Download or read book Interactions Among Climate Fire and Vegetation in the Alaskan Boreal Forest written by Paul Arthur Duffy and published by . This book was released on 2006 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The boreal forest covers 12 million km2 of the northern hemisphere and contains roughly 40% of the world's reactive soil carbon. The Northern high latitudes have experienced significant warming over the past century and there is a pressing need to characterize the response of the disturbance regime in the boreal forest to climatic change. The interior Alaskan boreal forest contains approximately 60 million burnable hectares and, relative to the other disturbance mechanisms that exist in Alaska, fire dominates at the landscape-scale. In order to assess the impact of forecast climate change on the structure and function of the Alaskan boreal forest, the interactions among climate, fire and vegetation need to be quantified. The results of this work demonstrate that monthly weather and teleconnection indices explain the majority of observed variability in annual area burned in Alaska from 1950-2003. Human impacts and fire-vegetation interactions likely account for a significant portion of the remaining variability. Analysis of stand age distributions indicate that anthropogenic disturbance in the early 1900's has left a distinct, yet localized impact. Additionally, we analyzed remotely sensed burn severity data to better understand interactions among fire, vegetation and topography. These results show a significant relationship between burn severity and vegetation type in flat landscapes but not in topographically complex landscapes, and collectively strengthen the argument that differential flammability of vegetation plays a significant role in fire-vegetation interactions. These results were used to calibrate a cellular automata model based on the current conceptual model of interactions among weather, fire and vegetation. The model generates spatially explicit maps of simulated stand ages at 1 km resolution across interior Alaska, and output was validated using observed stand age distributions. Analysis of simulation output suggests that significant temporal variability of both the mean and variance of the stand age distribution is an intrinsic property of the stand age distributions of the Alaskan boreal forest. As a consequence of this non-stationarity, we recommend that simulation based methods be used to analyze the impact of forecast climatic change on the structure and function of the Alaskan boreal forest"--Leaf iii.

Download or read book Alaska s Changing Boreal Forest written by F. Stuart Chapin and published by Oxford University Press. This book was released on 2006-01-12 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The boreal forest is the northern-most woodland biome, whose natural history is rooted in the influence of low temperature and high-latitude. Alaska's boreal forest is now warming as rapidly as the rest of Earth, providing an unprecedented look at how this cold-adapted, fire-prone forest adjusts to change. This volume synthesizes current understanding of the ecology of Alaska's boreal forests and describes their unique features in the context of circumpolar and global patterns. It tells how fire and climate contributed to the biome's current dynamics. As climate warms and permafrost (permanently frozen ground) thaws, the boreal forest may be on the cusp of a major change in state. The editors have gathered a remarkable set of contributors to discuss this swift environmental and biotic transformation. Their chapters cover the properties of the forest, the changes it is undergoing, and the challenges these alterations present to boreal forest managers. In the first section, the reader can absorb the geographic and historical context for understanding the boreal forest. The book then delves into the dynamics of plant and animal communities inhabiting this forest, and the biogeochemical processes that link these organisms. In the last section the authors explore landscape phenomena that operate at larger temporal and spatial scales and integrates the processes described in earlier sections. Much of the research on which this book is based results from the Bonanza Creek Long-Term Ecological Research Program. Here is a synthesis of the substantial literature on Alaska's boreal forest that should be accessible to professional ecologists, students, and the interested public.

Download or read book Fire Climate Change and Carbon Cycling in the Boreal Forest written by Eric S. Kasischke and published by Springer Science & Business Media. This book was released on 2012-08-22 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discussion of the direct and indirect mechanisms by which fire and climate interact to influence carbon cycling in North American boreal forests. The first section summarizes the information needed to understand and manage fires' effects on the ecology of boreal forests and its influence on global climate change issues. Following chapters discuss in detail the role of fire in the ecology of boreal forests, present data sets on fire and the distribution of carbon, and treat the use of satellite imagery in monitoring these regions as well as approaches to modeling the relevant processes.

