Download or read book Fire induced Tree Mortality in the Mixed Conifer Forests of the Sierra Nevada California written by Phillip John Van Mantgem and published by . This book was released on 2001 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Thinning and Prescribed Burning on Tree Resistance to Extreme Drought in a Sierra Nevada Mixed conifer Forest California USA written by Chance C. Callahan and published by . This book was released on 2019 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drought-induced tree mortality can drastically alter forest composition, structure, carbon dynamics, and ecosystem function. Increasingly, forest policy and management focuses on how to improve forest resistance and resilience to drought stress. This study used tree ring data at Teakettle Experimental Forest (TEF), a historically frequent fire mixed-conifer forest in the California Sierra Nevada, to quantify how prescribed fire and mechanical thinning conducted in 2001-2002 influenced stand and tree-level growth responses to the extreme California drought of 2012-2016. Overstory thinning and understory thinning significantly enhanced growth responses to treatments alone and treatments during the drought at the stand-level. In each year of the drought, distinct tree species were the only significant predictors of drought resistance at the stand-level. As drought persisted, shade-intolerant pine species yielded greater drought resistance values than shade-tolerant white fir and incense cedar. No prescribed burn effects were found, likely due low fire intensity. At the tree-level, tree diameter (DBH), tree height (HT), crown ratio (CRNR), topographic position index (TPI), and change in growing space over time (competition) were the most important predictors of growth responses to treatments and drought resistance. Mechanical thinning, in both understory and overstory thinning can enhance mixed-conifer forests ability to resist drought by reducing competition and increasing resource availability. This study suggests forest managers have flexibility in prescribing various thinning intensities to promote drought resistance. Prescribed burn effects were not found in this study, but further research is needed to understand long-term burn effects for promoting drought resistance in Sierra Nevada mixed-conifer forests.

Download or read book Early Seral Mixed conifer Forest Structure and Composition Following a Wildfire Reburn in the Sierra Nevada written by Erin Alvey and published by . This book was released on 2016 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Before the era of modern fire suppression, California's northern Sierra Nevada mixed-conifer and yellow pine forests were self-regulating; recurring short-interval, low-mixed severity wildfires maintained forest structure and composition, which in turn exerted bottom-up controls on subsequent wildfires. As a result of fire suppression, and coupled with the effects of climate warming and other anthropogenic disturbances, the fundamental structure of mixed-conifer and yellow pine forests has shifted. Wildfires may now be increasing in size, severity, and frequency across western North America. However, little is known about the post-fire impacts of repeat wildfire on a forest after a long era of suppression. In this study, I report findings regarding early successional vegetation of Sierra Nevada mixed conifer forests that experienced two large wildfires, the Storrie Fire (in 2000) and the Chips Fire (in 2012). These wildfires burned within the historic fire frequency window for this ecosystem, but much of the forest within their fire footprints had not burned for at least 100 years beforehand. I addressed three questions: (1) how does wildfire affect plant community structure and composition among yellow pine and mixed-conifer forests?; (2) do fire severity and fire frequency interact to influence post-fire vegetation conditions?; and (3) are post-fire responses similar between forests that have burned once, twice, or have not burned in the past century, or that have burned at high, moderate, or low severity? In 2014, I sampled 74 plots in the Plumas and Lassen National Forests. Of these plots, 50 plots were sampled from three fire severity classes and two fire frequencies in and around the Chips Fire (2012). A portion of the Chips Fire had reburned the Storrie Fire (2000), affording the opportunity to compare them to post-fire effects of a single burn on fire-suppressed forests at the same stage of post-fire succession. I also collected data in 24 unburned plots to contrast fire-suppressed plots with plots that experienced wildfire. Wildfire decreased tree density but also decreased available seed sources, which can limit tree regeneration in high severity fire or reburns. Increased tree mortality also produced greater fuel loading in reburns compared to single burns, though burned plots exhibited less fuel loading and fuel connectivity than unburned plots. I also observed that wildfire diversified species composition in single burns, increasing species richness, evenness, and diversity. However, reburning plots appeared to reduce species richness, causing reburns to exhibit richness similar to unburned plots. Still, reburn plots only shared about half of its species with unburned plots, and 13% of species were exclusive to reburns. My study was limited to a particular time (two years post-fire), and post-fire effects may become more pronounced as early seral communities continue to respond to the effects of the wildfire. Nonetheless, my results indicate that wildfire can produce forest structure and composition that is dramatically different from fire-suppressed mixed-conifer forests. Though it is unknown whether ecological processes can be restored by just one or two wildfire events within a short time-span in fire-suppressed landscapes, the post-fire conditions observed in my study have begun to resemble pre-suppression conditions by exhibiting reduced tree densities, lower fuel loads, and enhanced species diversity, especially at low to moderate fire severities. Because post-fire vegetation response is a stochastic and long-term process, understanding the effects of wildfire reintroduction and reburn will likely take multiple observations.

