Large predators and trophic cascades in terrestrial ecosystems of the western United States

摘要: Large predators potentially can help shape the structure and functioning of terrestrial ecosystems, yet strong evidence top-down herbivore limitation has not been widely reported in scientific literature. Herein we synthesize outcomes recent tri-trophic cascades studies involving presence absence large for five national parks western United States, including Olympic, Yosemite, Yellowstone, Zion, Wind Cave. Historical observations by park biologists regarding woody browse species recently compiled age data deciduous trees indicate major impacts to plant communities ungulates following extirpation or displacement predators. Declines long-term tree recruitment indexed additional effects ecological processes, as well shifts towards alternative ecosystem states. The magnitude consistency vegetation found within these parks, conjunction with other North American studies, that broad changes processes lower trophic level may have occurred parts States where extirpated displaced. Thus, significantly altered native predators, restoration flora is urgently needed recover former services. Following reintroduction previously gray wolves Canis lupus into Yellowstone National Park, a spatially patchy recovery (e.g., aspen Populus tremuloides, willow Salix spp., cottonwood spp.) begun, indicating predator represent an important strategy ecosystems degraded wild ungulates.