Simulating the Effects of Climate Change, Wildfire and Fuel Treatment on Sierra Nevada Forests PDF Download
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Author: Shuang Liang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Sierra Nevada forests represent a major ecological and economic resource for the state of California. Changes in climate and disturbance regimes, compounded with changes in forest structure from fire-exclusion, pose a critical challenge to managing Sierran forests for sustained carbon (C) sequestration and ecosystem services. My dissertation research sought to improve our understanding of how changing climate and disturbance will affect forest ecosystems in the Sierra Nevada by accounting for species-specific dynamics and interacting spatial processes that were underrepresented in landscape projections. Given the diverse tree species and forest types that differ in their optimal climate for growth and tolerance of stressors, I simulated forest dynamics in the Sierra Nevada under projected future climate and area burned as well as alternative management strategies with a species-specific, spatially explicit forest landscape model. First, I quantified how projected climate-wildfire interactions would affect forest communities and associated C dynamics. Here, results suggest that, across the Sierra Nevada, forest communities may not change as intact unit over the 21st Century and potential exists for substantial community change and C sequestration decline beyond this century. Then, I assessed the long-term successional trajectory and the ability of the system to sequester C beyond the 21st Century. Assuming climate and wildfire distributions equilibrate at late-century conditions, the results show a committed decline in forest cover and C carrying capacity, suggesting a steep reduction in the contribution of Sierra Nevada forest to the terrestrial C sink. Finally, I quantified how large-scale restoration treatments would alter the effects of changing climate and wildfire on forest C balance. I found that widespread application of fuel treatments would confer greater forest C stock stability. This work offers an improved understanding of how changing environmental conditions will affect the forest ecosystems in the Sierra Nevada and provides insights into using large-scale management strategy to manage the Sierran landscape under novel conditions.
Author: Shuang Liang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Sierra Nevada forests represent a major ecological and economic resource for the state of California. Changes in climate and disturbance regimes, compounded with changes in forest structure from fire-exclusion, pose a critical challenge to managing Sierran forests for sustained carbon (C) sequestration and ecosystem services. My dissertation research sought to improve our understanding of how changing climate and disturbance will affect forest ecosystems in the Sierra Nevada by accounting for species-specific dynamics and interacting spatial processes that were underrepresented in landscape projections. Given the diverse tree species and forest types that differ in their optimal climate for growth and tolerance of stressors, I simulated forest dynamics in the Sierra Nevada under projected future climate and area burned as well as alternative management strategies with a species-specific, spatially explicit forest landscape model. First, I quantified how projected climate-wildfire interactions would affect forest communities and associated C dynamics. Here, results suggest that, across the Sierra Nevada, forest communities may not change as intact unit over the 21st Century and potential exists for substantial community change and C sequestration decline beyond this century. Then, I assessed the long-term successional trajectory and the ability of the system to sequester C beyond the 21st Century. Assuming climate and wildfire distributions equilibrate at late-century conditions, the results show a committed decline in forest cover and C carrying capacity, suggesting a steep reduction in the contribution of Sierra Nevada forest to the terrestrial C sink. Finally, I quantified how large-scale restoration treatments would alter the effects of changing climate and wildfire on forest C balance. I found that widespread application of fuel treatments would confer greater forest C stock stability. This work offers an improved understanding of how changing environmental conditions will affect the forest ecosystems in the Sierra Nevada and provides insights into using large-scale management strategy to manage the Sierran landscape under novel conditions.
Author:
Publisher:
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Category :
Languages : en
Pages : 440
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The research presented in this dissertation aims to 1) assess the water balance of headwater catchments in the Sierra Nevada and determine if fuel treatments implemented in 2012 impacted runoff, 2) use a hydro-ecologic model to simulate the effects of fuel treatments and modeled wildfire at a larger fireshed scale, and 3) to investigate the interaction of vegetation disturbance and projected temperature increases through 2100 to determine relative impacts on hydrologic fluxes. The high variability in annual precipitation, combined with low post-treatment precipitation, masked any detectable changes in headwater catchment runoff from fuel treatments. Model results, however, do show the potential of increased runoff with treatments at both the headwater and fireshed scales, particularly in the high precipitation region of the American River Basin, where vegetation is less water-limited. While the potential for increasing runoff with fuel treatments exists, and may be a co-benefit of reduced fire risk, high-precision equipment for measuring stream discharge may be necessary to verifiable detect these increases. Although increasing temperatures adversely affect snowpack storage, changes in runoff and evapotranspiration are limited to the highest potential temperature increases towards the end of the century, and have less of an impact than vegetation disturbances.
