Download or read book Variable Tree Growth After Fire Protects Forests from Future Bark Beetle Outbreaks written by Kelly April Tyrrell and published by . This book was released on 2016 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Do severe wildfires make forests in the western United States more susceptible to future bark beetle outbreaks? The answer, in a study published Monday (Nov. 7, 2016) in the Proceedings of the National Academy of Sciences, is no. By leading to variability in the density and size of trees that grow during recovery, large fires reduce the future vulnerability of forests to synchronous bark beetle attacks and broad-scale outbreaks. -- Summary.
Download or read book Spatial Variability in Tree Regeneration After Wildfire Delays and Dampens Future Bark Beetle Outbreaks written by Rupert Seidl and published by . This book was released on 2016 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change is altering the frequency and severity of forest disturbances such as wildfires and bark beetle outbreaks, thereby increasing the potential for sequential disturbances to interact. Interactions can amplify or dampen disturbances, yet the direction and magnitude of future disturbance interactions are difficult to anticipate because underlying mechanisms remain poorly understood. We tested how variability in postfire forest development affects future susceptibility to bark beetle outbreaks, focusing on mountain pine beetle (Dendroctonus ponderosae) and Douglas-fir beetle (Dendroctonus pseudotsugae) in forests regenerating from the large high-severity fires that affected Yellowstone National Park in Wyoming in 1988. We combined extensive field data on postfire tree regeneration with a well-tested simulation model to assess susceptibility to bark beetle outbreaks over 130 y of stand development. Despite originating from the same fire event, among-stand variation in forest structure was very high and remained considerable for over a century. Thus, simulated emergence of stands susceptible to bark beetles was not temporally synchronized but was protracted by several decades, compared with stand development from spatially homogeneous regeneration. Furthermore, because of fire-mediated variability in forest structure, the habitat connectivity required to support broad-scale outbreaks and amplifying cross-scale feedbacks did not develop until well into the second century after the initial burn. We conclude that variability in tree regeneration after disturbance can dampen and delay future disturbance by breaking spatiotemporal synchrony on the landscape. This highlights the importance of fostering landscape variability in the context of ecosystem management given changing disturbance regimes.
Download or read book Bark Beetle fire forest Interactions in the Greater Yellowstone Ecosystem written by Martin Simard and published by . This book was released on 2010 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Western Bark Beetle Report written by United States. Forest Service and published by . This book was released on 2002 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluating Post outbreak Management Effects on Future Fuel Profiles and Stand Structure in Bark Beetle impacted Forests of Greater Yellowstone written by Daniel C. Donato and published by . This book was released on 2013 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-scale bark beetle (Curculionidae: Scolytinae) outbreaks across western North America have prompted widespread concerns over changes to forest wildfire potentials. Management actions following outbreaks often include the harvest of beetle-killed trees and subsequent fuel treatments to mitigate expected changes to fuel profiles, but few data exist to inform these actions. In both lodgepole pine (Pinus contorta var. latifolia) and Douglas-fir (Pseudotsuga menziesii var. glauca) forests of the Greater Yellowstone Ecosystem, Wyoming, USA, we used the Forest Vegetation Simulator to evaluate how fuel profiles, stand structure, and biomass carbon storage are influenced by various post-outbreak fuel treatments (removal of beetle-killed trees ['salvage'] followed by either no treatment, prescribed burning, pile-and-burn, or whole-tree-removal). The model was initialized with field data from five unmanaged gray-stage stands in each forest type and projected over 50 years of post-treatment time. Across all treatment methods, the strongest projected effects relative to unharvested stands were reductions in coarse woody surface fuels (after 10-20 yr), fewer well-decayed standing snags (after 40 yr), and reduced biomass carbon storage (throughout all 50 years). The reduction in coarse woody surface fuels suggests reduced heat release and resistance to control in future fires. Projected effects on fine fuels, both in the canopy and surface layers, were surprisingly minor or short-lived; natural fall and decay of fine material in unharvested stands led to the convergence of most fuel variables between treated and untreated stands within about a decade, especially in Douglas-fir forests. Most follow-up treatment methods - whether unmerchantable tree parts were left in place, burned, piled, or removed entirely - had similar impacts on most aspects of fuel and stand structure in both lodgepole pine and Douglas-fir forests. However, the prescribed burning treatment was distinct and generally had the strongest effects, owing to greater consumption of forest floor mass and mortality of small trees, which had persistent influences on both the canopy and surface fuel layers. Treatment effectiveness in reducing fuels was mirrored by reductions in biomass carbon storage and recruitment of well-decayed snags, illustrating common tradeoffs involved in fuel treatments. Harvest of beetle-killed trees and subsequent treatments altered the fuel profile and structure of outbreak-impacted stands, but overall effects were similar among treatments, suggesting flexibility in management options in post-outbreak forests.
