The Relationship Of Plant Species Diversity And Productivity Of Plant Community In Qinghai-Tibetan Sub-alpine Meadow

In this paper, we studied 5 plant communities with different succession periods (6 yr,9 yr,11 yr,21 yr and 31 yr) in the Qinghai-Tibetan sub-alpine meadow. Using field investigation and laboratory experiments, we analyzed species composition, species diversity, the relationship between species diversity and productivity, and the similarity between communities in communities of different succession stages.(1) Either using species richness or evenness index, the trend of diversity of sub-alpine meadow plant communities of different succession gradient was roughly the same:6 years＜9 years＜21 years＜11 years＜31 years. Shannon-Wiener diversity index increased gradually with the succession time, whereas Simpson diversity index increased first and then decreased with increased succession time. Generally speaking, the community changed from the non-equilibrium state to the more stable one.(2) The analysis ofβdiversity between communities showed that, most pair wised P diversity index were relatively high, except that between the communities of 11 years and 31 years of succession periods. Jaccard index and the Sorensen index decreased, while the community similarity index increased, with reduced succession interval between two communities. The natural succession speed was not very fast. Some proper methods, i.e. growing certain plants and artificial fertilization can be taken to speed up community recovery.(3) The production of the community increased with species diversity if these 5 communities were mixed together (p＜0.05, r= 0.914). However, there is no relationship between species diversity and community productivity at the early succession stages (6 years,9years,11 years,21 years) (p＞0.5), whereas the community productivity increased with species diversity at late succession stage (31 years) (P＜0.05, r=0.91).(4) Species traits (SLA, LDMC, LNC, LPC) had no effect on species abundance in all these 5 communities (P＞0.1), except for species abundance and LDMC were positively correlated in 31-year abandoned sample plot(R=0.579,P=0.02). Along the succession scale, SLA was irrelevant (P=0.506,R=-0.083), LNC was positively correlated (R= 0.212, P=0.041), LPC and LDMC negatively correlated (R=-0.287, P=0.034 and R=-0.358, P=0.003, respectively) with succession time.