Author: Andrzej Bytnerowicz
Publisher: Elsevier
ISBN: 0080560490
Category : Science
Languages : en
Pages : 687
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Book Description
The interaction between smoke and air pollution creates a public health challenge. Fuels treatments proposed for National Forests are intended to reduce fuel accumulations and wildfire frequency and severity, as well as to protect property located in the wild land-urban interface. However, prescribed fires produce gases and aerosols that have instantaneous and long-term effects on air quality. If fuels treatment are not conducted, however, then wild land fires become more severe and frequent causing worse public health and wellfare effects. A better understanding of air pollution and smoke interactions is needed in order to protect the public health and allow for socially and ecologically acceptable use of fire as a management tool. Wildland Fires and Air Pollution offers such an understanding and examines innovative wide-scale monitoring efforts (field and remotely sensed), and development of models predicting spatial and temporal distribution of air pollution and smoke resulting from forests fires and other sources. Collaborative effort of an international team of scientists High quality of invited chapters Full colour
Author: Frank A. Albini
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 100
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This paper presents a brief survey of the research literature on wildfire behavior and effects and assembles formulae and graphical computation aids based on selected theoretical and empirical models. The uses of mathematical fire behavior models are discussed, and the general capabilities and limitations of currently available models are outlined.
Author: Leda Nikola Kobziar
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 416
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"Throughout fire-adapted forests of the western US, and in the Sierra Nevada of California specifically, wildfire suppression has produced forest structures conducive to more severe, costly, and ecologically deleterious fires. Recent legislation has identified the necessity of management practices that manipulate forests towards less fire-hazardous structures. In the approximately 30 year old pine plantations of the Stanislaus National Forest, extensive fuels reduction procedures are being implemented. This dissertation addresses whether silvicultural and burning treatments are effective at reducing the intensity and severity of potential fire behavior, and how, along with wildfire, these treatments impact the evolution of carbon dioxide from the soil to the atmosphere. The first chapter addresses the relationships between soil respiration, tree injury, and forest floor characteristics in high and low severity wildfire burn sites in a salvage-logged mixed-conifer forest. The results indicate that fire severity influences soil CO2 efflux and should be considered in ecosystem carbon modeling. In the next chapter, fire models suggest that mechanical shredding of understory vegetation (mastication) is detrimental, and prescribed fire most effective in reducing potential fire behavior and severity in pine plantations. The third chapter documents the impact of alternative fuels treatments on soil carbon respiration patterns in the pine plantations, and shows that mastication produces short-term reductions in respiration rates and soil moisture. The final chapter further examines the relationships of fire-induced tree injuries, forest floor structure, and environmental factors to soil respiration response to fuels treatments. Each chapter is written as an independent manuscript; they collectively serve to expand the limited understanding of the effectiveness and ecological consequences of fire and fuels treatments in coniferous forests."--Abstract
Author: Heather Navle
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Wildfires in the mixed conifer forests of California's Sierra Nevada have been a common and natural disturbance for thousands of years, historically occurring every 3 to 30 years. The flora and fauna of the mixed conifer forest have evolved to depend on low to moderate severity wildfires for reproduction, foraging, and habitat. However, the Sierra Nevada has experienced dramatic environmental changes over the past ~150 years as a result of three main factors: wildfire suppression, climate change, and habitat loss. Because of the threat wildfires pose to human lives, property and timber harvest, they have been suppressed to an extent that has completely altered mixed conifer ecosystems. One of the changes to these ecosystems is increased vegetative fuel density, which can result in stand-replacing mega fires. To mitigate these high-severity mega wildfires, forest managers incorporate various fuel reduction methods into forest management plans. These impacts can have negative effects on forest ecosystems, degrading ecosystem characteristics that are critical for adapting to climate change. Thus, the two main objectives of this paper are to compare and contrast four different fuel reduction methods based on their effectiveness to (I) reduce wildfire risk and (II) promote climate change resiliency. The four fuel reduction methods are: low thinning, canopy thinning, selective thinning, and prescribed fire. These four fuel reduction methods have been compared in syntheses tables for the two main objectives. Qualitative and quantitative metric data, based on a literature review, were used to compare the optimal effects of each fuel reduction method. It was found that prescribed fire or thinning with prescribed fire resulted in the most optimal effects when considering both reduced wildfire risk and climate change resilience. However, tree mortality and the risk of fire escaping controlled boundaries are increased during prescribed fire operations. Additionally, results showed that all four fuel reduction methods displayed both positive and negative effects, depending on the metric used to evaluate the objective, which suggests that appropriate application of fuel reduction methods is highly variable depending on the goals and the environment. For example, canopy thinning alone may have desirable effects when prescribed fire is financially unfeasible or unsafe due to proximity to buildings. Applying prescribed fire is the most optimal fuel reduction method in most forest conditions; however, it is recommended that forest managers evaluate forest structure, density, and tree species prior to selecting the most appropriate fuel reduction method for their situation.
