River channel dynamics following extirpation of wolves in northwestern Yellowstone National Park, USA

摘要: Historical records indicate that gray wolves (Canis lupus) were extirpated from the upper Gallatin River Basin in early 1900s. Following removal of these large carnivores, elk (Cervis elaphus) began to increasingly browse streamside vegetation winter range, causing widespread loss formerly extensive willow (Salix spp.) communities. aerial photographs and chronosequences ground used characterize general changes channel morphology over time. In August 2004, riparian cross-sections surveyed along three reaches River. Reach A was located upstream range (control reach) whereas B C (treatment reaches) within range. Willow cover on floodplains averaged 85 per cent for reach A, but only 26 5 C, respectively. The average return period calculated bankfull discharges 3·1 yrs increased 32·4 10·6 long-term allowed channels generally increase hydraulic capacity (via increases width, incision or both) decrease their hydrologic connectivity with adjacent floodplains. This study documents, perhaps first time, resultant impacts functions stream characteristics following extirpation a mammalian carnivore. Copyright © 2006 John Wiley & Sons, Ltd.