Download or read book Variable Fire Severity in Alaska s Boreal Forest written by Rachel E. Lord and published by . This book was released on 2008 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Over 1 million hectares burn annually across interior Alaska's boreal forest, altering the composition and distribution of vegetation communities that provide critical winter habitat for Alaskan moose (Alces alces gigas). Within a burn, fire severity (the amount of residual soil organic matter following a fire event) is spatially variable and influences the trajectories of post-fire succession. I examined the response of moose to patterns of regeneration resulting from variable fire severity within two burns in interior Alaska. I found significantly higher production of forage biomass (kg/ha) in high fire severity sites than in low severity sites. Proportional removal of forage biomass by moose was 36% higher on sites with higher fire severity compared with low severity sites. I used multiple regression models to examine the role of post-fire forage distribution on proportional removal. The overall explanatory power of any landscape descriptor was moderate at best. Winter forage is a limiting factor for moose reproductive potential, especially in areas with low predation rates. Changes in moose habitat potential is easily measured using remote sensing and GIS techniques and should be assessed to combine field-based knowledge of moose response to variations in regeneration to large-scale patterns of vegetation regeneration following wildfires"--Leaf iii.
Download or read book Post fire Variability in Siberian Alder in Interior Alaska written by Brian Richard Houseman and published by . This book was released on 2017 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: The circumpolar boreal forest is responsible for a considerable proportion of global carbon sequestration and is an ecosystem with limited nitrogen (N) pools. Boreal forest fires are predicted to increase in severity, size, and frequency resulting in increased losses of N from this system due to volatilization. Siberian alder (Alnus viridis ssp. fruticosa) N-fixation is a significant source of N-input within the interior Alaskan boreal forest and likely plays a pivotal, though poorly understood, role in offsetting losses of N due to fire. This study disentangles the effects of fire severity, post-fire age, and environmental variables on Siberian alder N-input across the upland boreal forest and quantifies the landscape-level implications of Siberian alder N-input on N pool balance. Stand types of an early- and intermediate-age burn scar were determined by relevé plot sampling, hierarchical clustering, and indicator species analysis. Alder growth traits (density, nodule biomass, nodule N-fixation, and other traits) were sampled across all stand types, burn scars, and a fire severity gradient. Pre- and post-fire landscape-level N-fixation inputs were quantified within the early-age burn scar by scaling-up Siberian alder growth traits to the stand-level and then mapping the total area of pre- and post-fire stand types. Results show that fire severity shares a complex relationship with Siberian alder N-input in black spruce stands, wherein moderate fire severity has a negligible effect on Siberian alder N-input, moderate to high fire severity increases Siberian alder N-input, and high fire severity reduces Siberian alder N-input. Fire likely limited alder vegetative propagation in post-fire black spruce trajectory stands but enhanced propagation in post-fire deciduous trajectory stands that experienced moderate severity. Following the 2004 Boundary Fire, Siberian alder N-input showed an overall increase across the landscape, mostly within post-fire deciduous stand types. Future increases of fire severity and subsequent conversions of stand type from black spruce to deciduous dominance have the potential to increase total short-term N-input on the landscape, but a majority of those gains will be concentrated within a small proportion of the post-fire landscape (i.e. deciduous trajectory stand types). In the boreal forest, the temporal and spatial pattern of ecosystem processes that rely on N fixation inputs is dependent on the recruitment and growth of Siberian alder, which is in turn dependent on a complex relationship between fire severity, stand type, and post-fire age.
Download or read book Quantifying Fire Severity and Carbon and Nitrogen Pools and Emissions in Alaska s Boreal Black Spruce Forest written by Leslie A. Boby and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Fire severity can be defined as the amount of biomass combusted by wildfire. Stored carbon (C) and nitrogen (N) are emitted into the atmosphere as wildfires consume vegetation and soil organic layers, thus C and N emissions should be related to fire severity. Since boreal forests store 30% of the world's terrestrial C and are subject to high-intensity, stand-replacing wildfires, it is critical to be able to estimate C fluxes from wildfires. Furthermore, quantifying fire severity is important for predicting post-fire vegetation recovery and future C sequestration. We reconstructed pre-fire organic soil layers and quantified fire severity levels from the 2004 wildfires in Interior Alaska with the adventitious root height (ARH) method. We tested the ARH method in unburned stands and by comparing our reconstructed values in burned stands with actual prefire measurements. We found that ARH correlated to organic soil height in unburned stands (with a small offset of 3 cm). We measured organic soil (using the ARH method) and stand characteristics in boreal black spruce forest and estimated the amount of soil and canopy biomass consumed by fire. We compared these results to the composite burn index (CBI), a standardized visual method, which has not been widely used in the boreal forest. CBI assessments were significantly related to our ground and canopy fire severity estimates. We calculated C and N pools using C and N concentration and bulk density estimates from soils sampled in burned and unburned stands. We conclude that the ARH method can be used to reconstruct pre-fire organic soil depth, C and N pools and to assess fire severity. Furthermore, CBI shows promise as a way of estimating fire severity quickly and is a reasonably good predictor of biomass and soil C loss.
