the response of the whole tree from its parts (i.e. branches).

  10. Evaluation of spatial models to predict vulnerability of forest birds to brood parasitism by cowbirds

    USGS Publications Warehouse

    Gustafson, E.J.; Knutson, M.G.; Niemi, G.J.; Friberg, M.

    2002-01-01

    We constructed alternative spatial models at two scales to predict Brown-headed Cowbird (Molothrus ater) parasitism rates from land cover maps. The local-scale models tested competing hypotheses about the relationship between cowbird parasitism and distance of host nests from a forest edge (forest-nonforest boundary). The landscape models tested competing hypotheses about how landscape features (e.g., forests, agricultural fields) interact to determine rates of cowbird parasitism. The models incorporate spatial neighborhoods with a radius of 2.5 km in their formulation, reflecting the scale of the majority of cowbird commuting activity. Field data on parasitism by cowbirds (parasitism rate and number of cowbird eggs per nest) were collected at 28 sites in the Driftless Area Ecoregion of Wisconsin, Minnesota, and Iowa and were compared to the predictions of the alternative models. At the local scale, there was a significant positive relationship between cowbird parasitism and mean distance of nest sites from the forest edge. At the landscape scale, the best fitting models were the forest-dependent and forest-fragmentation-dependent models, in which more heavily forested and less fragmented landscapes had higher parasitism rates. However, much of the explanatory power of these models results from the inclusion of the local-scale relationship in these models. We found lower rates of cowbird parasitism than did most Midwestern studies, and we identified landscape patterns of cowbird parasitism that are opposite to those reported in several other studies of Midwestern songbirds. We caution that cowbird parasitism patterns can be unpredictable, depending upon ecoregional location and the spatial extent, and that our models should be tested in other ecoregions before they are applied there. Our study confirms that cowbird biology has a strong spatial component, and that improved spatial models applied at multiple spatial scales will be required to predict the effects of

  11. Evaluation of parathyroid autograft growth and function in hemodialysis patients

    SciTech Connect

    Karsenty, G.; Petraglia, A.; Bourdeau, A.; Gambini, D.J.; Moreau, J.F.; Lecharpentier, Y.; Zingraff, J.; Bournerias, F.; Buisson, C.; Dubost, C.

    1986-07-01

    The aim of our study was to evaluate the function and growth of parathyroid tissue autografted into the forearm of hemodialysis patients using several presently available methods. In a dynamic study, the secretory function of autografted tissue was evaluated in seven patients using either zero calcium dialysate or calcium infusion. In an additional prospective study, seven patients had repeated determinations of plasma immunoreactive parathyroid hormone (iPTH) concentration on samples from both forearms, a radionuclide evaluation of autograft function using thallium-201 chloride, and real time ultrasonography. Light microscopy analysis was performed in two patients. The dynamic study demonstrated that induction of hypocalcemia was followed by an increase, and induction of hypercalcemia by a decrease in circulating iPTH in both forearms using three different radioimmunoassays similar to what has been reported for normal parathyroid tissue. A significant gradient (ie, greater than 2.0) of plasma iPTH concentration in samples from both forearms was observed in only three out of the seven patients of the prospective study. Two of these patients disclosed an increased uptake of /sup 201/TI chloride at the site of autografted tissue and had an echographically detectable mass. In both, hyperplastic parathyroid tissue was removed. At present, the remaining third patient does not have other features of recurrent hyperparathyroidism. In conclusion, autotransplanted parathyroid tissue of hemodialysis patients shows an adequate response to physiologic stimuli such as hypo- and hypercalcemia. Dynamic tests, therefore, appear to be a useful tool in the assessment of its function. In addition, radionuclide and echographic studies may be reliable adjuncts in the detection of marked parathyroid autograft hyperplasia.

  12. Comparative Model Evaluation Studies of Biogenic Trace Gas Fluxes in Tropical Forests

    NASA Technical Reports Server (NTRS)

    Potter, C. S.; Peterson, David L. (Technical Monitor)

    1997-01-01

    Simulation modeling can play a number of important roles in large-scale ecosystem studies, including synthesis of patterns and changes in carbon and nutrient cycling dynamics, scaling up to regional estimates, and formulation of testable hypotheses for process studies. Recent comparative studies have shown that ecosystem models of soil trace gas exchange with the atmosphere are evolving into several distinct simulation approaches. Different levels of detail exist among process models in the treatment of physical controls on ecosystem nutrient fluxes and organic substrate transformations leading to gas emissions. These differences are is in part from distinct objectives of scaling and extrapolation. Parameter requirements for initialization scalings, boundary conditions, and time-series driven therefore vary among ecosystem simulation models, such that the design of field experiments for integration with modeling should consider a consolidated series of measurements that will satisfy most of the various model requirements. For example, variables that provide information on soil moisture holding capacity, moisture retention characteristics, potential evapotranspiration and drainage rates, and rooting depth appear to be of the first order in model evaluation trials for tropical moist forest ecosystems. The amount and nutrient content of labile organic matter in the soil, based on accurate plant production estimates, are also key parameters that determine emission model response. Based on comparative model results, it is possible to construct a preliminary evaluation matrix along categories of key diagnostic parameters and temporal domains. Nevertheless, as large-scale studied are planned, it is notable that few existing models age designed to simulate transient states of ecosystem change, a feature which will be essential for assessment of anthropogenic disturbance on regional gas budgets, and effects of long-term climate variability on biosphere-atmosphere exchange.

  13. SILVA: a model for forecasting the effects of SO/sub 2/ pollution on growth and succession in a western coniferous forest

    SciTech Connect

    Kercher, J.R.; Axelrod, M.C.

    1981-02-26

    A forest succession simulator, SILVA, has been developed for the mixed conifer forest type of the Sierra Nevada, California (seven major species), to simulate the effects of SO/sub 2/ on forest dynamics. SILVA was developed by extensively modifying a northeastern US simulator. The model simulates growth and includes the development in time of tree diameter, tree height, leaf area index, and available light for each tree. Recruitment and mortality are modeled stochastically. Modifications include the introduction of fire ecology and the use of temporal seed-crop patterns and seedling survival factors unique to Sierra Nevada forests. Probability of mortality is determined by height of crown scorch (which is a function of fire intensity), dbh, and bark thickness. Pollutant impacts are modeled as an effect on tree growth. Dose-response functions relating change in tree growth to increases in pollutant loads were developed using published data. The model simulates community dynamical and structural response to many factors quite well. For 500-year simulations from clearcut, the ratios of the time-averaged basal area fraction of Pinus ponderosa to Abies concolor were 5.2:1 and 1:16 for elevations of 1524 m and 1829 m, respectively. At 1524 m, the ratio of P. ponderosa to A. concolor decreased 59% with the introduction of fire suppression. To investigate effects of low-level chronic SO/sub 2/ fumigation in sample runs, the pollutant level is set to cause these annual reductions in growth: P. ponderosa, 10%; Pseudotsuga menziesii, 18%; and SO/sub 2/-tolerant species such as A. concolor, 1 to 2%. Time-averaged P. ponderosa basal area fraction decreased 28% and A. concolor (SO/sub 2/ tolerant) increased by 260% at 1524 m elevation. Three scenarios of pollutant time histories are investigated: rising levels, constant levels, and rising and falling levels. We also calculate the sensitivities of the model parameters to determine relative importance for model behavior.

  14. Mapping the optimal forest road network based on the multicriteria evaluation technique: the case study of Mediterranean Island of Thassos in Greece.

    PubMed

    Tampekis, Stergios; Sakellariou, Stavros; Samara, Fani; Sfougaris, Athanassios; Jaeger, Dirk; Christopoulou, Olga

    2015-11-01

    The sustainable management of forest resources can only be achieved through a well-organized road network designed with the optimal spatial planning and the minimum environmental impacts. This paper describes the spatial layout mapping for the optimal forest road network and the environmental impacts evaluation that are caused to the natural environment based on the multicriteria evaluation (MCE) technique at the Mediterranean island of Thassos in Greece. Data analysis and its presentation are achieved through a spatial decision support system using the MCE method with the contribution of geographic information systems (GIS). With the use of the MCE technique, we evaluated the human impact intensity to the forest ecosystem as well as the ecosystem's absorption from the impacts that are caused from the forest roads' construction. For the human impact intensity evaluation, the criteria that were used are as follows: the forest's protection percentage, the forest road density, the applied skidding means (with either the use of tractors or the cable logging systems in timber skidding), the timber skidding direction, the visitors' number and truck load, the distance between forest roads and streams, the distance between forest roads and the forest boundaries, and the probability that the forest roads are located on sights with unstable soils. In addition, for the ecosystem's absorption evaluation, we used forestry, topographical, and social criteria. The recommended MCE technique which is described in this study provides a powerful, useful, and easy-to-use implement in order to combine the sustainable utilization of natural resources and the environmental protection in Mediterranean ecosystems. PMID:26463090

