Spatial patterns of plant diversity and communities in Alpine ecosystems of the Hengduan Mountains,Northwest Yunnan,China

Aims Conduct a quantitative, but rapid, regional-level assessment of the alpine flora across northwest Yunnan (NWY) to provide a broad-based understanding of local and regional patterns of the composition, diversity and health of alpine ecosystems across NWY.Methods A stratified random sampling design was employed to select sites across the different mountain ranges of NWY. Vegetation was sampled by stratifying each site by the three major alpine vegetation community types: meadow, dwarf shrub and scree. Two 50-m transects were randomly located within each community type at each sampling site with 10 1-m 2 subplots systematically placed along each transect. Environmental variables were recorded at each transect. Multivariate analyses were used to classify the major plant community assemblages and link community patterns to environmental and habitat variables.Important findings Forb species richness varied from 19 to 105 species per site (21 sites total) with an average of 59 species per site (60 m 2 sampled per site). Most species were patchily distributed with narrow distributions and/or small population sizes; over half the species occurred at only one or two sites. Distinct species assemblages were identified in the meadow vegetation that was strongly aggregated by geographic location suggesting the presence of distinct phytogeographic zones of the meadow alpine flora. Elevation and geographic location were the dominant environmental gradients underlying the variations in species composition. Jaccard's coefficient of similarity averaged only 10% among sites indicating there was little similarity in the alpine flora across the region. The alpine vegetation is highly heterogeneous across the complex landscape of the Hengduan Mountains of NWY. Conservation strategies need to take into account the large geographic differences in the flora to maximize protection of biodiversity.