Download or read book Advancing Wildfire Fuel Mapping and Burn Severity Assessment in Alaskan Boreal Forest Using Multi sensor Remote Sensing written by Christopher William Smith and published by . This book was released on 2021 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wildfires in Alaska have been increasing in frequency, size, and intensity putting a strain on communities across the state, especially remote communities lacking firefighting infrastructure to address large scale fire events. Advances in remote sensing techniques and data provide an opportunity to generate high quality map products that can better inform fire managers to allocate resources to areas of most risk and inform scientists how to predict and understand fire behavior. The overarching goal of this thesis is therefore to build insight into methods that can be applied to create highly detailed fire statistic map products in Alaska. To address this overarching goal we tested several methods for generating fire fuel, burn severity, and wildfire hazard maps that were validated using data collected in the field. Applying the Random Forest classifier on Airborne Visible/ Infrared Imaging Spectrometer Next-Generation (AVIRIS-NG) hyperspectral data we were able to produce a fire fuel map with an 81% accuracy. We then tested two supervised machine learning classifiers, post fire standard spectral indices, and differenced spectral indices for their performance in assessing burn severity. We found that supervised machine learning classifiers outperform other algorithms when there is an adequate amount of training data. Using the support vector machine and random forest classifiers we were able to generate burn severity maps with 83% accuracy at the 2019 Shovel Creek Fire. Lastly, we looked for a relationship between burn severity and environmental conditions prevalent during the Shovel Creek and Nugget Creek fires. Overall, these products can be used by fire managers and scientists to assess fire risk, limit the damages caused by wildfires through adequate resource allocation, and provide the guidelines for creating future high quality fire fuel maps.
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 Temporal and Spatial Variation of Broadleaf Forest Flammability in Boreal Alaska written by Maija I. Wehmas and published by . This book was released on 2018 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The boreal forest is a carbon reservoir containing roughly 40% of the world’s reactive soil carbon, which is mainly cycled by wildland fires. Climate warming in boreal Alaska has changed the wildfire regime such that an increase in broadleaf forest relative to conifer forest is likely, which may reduce landscape flammability. However, the current and future flammability of broadleaf forest in a warming climate is not well understood. We used pre-fire and post-fire geospatial data to investigate the flammability of upland boreal forest patches in Interior Alaska in relation to summer weather conditions. Our objectives were to assess burning of broadleaf forest patches during “Normal” vs. “Large Fire Years”, by week within a fire season, and by topographic position. Using 30-meter land-cover and fire-severity grids, we estimated the flammability of upland broadleaf forest patches during Large and Normal Fire Years. We then tested for topographic effects using a solar radiation index to eliminate potential deviations within the vegetation. Finally, Moderate Resolution Imaging Spectroradiometer (MODIS) hotspots were used to track the spatial extent of burns during the fire season by examining the periods of fire activity and intensity. Flammability of broadleaf forest patches varied both in time and space. Even during Normal Fire Years, broadleaf forest patches exhibited substantial flammability, with a mean of over 50% patch area burned. Patch flammability was significantly higher during Large Fire Years. Burning of broadleaf patches varied with topographic position and correlated with potential insolation. Broadleaf forest patches burned most frequently in late June-early July. Contrary to “conventional wisdom”, broadleaf forest patches in boreal Alaska are susceptible to burning even during Normal Fire Years. With climate warming, the flammability of broadleaf forest is likely to increase due to more extreme fire weather events. Thus, although the frequency of broadleaf forest patches on the landscape is likely to increase with more frequent and severe wildfires, their effectiveness as a fire break may decrease in the future.
