NUMERICAL-ANALYSES OF VEGETATION BASED ON ENVIRONMENTAL RELATIONSHIPSIN THE SOUTHERN CHIHUAHUAN DESERT

Relationships between environmental factors and vegetation types in a southern part of the Chihuahuan Desert were explored. Species presence -absence data and cover data from 44 samples were analyzed. Eight cate gorical and seven continuous environmental variables were recorded at each sampling site. Classification analysis identified four vegetation types: crassicaulous scrub, rosetophyllous scrub, microphyllous scrub , and mesquital. A regression of ordination scores from a principal co mponents analysis on environmental variates indicated that vegetation variation was strongly correlated with geomorphological variables. Dis criminant analysis based on environmental variables showed a clear seg regation of the four vegetation types.