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Evidence Of A Trophic Cascade Among Wolves Elk And Aspen In Yellowstone National Park Usa
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Book Synopsis Evidence of a Trophic Cascade Among Wolves, Elk, and Aspen in Yellowstone National Park, USA by : Joshua Simon Halofsky
Download or read book Evidence of a Trophic Cascade Among Wolves, Elk, and Aspen in Yellowstone National Park, USA written by Joshua Simon Halofsky and published by . This book was released on 2007 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: According to general top-down trophic theory, in the presence of carnivores, herbivore behavior and/or densities could change and result in an overall decrease in herbivory on plant communities. In this dissertation, I examined the potential relationship between gray wolf (Canis lupus) presence and absence on elk (Cervus elaphus) herbivory of aspen (Populus tremuloides). Based on aspen tree cores and an age-diameter relationship, I approximated aspen origination dates both within and outside two elk exclosures to study long-term patterns of aspen recruitment in the Gallatin elk winter range of northwestern Yellowstone National Park, USA. From aspen data, I concluded that while a host of interacting biophysical factors may influence aspen recruitment and growth, the observed pattern of aspen decline is most correlated with elk herbivory, coincident with the presence and absence of wolves. Outside of the elk winter range, but still within the northwestern portion of the park, I studied growth patterns of clonal upland aspen thickets since wolf reintroduction. Growth patterns were compared in an area burned in the 1988 fires to an adjacent area that was unburned. From the results, I proposed that in addition to any wolf-mediated changes in elk densities, a recoupling of fire with increased elk predation risk in the presence of wolves may improve upland clonal aspen recruitment. To examine the potential for a trophic cascade from the perspective of elk, I measured vigilance behavior in female elk throughout the park during both winter and summer seasons. After vigilance behavior was recorded, I noted the distance to, and type of, objects that could have impeded observed female elk escape from predators. From my model selection procedure, I concluded elk foraging behavior appeared to vary with physical features in the landscape. This variation in foraging behavior with risk of predation provides a potential mechanism to explain the patchy release of preferred woody browse species within the Park. Therefore, in addition to density-mediated effects, the results are consistent with a behaviorally-mediated top-down trophic cascade between wolves, elk, and aspen.
Book Synopsis Trophic Cascades and Large Mammals in the Yellowstone Ecosystem by : Luke E. Painter
Download or read book Trophic Cascades and Large Mammals in the Yellowstone Ecosystem written by Luke E. Painter and published by . This book was released on 2013 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reintroduction of wolves to Yellowstone National Park (YNP) in 1995-96 provided a rare opportunity to observe the response of an ecosystem to the return of a top predator, including possible reversal of decades of decline of aspen, cottonwood, and tall willows suppressed by intensive herbivory on elk winter ranges. To investigate changes in aspen stands in northern Yellowstone since the return of wolves, I compared browsing intensity and heights of young aspen in 87 randomly selected stands in 2012 to similar data collected in the same stands in 1997-98. I also measured the spatial density of elk and bison scat piles as an index to relative population densities, and used annual counts of elk to calculate trends in elk density. In 1998, browsing rates averaged 88%, heights were suppressed, and no tall saplings (???200 cm) were found in sampling plots. In 2012, browsing rates in 2012 were much lower averaging 44%, and 28% of plots had at least one sapling???200 cm, tall enough to escape browsing and therefore more likely to survive to replace dying overstory trees. Heights of young aspen were inversely related to browsing intensity, but not significantly related to leader length, suggesting that differences in height were primarily due to differences in browsing, not factors related to productivity. Aspen recovery was patchy, possibly due in part to locally high elk or bison densities in some parts of the winter range. These results of reduced browsing with increased sapling recruitment were consistent with a trophic cascade from wolves to elk to aspen resulting in a widespread and spatially variable recovery of aspen stands. There was wide variation in browsing intensity and aspen height between sectors of the Yellowstone northern ungulate winter range (northern range). The east sector generally had lower rates of browsing and more stands with tall saplings than the central and west sectors, a pattern that matched recent trends in elk population densities. Only a small minority of stands in the west sector had tall saplings, consistent with higher elk densities in the west. Densities of elk in winter on the northern range recently have been highest in the northwest sector outside the park boundary, where elk benefit from