Download or read book Fire on the Mountain written by Commission on California State Government Organization and Economy and published by . This book was released on 2018 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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."--

Download or read book Fire in Sierra Nevada Forests written by George E. Gruell and published by . This book was released on 2001 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Fire in Sierra Nevada Forests, George Gruell examines the woodlands through repeat photography: rephotographing sites depicted in historical photographs to compare past vegetation to present. The book asks readers to study the evidence, then take an active part in current debates over prescribed fire, fuel buildup, logging, and the management of our national forests.

Download or read book The Effects of Fire and Fuels Reduction Treatments on Fire Hazard and Soil Carbon Respiration in a Sierra Nevada Pine Plantation written by Leda Nikola Kobziar and published by . This book was released on 2006 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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

Download or read book Synthesis of Research Into the Long term Outlook for Sierra Nevada Forests Following the Current Bark Beetle Epidemic written by and published by . This book was released on 2019 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper summarizes the 2012-2017 bark beetle epidemic in the Sierra Nevada and its implications for long-term changes in tree species composition and forest structure. Preliminary plot and landscape-scale data are reviewed, showing higher levels of mortality for pine species and greater impacts in the southern Sierra Nevada compared to the northern portions of the range. The federal government owns approximately three quarters of the forested area impacted by high levels of tree morality, with the remainder of the land controlled by nonindustrial (18%) and industrial (6%) ownerships. The accumulation of dead and downed fuel and standing dead trees is expected to increase fire intensity and severity, and pose significant hazards for fire control efforts. Potential long-term changes in Sierra Nevada forest composition were explored with a GIS analysis conducted for the Sierra National Forest, located in the southern Sierra. GIS layers included very high fire threat, aspect, high tree mortality, topographic position classification, and climatic exposure. A factor of one was assigned to each parameter (i.e., no weighting for any of the variables). The modeling showed that 4% of the Sierra National Forest is at very high risk for type conversion from mixed conifer to shrublands, and 12% is at high risk. This information can inform landowners regarding the general locations where successful reforestation will be most challenging, as well as illustrate the scale of concern for one national forest in the southern Sierra Nevada. Changes to disturbance regimes, continuing land use changes, and climate change with associated species shifts pose significant challenges for maintaining healthy and resilient forests in the Sierra Nevada. Significant unknowns exist regarding the future species composition for vast portions of this region, but type conversions from mixed conifer to shrublands or oak/grass/woodland appear likely for some areas. Recommended best management practices focus on reducing tree densities, achieving successful reforestation, and using adaptive management in the face of currently unknown future changes in growing conditions. With the exception of the bark beetle epidemic in southern California in the early 2000s, lessons learned from other locations in western North America that have had sustained bark beetle epidemics in the past decade are not directly applicable to Sierra Nevada, with its Mediterranean climate, complex topography, and mixed-conifer forests. For these reasons, ongoing research efforts to characterize and understand tree mortality drivers and changes in forest structure and composition in the Sierra Nevada are extremely important.

Download or read book Effectiveness of Prescribed Fire as a Fuel Treatment in Californian Coniferous Forests written by Nicole Marie Vaillant and published by . This book was released on 2005 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fire in California s Ecosystems written by Neil G. Sugihara and published by Univ of California Press. This book was released on 2006-11-29 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on California and issues specific to fire ecology and management in the state's bioregions, this work provides scientific information for use in land restoration and other management decisions made in the field. It introduces the basics of fire ecology, and includes an overview of fire, vegetation and climate in California; and more.

