Natural Tree Regeneration Dynamics a Decade After the Storrie Fire in the Lassen National Forest PDF Download

Author: Justin S. Crotteau
Publisher:
ISBN:
Category : Conifers
Languages : en
Pages : 192

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Author: Kevin Robert Welch
Publisher:
ISBN: 9781321807653
Category :
Languages : en
Pages :

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This study examines postfire regeneration patterns in low to mid-elevation forests of northern and central California where conifers co-exist and compete with hardwoods and shrubs in the postfire environment. Due to fire suppression policies, timber harvest, and other management practices over the last century, many low- to mid-elevation forests in California have accumulated high fuel loads and dense, multi-layered canopies that are dominated by shade-tolerant and fire-sensitive conifers. These conditions promote high-intensity fires, which have major effects on forest structure, function, and composition. We established 1,854 survey plots in nineteen wildfires on ten National Forests across a range of elevations, forest types, and fire severities in central and northern California to provide insight into factors that promote natural tree regeneration after wildfires and the differences in post-fire responses of the most common conifer species and hardwood species. We developed a zero-inflated negative binomial mixed model with random effects to understand the importance of ten environmental variables in predicting conifer regeneration. This model identified as important factors distance to potential seed tree, annual precipitation, presence of regenerating shrubs, litter cover, fire severity and pre-existing forest type. We documented widespread conifer regeneration failure with nearly 50% of all plots devoid of conifer regeneration. When regeneration did occur, it was dominated by shade-tolerant but fire-sensitive firs, Douglas-fir and incense cedar. Active forest restoration (planting, brush control, reduction of undesirable species, etc.) may be necessary in more severely burned areas farther from seed trees where natural regeneration is insufficient to restore forest composition and structure, increasing forest resiliency in the face of climate change and augmented levels of fire disturbance. However, conifers do not exist in isolation in these forests and the interaction with other functional woody plant types must be considered. This study adds a unique contribution to understanding postfire regeneration dynamics by comparing the relative success of hardwoods to conifers across a fire severity gradient and in the first decade after mixed-severity fires. By utilizing vegetative sprouting (and to a lesser extent sexual reproduction), hardwood trees and shrubs are able to quickly capitalize on available resources and this ability may confer a competitive advantage to hardwoods. The results of this study indicate that increased fire severity leads to greater relative density of hardwoods via a combined impact of resprouts and seedlings, creating alternative states where hardwoods and shrubs (that suppress the relatively few conifer seedlings that do establish) may dominate for many years after disturbance. To a great extent, the future status of California's forests will depend on tree species' responses to patterns and trends in fire activity and behavior and post-fire management decisions.

Author: Martin John Brown
Publisher:
ISBN:
Category : Conifers
Languages : en
Pages : 50

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We monitored coarse woody debris dynamics and natural tree regeneration over a 14-year period after the 1991 Warner Creek Fire, a 3631-ha (8,972-ac) mixed severity fire in the western Cascade Range of Oregon. Rates for tree mortality in the fire, postfire mortality, snag fall, and snag fragmentation all showed distinct patterns by tree diameter and species, with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) more likely to survive a fire, and to remain standing as a snag, than other common tree species. Natural seedling regeneration was abundant, rapid, and highly variable in space. Densities of seedlings >10 cm height at 14 years postfire ranged from 1,530 to 392,000 per ha. Seedling establishment was not concentrated in a single year, and did not appear to be limited by the abundant growth of shrubs. The simultaneous processes of mortality, snag fall, and tree regeneration increased the variety of many measures of forest structure. The singular event of the fire has increased the structural diversity of the landscape.

Author: Dani Niziolek
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Contemporary fires in California are becoming larger, more frequent, and increasingly severe, and this trend is expected to continue in the coming decades. Increases in area burned and area burned at high severity generate larger high severity patches without a tree canopy, which can impede forest recovery by limiting seed dispersal from live trees and triggering vegetation type change. Although there is an emerging body of research on post-fire conifer regeneration, there is uncertainty in how landscape and local site conditions interact to influence regeneration. This thesis identifies dominant drivers of postfire conifer regeneration in Lassen Volcanic National Park in the southern Cascades. We studied post-fire conifer regeneration in the footprint of nine fires, between 7 and 26 years after the burn, quantifying pre- and post-fire forest condition, topography and topoclimate, and local terrain and ground cover at each plot. Random Forest models assessed the relationship between these environmental conditions and regeneration stocking or species occurrence. We found that post-fire conifer regeneration was relatively abundant in Lassen Volcanic National Park, and abundance was related toto topography, vegetation type, and characteristics of the pre- and post-fire forest. Regeneration was densest in cooler, wetter topographic positions, and although overall regeneration did not respond to post fire water balance, species showed different responses to moisture availability. Regeneration responded positively to proximity to forest edge and longer time since fire, with the strongest regeneration occurring within 200 m of forest edge and >10 years since fire. Though high levels of shrub cover inhibited regeneration, at lower levels shrub cover supported more dense tree regeneration. These findings support trends found in the literature, and highlight the importance of studying regeneration over longer periods after fire, and incorporating characteristics of the local environment in studies of post-fire conifer regeneration.