lower wolf densities and milder winters. Aspen stands did not recover at a comparable range-wide elk density when elk were culled in the park in the 1950s and 1960s, suggesting that the influence of wolves may be an important factor in the recent redistribution and reduction of herbivory impacts by elk. To examine the relationship between elk and aspen outside of YNP, I assessed browsing intensity and sapling recruitment in 43 aspen stands in the Shoshone National Forest east of the park, compared to data collected in the same stands in 1997-98. As in northern YNP, results were consistent with a trophic cascade with reduced browsing and increased recruitment of aspen saplings, but aspen recovery was patchy. Elk densities were moderate to high in most of the area, suggesting that the partial aspen recovery may involve a behavioral response to predation or other factors resulting in local variation in browsing impacts. Livestock may also have limited aspen recruitment. Recovery of some aspen stands in the Shoshone National Forest may provide some of the first evidence of a trophic cascade from wolves to elk to aspen outside of a national park, a trophic cascade possibly weakened by the influence of another large herbivore (cattle). Like cattle, bison in northern Yellowstone may have an effect on woody browse plants. Bison have increased in number and may prevent recovery of some aspen stands in places of high bison density. I also examined browsing impacts of bison on willow and cottonwood in the Lamar Valley. To distinguish the effects of bison from those of elk, I compared browsing at different heights on tall willows, below and above the reach of bison. Because elk were absent from the area in summer when bison were present at high density, I also measured browsing that occurred in the summer. I found high rates of summer browsing, and growth of willows and cottonwoods was suppressed in the Lamar Valley. Above the reach of bison (>100 cm), growth was not suppressed and browsing rates were low, suggesting that these plant species have been released from suppression by elk but bison have compensated for some of the reduction in elk browsing. This study provided the first evidence of significant herbivory by bison of woody browse plants in Yellowstone, and revealed some of the complexity of the Yellowstone food web. In summary, these research results support the hypothesis of a trophic cascade resulting from large carnivore restoration and subsequent changes in elk population densities and distribution. The return of wolves may have combined with other factors such as changes in hunting and land ownership, and increased predation by bears, to result in large-scale shifts in the distribution of elk in northern Yellowstone and greatly reduced elk densities in some areas. If these trends continue, the result may be a new alternative state with lower elk densities, and potential for enhanced biodiversity through reduced herbivory of woody browse species.
Book Synopsis Are Wolves Saving Yellowstone's Aspen? by : Matthew J. Kauffman
Download or read book Are Wolves Saving Yellowstone's Aspen? written by Matthew J. Kauffman and published by . This book was released on 2010 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Behaviorally mediated trophic cascades (BMTCs) occur when the fear of predation among herbivores enhances plant productivity. Based primarily on systems involving small-bodied predators, BMTCs have been proposed as both strong and ubiquitous in natural ecosystems. Recently, however, synthetic work has suggested that the existence of BMTCs may be mediated by predator hunting mode, whereby passive (sit-and-wait) predators have much stronger effects than active (coursing) predators. One BMTC that has been proposed for a wide-ranging active predator system involves the reintroduction of wolves (Canis lupus) to Yellowstone National Park, USA, which is thought to be leading to a recovery of trembling aspen (Populus tremuloides) by causing elk (Cervus elaphus) to avoid foraging in risky areas. Although this BMTC has been generally accepted and highly popularized, it has never been adequately tested. We assessed whether wolves influence aspen by obtaining detailed demographic data on aspen stands using tree rings and by monitoring browsing levels in experimental elk exclosures arrayed across a gradient of predation risk for three years. Our study demonstrates that the historical failure of aspen to regenerate varied widely among stands (last recruitment year ranged from 1892 to 1956), and our data do not indicate an abrupt cessation of recruitment. This pattern of recruitment failure appears more consistent with a gradual increase in elk numbers rather than a rapid behavioral shift in elk foraging following wolf extirpation. In addition, our estimates of relative survivorship of young browsable aspen indicate that aspen are not currently recovering in Yellowstone, even in the presence of a large wolf population. Finally, in an experimental test of the BMTC hypothesis we found that the impacts of elk browsing on aspen demography are not diminished in sites where elk are at higher risk of predation by wolves. These findings suggest the need to further evaluate how trophic cascades are mediated by predator-prey life history and ecological context.
