The original author(s) and source must be cited. This version of this article is open access and can be downloaded and shared. This entry was posted in Trophic Cascade and tagged channel morphology, elk, riparian plant communities, trophic cascades, wolves. License © 2005 Ecological Society of America. Document: 2008-Beschta-Ripple-Olympic-trophic-cascades.pdf.Trophic Cascade: A Wolfs Role in the Ecosystem of Yellowstone. Thus, conservation strategies based on the trophic importance of large carnivores have increased support in terrestrial ecosystems. Trophic Cascade: A Wolfs Role in the Ecosystem of Yellowstone - graphgists. Human activity strongly mediated these cascade effects, through a depressing effect on habitat use by wolves. These alternating patterns across trophic levels support the wolf-caused trophic cascade hypothesis. Beaver lodge density was negatively correlated to elk density, and elk herbivory had an indirect negative effect on riparian songbird diversity and abundance. Wolf exclusion decreased aspen recruitment, willow production, and increased willow and aspen browsing intensity. 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.). These impacts include: This diagram illustrates trophic cascade caused by removal of the top predator. Annual recruitment of calves was 15% in the high-wolf area vs. Trophic cascades also impact the biodiversity of ecosystems, and when examined from that perspective wolves appear to be having multiple, positive cascading impacts on the biodiversity of Yellowstone National Park. Annual survival of adult female elk was 62% in the high-wolf area vs. Elk population density diverged over time in the two treatments, such that elk were an order of magnitude more numerous in the low-wolf area compared to the high-wolf area at the end of the study. We compared effects of recolonizing wolves on these response variables using the log response ratio between the low-wolf and high-wolf treatments. We investigated the effects of differential wolf predation between these two areas on elk (Cervus elaphus) population density, adult female survival, and calf recruitment aspen (Populus tremuloides) recruitment and browse intensity willow (Salix spp.) production, browsing intensity, and net growth beaver (Castor canadensis) density and riparian songbird diversity, evenness, and abundance. High human activity partially excluded wolves from one area of the Bow Valley (low-wolf area), whereas wolves made full use of an adjacent area (high-wolf area). The first wolf pack recolonized the Bow Valley of Banff National Park in 1986. A serendipitous natural experiment provided an opportunity to test the trophic cascade hypothesis for wolves (Canis lupus) in Banff National Park, Canada. Now, if only we, the human element, could come to understand the meaningful role we should be playing in this grand theatre….Human Activity Mediates a Trophic Cascade Caused By WolvesĪbstract: Experimental evidence of trophic cascades initiated by large vertebrate predators is rare in terrestrial ecosystems. The reintroduction of wolves to Yellowstone National Park is a classic example of the far reaching - and might I also say rapid - effects of putting things back the way they were…. Scientists called this beneficial effect the trophic cascade, as wolves initiated a more natural ecosystem balance. Whilst we may not completely understand the importance of specific elements in the eco-system around us, at the very least we can learn to submit to its greater wisdom - recognising that these systems functioned long before our machines, our economy, and our greed came along to destroy it. The Trophic Cascade The result of the wolf reintroduction was an explosion of life and biodiversity as wolves returned to their natural place as apex predators. During the seven-decade wolf-free period, the collapse of a tri-trophic cascade allowed elk (Cervus elaphus) to signicantly impact wildlife habitat, soils, and woody plants. While the important role each ‘character’ plays out in the grand ‘theatre’ of life is rarely fully understood, even by the more eco-literate amongst us, this is where we, the human actor, need to treat the world around us with humble respect. and now presence of wolves in Yellowstone National Park (YNP) represents a natural experiment through time and an opportunity to study cascading trophic interactions. The eradication of wolves from Yellowstone National Park is a classic example of the Us and Them approach to wildlife management - where a simplistic, selfish and reductionist mindset sees nature as something to battle and compete against, rather than recognising that each wildlife entity has an important role to play in helping the systems we depend on to flourish. When we try to pick out anything by itself, we find it hitched to everything else in the Universe.
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