Download or read book Interactions Between Bark Beetle Outbreak and Wildland Fire in Intermountain Subalpine Forests of the Western United States written by Nathan Paul Mietkiewicz and published by . This book was released on 2015 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms and Spatial Patterns of Bark Beetle associated Mortality Following Variable Density Thinning Treatments in a Sierra Mixed conifer Forest written by Alexis Bernal and published by . This book was released on 2019 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-term trends of tree mortality have increased over the last several decades, coinciding with above-average temperatures, high climatic water deficits, and bark beetle outbreaks. With the anticipation that drought and bark beetles may increase with climate change, uncertainty exists over the appropriate treatments that could ensure the future sustainability of forest resources and the ecosystem services that forests provide. Conventional thinning treatments are used to reduce stand density, with the assumption that reductions in competition can alleviate drought stress and enable trees to resist bark beetle attack. Alternative thinning treatments may also reduce stand density, but have a greater focus on increasing spatial heterogeneity. Variable density thinning is a management method intended to mimic the spatial heterogeneity that was present in mixed-conifer forests prior to logging and fire exclusion. Although the added benefits of increasing spatial heterogeneity include biodiversity, wildlife, recreation, and restoration, information is lacking on the effects that these treatments have on tree resistance to disturbances. Since 2012, the Sierra Nevada experienced widespread tree mortality coinciding with severe drought conditions and bark beetle outbreak. This provided a unique opportunity to explore the mechanisms driving bark beetle-associated mortality following variable density thinning treatments in the central Sierra Nevada. Using dendrochronological methods, we modeled the relationship between drought resistance and bark beetle-associated mortality to evaluate if reductions in competition enhance tree resistance to bark beetles. We also determined if structural elements within variable density thinning treatments influenced the level and spatial pattern of bark beetle-associated mortality. By exploring these relationships, our findings could provide a greater understanding on the underlying mechanisms that drive mortality to disturbances and also provide information to help develop prescriptions for enhancing resistance to drought and bark beetles.
Download or read book Mitigating Old Tree Mortality in Long Unburned Fire Dependent Forests written by Sharon M. Hood and published by DIANE Publishing. This book was released on 2011 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a print on demand edition of a hard to find publication. This report synthesizes the literature and current state of knowledge pertaining to re-introducing fire in stands where it has been excluded for long periods and the impact of these introductory fires on overstory tree injury and mortality. Only forested ecosystems in the United States that are adapted to survive frequent fire are included. Treatment options that minimize large-diameter and old tree injury and mortality in areas with deep duff and methods to manage and reduce duff accumulations are discussed. Pertinent background information on tree physiology, properties of duff, and historical versus current disturbance regimes are also discussed. Charts and tables.
Download or read book Cutting a Course written by Jenna Elizabeth Morris and published by . This book was released on 2020 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bark beetle outbreaks are major natural disturbances in temperate forests across the northern hemisphere, contributing to extensive tree mortality and driving forest change. Recent widespread and severe outbreaks--and projected climate-driven changes to disturbance activity--have raised concerns about forest resilience and the interaction of future outbreaks with other disturbances (e.g., fire). Thinning (i.e., density reduction) treatments may promote resilience to bark beetles by fostering resistance or bolstering forest capacity to respond post outbreak, but opportunities to test treatment efficacy and longevity have been rare. Further, forest managers must consider the effects of thinning on additional objectives such as tradeoffs between fire hazard mitigation and carbon storage. Here, I used a replicated study of old-growth lodgepole pine stands thinned in 1940 and affected by a recent (early 2000s) severe mountain pine beetle outbreak to examine the effects of thinning on (1) components of resilience to outbreak, and (2) post-outbreak fire hazard and carbon storage. I measured stand structural attributes in the field ~8 years post-outbreak and compared resistance to beetle attack (tree- and stand-scale survival), successional trajectories, fuel profiles, and aboveground carbon biomass between uncut (control) and thinned treatment units. Thinning six decades prior to mountain pine beetle outbreak had limited effects on resistance, but additional effects of thinning on stand trajectories, surface and canopy fuel profiles, and aboveground carbon storage persisted following severe outbreak. This study broadens the temporal extent of our understanding of thinning effects on directing forest response to bark beetle outbreaks, with important implications for developing effective management decisions in the face of global change.