Book Synopsis Yellowstone Wolves by : Douglas W. Smith
Download or read book Yellowstone Wolves written by Douglas W. Smith and published by University of Chicago Press. This book was released on 2020-12-28 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This beautifully illustrated volume on the Yellowstone Wolf Project includes an introduction by Jane Goodall and an exclusive online documentary. The reintroduction of wolves to Yellowstone National Park was one of the greatest wildlife conservation achievements of the twentieth century. Eradicated after the park was first established, these iconic carnivores returned in 1995 when the US government reversed its century-old policy of extermination. In the intervening decades, scientists have built a one-of-a-kind field study of these wolves, their behaviors, and their influence on the entire ecosystem. Yellowstone Wolves tells the incredible story of the Yellowstone Wolf Project, as told by the people behind it. This wide-ranging volume highlights what has been learned in the decades since reintroduction, as well as the unique blend of research techniques used to gain this knowledge. We learn about individual wolves, population dynamics, wolf-prey relationships, genetics, disease, management and policy, and the rippling ecosystem effects wolves have had on Yellowstone’s wild and rare landscape. Featuring a foreword by Jane Goodall, beautiful images, a companion online documentary by celebrated filmmaker Bob Landis, and contributions from more than seventy wolf and wildlife conservation luminaries from Yellowstone and around the world, Yellowstone Wolves is an informative and beautifully realized celebration of the extraordinary Yellowstone Wolf Project.
Book Synopsis Trophic Cascades in Yellowstone by : William J. Ripple
Download or read book Trophic Cascades in Yellowstone written by William J. Ripple and published by . This book was released on 2012 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1995/1996 reintroduction of gray wolves (Canis lupus) into Yellowstone National Park after a 70 year absence has allowed for studies of tri-trophic cascades involving wolves, elk (Cervus elaphus), and plant species such as aspen (Populus tremuloides), cottonwoods (Populus spp.), and willows (Salix spp.). To investigate the status of this cascade, in September of 2010 we repeated an earlier survey of aspen and measured browsing and heights of young aspen in 97 stands along four streams in the Lamar River catchment of the park?s northern winter range. We found that browsing on the five tallest young aspen in each stand decreased from 100% of all measured leaders in 1998 to means of
Book Synopsis Linkages Between Wolf Presence and Aspen Recruitment in the Gallatin Elk Winter Range of Southwestern Montana, USA by : Joshua Simon Halofsky
Download or read book Linkages Between Wolf Presence and Aspen Recruitment in the Gallatin Elk Winter Range of Southwestern Montana, USA written by Joshua Simon Halofsky and published by . This book was released on 2008 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The decline of aspen (Populus tremuloides) in Yellowstone National Park (YNP) has been attributed to conifer encroachment, climatic influences, ungulate herbivory and more recently, a lack of grey wolves (Canis lupus) via trophic cascades. The current study explores evidence of a trophic cascade on aspen decline. We conducted the study in the Gallatin elk winter range of YNP, an area where aspen have not previously been studied. We approximated aspen origination dates fom an age-diameter relationship to examine potential correlations between wolf presence and absence, elk (Cervus elaphus) herbivory and aspen recruitment. A comparative analysis was also conducted between the aspen data collected in the winter range and aspen data collected within two elk exclosures. Within the elk exclosures, aspen recruitment into mature stems began to decline in the 1920s (during wolf extirpation), completely ceased after the 1950s and has only been observed since the 1990s (post-wolf reintroduction). While a host of interacting biophysical factors may influence aspen recruitment and growth, the correlative results between aspen recruitment and historical elk browsing activities, coincident with the presence and absence of wolves, are consistent with a top-down trophic cascade." --Summary.
