Plant Diversity along the Eastern and Western Slopes of Baima Snow Mountain, China

Species richness and turnover rates differed between the western and eastern aspects of Baima Snow Mountain: maximum species richness (94 species in a transect of 1000 m(2)) was recorded at 2800 m on the western aspect and at 3400 m on the eastern aspect (126 species), which also recorded a much higher value of gamma diversity (501 species) than the western aspect (300 species). The turnover rates were the highest in the transition zones between different vegetation types, whereas species-area curves showed larger within-transect beta diversity at middle elevations. The effect of elevation on alpha diversity was due mainly to the differences in seasonal temperature and moisture, and these environmental factors mattered more than spatial distances to the turnover rates along the elevation gradient, although the impact of the environmental factors differed with the growth form (herb, shrubs or trees) of the species. The differences in the patterns of plant biodiversity between the two aspects helped to assess several hypotheses that seek to explain such patterns, to highlight the impacts of contemporary climate and historical and regional factors and to plan biological conservation and forest management in this region more scientifically.