Long-term Effectiveness of Fuel Treatments in Oak and Chaparral Stands of Northern California PDF Download

Author: Caroline Martorano
Publisher:
ISBN:
Category : Forest thinning
Languages : en
Pages : 40

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Book Description
Fuel reduction treatments are broadly implemented to reduce the risk of extreme wildfire. Yet, research on the long-term effectiveness and ecological consequences among these treatments is lacking. In this study, I examined short- and long-term changes in fuels and understory vegetation after treatment in chaparral and oak-dominated stands of Whiskeytown National Recreation Area. Treatments included mastication and spring burning, spring burning only, mastication only, and hand-thinning. Treatments were applied randomly to 1 to 2 units within each of 10 blocks. Two plots were established in each treatment unit and fuel and vegetation data was collected and analyzed at the block level (n=10). Results showed all treatments, except spring burn only, reduced live shrub height compared to the control. The combined mastication and spring burn treatment had up to 2.3 times higher live shrub density than the other treatments. Mechanical or manual only treatments promoted reductions in fine dead woody surface fuel loading compared to the control 15 years after treatment. There were subtle changes in the understory plant community, including an increase in species richness in the mastication and spring burn treatment and a decrease in species richness over time. The effects of fuel treatments on fuels and understory vegetation were highly varied with some level of trade-off in effectiveness. Optimal fuel treatments will likely depend on the specific site objectives. However, results from this study indicate that mastication and hand removal treatments can provide substantial decreases in live and dead fuel loading over the long- term without substantial changes to the understory plant community.

Author: Abigail M. Jones
Publisher:
ISBN:
Category : Chaparral
Languages : en
Pages : 80

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The issue of wildfires, hazard fuels management, and post-fire tree mortality has become an increasingly common topic in the western United States. This thesis is composed of two studies, with the first study, Chapter 1, examining fuel treatment effectiveness and the second study, Chapter 2, striving to characterize post-fire mortality in oaks. Prior to wildfire, fuel reduction projects may take place to decrease the likelihood of high severity fire around human infrastructure and communities. Within California’s chaparral ecosystems, common treatment types include hand-thinning, prescribed burning, mechanical mastication, and mechanical mastication followed with prescribed burning. Because chaparral has a longer historical fire return interval and these ecosystems do not need frequent fire disturbance, the efficacy of these treatment types is debated. Our study had the rare opportunity to collect data on fine woody fuel loading, shrub density, and vegetation both immediately before and one year following wildfire in northern California’s Whiskeytown National Recreation Area. Using these comparisons, our goal was to determine the post-fire response of each treatment type and determine an effective fuels treatment in chaparral to mitigate fire behavior, while maintaining ecosystem integrity and supporting native species habitat. The severity of the wildfire was moderate across the study site and did not differ among treatments. Post-fire live shrub density and live shrub height also were not influenced by treatment type, but oak dominated sites had greater live shrub density after wildfire. Fine woody fuel loading levels differed by treatment type, with prescribed burned units having the greatest levels in both chaparral and oak sites. Fine woody fuel consumption was lowest in hand-thinned units. Total plant species richness increased in all treatment types following wildfire, largely driven by an increase in exotic species, as native plant cover decreased and exotic species cover increased across all treatments. This study suggests that areas of chaparral may need to be retreated sooner than this timeframe to reduce fire severity. However, retreating these systems may not be economically feasible and it remains unclear if treatments will meet fuel and fire behavior objectives. Land managers are concerned about post-fire mortality of trees and rely on statistical models of tree mortality in post-fire decision making. While many studies have evaluated the accuracy of these models in conifers, the performance of these models on hardwood species, specifically oak species, has been understudied. Models, such as FOFEM and FVS-FFE, can help land managers to predict which trees will die following fire and can help in hazard tree removal and post-fire salvage logging operations. These models, however, have been exclusively developed using western United States conifer species, bringing into question the veracity of these models for hardwood species. The purpose of this study was to test current mortality models using observations from wildfire and prescribed burn sites in northern California for two oak species, California black oak (Quercus kelloggii) and canyon live oak (Quercus chrysolepis). Our findings suggest that both modeling approaches performed well, but Random Forest was better at predicting probability of mortality for an imbalanced dataset. When using imbalanced datasets, logistic regression can underpredict mortality, which can have negative repercussions for land managers dealing with recently burned ecosystems containing oaks.

