Use of riparian water table depths to predict sedge-willow potential in disturbed communities of the Upper Henry's Fork basin, Idaho.

Decades of neglect have degraded many streams in the Upper Henry's Fork bas in, Idaho. As part of a fishery restoration project, the Henry's Fork Found ation and the Riparian and Wetland Research Program at The University of Mo ntana co-sponsored research to investigate riparian vegetation potential at disturbed stream sites. Dominance by sedges (Carex spp.) and willows (Sali x spp.) in reference sites suggested that revegetation with some combinatio n of the two genera would be most efficient. To determine if riparian water table depth was a useful indicator of sedge/willow composition, we compare d water table depths in 45 sites dominated by sedges, willows, or mixtures of the two. Analysis using the Kruskal-Wallis test indicated significant di fferences in average and seasonal riparian water table depths between sedge , willow, and mixed vegetation types. These differences were most significa nt (tied p-value .0003) in late August. Results suggest that in low gradien t riparian communities of the Upper Henry's Fork basin, willows and sedges segregate on the basis of tolerance to late summer inundation, with sedges being more tolerant than willows. Identification of late summer water table depths appears to be an easy way to help predict sedge/willow potential in disturbed sites and might be another useful riparian assessment tool.