Download or read book Mitigating Old Tree Mortality in Long Unburned Fire Dependent Forests written by Sharon M. Hood and published by CreateSpace. This book was released on 2012-10 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historically, many forested ecosystems in the United States burned frequently, both from lightning ignited fires and from Native American burning. Frequent fire maintained low fuel loadings and shaped forests composed of tree species adapted to survive low-intensity frequent fire. In the early 1900s, the United States government initiated a program to suppress all fires, both natural and anthropogenic. Many unintended consequences have resulted from over a century of fire suppression, such as increased tree densities and fuel, increased stress on older trees from competition, and greater risk of bark beetle attacks. These consequences are especially apparent in forests that historically burned frequently and have thus missed many fire cycles. Maintaining old trees and perpetuating large-diameter trees is an increasing concern. Stands of old trees that were historically common across vast landscapes in the United States are now relatively rare on the landscape because of harvesting (Noss and others 1995). Though logging is no longer the principal threat to most old-growth forests, they now face other risks (Vosick and others 2007). Prescribed fire has become a major tool for restoring fire-dependent ecosystem health and sustainability throughout the United States and use will likely increase in the future. However, increased mortality of large-diameter and old trees following fire has been reported in many areas around the country, and there is increased concern about maintaining these on the landscape (Kolb and others 2007; Varner and others 2005). As early as 1960, Ferguson and others (1960) reported high longleaf pine mortality after a low-intensity prescribed burn consumed the majority of heavy duff accumulations around the base of the trees. Mortality of pre-settlement ponderosa pines in prescribed burn areas in Grand Canyon National Park was higher than in control plots (Kaufmann and Covington 2001). After beginning a forest restoration program that reintroduced fire by prescribed burning at Crater Lake National Park, excessive post-fire mortality of larger ponderosa pine was observed in the burn areas, and early season burns had an even higher mortality than late season burns (Swezy and Agee 1991). Both Swezy and Agee (1991) and McHugh and Kolb (2003) reported a U-shaped mortality distribution for ponderosa pine following wildfires, with smaller- and larger-diameter trees having higher mortality than mid-diameter trees. Forest managers around the country have expressed concerns about large-diameter and old tree mortality when prescribed burning in long-unburned forests. The synthesis herein suggests recommendations for maintaining and perpetuating old trees in fire-dependent ecosystems. It expands on efforts funded by the Joint Fire Science Program (JFSP) to define the issues surrounding burning in fire excluded forests of the United States that are adapted to survive frequent fire. When the JFSP initially funded this synthesis, two JFSP projects were examining the effect of raking on reducing old ponderosa and Jeffrey pine (subsequently published in Fowler and others 2010; Hood and others 2007a). Another JFSP project examined the effect of prescribed burning under different duff moisture conditions on long-unburned old longleaf pine mortality (Varner and others 2007). Two other syntheses were also recently published on this subject: Perpetuating old ponderosa pine (Kolb and others 2007) and The conservation and restoration of old growth in frequent-fire forests of the American West (Egan 2007). The scope of the synthesis herein focuses only on limiting over story tree mortality in species adapted to survive frequent fire; therefore, the implications of fire suppression and fuel treatments on other ecosystem components are not discussed.