Download or read book Topics in Forest Pathology and Ecology in the Sierra Nevada and the Sierra San Pedro Martir Baja written by Patricia Ellen Maloney and published by . This book was released on 2000 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Logging and fire exclusion policies in the Lake Tahoe Basin have increased tree densities over the past 150 years. Current tree densities range up to 450 trees/ha. Cumulative tree mortality in logged (mean = 25%) and unlogged (mean = 21%) stand types were significantly and positively correlated with tree density. The synergistic effect of bark beetles, pathogens, and stand density linked with drought events largely explain mortality in these forests. Unlogged, mixed-conifer forests with the historical fire regime still intact were studied in the Sierra San Pedro Martir, Baja, Mexico. Average tree density was low at 160 trees/ha. Cumulative mortality was 12.7%, with the greatest amount of mortality occurring to larger trees. Most tree mortality (78%) was due to pathogens and bark beetles. Mistletoe and a bark beetle species were widespread on Abies concolor. Mistletoe severity was negatively correlated to A. concolor regeneration. White pine blister rust (WPBR) is a heteroecious rust fungus that alternates between 5-needle pines, and Ribes to complete its life-cycle. In mixed-conifer forests, WPBR prevalence on Pinus lambertiana was correlated with the nearness of Ribes and influenced by environmental conditions favorable for rust infection. Disease was spatially aggregated with new infections occurring annually. In subalpine forests, disease was not correlated with the presence of Ribes. In this exposed location, disease may be episodic rather than chronic. When conditions are favorable, wind allows for widespread dispersal of spores. Demographic effects of this disease on its pine hosts include juvenile mortality and reduced cone production. In two locations in the Sierra Nevada, we found the prevalence and severity of dwarf mistletoe (DWM) on A. concolor was not or weakly correlated to host density, but severity was positively correlated to host size. On Pinus jeffreyi, DWM prevalence and severity were positively correlated with host density. Individuals of all sizes were susceptible to DWM, with less than expected becoming infected in the seedling-10 cm diameter class. Both aggregated and random spatial patterns were found for DWM, suggesting that the degree of infection and logging history are important in the spatial dynamics of DWM species."--Abstract

Download or read book Wildland Fire in Ecosystems written by and published by . This book was released on 1998 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Prescribed Fire on Sugar Pine Mortality in Sequoia and Kings Canyon National Parks written by Jonny CB. Nesmith and published by . This book was released on 2011 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fire is one of the main agents controlling composition, structure, and function of mixed conifer forests in the Sierra Nevada, CA. Over the past century, there has been a dramatic shift in the role of fire in these forests as fire regimes shifted from low intensity, frequent fires prior to European settlement in the region, to extended periods of fire exclusion due to a policy of active fire suppression. This led to many unintended consequences such as increased stand density, shifts in species composition towards more shade tolerant species such as white fir, and an increase in fire severity and extent when fires do occur due to increased fuels and changing climate. In the past several decades, prescribed fire has become one of the most important tools for forest restoration and management, yet its effects are still not fully understood. This uncertainty is especially true for sugar pine, a species that is being affected not only by changing forest conditions, but also by the introduced pathogen white pine blister rust. These multiple factors, and potential interactions among them, have led to population declines of sugar pine in some areas and have raised concerns about potential mortality during prescribed fire. The goal of this research was to better understand what processes were most important in controlling post-fire mortality of sugar pine, use this information to produce more accurate predictive models of post-fire mortality, and to evaluate simple management actions that could ameliorate the risk of mortality following fire. The first chapter serves as an introduction to the mixed conifer ecosystem and sugar pine in particular. It discusses the main factors that control mortality following prescribed fire and highlights some of the main findings of this research. In the second chapter, structural equation modeling (SEM) was used to assess the direct and indirect effects of multiple variables related to tree health, beetle activity, blister rust, and fire effects and their relative importance in controlling sugar pine mortality following prescribed fire in Sequoia and Kings Canyon National Parks. Multiple factors are known to influence mortality following fire including fuel loads, fire intensity, beetle activity, and tree size, yet little is known about how these factors interact to control post-fire mortality. A total of 436 sugar pine were measured within three separate prescribed fires in Sequoia and Kings Canyon National Parks. SEM was used to evaluate a network of causal relationships between factors that affect post-fire mortality of sugar pine and to assess both direct and indirect effects. Several factors were found to significantly influence post-fire mortality, with crown volume scorch, diameter at breast height (dbh), and post-fire beetle activity showing the strongest effects; though the magnitude of these effects differed among sites. Other factors such as blister rust infection and pre-fire beetle activity had little impact on post-fire mortality. A causal model was developed that considered both indirect and direct effects of multiple factors associated with post-fire mortality while demonstrating the variability in the relative strength of these causal relationships based on specific attributes. This model can be used in forest management to provide a clear understanding of how fire effects interrelate with multiple processes to control post fire sugar pine mortality. The third chapter examined whether the inclusion of pre-fire tree health (based on tree ring records) in models looking at post-fire sugar pine mortality improved model fit over models based on measures of fire effects alone. This study was conducted within an old-growth mixed-conifer forest in Sequoia National Park that had been prescribed burned during 2001 or 2002. Fire effects measured by percent crown volume scorched and stem char height, and pre-fire tree health measured by multiple indices of growth calculated from tree cores and measures of crown health were assessed for 105 sugar pine. Health status (live or dead) was observed prior to the fire, immediately post-fire and five years post-fire. Logistic regression models were used to evaluate the effects of fire and pre-fire tree health on post-fire mortality. Models based only on tree size and fire effects were compared to models that included fire effects and measures of pre-fire tree health using AICc. Five years following fire, the model that best predicted mortality included dbh, crown volume scorch, 30 year growth trend, and count of sharp declines over a 30 year period. The inclusion of long-term measures of growth markedly improved model fit compared to models based only on fire effects ([Delta]AICc = 26.4). However, immediately after fire, models that included measures of pre-fire tree health resulted in only marginal improvements over models based only on measures of fire effects ([Delta]AICc = 2.1). These results imply that multiple processes, in addition to fire, are functioning to influence delayed mortality and that the inclusion of measures of tree health can provide more accurate predictions of post-fire mortality. Finally, chapter four tests whether raking away duff and litter from the base of the stem can be used as an effective means of reducing sugar pine mortality following prescribed fire. This study was conducted in three prescribed fires in Sequoia and Kings Canyon National Parks and included 457 trees, half of which were raked to mineral soil to 0.5 m away from the stem. Fire effects were assessed and tree mortality was followed for three years after prescribed fires. Overall, raking had no detectable effect on mortality as raked trees averaged 30 % mortality compared to 36 % for unraked trees. There was a significant interaction, however, between raking and average pre-treatment forest floor fuel depth: The predicted probability of survival of a 50 cm dbh tree was 0.94 vs. 0.96 when average pre-treatment fuel depth was 0 cm for a raked and unraked tree, respectively. When average pre-treatment forest floor fuel depth was 30 cm, the predicted probability of survival for a raked 50 cm tree was 0.60 compared to only 0.07 for an unraked tree. Raking did not affect mortality when fire intensity, measured as percent crown volume scorched, was very low (0 % scorch) or very high (>80 % scorch), but the raking treatment significantly increased the proportion of trees that survived by 9.6 % for trees that burned under moderate fire intensity (1 % to 80 % scorch). Raking significantly reduced the likelihood of bole charring and bark beetle activity three years post-fire. This implies that raking can be an effective management tool to reduce tree mortality following prescribed fire under specific fuel and burning conditions.