  15. Evaluation of the efficiency of some sediment trapping methods after a Mediterranean forest fire.

    PubMed

    Fox, D M

    2011-02-01

    Forest fires are common in Mediterranean environments and may become increasingly more frequent as the climate changes. Destruction of the forest cover and litter layer leads to greater overland flow and increased erosion rates. The greatest risk occurs during the first rainstorms following a major fire, so local authorities must act quickly to put erosion control methods in place in order to avoid excessive post-fire sediment loads in river channels. Deciding on which methods to use requires accurate knowledge of their impact on sediment load and an estimate of their cost efficiency. The objective of this study was to evaluate the efficiency of Log Debris Dams (LDDs) and a sedimentation basin for their effectiveness in trapping sediments. Paired sub-catchments were studied to quantify the amount of sediments trapped in stream channels by a series of LDDs and a sedimentation basin. Cost efficiency was evaluated for each of the measures as a function of the cost per unit volume of sediments trapped. In addition, grain size analyses were performed to characterise the nature of the sediments trapped. A third sediment trapping method, Log Erosion Barriers (LEBs) was evaluated more superficially than the first two and conclusions regarding this method are tentative. LDDs trapped a mean volume of 1.57 m³ per unit (median=1.28 m³); mean LDD height was 105.4 cm (std. dev.=21.9 cm), and mean height of trapped sediments was only 50.0 cm (std. dev.=22.9 cm), showing that the traps were only half filled. Sediment height was limited by the presence of gaps between logs or branches that allowed runoff to flow through. Comparison of the textural characteristics of slope and trapped sediments showed distinct sorting: particles greater than 20mm were not mobilised from the slopes during the study period, sediments in the medium to coarse sand size fractions were trapped preferentially by the LDDs, and sediments in the sedimentation basin were enriched by clay and silt sized (< 0

  16. Reducing uncertainties associated with remotely sensed estimates of forest growth and carbon exchange in the Great Lakes Region

    NASA Astrophysics Data System (ADS)

    Cook, Bruce Douglas

    NASA satellites Terra and Aqua orbit the Earth every 100 minutes and collect data that is used to compute an 8 day time series of gross photosynthesis and annual plant production for each square kilometer of the earth's surface. This is a remarkable technological and scientific achievement that permits continuous monitoring of plant production and quantification of CO2 fixed by the terrestrial biosphere. It also allows natural resource scientists and practitioners to identify global trends associated with land cover/use and climate change. Satellite-derived estimates of photosynthesis and plant production from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) generally agree with independent measurements from validation sites across the globe, but local biases and spatial uncertainties exist at the regional scale. This dissertation evaluates three sources of uncertainty associated with MODIS algorithms in the Great Lakes Region, and evaluates LiDAR (Light Detection and Ranging) remote sensing as a method for improving model inputs. Chapter 1 examines the robustness of model parameters and errors resulting from canopy disturbances, which were assessed by inversion of flux tower observations during a severe outbreak of forest tent caterpillars. Chapter 2 examines model logic errors in wetland ecosystems, focusing on surface water table fluctuations as a potential constraint to photosynthesis that is not accounted for in the MODIS algorithm. Chapter 3 examines errors associated with pixel size and poor state data, using fine spatial resolution LiDAR and multispectral satellite data to derive estimates plant production across a heterogeneous landscape in northern Wisconsin. Together, these papers indicate that light- and carbon-use efficiency models driven by remote sensing and surface meteorology data are capable of providing accurate estimates of plant production within stands and across landscapes of the Great Lakes Region. It is demonstrated that model

  17. Importance of Small Isolated Wetlands for Herpetofaunal Diversity in Managed, Young Growth Forests in the Coastal Plain of South Carolina

    SciTech Connect

    Russell, K.R.; Guynn, D.C., Jr.; Hanlin, H.G.

    2002-03-27

    Assessment and comparison of richness, abundance and difference of herpetofauna at five small isolated wetlands located within a commercial forest landscape in the South Carolina Coastal Plain. Data indicates small isolated wetlands are focal points of herpetofaunal richness and abundance in managed coastal plain forest and contribute more to regional biodiversity than is implied by their small size or ephemeral hydrology.

  18. Forest dynamics in Oregon landscapes: Evaluation and application of an individual-based model

    USGS Publications Warehouse

    Busing, R.T.; Solomon, A.M.; McKane, R.B.; Burdick, C.A.

