Study On Interspcific Association And Niche Communities In Taibai Moutain

Based on the populations and coverages of Pyrola decorata and Pyrola calliantha communities in Taibai Moutain, the paper covered six parts:testing the overall association with analysis of variance ratio、testing the interspecific association of all species-pairs via X2-test based on a2×2contingency table and the test of association indices (Jaccard、Dice and Ochiai)、niche breadth, niche similar proportion and niche overlap for main species. The results were as follows:(1) interspecific association of Pyrola Decorata community:The overall association of24species in the community was slightly positive. The proportion of positive and negative association was0.9; Just5species-pairs were revealed significant positive association,2species-pairs observed very significant positive association, and the rest were all under significant level.84.42%Jaccard index of the species-pairs in the community was under0.25,91.66%Dice index under0.5and89.85%Ochiai under0.5. These reflect the interspecific association of the species is low, who are independent.(2) niche of Pyrola Decorata community:In the community, importance value of Pyrola Decorata was higher than others. Niche breadth values of24species were all above0.4. There were20.29%species-pairs, whose niche similar proportion was above0.2. On the whole, the similarity ratio was higher between the species with larger niche breadth and Pyrola decorata, and that was lower for the species with smaller niche breadth. Niche overlap Lik was higher than Lki, but the values were all very low. What was more, niche overlap was lower between Pyrola decorata and the species with smaller niche breadth, and Lkl was also lower.(3) interspecific association of Pyrola calliantha community:The overall association of15species in the community was slightly positive (VR=1.028>1). The numbers of species-pairs who had positive and negative association were almost the same. Most of the Jaccard index between species-pairs were0-0.4, most Dice index and Ochiai index between0.2and0.6; the interspecific associations of species-pairs were low.(4) niche of Pyrola calliantha community:Niche breadth values of Pyrola calliantha, Saussurea licentiana, Carex rigescens, Fragaria vesca and Viola verecunda were higher (above1.0); others were very low. Among15main species, there were only15.24%species-pairs (16pairs), whose niche similar proportion was above0.5000; the similarity ratio was higher between the species with larger niche breadth and Pyrola calliantha, and that was lower for the species with smaller niche breadth. Niche overlap between15main species mostly focused on0.0300-0.1400(Lik) and0-0.1400(Lki), who had an obvious trend sharing the resource, in a relatively stable state; for Pyrola calliantha, Lik was obviously above Lki, what was more, niche overlap was lower between Pyrola calliantha and the species with smaller niche breadth, and Lkl was also lower.