title: Stream hydrology limits recovery of riparian ecosystems after wolf reintroduction.
abstract: Efforts to restore ecosystems often focus on reintroducing apex predators to re-establish coevolved relationships among predators, herbivores and plants. The preponderance of evidence for indirect effects of predators on terrestrial plant communities comes from ecosystems where predators have been removed. Far less is known about the consequences of their restoration. The effects of removal and restoration are unlikely to be symmetrical because removing predators can create feedbacks that reinforce the effects of predator loss. Observational studies have suggested that the reintroduction of wolves to Yellowstone National Park initiated dramatic restoration of riparian ecosystems by releasing willows from excessive browsing by elk. Here, we present results from a decade-long experiment in Yellowstone showing that moderating browsing alone was not sufficient to restore riparian zones along small streams. Instead, restoration of willow communities depended on removing browsing and restoring hydrological conditions that prevailed before the removal of wolves. The 70-year absence of predators from the ecosystem changed the disturbance regime in a way that was not reversed by predator reintroduction. We conclude that predator restoration may not quickly repair effects of predator removal in ecosystems.
authors: Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523-1499, USA. kristin.marshall@noaa.gov
authors: Kristin N
authors: KN
authors: Marshall
authors: N Thompson
authors: NT
authors: Hobbs
authors: David J
authors: DJ
authors: Cooper
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources / Q000379:methods*; D003670:Deer; D017753:Ecosystem; D008137:Longitudinal Studies; D011157:Population Dynamics; D011235:Predatory Behavior; D045483:Rivers; D012377:Rodentia; D032108:Salix; D019596:Wolves
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