    2007-01-01

    The FORCLIM model of forest dynamics was tested against field survey data for its ability to simulate basal area and composition of old forests across broad climatic gradients in western Oregon, USA. The model was also tested for its ability to capture successional trends in ecoregions of the west Cascade Range. It was then applied to simulate present and future (1990-2050) forest landscape dynamics of a watershed in the west Cascades. Various regimes of climate change and harvesting in the watershed were considered in the landscape application. The model was able to capture much of the variation in forest basal area and composition in western Oregon even though temperature and precipitation were the only inputs that were varied among simulated sites. The measured decline in total basal area from tall coastal forests eastward to interior steppe was matched by simulations. Changes in simulated forest dominants also approximated those in the actual data. Simulated abundances of a few minor species did not match actual abundances, however. Subsequent projections of climate change and harvest effects in a west Cascades landscape indicated no change in forest dominance as of 2050. Yet, climate-driven shifts in the distributions of some species were projected. The simulation of both stand-replacing and partial-stand disturbances across western Oregon improved agreement between simulated and actual data. Simulations with fire as an agent of partial disturbance suggested that frequent fires of low severity can alter forest composition and structure as much or more than severe fires at historic frequencies. ?? 2007 by the Ecological Society of America.

  19. Evaluating the Impacts of Unexpected Forest Disturbances on Paired Catchment Calibrations of Sediment Yield and Turbidity

    NASA Astrophysics Data System (ADS)

    Herlein, K.; Silins, U.; Williams, C.; Wagner, M. J.; Martens, A. M.

    2015-12-01

    The paired catchment approach of studying the impacts of disturbance on catchment hydrology remains as perhaps the most powerful approach for direct verification of catchment scale impacts from disturbance. However, paired catchment studies are also dependent on the stability of the relationships between treated and reference catchments during calibration and evaluation periods. A long-term paired catchment study of forest harvest impacts on sediment yield and turbidity in the Rocky Mountains of southwestern Alberta, Canada has a robust 11-year pre-treatment data record. The study intends to evaluate three alternative logging practices: clear-cutting, strip-shelterwood, and partial cutting. 3 sub-catchments in Star Creek (1035 ha) underwent harvest treatments while North York Creek (865 Ha) serves as the reference. The objective of this particular study was to explore the potential effects of unplanned and unanticipated watershed changes in two watersheds during an 11-year calibration. Sediment yield (kg ha-1 d-1) and turbidity (NTU) were monitored throughout the calibration period (2004-2014) prior to the 2015 harvest in Star Creek. Two unanticipated disturbances including backcountry trail rehabilitation in North York (2010) followed by a >100 year storm event in both watersheds in June 2013 may have affected the sediment yield and turbidity calibration relationships. Analysis of covariance (ANCOVA) was used to evaluate the effects of this trail rehabilitation and flooding by comparing the calibration relationships before and after these disturbances. Despite qualitative field observations of periodically affected sediment regimes, no impact on pre- or post- calibration relationships was observed. Backcountry trail rehabilitation in North York (p=0.904 and 0.416 for sediment yield and turbidity, respectively) or flooding in both watersheds (p=0.364 and 0.204 for sediment yield and turbidity, respectively) did not produce significant changes to the calibrations

  20. Regional framework of early growth response for loblolly pine relative to herbaceous, woody, and complete competition control: The comproject. Forest Service general technical report

    SciTech Connect

    Miller, J.H.; Zutter, B.R.; Zedaker, S.M.; Edwards, M.B.; Newbold, R.A.

    1995-09-01

    A common study design has been installed at 13 locations throughout the Southeastern United States to track the growth of loblolly pine (Pinus taeda L.) plantations established with four different competition control treatments: no control (only chopping-burning), woody control for 5 years, herbaceous control for 4 years, and total control after site preparation. This regionwide investigation is known as the competition Omission Monitoring Project, a coordinated study with the Auburn University Silvicultural Herbicide Cooperative (Study HB-4F). Data summaries for each location are presented for loblolly pine growth and competition intensities for the first 8 years. Approximately 10,000 loblolly pine seedlings have been measured annually. Responses from this network of studies should be useful in assessing and reporting relative growth of loblolly pines for other studies and operational plantings. These data sets should also be useful for the future forest growth modeling efforts.

