[Plant diversity variations in zokor-mound communities along a successional stage]

Using an approach of spatial sequence instead of temporal sequence, this paper studied the composition and diversity of plant species on zokor-mound along a successional gradient in alpine meadow. The results indicated that the species composition and structure of vegetations on zoker-mound along different successional stages were quite different from those of original vegetations. During the early stage of succession, the pioneer species with numerous widely dispersed seeds or spores (r strategy), such as Elsholtzia ciliata, Chenopodium glaucum, Potentilla anserina, and Ajania tenuifolia, dominated in the community. As the progression of succession, the proportion of species with vegetative expansion (k strategy), such as Saussurea hieracioides, Elymus nutans, Kobresia kansuensis, and Kobersia capillifolia, increased in the community. The analysis of Alpha diversity indicated that both species richness and evenness, in increasing order, changes as stage 1 < stage 2 < stage 3 < stage 4 < original vegetation, while Simpson index (D) and Shannon-Wiener index (H') increased significantly as the progression of succession. The analysis of Beta diversity showed that the similarity coefficient of species composition of community between stage 1 and stage 4 and between stage 1 and original vegetation was the lowest (0.18), while that of community between stage 1 and stage 2 was the highest (0.62). The functional diversity of lif form also manifested some obvious changes along the successional gradient, showing that plant community and mini-habitat changed along a successional gradient on zokor-mound.