Book Synopsis Wolves, Elk, Bison, and Secondary Trophic Cascades in Yellowstone National Park by : William J. Ripple
Download or read book Wolves, Elk, Bison, and Secondary Trophic Cascades in Yellowstone National Park written by William J. Ripple and published by . This book was released on 2010 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wolves were reintroduced into Yellowstone National Park in 1995/96, likely reestablishing a trophic cascade involving wolves, elk, and woody browse species. The return of wolves may have also triggered a secondary trophic cascade involving bison, which are generally a minor prey species for wolves in northern Yellowstone. We hypothesize a sequence of events in northern Yellowstone where: 1) wolves prey on elk, changing elk behavior and reducing elk numbers, 2) causing reduced elk herbivory and more forage available to bison, and 3) allowing higher bison densities and additional bison effects on the ecosystem. This secondary trophic cascade, whereby wolf predation may have indirectly allowed bison numbers to increase through a reduction in inter-specific competition with elk, may represent an example of an alternative top-down pathway by which predators can influence multiple trophic levels through mediating the competitive interaction between two prey species. Both wolves and bison can have important effects on ecosystems, and there is growing interest in restoring these animals to wider portions of their former range. However, there are many potential routes for interactions between species and it is important to consider the conservation implications of other cascading effects when reintroducing such ecologically influential species into wild landscapes. The potential benefits of bison to their native ecosystems may not be realized in situations with low predation pressure, high bison densities, and constraints on bison movement and migration, thus likely contributing to impairment of resources.
Book Synopsis Ecological Issues on Reintroducing Wolves Into Yellowstone National Park by : Robert Sewell Cook
Download or read book Ecological Issues on Reintroducing Wolves Into Yellowstone National Park written by Robert Sewell Cook and published by . This book was released on 1993 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Ecology of Large Mammals in Central Yellowstone by : Robert A. Garrott
Download or read book The Ecology of Large Mammals in Central Yellowstone written by Robert A. Garrott and published by Academic Press. This book was released on 2008-11-25 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an authoritative work on the ecology of some of America’s most iconic large mammals in a natural environment - and of the interplay between climate, landscape, and animals in the interior of the world’s first and most famous national park.Central Yellowstone includes the range of one of the largest migratory populations of bison in North America as well as a unique elk herd that remains in the park year round. These populations live in a varied landscape with seasonal and often extreme patterns of climate and food abundance. The reintroduction of wolves into the park a decade ago resulted in scientific and public controversy about the effect of large predators on their prey, a debate closely examined in the book. Introductory chapters describe the geography, geology and vegetation of the ecosystem. The elk and bison are then introduced and their population ecology described both pre- and post– wolf introduction, enabling valuable insights into the demographic and behavioral consequences for their ungulate prey. Subsequent chapters describe the wildlife-human interactions and show how scientific research can inform the debate and policy issues surrounding winter recreation in Yellowstone. The book closes with a discussion of how this ecological knowledge can be used to educate the public, both about Yellowstone itself and about science, ecology and the environment in general. Yellowstone National Park exemplifies some of the currently most hotly debated and high-profile ecological, wildlife management, and environmental policy issues and this book will have broad appeal not only to academic ecologists, but also to natural resource students, managers, biologists, policy makers, administrators and the general public. Unrivalled descriptions of ecological processes in a world famous ecosystem, based on information from 16 years of painstaking field work and collaborations among 66 scientists and technical experts and 15 graduate studies Detailed studies of two charismatic North American herbivore species – elk and bison Description of the restoration of wolves into central Yellowstone and their ecological interactions with their elk and bison prey Illustrated with numerous evocative colour photographs and stunning maps
Book Synopsis Wolves for Yellowstone?: Research & analysis by : Yellowstone National Park
Download or read book Wolves for Yellowstone?: Research & analysis written by Yellowstone National Park and published by . This book was released on 1990 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vol. 3-4 edited by John D. Varley and Wayne G. Brewster; Sarah E. Broadbent and Renee Evanoff, technical editors.
Book Synopsis The Yellowstone Wolf by : Paul Schullery
Download or read book The Yellowstone Wolf written by Paul Schullery and published by University of Oklahoma Press. This book was released on 2003 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: All royalties from sales of this book go to Yellowstone’s wolf recovery project Few animals inspire such a mixture of fear, curiosity, and wonder as the wolf. Highly regarded but often misunderstood, the wolf has as many friends as enemies, and its reintroduction into Yellowstone National Park has sparked both fascination and controversy. Early in Yellowstone’s history, wolves were thought supernaturally evil, and scores were destroyed. Northern Rocky Mountain wolves were native to Yellowstone when the park was established in 1872, but “predator control” led to determined eradication, and by the 1940s they were gone. Amid much fanfare, however, wolves were reintroduced to one of the nation’s oldest national parks in the 1990s. This comprehensive reference documents the prehistory, management, and nature of the Yellowstone wolf. Historian-naturalist Paul Schullery has assembled the voices of explorers, naturalists, park officials, tourists, lawmakers, and modern researchers to tell the story of what may be the most famous wolf population in the world. This unique book includes numerous scientific studies of interest to wolf enthusiasts and scholars of western wildlife issues, conservation, and national parks. In a new afterword, Schullery discusses recent developments in the recovery project.
