Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years

Presentation entitled : Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years / by Schyler Reis, Lisa Ellsworth and J. Boone KauffmanHart Mountain National Antelope Refuge (HMNAR) established in 1936, is 101,000 ha in area. The refuge was grazed by domestic livestock from the 1870s until their exclusion in 1990. Just prior to removal of livestock, photopoints were taken at various riparian and wetland locations throughout the refuge to document riparian condition following decades of use by domestic livestock. The objective of this study was to relocate and rephotograph these photopoints, collect associated stream channel data, estimate the change in channel width and depth and quantify stream side vegetation composition. Photopoints (N=23) with sufficient distinct background features necessary to allow relocation were selected. Of the 23 photopoints, 13 pairs of stream channel data could be quantified using field data (current) and images (historical and current). In historical photos heavy use of riparian areas by livestock was evident. There were large areas of bare ground cover associated with trampling damage, and the stream banks were highly eroded. Following 21 years of livestock rest there is a dramatic reduction in exposed banks, a return of stream side vegetation including willows (Salix spp.), and a widening of riparian vegetation zone. In the uplands there are encroachment of Western Juniper (Juniperus occidentalis). Over twenty years of cattle exclusion has lead to dramatic changes in stream channel width to depth ratios. The mean width to depth ratio of the remnant channels were found to be much higher (mean 16.75, SD 13.48) than the current channel's ratio (mean 4.19 2.47, p= 0.007). The mean width of remnant channels were found to be much higher(mean 7.6m) than the current channels width(mean1.2m), a reduction of 84%. Current mean streamside vegetation composition of understory vegetation is as follows (N=17): Bare ground: 4.8%, Litter: 21.7%, Forbs: 16.4%, Grasses: 22% and Sedges:34.1%