Multivariate Analysis of Alpine Snow-Patch Vegetation Cover near Milner Pass, Rocky Mountain National Park, Colorado, U.S.A.

Abstract

This study attempts to quantify alpine snow-patch vegetation-soil communities with respect to distance from the center of the snow patch on north and south sites. Discriminant models using vegetation and environmental parameters were developed for determining differences within transects and between sites using four snow patches on northand southfacing slopes in Rocky Mountain National Park, Colorado. Data for two independently selected snow patches were used to validate the model. Collected vegetation data included cover by species while soil measurements included temperature, moisture tension, pH, percent organic matter, and texture. Slope, aspect, snow depth, and distance of the quadrat from the snow-patch basin edge were also recorded. The species composition of contiguous vegetation stands along a transect were statistically different on a multivariate basis but few univariate differences were observed. Trifolium parryi occurred more in the inner stands of the south site while T. dasyphyllum had larger cover, values in the outer stands. On the north site, however, T. parryi, Artemisia norvegica, and Geum rossii had more cover in outer stands while Deschampsia caespitosa occurred more in inner stands. Although T. parryi occurred at different distances on the two slopes, the microsites it occupied were similar in moisture and snow cover characteristics. Vegetation differed between slopes, and validation stands could be properly assigned to aspects based on a discriminant function which contained pH or gravel percentage and cover for species with small amounts of cover, such as Lewisia pygmaea, Thlaspi alpestre, or Solidago decumbens.