Author: Lindsay Aney Chiono
Publisher:
ISBN:
Category :
Languages : en
Pages : 162

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Historic fire regimes in the dry conifer forests of the southern Cascade and northern Sierra Nevada regions of California were characterized by relatively frequent fires of low and mixed severity. Human management practices since the mid-19th century have altered the disturbance role of fire in these dry yellow pine and mixed conifer forest ecosystems. Fire suppression, high-grade timber harvesting, and livestock grazing have reduced the frequency of burning and caused a shift in the structure and species composition of forest vegetation. These changes, including high levels of accumulated fuel and increased structural homogeneity and dominance of shade-tolerant tree species, combined with a warming climate, have rendered many stands susceptible to high-severity fire. In many forests of the western United States, wildfires are increasingly difficult and costly to control, and human communities are regularly threatened during the fire season. Treating wildland fuels to reduce wildfire hazards has become a primary focus of contemporary forest management, particularly in the wildland-urban interface. The specific objectives of treatment are diverse, but in general, treatments address accumulated surface fuels, the fuel ladders that carry fire into the forest canopy, and surface and canopy fuel continuity. These modifications to forest fuels can alleviate the severity of a future wildfire and support suppression activities through improved access and reduced fire intensity. While fuel reduction treatments are increasingly common in western forests, the long-term structural and ecological effects of treatment remain poorly understood. This dissertation uses a chronosequence of treated stands to examine the temporal influence of treatment on forest structure, the understory plant community, and wildfire hazard. The first chapter examines the effects of fuels reduction treatment on stand structure, overstory species composition, and ground and surface fuels. The stand structures and reduced surface fuel loads created by fuels modification are temporary, yet few studies have assessed the lifespan of treatment effects. The structural legacies of treatment were still present in the oldest treatment sites. Treatments reduced site occupancy (stand density and basal area) and increased quadratic mean diameter by approximately 50%. The contribution of shade-tolerant true firs to stand density was also reduced by treatment. Other stand characteristics, particularly timelag fuel loads, seedling density, and shrub cover, exhibited substantial variability, and differences between treatment age classes and between treatment and control groups were not statistically significant. The second chapter evaluates fuel treatment longevity based on potential wildfire behavior and effects on vegetation. Forest managers must divide scarce resources between fuel treatment maintenance, which is necessary to retain low hazard conditions in treated stands, and the construction of new treatments. Yet the most basic questions concerning the lifespan of treatment effectiveness have rarely been engaged in the literature. In this study, field-gathered fuels and vegetation data were used to aid fuel model selection and to parameterize a fire behavior and effects model, Fuels Management Analyst Plus. In addition, a semi-qualitative, semi-quantitative protocol was applied to assess ladder fuel hazard in field sampling plots. Untreated sites exhibited fire behavior that would challenge wildfire suppression efforts, and projected overstory mortality was considerable. In contrast, estimated fire behavior and severity were low to moderate in even the oldest fuel treatments, those sampled 8-26 years after treatment implementation. Findings indicate that in the forest types characteristic of the northern Sierra Nevada and southern Cascades, treatments for wildfire hazard reduction retain their effectiveness for more than 10-15 years and possibly beyond a quarter century. Fuel treatment activities disturb the forest floor, increase resource availability, and may introduce non-native plant propagules to forest stands. Non-native plant invasions can have profound consequences for ecosystem structure and function. For these reasons, there is concern that treatment for fire hazard reduction may promote invasion by exotic species. Several short-term studies have shown small increases in non-native abundance as a result of treatment, but the long-term effects have rarely been addressed in the literature. The final chapter examines treatment effects on the understory plant community and on cover of the forest floor, as mineral soil exposure has been linked to invasion. Regression tree analysis provided insights into the influence of treatment and site characteristics on these variables. Treatments increased forb and graminoid cover, but temporal trends in abundance were opposite. An initial increase in forb cover in the most recently treated sites was followed by a gradual decline, while mean graminoid cover was highest in the oldest treatments. Shrubs dominated live plant abundance. Shrub cover showed few temporal trends, but was negatively associated with canopy cover. Mineral soil exposure was increased by treatment and declined slowly over time, remaining elevated in the oldest treatments. Non-native plant species were very rare in the treatment sites sampled in this study. Despite the availability of bare mineral soil and the proximity of transportation corridors, a source of non-native propagules, non-natives were recorded in only 2% of sampling plots. This study suggests that forest disturbance associated with treatment for hazardous fuels reduction may not produce significant invasions in these forest types.

