PATTERNS OF VEGETATION AND WATER CHEMISTRY IN PEATLANDS OF THE WEST-CENTRAL WIND RIVER RANGE, WYOMING, USA

Seventeen peatland complexes were investigated in a 2000-ha study area in the Barnes Lake region of the west-central Wind River Range in Wyoming, U.S.A. Sites ranged in elevation from 2970 to 3200 m. The peatlands are generally less than 2 ha in size and are supported by groundwater flow systems. Seventeen plant community types are recognized using two-way indicator species analysis and Braun-Blanquet table methods, including 4 aquatic communities, 6 peatland expanse communities, and 7 peatland margin communities. Surface water in the study area is neutral to slightly acidic with very low cation concentrations. The water pH and flora indicate rich fen conditions, while the cation concentrations are more comparable to poor fens or even bogs. We propose calling the study area peatlands transitional rich fens, which are fed by mineral-poor water. The chemical composition of surface waters was found to be similar among different communities. Patterns of plant species and plant community distribution are a function of the water table depth and duration gradient and flow rates of the water supply. The rich-poor and peatland expanse - peatland margin gradients that reflect nutrient gradients do not appear to be important in the study area.