Download or read book Assessing Post Fire Douglas Fir Mortality and Douglas Fir Beetle Attacks in the Northern Rocky Mountains written by Sharon Hood and published by Createspace Independent Pub. This book was released on 2012-10-22 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many coniferous species have life history traits and characteristics that greatly enhance their resistance to injury from fire, thereby increasing post-fire survival rates. Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), for example, is known for its fire tolerance, in large part, due to thick insulating bark that develops with age and protects the inner cambium from heat injury. Mortality following fire, however, depends not only on tree species, but also on type and degree of fire-caused injuries, initial tree vigor, and post-fire environment. These same factors may also influence timing of tree death, which can be delayed as long as 4 years post-fire. Within a few months to a few years following fire, bark and wood boring beetles may preferentially attack, and wood deterioration caused by staining, decay pathogens, and/or checking can occur. Parker and others provide an extensive review of interactions between insects and fire (prescribed and wildfire) in coniferous forests of interior western North America. Development of management plans immediately following fire, therefore, can be difficult due to the timing and uncertainty of many interacting factors. Reliable estimates of post-fire Douglas-fir mortality, predicted from field-based characterizations of fire injury, would greatly facilitate informed post-fire management, including salvage, following both mixed-severity wildfires and applications of prescribed fire. Prediction of fire- and beetle-caused delayed tree mortality is also an important component in the development of prescribed burn plan objectives. Managers must know what fire intensity levels are needed to accomplish mortality related objectives. Also, in adaptive management, a key part to determining if burn objectives were met is installation of monitoring plots. By revisiting prescribed burns and monitoring fire effects, future burn prescriptions can be adjusted to better achieve desired results. To do this, field crews must be able to accurately assess post-fire tree injury and the potential for delayed mortality. Fire behavior and effects models, such as the First Order Fire Effects Model (FOFEM) and BehavePlus, are available for use in predicting post-fire tree mortality. The tree mortality model in these software packages is based on models developed by Ryan and Reinhardt (1988) and Ryan and Amman (1994). However, this tree mortality model was developed from data for several different tree species. More importantly, this model does not fully account for bark beetle effects on post-fire tree mortality. Douglas-fir bark beetles (Dendroctonus pseudotsugae Hopkins Coleoptera: Curculionidae, Scolytine) are highly attracted to fire-injured Douglas-fir and can cause significant tree mortality, apart from fire injuries alone. If Douglas-fir beetle populations are a concern following fire, it is important to characterize the fire-related tree injuries most conducive to beetle attack and successful brood production and survival. Hood and Bentz (2007) developed a model to predict the probability of Douglas-fir mortality and one to predict the probability of Douglas-fir beetle attacks within 4 years post-fire based on data collected from three mixed-severity wildfires in western Montana and Wyoming. The intent of this guide is to facilitate use of these models in post-fire management and prescribed burn planning. We note that ecological and economic constraints make forest management following wildfire a complex task. Our models are meant to be used as part of a multidisciplinary strategy aimed at maximizing benefits to post-fire ecological communities and forest management. Following a brief description of the two models, variables significant in predicting post-fire Douglas-fir mortality and Douglas-fir beetle attack are described.
Download or read book Influence of Recent Bark Beetle Outbreak on Fire Severity and Postfire written by Brian J. Harvey and published by . This book was released on 2013 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding how disturbances interact to shape ecosystems is a key challenge in ecology. In forests of western North America, the degree to which recent bark beetle outbreaks and subsequent fires may be linked (e.g., outbreak severity affects fire severity) and/ or whether these two disturbances produce compound effects on postfire succession is of widespread interest. These interactions remain unresolved, largely because field data from actual wildfires following beetle outbreaks are lacking. We studied the 2008 Gunbarrel Fire, which burned 27 200 ha in Douglas-fir (Pseudotsuga menziesii) forests that experienced a bark beetle outbreak 4-13 years prefire ("gray stage, " after trees have died and needles have dropped), to determine whether outbreak severity influenced subsequent fire severity and postfire tree regeneration. In 85 sample plots we recorded prefire stand structure and outbreak severity; multiple measures of canopy and forest-floor fire severity; and postfire tree seedling density. Prefire outbreak severity was not related to any measure of fire severity except for mean bole scorch, which declined slightly with increasing outbreak severity. Instead, fire severity varied with topography and burning conditions (proxy for weather at time of fire). Postfire Douglas-fir regeneration was low, with tree seedlings absent in 65% of plots. Tree seedlings were abundant in plots of low fire severity that also had experienced low outbreak severity (mean = 1690 seedlings/ha), suggesting a dual filter on tree regeneration. Although bark beetles and fire collectively reduced live basal area to 5% and increased snag density to 2000% of pre-outbreak levels, the lack of relationship between beetle outbreak and fire severity suggests that these disturbances were not linked. Nonetheless, effects on postfire tree regeneration suggest compound disturbance interactions that contribute to the structural heterogeneity characteristic of mid/lower montane forests.