Download or read book Role of Fire Severity in Controlling Patterns of Stand Dominance Following Wildfire in Boreal Forests written by Aditi Shenoy and published by . This book was released on 2016 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global trends of climate warming have been particularly pronounced in northern latitudes, and have been linked to an intensification of the fire regime in Arctic and boreal ecosystems. Increases in fire frequency, extent, and severity that have been observed over the past several decades are expected to continue under a warming climate. Severe fires can drastically reduce or remove the deep organic layers that accumulate in mature black spruce forests. Extensive studies in the boreal forests of interior Alaska and Canada have shown that parts of the landscape that undergo severe burning provide favorable seedbeds for the recruitment of deciduous tree seedlings, and thereby reduce the relative abundance of coniferous seedling recruitment in these areas shortly after fire. The persistence of deciduous species such as aspen beyond the seedling recruitment and establishment stage is as yet relatively unknown. To address this knowledge gap, I asked the question: is increased deciduous recruitment observed in severely burned areas transient, or does it result in persistent changes in stand composition later in succession? I examined changes in relative dominance patterns of aspen and black spruce that had occurred between 8 and 14 years post-fire along an organic layer depth gradient within a single burn. I found that patterns of relative species dominance established shortly after fire persisted into the second decade of succession, resulting in productive aspendominated stands in severely burned areas with shallow organic layers, and black spruce dominated stands in lightly burned areas with deep organic layers. These patterns of stand dominance in relation to post-fire organic layer depth were also observed in several other burns in the region. Therefore, deep burning fires are likely to result in a persistent shift from black spruce to aspen dominance in severely burned parts of the boreal forest. In order to understand how variation in organic layer depth is driving these alternate successional pathways, I measured nutrient uptake rates of aspen and spruce in severely and lightly burned sites within a single burn. I also examined relationships between post-fire organic layer depth and a suite of soil variables, and evaluated the relative importance of these soil variables in explaining variation in stand level aspen biomass, spruce biomass, and the relative dominance of aspen vs. spruce. I found that variations in post-fire organic layer depth result in contrasting soil environments, with soils in shallow organic layer sites being warmer, drier, and more alkaline than soils in deep organic layer sites. Variations in aspen biomass and aspen: spruce biomass were largely being driven by substrate conditions, whereas stand level spruce biomass was less sensitive to these same variations in soil conditions. Nutrient uptake rates of both aspen and spruce were higher in severely burned areas with shallow organic layers, but the differences between species were magnified by stand biomass patterns in relation to post-fire organic layer depth. My results suggest that the positive effects of soil conditions associated with mineral soil substrates extend well beyond the initial seedling recruitment phase, and may continue to influence aspen growth rates into the second decade of succession resulting in the differential patterns of biomass accumulation and stand dominance in relation to post-fire organic layer depth. With the predicted increase in fire severity and shortening of the fire cycle, the proportion of aspen dominated stands on the landscape is likely to increase, which will incur substantial changes in ecosystem function (e.g., land-atmosphere energy exchange, C and N storage, nutrient cycling, net primary productivity, and wildlife habitat quality) compared to the current forests dominated by conifers.
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 369 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 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 Mixed Severity Fires written by Dominick A. DellaSala and published by Elsevier. This book was released on 2024-06-21 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Mixed Severity Fires: Nature’s Phoenix focuses on wildfire as a keystone ecological process that has shaped plant and animal communities for over 400 million years. The book will describe the renewal process that follows wildfires in forests and chaparral ecosystems as "nature’s phoenix" by drawing from examples of wildfire effects in several regions of the world.In addition, the book will describe management and policies that have contributed to wildfire problems, including climate change and land-use practices incompatible with nature’s phoenix and what must happen to get to coexistence with wildfires that are not going away no matter how much we try to suppress or alter fire behavior. This second edition of Mixed Severity Fires: Nature’s Phoenix provides a comprehensive reference for documenting and synthesizing fire's ecological role. Comprehensive and complete reference on wildfire ecology that includes the latest science and citations Debunks debates on wildfire management that can be used by conservation groups and decision-makers to shift egregious wildfire policies Contains a broad synthesis of the ecology of mixed- and high-severity fires, covering such topics as vegetation, birds, mammals, insects, aquatics, and management actions