Download or read book Climate induced Changes in Ecological Dynamics of the Alaskan Boreal Forest written by Dana Rachel Nossov Brown and published by . This book was released on 2016 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: A warming climate is expected to cause widespread thawing of discontinuous permafrost, and the co-occurrence of wildfire may function to exacerbate this process. Here, I examined the vulnerability of permafrost to degradation from fire disturbance as it varies across different landscapes of the Interior Alaskan boreal forest using a combination of observational, modeling, and remote sensing approaches. Across all landscapes, the severity of burning strongly influenced both post-fire vegetation and permafrost degradation. The thickness of the remaining surface organic layer was a key control on permafrost degradation because its low thermal conductivity limits ground heat flux. Thus, variation in burn severity controlled the local distribution of near-surface permafrost. Mineral soil texture and permafrost ice content interacted with climate to influence the response of permafrost to fire. Permafrost was vulnerable to deep thawing after fire in coarse-textured or rocky soils throughout the region; low ice content likely enabled this rapid thawing. After thawing, increased drainage in coarse-textured soils caused reductions in surface soil moisture, which contributed to warmer soil temperatures. By contrast, permafrost in fine-textured soils was resilient to fire disturbance in the silty uplands of the Yukon Flats ecoregion, but was highly vulnerable to thawing in the silty lowlands of the Tanana Flats. The resilience of silty upland permafrost was attributed to higher water content of the active layer and the associated high latent heat content of the ice-rich permafrost, coupled with a relatively cold continental climate and sloping topography that removes surface water. In the Tanana Flats, permafrost in silty lowlands thawed after fire despite high water and ice content of soils. This thawing was associated with significant ground surface subsidence, which resulted in water impoundment on the flat terrain, generating a positive feedback to permafrost degradation and wetland expansion. The response of permafrost to fire, and its ecological effects, thus varied spatially due to complex interactions between climate, topography, vegetation, burn severity, soil properties, and hydrology. The sensitivity of permafrost to fire disturbance has also changed over time due to variation in weather at multi-year to multi-decadal time scales. Simulations of soil thermal dynamics showed that increased air temperature, increased snow accumulation, and their interactive effects, have since the 1970s caused permafrost to become more vulnerable to talik formation and deep thawing from fire disturbance. Wildfire coupled with climate change has become an important driver of permafrost loss and ecological change in the northern boreal forest. With continued climate warming, we expect fire disturbance to accelerate permafrost thawing and reduce the likelihood of permafrost recovery. This regime shift is likely to have strong effects on a suite of ecological characteristics of the boreal forest, including surface energy balance, soil moisture, nutrient cycling, vegetation composition, and ecosystem productivity.

Download or read book The Interaction of Fire Climate and Vegetation in the Boreal Forest of Alaska Yukon During the Holocene written by Leanne Franklin-Smith and published by . This book was released on 2006 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vegetation climate Interactions Along a Transition from Tundra to Boreal Forest in Alaska written by Catharine Copass Thompson and published by . This book was released on 2005 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The climate of the Alaskan Arctic is warming more rapidly than at any time in the last 400 years. Climate changes of the magnitude occurring in high latitudes have the potential to alter both the structure and function of arctic ecosystems. Structural responses reflect changes in community composition, which may also influence ecosystem function. Functional responses change the biogeochemical cycling of carbon and nutrients. We examined the structural and functional interactions between vegetation and climate across a gradient of vegetation types from arctic tundra to boreal forest. Canopy complexity combines vegetation structural properties such as biomass, cover, height, leaf area index (LAT) and stem area index (SAT). Canopy complexity determines the amount of the energy that will be available in an ecosystem and will also greatly influence the partitioning of that energy into different land surface processes such as heating the air, evaporating water and warming the ground. Across a gradient of sites in Western Alaska, we found that increasing canopy complexity was linked to increased sensible heating. Thus, vegetation structural changes could represent an important positive feedback to warming. Structural changes in ecosystems are linked to changes in ecosystem function. High latitude ecosystems play an important role in the earth's climate system because they contain nearly 40% of the world's reactive soil carbon. We examined Net Ecosystem Production (NEP) in major community types of Northern Alaska using a combination of field-based measurements and modeling. Modeled NEP decreased in both warmer and drier and warmer and wetter conditions. However, in colder and wetter conditions, NEP increased. The net effect for the region was a slight gain in ecosystem carbon; however, our research highlights the importance of climate variability in the carbon balance of the study region during the last two decades. The next step forward with this research will be to incorporate these results into coupled models of the land-atmosphere system. Improved representations of ecosystem structure and function will improve our ability to predict future responses of vegetation composition, carbon storage, and climate and will allow us to better examine the interactions between vegetation and the atmosphere in the context of a changing climate"--Leaves iii-iv.