Author: Andrew James Amacher
Publisher:
ISBN:
Category : Animals
Languages : en
Pages : 158
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Author: Jens Turner Stevens
Publisher:
ISBN: 9781321213010
Category :
Languages : en
Pages :
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Montane coniferous forests in western North America are experiencing rapid environmental change, due in part to increasing fire severity and decreasing winter snowpack. Many of these forests experienced frequent low-severity fires prior to intensive logging and fire suppression during the nineteenth and twentieth centuries, which have led to increased fuel loads and increased dominance by fire-sensitive, shade-tolerant tree species. Forest managers seeking to mitigate increases in fire size and severity are increasingly implementing fuel-reduction treatments, which target small trees and surface fuels for removal. However, the ecological effects of these treatments on subsequent wildfire behavior, forest resilience, understory plant community dynamics, and plant invasions have not been well documented. In Chapter 1, I utilized a large-scale natural experiment to investigate the effects of recent fuel treatments on subsequent wildfire severity and structural resilience, in twelve different yellow pine and mixed-conifer forest sites in the mountains of eastern California. By quantifying forest structure in treated and adjacent untreated stands, both after wildfire and without wildfire, I demonstrated that treatments reduced the amount of structural change caused by wildfire, as a result of their moderating effect on fire severity. Two years post-wildfire, treated stands resembled pre-wildfire stands, in that they had greater tree litter cover, more tree seedling regeneration, less shrub cover and recruitment, and less bare soil relative to untreated stands, which generally burned at very high severity. In Chapter 2, I used the same network of twelve sites to test whether the gradient of disturbance severity, from untreated and unburned stands to high-severity wildfire stands, generated predictable patterns of understory plant community composition and diversity. I incorporated information on the evolutionary history of the native flora to show that increasing disturbance severity favored understory species with southern biogeographic affinity. Analysis of leaf functional traits indicated that increases in microclimatic water deficit in high-severity stands favored species with reduced specific leaf area relative to their leaf Nitrogen concentration. Native plant diversity at the stand scale was greatest in treated stands that subsequently burned in a wildfire, however this diversity peak was due to increased plot-scale alpha diversity relative to undisturbed stands, and increased between-plot beta diversity relative to high-severity wildfire stands. Conversely, exotic plant diversity peaked in high-severity wildfire stands that had not been previously treated. In Chapter 3, I investigated the population-level response of non-native species to interactions between forest harvesting strategies, prescribed fire, and winter snowpack depth using a transplant experiment with two non-native shrubs: Scotch broom (Cytisus scoparius L. (Link)) and Spanish broom (Spartium junceum L.). Both species had the strongest positive population growth responses to canopy thinning, rather than clearcuts or dense canopies. Despite positive effects of prescribed fire on seed germination, frequent prescribed fire was shown to decrease population growth rates for both species. However, experimental snowpack reductions led to increased winter survival by both species, which translated into strong positive effects on population growth rates. Under a future climate scenario where winter snowpack levels increase in elevation, middle-elevation forests that experience fuel treatments may therefore be at increased risk of invasion by non-native plants due to synergies between climate and management regimes.
Author:
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 52
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Author: Carol Miller
Publisher:
ISBN:
Category : Forest ecology
Languages : en
Pages : 264
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