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 Insects and Diseases of Mediterranean Forest Systems written by Timothy D. Paine and published by Springer. This book was released on 2016-01-06 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt: Insect and disease issues are often specific to the Mediterranean forest systems rather than shared with the temperate forests. In addition to the specific native insects and diseases, the forests are subject to the invasion of exotic species. The forests are also at risk from high degrees of human activity, including changing patterns of forest fires, land management activities, intensive plantation forestry using introduced timber species from other Mediterranean climate zones, and atmospheric deposition. Combined with elements of global climate change that may disproportionately affect Mediterranean climate systems, this creates a number of significant management issues that are unique to the Mediterranean forests. It is our goal that the information contained in this volume will contribute to understanding the unique aspects of Mediterranean forest systems and to protecting these critical resources.
Download or read book Progress in Understanding Bark Beetle Effects on Fire Behavior Using Physics based Models written by and published by . This book was released on 2013 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bark beetle outbreaks are a major disturbance of forests throughout western North America affecting ecological processes and social and economic values (Amman 1977, Bond and Keeley 2005). Since the 1990s, bark beetle outbreaks have affected between 1.1 and 13.5 million acres in the western United States and an additional 13.5 million acres in British Columbia (Meddens et al. 2012). Tree mortality resulting from bark beetles has affected lodgepole pine, ponderosa pine, spruce- r, Douglas- rand pinyon pine forest types (Figure 1). The extent of the recent tree mortality due to bark beetle outbreaks has led to increased scientific, management and public interest in the implications of bark beetle-caused tree mortality for the behavior of subsequent wildfires.
Download or read book Bark Beetles written by Fernando E. Vega and published by Academic Press. This book was released on 2014-12-29 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bark Beetles: Biology and Ecology of Native and Invasive Species provides a thorough discussion of these economically important pests of coniferous and broadleaf trees and their importance in agriculture. It is the first book in the market solely dedicated to this important group of insects, and contains 15 chapters on natural history and ecology, morphology, taxonomy and phylogenetics, evolution and diversity, population dynamics, resistance, symbiotic associations, natural enemies, climate change, management strategies, economics, and politics, with some chapters exclusively devoted to some of the most economically important bark beetle genera, including Dendroctonus, Ips, Tomicus, Hypothenemus, and Scolytus. This text is ideal for entomology and forestry courses, and is aimed at scientists, faculty members, forest managers, practitioners of biological control of insect pests, mycologists interested in bark beetle-fungal associations, and students in the disciplines of entomology, ecology, and forestry. Provides the only synthesis of the literature on bark beetles Features chapters exclusively devoted to some of the most economically important bark beetle genera, such as Dendroctonus, Ips, Tomicus, Hypothenemus, and Scolytus Includes copious color illustrations and photographs that further enhance the content
Download or read book Whitebark Pine Communities written by Diana F. Tomback and published by Island Press. This book was released on 2001 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: Whitebark pine is a dominant feature of western high-mountain regions, offering an important source of food and high-quality habitat for species ranging from Clark's nutcracker to the grizzly bear. But in the northwestern United States and southwestern Canada, much of the whitebark pine is disappearing. Why is a high-mountain species found in places rarely disturbed by humans in trouble? And what can be done about it.Whitebark Pine Communities addresses those questions, explaining how a combination of altered fire regimes and fungal infestation is leading to a rapid decline of this once abundant -- and ecologically vital -- species. Leading experts in the field explain what is known about whitebark pine communities and their ecological value, examine its precarious situation, and present the state of knowledge concerning restoration alternatives. The book. presents an overview of the ecology and status of whitebark pine communities offers a basic understanding of whitebark pine taxonomy, distribution, and ecology, including environmental tolerances, community disturbance processes, regeneration processes, species interactions, and genetic population structure identifies the threats to whitebark pine communities explains the need for management intervention surveys the extent of impact and losses to dateMore importantly, the book clearly shows that the knowledge and management tools are available to restore whitebark pine communities both locally and on a significant scale regionally, and it provides specific information about what actions can and must be taken.Whitebark Pine Communities offers a detailed portrait of the ecology of whitebark pine communities and the current threats to them. It brings together leading experts to provide in-depth information on research needs, management approaches, and restoration activities, and will be essential reading for ecologists, land managers, and anyone concerned with the health of forest ecosystems in the western United States.