Download or read book Ecological Foundations for Fire Management in North American Forest and Shrubland Ecosystems written by J. E. Keeley and published by DIANE Publishing. This book was released on 2011-05 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an ecological foundation for mgmt. of the diverse ecosystems and fire regimes of N. America, based on scientific principles of fire interactions with vegetation, fuels, and biophysical processes. Detailed discussion of six ecosystems ¿ ponderosa pine forest (western N. America), chaparral (Calif.), boreal forest (Alaska and Canada), Great Basin sagebrush (inter-mountain West), pine and pine-hardwood forests (Southern Appalachian Mountains), and longleaf pine (Southeastern U.S.) ¿ illustrates the complexity of fire regimes and that fire mgmt. requires a clear regional focus that recognizes where conflicts might exist between fire hazard reduction and resource needs. Illustrations. This is a print on demand report.

Download or read book Fire and Successional Trajectories in Boreal Forest written by Jill Frances Johnstone and published by . This book was released on 2003 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Because of the key role played by fire in structuring boreal forest ecosystems, interactions between vegetation and fire regime may be an important and dynamic control of forest response to climate change. This research uses a series of field observations and experiments in boreal forests to examine the nature of several potential fire and vegetation interactions, and how such interactions may influence forest response to climate change. Long-term observations of post-fire succession provide information on the timing of tree establishment and the effects of early establishment on subsequent successional trajectories. The role of competitive interactions in driving patterns of early establishment was tested with experimental manipulations of aspen (Populus tremuloides) cover after fire. This research demonstrated that competition by aspen re-sprouts may reduce the success of conifer establishment and favor long-term dominance by deciduous trees. The effects of fire severity on successional trajectories were tested in a series of field experiments that contrasted patterns of seedling establishment across differences in depth of the post-fire organic layer. All species in the experiment responded negatively to decreased fire severity, but deciduous trees were more sensitive in their response than conifers. Thus, variations in bum severity are likely to mediate deciduous establishment in organic-rich stands. Observations of natural tree regeneration in stands that burned at different ages also indicate that a decrease in fire interval can influence the relative abundance of deciduous and coniferous species by reducing coniferestablishment. Over longer time scales, changes in biota caused by species migration may influence fire and vegetation interactions. Observations of post-fire regeneration at the current distribution limits of lodgepole pine (Pinus contorta) indicate that continued range expansion of pine could initiate rapid shifts in dominance from spruce to pine within a single fire cycle. Together, these results provide insight into the dynamic feedbacks between fire and vegetation that can lead to high levels of system resilience, while also promoting rapid responses when threshold conditions are crossed. A more complete understanding of these interactions will improve our ability to manage and predict boreal ecosystem responses to a changing climate"--Leaves iii-iv.