  1. Changes in soil respiration components and their specific respiration along three successional forests in the subtropics

    DOE PAGESBeta

    Han, Tianfeng; Liu, Juxiu; Wang, Gangsheng; Huang, Wenjuan; Zhou, Guoyi

    2016-01-16

    1.Understanding how soil respiration components change with forest succession is critical for modelling and predicting soil carbon (C) processes and its sequestration below-ground. The specific respiration (a ratio of respiration to biomass) is increasingly being used as an indicator of forest succession conceptually based on Odum's theory of ecosystem development. However, the hypothesis that specific soil respiration declines with forest succession remains largely untested. 2.We used a trenching method to partition soil respiration into heterotrophic respiration and autotrophic respiration (RH and RA) and then evaluated the specific RH and specific RA in three successional forests in subtropical China. 3.Our resultsmore » showed a clear seasonality in the influence of forest succession on RH, with no significant differences among the three forests in the dry season but a higher value in the old-growth forest than the other two forests in the wet season. RA in the old-growth forest tended to be the highest among the three forests. Both the specific RH and specific RA decreased with the progressive maturity of three forests. 4.Lastly, our results highlight the importance of forest succession in determining the variation of RH in different seasons. With forest succession, soil microbes and plant roots become more efficient to conserve C resources, which would result in a greater proportion of C retained in soils.« less

  2. Wildland forest fire smoke: health effects and intervention evaluation,Hoopa, California, 1999

    PubMed Central

    Mott, Joshua A; Meyer, Pamela; Mannino, David; Redd, Stephen C; Smith, Eva M; Gotway-Crawford, Carol; Chase, Emmett

    2002-01-01

    Objectives To assess the health effects of exposure to smoke fromthe fifth largest US wildfire of 1999 and to evaluate whether participation ininterventions to reduce smoke exposure prevented adverse lower respiratorytract health effects among residents of the Hoopa Valley National IndianReservation in northwestern California. Design Observational study:epidemiologists from the Centers for Disease Control and Preventionretrospectively reviewed medical records at the local medical center andconducted survey interviews of reservation residents. Setting HumboldtCounty, California. Participants Interviews were completed with 289 of385 residents, representing 26% of the households on the reservation. Of the289 participants, 92 (31.8%) had preexisting cardiopulmonary conditions.Results During the weeks of the forest fire, medical visits forrespiratory illnesses increased by 217 visits (from 417 to 634 visits, or by52%) over the previous year. Survey results indicated that although 181(62.6%) of 289 participants reported worsening lower respiratory tractsymptoms, those with preexisting cardiopulmonary conditions reported moresymptoms before, during, and after the smoke episode. An increased duration ofthe use of high-efficiency particulate air cleaners and the recollection ofpublic service announcements were associated with a reduced odds of reportingadverse health effects of the lower respiratory tract. No protective effectswere observed for duration of mask use or evacuation. ConclusionsTimely actions undertaken by the clinical staff of the local medical centerappeared beneficial to the respiratory health of the community. Futureprograms that reduce economic barriers to evacuation during smoke episodes mayalso improve intervention participation rates and decrease smoke exposures.Although promising, the effectiveness of these and other interventions need tobe confirmed in a prospective community intervention trial. PMID:12016236

  3. An Evaluation of the MOD17 Gross Primary Production Algorithm in a Mangrove Forest

    NASA Astrophysics Data System (ADS)

    Wells, H.; Najjar, R.; Herrmann, M.; Fuentes, J. D.; Ruiz-Plancarte, J.

    2015-12-01

    Though coastal wetlands occupy a small fraction of the Earth's surface, they are extremely active ecosystems and play a significant role in the global carbon budget. However, coastal wetlands are still poorly understood, especially when compared to open-ocean and terrestrial ecosystems. This is partly due to the limited in situ observations in these areas. One of the ways around the limited in situ data is to use remote sensing products. Here we present the first evaluation of the MOD17 remote sensing algorithm of gross primary productivity (GPP) in a mangrove forest using data from a flux tower in the Florida Everglades. MOD17 utilizes remote sensing products from the Moderate Resolution Imaging Spectroradiometer and meteorological fields from the NCEP/DOE Reanalysis 2. MOD17 is found to capture the long-term mean and seasonal amplitude of GPP but has significant errors describing the interannual variability, intramonthly variability, and the phasing of the annual cycle in GPP. Regarding the latter, MOD17 overestimates GPP when salinity is high and underestimates it when it is low, consistent with the fact that MOD17 ignores salinity and salinity tends to decrease GPP. Including salinity in the algorithm would then most likely improve its accuracy. MOD17 also assumes that GPP is linear with respect to PAR (photosynthetically active radiation), which does not hold true in the mangroves. Finally, the estimated PAR and air temperature inputs to MOD17 were found to be significantly lower than observed. In summary, while MOD17 captures some aspects of GPP variability at this mangrove site, it appears to be doing so for the wrong reasons.