Download or read book Ecological Effects of Forest Fires in the Interior of Alaska written by Harold John Lutz and published by . This book was released on 1956 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Satellite Remote Sensing of Active Wildfires in Alaska s Boreal Forest written by Christine F. Waigl and published by . This book was released on 2017 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research addresses improvements to the detection and characterization of active wildfires in Alaska with satellite-based sensors. The VIIRS I-band Fire Detection Algorithm for High Latitudes (VIFDAHL) was developed and evaluated against existing active fire products from the Visible Infrared Imaging Radiometer Suite (VIIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS). This new algorithm is based on VIIRS 375 m spatial resolution imagery and was tuned using fires in Alaska's boreal forest. It provides improved fire detection of low-intensity fires, especially during daytime and at sensor zenith angles smaller than approximately 50° off nadir. Low-intensity active fires, which represent residual combustion present after the passage of a high-intensity fire front, are not very well detected by existing active fire products. A second topic was fire remote sensing with ~30 m resolution imaging spectrometer (or hyperspectral instrument), the Hyperion sensor on NASA's EO-1 spacecraft, which was in use from 2000 to 2016. Hyperion had a much higher spectral resolution than VIIRS or MODIS, but no repeat imagery of the same active fire was available in Alaska. The investigation relied on absorption and emission features in the radiance spectra acquired at every pixel location. Three fire detection methods were evaluated using archived Hyperion data from three fires in interior Alaska from 2004 and 2009: A version of the Hyperspectral Fire Detection Algorithm (HFDI) produced excellent active fire maps; an approach that relies on a shortwave infrared carbon dioxide absorption feature and associated Continuum Interpolated Band Ratio (CO2 CIBR) proved to be useful, but was affected by sensor noise and clouds; finally, a potassium emission feature from biomass burning was not detectable in the Hyperion data. Fire temperatures were determined using the Hyperion shortwave infrared spectra between 1400 nm and 2400 nm. The temperatures of active fire, the corresponding partial pixel areas, and the pixel areas occupied by unburned and already-burned vegetation, respectively, were modeled within each fire pixel. A model with two reflected background components and two temperature endmembers, applied to the same three study scenes, yielded an excellent fit to Hyperion spectral radiance data. Fire temperatures ranged from approximately 500-600 K to approximately 800-900 K. The retrieved lower fire temperatures are within the range of smoldering combustion; high-temperature values are limited by Hyperion's saturation behavior. High-temperature fire occupying 0.2% of a pixel (2 m2) was detectable. Sub-pixel fire area and temperature were also retrieved using VIIRS 750 m (M-band) data, with comparable results. Uncertainties were evaluated using a Monte Carlo simulation. This work offers insight into the sensitivity of fire detection products to time of day (largely due to overpass timing), spatial distribution over the study area (largely due to orbital properties) and sensor zenith angle. The results are relevant for sensor and algorithm design regarding the use of new multi- and hyperspectral sensors for fire science in the northern high latitudes. Data products resulting from this research were designed to be suitable for supporting fire management with an emphasis on real-time applications and also address less time-sensitive questions such as retrievals of fire temperature and time series of fire evolution.
Download or read book Permafrost Ecosystems written by Akira Osawa and published by Springer Science & Business Media. This book was released on 2010-01-04 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing from a decade-long collaboration between Japan and Russia, this important volume presents the first major synthesis of current knowledge on the ecophysiology of the coniferous forests growing on permafrost at high latitudes. It presents ecological data for a region long inaccessible to most scientists, and raises important questions about the global carbon balance as these systems are affected by the changing climate. Making up around 20% of the entire boreal forests of the northern hemisphere, these ‘permafrost forest ecosystems’ are subject to particular constraints in terms of temperature, nutrient availability, and root space, creating exceptional ecosystem characteristics not known elsewhere. This authoritative text explores their diversity, structure, dynamics and physiology. It provides a comparison of these forests in relation to boreal forests elsewhere, and concludes with an assessment of the potential responses of this unique biome to climate change. The book will be invaluable to advanced students and researchers interested in boreal vegetation, forest ecology, silviculture and forest soils, as well as to researchers into climate change and the global carbon balance.
Download or read book Predicting Wildfire Behavior in Black Spruce Forests in Alaska written by Rodney A. Norum and published by . This book was released on 1982 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Ecological Importance of Mixed Severity Fires written by Dominick A. DellaSala and published by Elsevier. This book was released on 2015-06-08 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Ecological Importance of High-Severity Fires, presents information on the current paradigm shift in the way people think about wildfire and ecosystems. While much of the current forest management in fire-adapted ecosystems, especially forests, is focused on fire prevention and suppression, little has been reported on the ecological role of fire, and nothing has been presented on the importance of high-severity fire with regards to the maintenance of native biodiversity and fire-dependent ecosystems and species. This text fills that void, providing a comprehensive reference for documenting and synthesizing fire's ecological role. Offers the first reference written on mixed- and high-severity fires and their relevance for biodiversity Contains a broad synthesis of the ecology of mixed- and high-severity fires covering such topics as vegetation, birds, mammals, insects, aquatics, and management actions Explores the conservation vs. public controversy issues around megafires in a rapidly warming world
Download or read book FS Series written by and published by . This book was released on 1966 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wildland Fire Forest Dynamics and Their Interactions written by Marc-André Parisien and published by MDPI. This book was released on 2018-08-15 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Wildland Fire, Forest Dynamics, and Their Interactions" that was published in Forests
