Environmental Influence on Vegetation Properties of Frigid Wetlands on the Qinghai-Tibet Plateau, Western China

摘要

Wetlands on the Qinghai-Tibet Plateau fall into six types (alpine, piedmont, valley, riverine, floodplain, and lacustrine) from the geomorphic-centered perspective, each having its own species assemblage. This study attempts to explore its relationship with the environment. It is found that all wetland plants in Maduo County on the Plateau belong to 15 families, 35 genera and 56 species. Most species are associated with aecurrency sign3 types of wetlands, but have a minor dominance. Non-metric multidimensional scaling (nMDS) analysis reveals significant separation between the six wetland types in the ordination space (p < 0.001). Their biophysical predictors are species richness, species diversity, soil N, P and pH, all of which are correlated strongly with the position of the sampling sites in the ordination space (p < 0.001). Vegetative cover, species richness, species diversity, and plant height by wetland type are all correlated with each other (r > 0.635), and have a strong elevational gradient (R-2 aeyen 0.718) within the range of 4200-4400 m asl. In contrast, just over half of the variation in species diversity, vegetative cover, species richness can be explained by surface soil organic matter (R-2 aeyen 0.54), but marginally by soil P and pH. The strong altitudinal gradient at the zonal level disappears at the individual sample level because different types of wetland species assemblage overlap with each other in their spatial distribution.