Wildfire Effects on the Ecohydrology of a Sierra Nevada Watershed PDF Download
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Author: Gabrielle Boisrame Boisrame
Publisher:
ISBN:
Category : Ecohydrology
Languages : en
Pages : 160
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Book Description
The mountain watersheds of the Sierra Nevada supply the majority of California's water, but this supply has always been highly variable. The 2012-2016 drought in California has demonstrated that this water supply is also highly vulnerable to increasing temperatures and/or reduced precipitation. Not only did the 2012-2016 drought reduce water supply for human use, but it also led to unprecedented forest mortality and fire damage. Unfortunately, the fire suppression strategy that was nearly uniformly applied to mountain forests during the 20th century may have exacerbated the effects of drought by increasing vegetation density and thus increasing evapotranspiration and precipitation interception. Could restoring fire regimes to their pre-European settlement condition increase water yield from these forested catchments? Such a policy would also have the potential to restore the ecological function of landscapes and reduce the risk of catastrophic fires (such as the 2013 Rim Fire) by reducing fuel loads. This dissertation studies the hydrological and landscape-level ecological effects of restoring a frequent, mixed severity fire regime to the Illilouette Creek Basin in Yosemite National Park. A combination of field measurements, historical data analysis, remote sensing, and modeling approaches are employed to strengthen the argument by providing multiple lines of evidence. There is limited data available for Illilouette Creek Basin during much of the four decades in which the new fire regime became established, inhibiting direct evaluation of the fire regime's effects. Nevertheless, a variety of different metrics and analyses indicate a number of important changes that can be attributed to the restored fire regime: increased landscape diversity (including reduced forest cover), increased soil moisture and streamflow (both according to measurements and hydrological modeling), and decreased drought stress (both according to observations and from hydrological modeling).
Author: Gabrielle Boisrame Boisrame
Publisher:
ISBN:
Category : Ecohydrology
Languages : en
Pages : 160
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Book Description
The mountain watersheds of the Sierra Nevada supply the majority of California's water, but this supply has always been highly variable. The 2012-2016 drought in California has demonstrated that this water supply is also highly vulnerable to increasing temperatures and/or reduced precipitation. Not only did the 2012-2016 drought reduce water supply for human use, but it also led to unprecedented forest mortality and fire damage. Unfortunately, the fire suppression strategy that was nearly uniformly applied to mountain forests during the 20th century may have exacerbated the effects of drought by increasing vegetation density and thus increasing evapotranspiration and precipitation interception. Could restoring fire regimes to their pre-European settlement condition increase water yield from these forested catchments? Such a policy would also have the potential to restore the ecological function of landscapes and reduce the risk of catastrophic fires (such as the 2013 Rim Fire) by reducing fuel loads. This dissertation studies the hydrological and landscape-level ecological effects of restoring a frequent, mixed severity fire regime to the Illilouette Creek Basin in Yosemite National Park. A combination of field measurements, historical data analysis, remote sensing, and modeling approaches are employed to strengthen the argument by providing multiple lines of evidence. There is limited data available for Illilouette Creek Basin during much of the four decades in which the new fire regime became established, inhibiting direct evaluation of the fire regime's effects. Nevertheless, a variety of different metrics and analyses indicate a number of important changes that can be attributed to the restored fire regime: increased landscape diversity (including reduced forest cover), increased soil moisture and streamflow (both according to measurements and hydrological modeling), and decreased drought stress (both according to observations and from hydrological modeling).
Author:
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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: Robert Arnold Merriam
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 118
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Author:
Publisher:
ISBN:
Category : Fire ecology
Languages : en
Pages : 262
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Author: Shuang Liang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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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:
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ISBN:
Category : Sierra Nevada (Calif. and Nev.)
Languages : en
Pages : 28
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Author: Sierra Nevada Ecosystem Project
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 344
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Author: Jack E. Veenhuis
Publisher:
ISBN:
Category : Bandelier National Monument (N.M.)
Languages : en
Pages : 50
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Author: Zamir Libohova
Publisher:
ISBN:
Category : Forest thinning
Languages : en
Pages : 280
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Author: Sangki Lee
Publisher:
ISBN:
Category : Water-supply
Languages : en
Pages : 232
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Available studies on the effects of wildfire on water yield were conducted in small size watersheds (10km2) and little is known on the scalability of those findings to large watersheds. However, the frequency and occurrence of wildfires that burn large watersheds (100km2) have been increasing in the last decades, resulting on the need to predict their impacts on watershed hydrology. The impact of wildfire on watershed annual water yield is constrained by a complex interaction among several processes, which include hydrologic, geologic, ecologic, climatic alterations. This study investigates short- and long-term responses of annual water yield changes due to wildfire in large watersheds within a paired watershed framework. We, also, propose a new theoretical approach based on the Budyko framework to predict the change in annual water yield due to wildfires, which was originally proposed to explore alterations of water and energy balance within burned watersheds. Long-term responses of annual water yield were predicted by analyzing residuals between annual water yields measured in the field and estimated with paired watershed regression models. Paired watershed analyses were applied to 34 pairs between 11 burned watersheds and 8 unburned watersheds in the Salmon River and Payette River basin (Central Idaho USA), Yellowstone National Park (Wyoming, USA), and Klamath River basin (California, USA). The Budyko framework was conducted in 8 burned watersheds for 10 wildfires, were statistically significant from paired watershed analyses. The Budyko framework was applied both at the yearly time scale (one point for each year) and as originally developed as time averaged (one point for pre and one for post-fire period). This study employed (1) a simple linear model with evaporative index (AET/P) and (2) Fu [1981]'s equation with relative evaporative index (1-Q/P). Results show that annual water yield generally increases after wildfires that burned more than 10% of drainage area with negligible and undetectable changes for smaller burned areas. Exceptions to this trend are for watersheds whose hydrological system is dominated by baseflows (with large ground water storage) and those whose wildfire mainly burned short vegetation. Annual water yield tends to return toward pre-fire condition following the Kuczera's curve, which is related with changes in water demand following regrowth or resuccession of burned trees/vegetation. Post-fire annual water yield increased with burned area, and this correlation was more evident in Mediterranean than in arid climate regions. Post-fire change in annual water yield increases proportionally with drainage area in small watersheds, but this relationship is limited in large watersheds. Results of the Budyko framework show decrease in evapotranspiration rate in most burned watersheds. Reduction in evapotranspiration results in an increase of annual water yield. On the other hand, increase in evaporative index was detected in burned watershed where trees grew quickly during the post-fire period. Climatic conditions can affect the hydrological response during post-fire. Weather condition is an important factor for estimating the annual water yield responses against wildfire. Budyko framework shows that wildfire impact is mitigated under wet weather condition or enhanced under dry weather condition. Results of paired watershed analysis and Budyko framework show a good agreement that post-fire annual water yield responses are strongly correlated with changes in evapotranspiration rate associated with tree mortality or regrowth rate.