  4. Evaluation of a spatially resolved forest fire smoke model for population-based epidemiologic exposure assessment.

    PubMed

    Yao, Jiayun; Eyamie, Jeff; Henderson, Sarah B

    2016-05-01

    Exposure to forest fire smoke (FFS) is associated with multiple adverse health effects, mostly respiratory. Findings for cardiovascular effects have been inconsistent, possibly related to the limitations of conventional methods to assess FFS exposure. In previous work, we developed an empirical model to estimate smoke-related fine particulate matter (PM2.5) for all populated areas in British Columbia (BC), Canada. Here, we evaluate the utility of our model by comparing epidemiologic associations between modeled and measured PM2.5. For each local health area (LHA), we used Poisson regression to estimate the effects of PM2.5 estimates and measurements on counts of medication dispensations and outpatient physician visits. We then used meta-regression to estimate the overall effects. A 10 μg/m(3) increase in modeled PM2.5 was associated with increased sabutamol dispensations (RR=1.04, 95% CI 1.03-1.06), and physician visits for asthma (1.06, 1.04-1.08), COPD (1.02, 1.00-1.03), lower respiratory infections (1.03, 1.00-1.05), and otitis media (1.05, 1.03-1.07), all comparable to measured PM2.5. Effects on cardiovascular outcomes were only significant using model estimates in all LHAs during extreme fire days. This suggests that the exposure model is a promising tool for increasing the power of epidemiologic studies to detect the health effects of FFS via improved spatial coverage and resolution. PMID:25294305

  5. Temperature and food quality effects on growth, consumption and post-ingestive utilization efficiencies of the forest tent caterpillar Malacosoma disstria (Lepidoptera: Lasiocampidae).

    PubMed

    Levesque, K R; Levesque, K R; Fortin, M; Mauffette, Y

    2002-04-01

    Temperature and food quality can both influence growth rates, consumption rates, utilization efficiencies and developmental time of herbivorous insects. Gravimetric analyses were conducted during two consecutive years to assess the effects of temperature and food quality on fourth instar larvae of the forest tent caterpillar Malacosoma disstria Hübner. Larvae were reared in the laboratory at three different temperatures (18, 24 and 30 degrees C) and on two types of diet; leaves of sugar maple trees Acer saccharum Marsh. located at the forest edge (sun-exposed leaves) or within the forest interior (shade-exposed leaves). In general, larvae reared at 18 degrees C had lower growth rates and lower consumption rates than larvae reared at the warmer temperatures (24 and 30 degrees C). Moreover, the duration of the instar decreased significantly with increasing temperatures. Type of diet also affected the growth rates and amount of food ingested by larvae but did not affect the duration of the instar. Larvae fed sun-exposed leaves consumed more food and gained higher biomasses. Values of approximate digestibility and efficiency of conversion of ingested food were also higher when larvae were fed sun-exposed leaves. Higher growth rates with increasing temperatures were primarily the result of the shorter stadium duration. The higher growth rates of larvae fed sun-exposed leaves were possibly the result of stimulatory feeding and consequently greater food intake and also a more efficient use of food ingested. This study suggests that the performance of M. disstria caterpillars could be enhanced by warmer temperatures and higher leaf quality. PMID:12020370

  6. Vapor-liquid-solid epitaxial growth of Si1-xGex alloy nanowires. Composition dependence on precursor reactivity and morphology control for vertical forests

    DOE PAGESBeta

    Choi, S. G.; Manandhar, P.; Picraux, S. T.

    2015-07-07

    The growth of high-density group IV alloy nanowire forests is critical for exploiting their unique functionalities in many applications. Here, the compositional dependence on precursor reactivity and optimized conditions for vertical growth are studied for Si1- x Ge x alloy nanowires grown by the vapor-liquid-solid method. The nanowire composition versus gas partial-pressure ratio for germane-silane and germane-disilane precursor combinations is obtained at 350°C over a wide composition range (0.05 ≤ x ≤ 0.98) and a generalized model to predict composition for alloy nanowires is developed based on the relative precursor partial pressures and reactivity ratio. In combination with germane, silanemore » provides more precise compositional control at high Ge concentrations (x > 0.7), whereas disilane greatly increases the Si concentration for a given gas ratio and enables more precise alloy compositional control at small Ge concentrations (x < 0.3). Vertically oriented, non-kinking nano