The vegetation composition and interspecific association of patches distributing in Polygonum viviparum alpine meadow on northeast Qinghai-Tibetan Plateau

The vegetation composition and interspecific relationship reflect the interaction relationship of spatial distribution pattern among plant populations and communities. We analyzed the important value, diversity index of species, biomass composition, the Jaccard association index and spearman rank correlation coefficient of main species growing on patch in Polygonum viviparum alpine meadow (P. viviparum patch) and control (CK), in order to reveal the ecological mechanism of succession process in Alpine meadow. The results indicated that number of species in P. viviparum patch was bigeer than that in CK, and the change pattern of each group was similar between important value and biomass composition. P. viviparum patch dominated mainly by forbs and grasses, accounting for 60.9% and 22.1% of the green biomass, respectively, and P. viviparum accounted for about one third of the green biomass; while it dominated mainly by grasses and forbs, accounting for 53.3% and 27.1% of the green biomass, respectively. In P. viviparum patch and CK, the significantly associated species-pairs accounted for 16.4% and 33.0% of their respective total species-pairs. The interspecific association of most species-pairs was not significant, and the independence between species-pairs was stronger. The ratios of negative and positive correlations were 0.83 and 1.40, respectively. Plant communities of P. viviparum patch was a stable stage. The formation of P. viviparum patch can strengthen community stable of alpine meadow.