Beschta, R.L. and W.J. Ripple
Herein we synthesize outcomes of recent tri-trophic cascades studies involving the presence and absence of large predators for five national parks in the western United States, including Olympic, Yosemite, Yellowstone, Zion, and Wind Cave. Where ungulates have significantly altered native plant communities in the absence of large predators, restoration of native flora is urgently needed to recover former ecosystem services. Following the reintroduction of previously extirpated gray wolves Canis lupus into Yellowstone National Park, a spatially patchy recovery of woody browse species (e.g., aspen Populus tremuloides, willow Salix spp., cottonwood Populus spp.) has begun, indicating that large predator recovery may represent an important restoration strategy for ecosystems degraded by wild ungulates.