Download or read book Indian Fire based Management in the Sequoia mixed Conifer Forests of the Central and Southern Sierra Nevada written by Kat Anderson and published by . This book was released on 1993 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 The Effect of Forest Structure on Yellow Pine mixed conifer Resilience to Wildfire and Bark Beetle Disturbance in the Sierra Nevada California written by Michael J. Koontz and published by . This book was released on 2019 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Disturbances like wildfire and bark beetle activity can alter forest structure, which influences the outcomes of future disturbances. The long-term persistence of forest ecosystems hinges on these feedbacks, which promotes resilience. These feedbacks are explored by measuring disturbance severity as well as local-scale forest structure at broad spatial extents in the yellow pine/mixed-conifer forest system of the Sierra Nevada, California. Tools such as massively parallel cloud-based GIS and drone remote sensing were used to collect data about how forest structure affects wildfire and bark beetle disturbance. Overall, this work demonstrates how an understanding of the complexities of local forest structure, including the size, species, and spatial distribution of trees, can generate insight into how broader-scale patterns of tree mortality arise during wildfire and bark beetle disturbance.--adapted from abstract.

Download or read book Trees in Trouble written by Daniel Mathews and published by Catapult. This book was released on 2020-04-07 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: A troubling story of the devastating and compounding effects of climate change in the Western and Rocky Mountain states, told through in–depth reportage and conversations with ecologists, professional forest managers, park service scientists, burn boss, activists, and more. Climate change manifests in many ways across North America, but few as dramatic as the attacks on our western pine forests. In Trees in Trouble, Daniel Mathews tells the urgent story of this loss, accompanying burn crews and forest ecologists as they study the myriad risk factors and refine techniques for saving this important, limited resource. Mathews transports the reader from the exquisitely aromatic haze of ponderosa and Jeffrey pine groves to the fantastic gnarls and whorls of five–thousand–year–old bristlecone pines, from genetic test nurseries where white pine seedlings are deliberately infected with their mortal enemy to the hottest megafire sites and neighborhoods leveled by fire tornadoes or ember blizzards. Scrupulously researched, Trees in Trouble not only explores the devastating ripple effects of climate change, but also introduces us to the people devoting their lives to saving our forests. Mathews also offers hope: a new approach to managing western pine forests is underway. Trees in Trouble explores how we might succeed in sustaining our forests through the challenging transition to a new environment.

Download or read book Effects of Prescribed Fire on Understory Vegetation in Mixed conifer Forests of the Southern Sierra Nevada California written by Karen Webster and published by . This book was released on 2010 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: