The Influence of Grazing and Other Environmental Factors on Lichen Community Structure along an Alpine Tundra Ridge in the Uinta Mountains, Utah, U.S.A.

Abstract

ABSTRACT This study examined the influence of snowmelt, vascular plants, grazing, substrates, and soil characteristics on the distribution of lichen communities along an alpine tundra ridge in the Uinta Mountains of Utah. Percent cover of lichens, rocks, snow, and vascular plants were estimated at 18 study sites along an altitudinal transect. Vascular plant cover and species diversity were greatest at the lower elevation sites, and differences in plant communities were related to differences in rock cover and grazing. Lichens showed a similar trend, with rock cover, grazing, vascular plants, and timing of snowmelt all defining community structure. We hypothesize that domestic sheep have dispersed fragments of two lichen species from western Wyoming to grazed sites along the study transect. Generally, terricolous and epiphytic lichens differed between the lower and upper sites in species composition and growth-form distribution. Distribution of lichen growth forms was positively correlated with increasing rock cover. Late snowmelt areas were also distinguished by a defined group of lichens.