Download or read book Ecological Foundations for Fire Management in North American Forest and Shrubland Ecosystems written by and published by . This book was released on 2009 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: This synthesis provides an ecological foundation for management of the diverse ecosystems and fire regimes of North America, based on scientific principles of fire interactions with vegetation, fuels, and biophysical processes. Although a large amount of scientific data on fire exists, most of those data have been collected at small spatial and temporal scales. Thus, it is challenging to develop consistent science-based plans for large spatial and temporal scales where most fire management and planning occur. Understanding the regional geographic context of fire regimes is critical for developing appropriate and sustainable management strategies and policy. The degree to which human intervention has modified fire frequency, intensity, and severity varies greatly among different ecosystems, and must be considered when planning to alter fuel loads or implement restorative treatments. Detailed discussion of six ecosystems--ponderosa pine forest (western North America), chaparral (California), boreal forest (Alaska and Canada), Great Basin sagebrush (intermountain West), pine and pine-hardwood forests (Southern Appalachian Mountains), and longleaf pine (Southeastern United States)-- illustrates the complexity of fire regimes and that fire management requires a clear regional focus that recognizes where conflicts might exist between fire hazard reduction and resource needs. In some systems, such as ponderosa pine, treatments are usually compatible with both fuel reduction and resource needs, whereas in others, such as chaparral, the potential exists for conflicts that need to be closely evaluated. Managing fire regimes in a changing climate and social environment requires a strong scientific basis for developing fire management and policy.

Download or read book Sensitivity of Past Present and Future Fire Regimes to Climate and Vegetation Variability in Boreal Forest and Tundra Ecosystems written by Adam M. Young and published by . This book was released on 2018 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wildfire activity in North American boreal forest and tundra ecosystems is strongly controlled by climate, indicating the potential for widespread fire-regime shifts in response to ongoing and future climate change. This dissertation focuses on understanding how fire regimes in boreal forest and tundra ecosystems respond to variability in past, present, and future climate. Chapter 1 addresses how climate, vegetation, and topography control the spatial distribution of fire occurrence in Alaskan boreal forest and tundra ecosystems. Through statistical modeling, I found that climate was the primary control of historical fire activity. Informing these statistical models with 21st-century climate projections suggests tundra and forest-tundra ecosystems will be particularly vulnerable to fire-regime shifts, due to increasing summer temperatures. In some areas, fire may become four times more likely to occur by 2100, relative to the past 6,000-35,000 years. In Chapter 2, I studied the importance of vegetation as a control of fire activity across North American boreal forests, using continental-scale fire and vegetation datasets spanning the past several decades. After climate, fire activity was most strongly linked to landscape tree cover (%). The likelihood of burning was also not independent of past fire, suggesting negative fire-vegetation feedbacks exist across North American boreal forests. These feedbacks are estimated to have reduced total area burned by ≈ 2.7-3.6 x106 ha (4-5%) from 1981-2016, relative to expectations if there were no feedbacks. While these negative fire-vegetation feedbacks may offset climatically driven increases in fire activity for several decades, continued warming and increasing aridity will likely overwhelm the mediating effects of vegetation by the mid- to late-21st century. In Chapter 3, I evaluate the ability of the statistical models from Chapter 1 to project fire regimes outside of the observational period (i.e., 1950-2009 CE). I informed these models with GCM data from 850-1850 CE, and compared these paleo-projections to independent fire histories derived from lake-sediment records. The accuracy of the paleo-projections varied regionally, with uncertainty highest in regions close to an observed temperature threshold to burning. These results highlight how threshold relationships can cause significant uncertainty in anticipating the timing, location, and magnitude of future ecosystem change.