Author: Christopher J. Huggard
Publisher: University of Arizona Press
ISBN: 081653666X
Category : Science
Languages : en
Pages : 342

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The devastating fire that swept through Los Alamos, New Mexico, in the spring of 2000 may have been caused by one controlled burn gone wild, but it was far from an isolated event. All through the twentieth century, our national forests have been under assault from all sides: first ranchers and loggers laid their claims to our national forests, then recreationists and environmentalists spoke up for their interests. Who are our national forests really for? In this book, leading environmental historians show us what has been happening to these fragile woodlands. Taking us from lumber towns to Indian reservations to grazing lands, Forests under Fire reveals the interaction of Anglos, Hispanics, and Native Americans with the forests of the American Southwest. It examines recent controversies ranging from red squirrel conservation on Mt. Graham to increased tourism in our national forests. These case studies offer insights into human-forest relationships in places such as the Coconino National Forest, the Vallecitos Sustained Yield Unit, and the Gila Wilderness Area while also drawing on issues and concerns about similar biospheres in other parts of the West. Over the past century, forest management has evolved from a field dominated by the "conservationist" perspective—with humans exploiting natural resources-to one that emphasizes biocentrism, in which forests are seen as dynamic ecosystems. Yet despite this progressive shift, the assault on our forests continues through overgrazing of rangelands, lumbering, eroding mountainsides, fire suppression, and threats to the habitats of endangered species. Forests under Fire takes a closer look at the people calling the shots in our national forests, from advocates of timber harvesting to champions of ecosystem management, and calls for a reassessment of our priorities—before our forests are gone. Contents Introduction: Toward a Twenty-First-Century Forest Ecosystem Management Strategy / Christopher J. Huggard Industry and Indian Self-Determination: Northern Arizona’s Apache Lumbering Empire, 1870-1970 / Arthur R. Gómez A Social History of McPhee: Colorado’s Largest Lumber Town / Duane A. Smith The Vallecitos Federal Sustained-Yield Unit: The (All Too) Human Dimension of Forest Management in Northern New Mexico, 1945-1998 / Suzanne S. Forrest Grazing the Southwest Borderlands: The Peloncillo-Animas District of the Coronado National Forest in Arizona and New Mexico, 1906-1996 / Diana Hadley America’s First Wilderness Area: Aldo Leopold, the Forest Service, and the Gila of New Mexico, 1924-1980 / Christopher J. Huggard "Where There’s Smoke": Wildfire Policy and Suppression in the American Southwest / John Herron Struggle in an Endangered Empire: The Search for Total Ecosystem Management in the Forests of Southern Utah, 1976-1999 / Thomas G. Alexander Biopolitics: A Case Study of Political Influence on Forest Management Decisions, Coronado National Forest, Arizona, 1980s-1990s / Paul W. Hirt Epilogue: Seeing the Forest Not for the Trees: The Future of Southwestern Forests in Retrospect / Hal K. Rothman

Author: Stephen F. Arno
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 272

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In Mimicking Nature's Fire, forest ecologists Stephen Arno and Carl Fiedler present practical solutions to the pervasive problem of deteriorating forest conditions in western North America.

Author: Erin Alvey
Publisher:
ISBN:
Category : Conifers
Languages : en
Pages : 78

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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.

Author: Susan Husari
Publisher:
ISBN:
Category : Fire ecology
Languages : en
Pages : 0

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Author: Christopher Hale Carlson
Publisher:
ISBN:
Category : Atmospheric carbon dioxide
Languages : en
Pages : 57

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Forest fuel treatments such as thinning and burning have been proposed as tools to stabilize carbon stocks in fire-prone forests in the Western U.S. Although treatments immediately reduce forest carbon storage, losses may be paid back over the long-term if treatment sufficiently reduces future wildfire severity. Less severe wildfire produces fewer direct and indirect carbon emissions, and severely burned stands may be more susceptible to deforestation. Although fire severity and post-fire tree regeneration have been indicated as important influences on long-term carbon dynamics, it remains unclear how natural variability in these processes might affect the ability of fuel treatments to protect forest carbon resources. We surveyed a wildfire where fuel treatments were put in place before fire and estimated the short-term impact of treatment and wildfire on aboveground carbon stocks at our study site. We then used a common vegetation growth simulator in conjunction with sensitivity analysis techniques to assess how timescales of carbon recovery after fire are sensitive to variation in rates of fire-related tree mortality, and post-fire tree regeneration. We found that fuel reduction treatments were successful at ameliorating fire severity at our study site by removing an estimated 36% of aboveground biomass. Treated and untreated stands stored similar amounts of carbon three years after wildfire, but differences in fire severity were such that untreated stands maintained only 7% of aboveground carbon as live trees, versus 51% in treated stands. Over the long-term, our simulations suggest that treated stands in our study area will recover baseline carbon storage 10-35 years more quickly than untreated stands. Our sensitivity analysis found that rates of fire-related tree mortality strongly influence estimates of post-fire carbon recovery. Rates of regeneration were less influential on recovery timing, except when fire severity was high. Our ability to understand how anthropogenic and natural disturbances affect forest carbon resources hinges on our ability to adequately represent processes known to be important to long-term forest carbon dynamics. To the extent that fuel treatments are able to ameliorate tree mortality rates or prevent deforestation resulting from wildfire, treatments may be a viable strategy to stabilize existing forest carbon stocks.

Author: Anthony Godfrey
Publisher: U.S. Government Printing Office
ISBN:
Category : Nature
Languages : en
Pages : 688

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"United States Department of Agriculture, Forest Service, Pacific Southwest Region"