Author: Morris C. Johnson
Publisher: DIANE Publishing
ISBN: 1428987665
Category : Technology & Engineering
Languages : en
Pages : 310

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Book Description
Analyzes a range of fuel treatments for representative dry forest stands in the Western U.S. dominated by ponderosa pine, Douglas-fir, & pinyon pine. Six silvicultural options (no thinning; thinning from below to 50 trees per acre [tpa], 100 tpa, 200 tpa, & 300 tpa; & prescribed fire) are considered in combination with the surface fuel treatments (no treatment, pile & burn, & prescribed fire), resulting in a range of alternative treatments for each representative stand. Fuel treatment scenarios presented here can be used by resource managers to examine alternatives for Nat. Environ. Policy Act documents & other applications that require scientifically based info. to quantify the effects of modifying forest structure & surface fuels. Illustrations.

Author: Nicole Marie Vaillant
Publisher:
ISBN:
Category :
Languages : en
Pages : 100

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Author: Andrew T. Hudak
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 72

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Book Description
This report provides managers with the current state of knowledge regarding the effectiveness of fuel treatments for mitigating severe wildfire effects. A literature review examines the effectiveness of fuel treatments that had been previously applied and were subsequently burned through by wildfire in forests and rangelands. A case study focuses on WUI fuel treatments that were burned in the 2007 East Zone and Cascade megafires in central Idaho. Both the literature review and case study results support a manager consensus that forest thinning followed by some form of slash removal is most effective for reducing subsequent wildfire severity.

Author: Harold Mooney
Publisher: Univ of California Press
ISBN: 0520278801
Category : Nature
Languages : en
Pages : 1008

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Book Description
This long-anticipated reference and sourcebook for CaliforniaÕs remarkable ecological abundance provides an integrated assessment of each major ecosystem typeÑits distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of CaliforniaÕs ecological patterns and the history of the stateÕs various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the stateÕs ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of CaliforniaÕs environment and curious naturalists.

Author:
Publisher:
ISBN:
Category : Animal ecology
Languages : en
Pages : 92

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Author: Frank A. Albini
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 100

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Book Description
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: Jain
Publisher: CreateSpace
ISBN: 9781507655207
Category :
Languages : en
Pages : 342

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Book Description
This guide describes the benefits, opportunities, and trade-offs concerning fuel treatments in the dry mixed conifer forests of northern California and the Klamath Mountains, Pacific Northwest Interior, northern and central Rocky Mountains, and Utah. Multiple interacting disturbances and diverse physical settings have created a forest mosaic with historically low- to mixed-severity fire regimes. Analysis of forest inventory data found nearly 80 percent of these forests rate hazardous by at least one measure and 20 to 30 percent rate hazardous by multiple measures. Modeled mechanical treatments designed to mimic what is typically implemented, such as thinning, are effective on less than 20 percent of the forest in single entry, but can be self-funding more often than not. We provide: (1) exhaustive summaries and links to supporting guides and literature on the mechanics of fuel treatments, including mechanical manipulation, prescribed fire, targeted grazing and chemical use; (2) a decision tree to help managers select the best mechanical method for any situation in these regions; (3) discussion on how to apply prescribed fire to achieve diverse and specific objectives; (4) key principles for developing an effective monitoring plan; (5) economic analysis of mechanical fuel treatments in each region; and (6) discussion on fuel treatment longevity. In the electronic version of the document, we have provided links to electronic copies of cited literature available in TreeSearch online document library (http: //www.treesearch.fs.fed.us/