Download or read book Fire severity Effects on Plant fungal Interactions written by Rebecca E. Hewitt and published by . This book was released on 2014 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the complex mechanisms controlling treeline advance or retreat in the Arctic and Subarctic has important implications for projecting ecosystem response to climate change. Changes in landcover due to a treeline biome shift could alter climate feedbacks and ecosystem services such as wildlife and berry habitat. Major sources of uncertainty in predicting treeline advance or retreat are the controls over seedling establishment at treeline and in tundra. One often-overlooked yet physiologically important factor to seedling establishment is the symbiosis with ectomycorrhizal fungi (EMF), the obligate mycobionts of all boreal tree species. EMF provide soil nutrients and water to seedlings and protect against pathogens, enhancing their growth and reducing drought stress. The availability of these critical mycobionts may be limited across the forest-tundra ecotone and by disturbance events such as wildfire. Wildfires are the primary large-scale disturbance in Alaskan boreal forests and are increasingly prevalent in tundra and at treeline. Fire is the major driver of boreal tree seedling recruitment; however, fire also alters the community structure and reduces biomass of EMF, especially after high-severity fires. To investigate the potentially critical role of EMF in seedling establishment at and beyond current treeline in Alaska, I conducted two observational studies and one experimental study that address how fire-severity influences EMF community structure and plant-fungal interactions. These studies indicated that shrubs that survived and resprouted after fires at treeline and in tundra were a source of resilience for EMF diversity and function. Shrubs maintained latesuccessional stage EMF taxa, and the EMF taxa associated with shrubs at treeline were compatible with tree seedlings that naturally established after fire. Many of the EMF taxa that were shared by seedlings and shrubs were present across the low Arctic, suggesting that EMF compatible with boreal tree species are not limited within the predicted geographic range of treeline expansion. Additionally, I found that seedling growth was correlated with post-fire fungal inoculum. Seedling growth was promoted by EMF inoculum provided by resprouting shrubs after fire. However, when fungal inoculum lacked EMF in post-fire tundra soils, seedling biomass was related to the negative effect of soil pathogens and the positive influence of dark septate endophytes. Together these results illustrate the important role of resprouting tundra shrubs as fungal nurse plants for establishment of boreal tree species at and potentially beyond current treeline, and that biotic factors such as EMF-tree interactions are important to seedling performance. My results suggest that the inclusion of biotic effects, like plant-fungal interactions, in simulation models of treeline dynamics will improve the accuracy of predictions of forestation and associated landscape flammability with future warming in Alaska.

Download or read book Climate Change Interactions at the Edge written by Joanna L. Nelson and published by . This book was released on 2011 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mathematical Models of Plant Herbivore Interactions written by Zhilan Feng and published by CRC Press. This book was released on 2017-09-07 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical Models of Plant-Herbivore Interactions addresses mathematical models in the study of practical questions in ecology, particularly factors that affect herbivory, including plant defense, herbivore natural enemies, and adaptive herbivory, as well as the effects of these on plant community dynamics. The result of extensive research on the use of mathematical modeling to investigate the effects of plant defenses on plant-herbivore dynamics, this book describes a toxin-determined functional response model (TDFRM) that helps explains field observations of these interactions. This book is intended for graduate students and researchers interested in mathematical biology and ecology.

Download or read book Feedback from Fire Regime to Climate in the Alaskan Boreal Forest FROSTFIRE written by Colin O'Dowd and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boreal Forests in the Face of Climate Change written by Miguel Montoro Girona and published by Springer Nature. This book was released on 2023-03-01 with total page 859 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book explores a new conceptual framework for the sustainable management of the boreal forest in the face of climate change. The boreal forest is the second-largest terrestrial biome on Earth and covers a 14 million km2 belt, representing about 25% of the Earth’s forest area. Two-thirds of this forest biome is managed and supplies 37% of global wood production. These forests also provide a range of natural resources and ecosystem services essential to humanity. However, climate change is altering species distributions, natural disturbance regimes, and forest ecosystem structure and functioning. Although sustainable management is the main goal across the boreal biome, a novel framework is required to adapt forest strategies and practices to climate change. This collaborative effort draws upon 148 authors in summarizing the sustainable management of these forests and detailing the most recent experimental and observational results collected from across the boreal biome. It presents the state of sustainable management in boreal forests and highlights the critical importance of this biome in a context of global change because of these forests' key role in a range of natural processes, including carbon sequestration, nutrient cycling, and the maintaining of biodiversity. This book is an essential read for academics, students, and practitioners involved in boreal forest management. It outlines the challenges facing sustainable boreal forest management within the context of climate change and serves as a basis for establishing new research avenues, identifying future research trends, and developing climate-adapted forest management plans.

