Forest Management, Wildfire, and Climate Impacts on the Hydrology of Sierra Nevada Mixed-conifer Watersheds PDF Download
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 440
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Book Description
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:
Publisher:
ISBN:
Category :
Languages : en
Pages : 440
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Book Description
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: Henry W. Anderson
Publisher:
ISBN:
Category : Forest hydrology
Languages : en
Pages : 124
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Book Description
Author: Heather Navle
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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: Jens Turner Stevens
Publisher:
ISBN: 9781321213010
Category :
Languages : en
Pages :
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Book Description
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 ecology
Languages : en
Pages : 684
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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309134374
Category : Science
Languages : en
Pages : 180
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Book Description
Of all the outputs of forests, water may be the most important. Streamflow from forests provides two-thirds of the nation's clean water supply. Removing forest cover accelerates the rate that precipitation becomes streamflow; therefore, in some areas, cutting trees causes a temporary increase in the volume of water flowing downstream. This effect has spurred political pressure to cut trees to increase water supply, especially in western states where population is rising. However, cutting trees for water gains is not sustainable: increases in flow rate and volume are typically short-lived, and the practice can ultimately degrade water quality and increase vulnerability to flooding. Forest hydrology, the study of how water flows through forests, can help illuminate the connections between forests and water, but it must advance if it is to deal with today's complexities, including climate change, wildfires, and changing patterns of development and ownership. This book identifies actions that scientists, forest and water managers, and citizens can take to help sustain water resources from forests.
Author: Great Britain. Forestry Commission
Publisher:
ISBN:
Category : Acid rain
Languages : en
Pages : 40
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Book Description
This work advises owners and managers how woodlands and forests influence the freshwater ecosystem, and gives guidance on how operations should be carried out in order to protect and enhance the water environment. The guidelines apply equally to forest enterprises and the private sector.
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: Malcolm North
Publisher: Createspace Independent Publishing Platform
ISBN: 9781482034882
Category : Nature
Languages : en
Pages : 196
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Book Description
There has been widespread interest in applying new forest practices based on concepts presented in U.S. Forest Service General Technical Report PSW-GTR-220, "An Ecosystem Management Strategy for Sierran Mixed-Conifer Forests." This collection of papers (PSW-GTR-237) summarizes the state of the science in some topics relevant to this forest management approach, presents case studies of collaborative planning efforts and field implementation of these new practices, and clarifies some of the concepts presented in GTR 220. It also describes a method for assessing forest heterogeneity at the stand level using the Forest Vegetation Simulator and a new geographic information system tool for project-level planning that classifies a landscape into different topographic categories. While this collection of papers presents information and applications relevant to implementation, it does not offer standards and prescriptions. Forest management should be flexible to adapt to local forest conditions and stakeholder interests. This report does, however, strive to clarify concepts and present examples that may improve communication with stakeholders and help build common ground for collaborative forest management.
Author: Commission on California State Government Organization and Economy
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 88
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Book Description
"In this report, the Commission calls for transformational culture change in its forest management practices. The U.S. Department of Agriculture (USDA) reported in December 2017 that approximately 27 million trees had died statewide on federal, state and private lands since November 2016. The tally brought to 129 million the number of trees that have died in California forests during years of drought and bark beetle infestations since 2010. During its review, the Commission found that California’s forests suffer from neglect and mismanagement, resulting in overcrowding that leaves them susceptible to disease, insects and wildfire. The Commission found commitment to long-lasting forest management changes at the highest levels of government, but that support for those changes needs to spread down not just through the state’s massive bureaucracy and law- and policymaking apparatuses, but among the general public as well. Complicating the management problem is the fact that the State of California owns very few of the forests within its borders – most are owned by the federal government or private landowners. Among the Commission’s nine recommendations, it urges the state to take a greater leadership role in collaborative forest management planning at the watershed level. The Good Neighbor Authority granted in the 2014 Farm Bill provides a mechanism for the state to conduct restoration activities on federal land, but state agencies must have the financial and personnel resources to perform this work. As part of this collaborative effort, it calls upon the state to use more prescribed fire to reinvigorate forests, inhibit firestorms and help protect air and water quality. Central to these efforts must be a statewide public education campaign to help Californians understand why healthy forests matter to them, and elicit buy-in for the much-needed forest treatments."--
