CLASSIFICATION AND ORDINATION OF COLEOGYNE COMMUNITIES IN SOUTHERN NEVADA

Woody plant community composition was analyzed throughout the range of Coleogyne ramosissima in the Spring and Sheep Mountain ranges of sout hern Nevada. The lower Coleogyne elevational boundary was analyzed in detail in Lucky Strike Canyon, on the eastern edge of the Spring Mount ains. TWINSPAN (2-way indicator species analysis) identified 4 primary species and stand groups from the 2 mountain ranges (extensive survey ), and 4 primary species and stand groups in the detailed study at the lower Coleogyne ecotone (intensive survey, Analysis of DECORANA (detr ended correspondence analysis) results indicated that elevation and so il depth were the environmental factors most significantly associated with distribution of species and stand groups in the extensive survey. Elevation was the only significant physical factor associated with di stribution of species and stand groups in the intensive survey. Five v egetation zones from the 2 mountain ranges were identified based on th eir dominant species in 15 extensive transects. Coleogyme were subdivi ded into pure stands and upper and lower ecotones for further investig ation of species distribution and environmental factors. Selected envi ronmental factors appear to play an important role in structuring the Mojave Desert vegetation zones in southern Nevada.