Download or read book The Relationship Between Wildfire Dynamics and Soil Carbon in Boreal Forests of Alaska Forest Management for Emissions Reduction in a Changing Climate written by James D Heaster and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The boreal region of Alaska has vast forests spanning hundreds of thousands of square kilometers in the central portion of the state that is prone to large stand replacing summer wildfires. The region stores considerable quantities of terrestrial carbon sequestered in soil horizons down to 1 meter in depth that are strongly influenced by a combination of climate change, permafrost dynamics, vegetative composition, and fire regimes. Data and literature establish that the boreal region of Alaska (and the rest of the Arctic) has been steadily warming at a rate nearly double that of lower latitudes. This warming has resulted in larger fires defined by shorter return intervals. This altered fire regime places the vast stocks of organic soil carbon at risk to greater degrees of combustion, potentially contributing millions more tons of CO2 to the atmosphere in the Arctic region. Between 2000-2015 roughly 5% (~28,000 km2) of the over 560,000 km2 of the boreal region burned, raising CO2 levels and supporting a positive feedback loop between climate and fires; when considering that this region of Alaska is larger than the state of California (~420,000 km2) these emissions are significant. Mean summer temperatures have risen by 1.4° C over the last 100 years, resulting in shorter fire return intervals characterized by more severe and intense, longer fire seasons. This warming is driving more pronounced permafrost degradation that is altering both the extent and depth of regional permafrost layers, increasing labile carbon stocks that serve as additional fuel pools for fires. While permafrost layers are fluctuating more frequently, the warmer temperatures are supporting increased vegetation growth with expansion of the boreal forest into landscapes that were previously hostile, increasing novelty in these area's fire regimes and subsequent emissions. As fire activity increases in the region, forest composition is being altered toward a greater dominance by deciduous rather than coniferous trees, a development that is increasing soil carbon levels as these stands mature. Human suppression policies, despite being well intentioned, are driving more frequent and severe fires due to an unnatural buildup of fuels, especially around regional population centers. Because of these findings, I recommend closing critical data gaps with further data additions, changing timber harvesting and forest management policies, and reexamining fire suppression policies.

Download or read book Effects of Timber Harvest Following Wildfire in Western North America written by and published by . This book was released on 2009 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This synthesis provides an ecological foundation for management of the diverse ecosystems and fire regimes of North America, based on scientific principles of fire interactions with vegetation, fuels, and biophysical processes. Although a large amount of scientific data on fire exists, most of those data have been collected at small spatial and temporal scales. Thus, it is challenging to develop consistent science-based plans for large spatial and temporal scales where most fire management and planning occur. Understanding the regional geographic context of fire regimes is critical for developing appropriate and sustainable management strategies and policy. The degree to which human intervention has modified fire frequency, intensity, and severity varies greatly among different ecosystems, and must be considered when planning to alter fuel loads or implement restorative treatments. Detailed discussion of six ecosystems--ponderosa pine forest (western North America), chaparral (California), boreal forest (Alaska and Canada), Great Basin sagebrush (intermountain West), pine and pine-hardwood forests (Southern Appalachian Mountains), and longleaf pine (Southeastern United States)--illustrates the complexity of fire regimes and that fire management requires a clear regional focus that recognizes where conflicts might exist between fire hazard reduction and resource needs. In some systems, such as ponderosa pine, treatments are usually compatible with both fuel reduction and resource needs, whereas in others, such as chaparral, the potential exists for conflicts that need to be closely evaluated. Managing fire regimes in a changing climate and social environment requires a strong scientific basis for developing fire management and policy. --