Book Synopsis Continental Conservation by : Michael E. Soulé
Download or read book Continental Conservation written by Michael E. Soulé and published by Island Press. This book was released on with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continental Conservation is an important guidebook that can serve a vital role in helping fashion a radically honest, scientifically rigorous land-use agenda.
Download or read book Rewilding written by Nathalie Pettorelli and published by Cambridge University Press. This book was released on 2019-01-31 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discusses the benefits and risks, as well as the economic and socio-political realities, of rewilding as a novel conservation tool.
Download or read book Trophic Cascades written by John Terborgh and published by Island Press. This book was released on 2013-06-25 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trophic cascades—the top-down regulation of ecosystems by predators—are an essential aspect of ecosystem function and well-being. Trophic cascades are often drastically disrupted by human interventions—for example, when wolves and cougars are removed, allowing deer and beaver to become destructive—yet have only recently begun to be considered in the development of conservation and management strategies. Trophic Cascades is the first comprehensive presentation of the science on this subject. It brings together some of the world’s leading scientists and researchers to explain the importance of large animals in regulating ecosystems, and to relate that scientific knowledge to practical conservation. Chapters examine trophic cascades across the world’s major biomes, including intertidal habitats, coastal oceans, lakes, nearshore ecosystems, open oceans, tropical forests, boreal and temperate ecosystems, low arctic scrubland, savannas, and islands. Additional chapters consider aboveground/belowground linkages, predation and ecosystem processes, consumer control by megafauna and fire, and alternative states in ecosystems. An introductory chapter offers a concise overview of trophic cascades, while concluding chapters consider theoretical perspectives and comparative issues. Trophic Cascades provides a scientific basis and justification for the idea that large predators and top-down forcing must be considered in conservation strategies, alongside factors such as habitat preservation and invasive species. It is a groundbreaking work for scientists and managers involved with biodiversity conservation and protection.
Download or read book Aspen written by and published by . This book was released on 1985 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Information about the biology, ecology, and management of quaking aspen on the mountains and plateaus of the interior western United States, and to a lesser extent, Canada, is summarized and discussed. The biology of aspen as a tree species, community relationships in the aspen ecosystem, environments, and factors affecting aspen forests are reviewed. The resources available within and from the aspen forest type, and their past and potential uses are examined. Silvicultural methods and other approaches to managing aspen for various resources and uses are presented.
Book Synopsis The Northern Yellowstone Elk by : Douglas B. Houston
Download or read book The Northern Yellowstone Elk written by Douglas B. Houston and published by Free Press. This book was released on 1982 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Trophic Cascades from Wolves to Alders in Yellowstone by : William J. Ripple
Download or read book Trophic Cascades from Wolves to Alders in Yellowstone written by William J. Ripple and published by . This book was released on 2015 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We explored possible interactions among gray wolves (Canis lupus), Rocky Mountain elk (Cervus elaphus), and thinleaf alder (Alnus incana spp. tenuifoli) in northern Yellowstone National Park. We developed an alder age structure based on annual growth rings for plants growing along six streams in areas accessible to ungulates on the northern range. Alder stems (n = 412) along the six streams originated only after wolf reintroduction. By 2013, 80% of the sampled alders along these streams were taller than 2 m, in contrast with a historical pattern of height suppression by ungulate herbivory. This pattern of alder recruitment is consistent with a trophic cascade whereby new alder growth occurred across all study streams within several years after wolf reintroduction. Although declines in elk density since wolf reintroduction likely contributed to the release of alder from herbivory, the immediate onset of new alder recruitment following wolf reintroduction indicates that behavioral responses to predation may also have been an important component in the resulting trophic cascade. These results suggest that predator conservation could play a role in the management and ecological restoration of riparian areas.
