Great Basin Naturalist


Coleogyne ramosissima is a desert shrub that forms a nearly monospecific shrubland and occupies a well-defined elevational band between approximately 1050 and 2150 m on mountain ranges in southern Nevada. The Coleogyne shrubland shares relatively broad upper and lower ecotones with Pinus-Juniperus and Larrea-Ambrosia plant communites, respectively. We characterized the extent that environmental factors correlate with Coleogyne density and examined variation in biotic and abiotic factors along the lower elevational boundary of Coleogyne in Lucky Strike Canyon near Las Vegas, Nevada. Coleogyne density was positively correlated with gravimetric soil moisture, soil organic matter, Coleogyne water potential, Coleogyne stem and leaf phosphorus, and Coleogyne leaf biomass. However, Coleogyne density was negatively correlated with soil temperatures, soil compaction, and Coleogyne stem and leaf nitrogen. Coleogyne stem biomass and elongation were generally negatively correlated with Coleogyne density. Coleogyne density was weakly correlated with soil pH, soil depth, soil nitrogen, soil and leaf phosphorus; these variables did not exhibit a consistent pattern with increasing elevation. Edaphic factors, particularly soil moisture and soil organic matter, appear to play a major role in determining the distribution of Coleogyne shrublands in southern Nevada.