Habitat Associations Contributing To The Maintenance Of Biodiversity In A Subtropical Forest Plot

A central issue in community ecology is how different species coexist and how biodiversity can be maintained in a forest. Presently, many theories have been advanced to explain how species richness is maintained, but a little concensus has been reached. There are two major perspectives of species coexistence: niches theory and neutral theory. However, there are only a handful of similar studies on subtropical broad-leaved evergreen forest. To provide further information and evidences and reveal the contributions of niches theory and neutral theory to maintenance mechanisms of biodiversity in subtropical broad-leaved evergreen forest, we examine the species-habitat associations in the forest of 24 hm2 Gutianshan plot in Zhejiang province, China.We analyzed the relationship between microtopography (mean elevation, convexity, slope) and the distribution of 106 wood species with individuals>18 stems and DBH≥10mm in the 24- hm2 permanent plot in the subtropical broad-leaved evergreen forest at Gutianshan, Zhejiang Province, China. We used Chi-squared test to analyze the species-habitat associations. Our results indicated that 84 (79%) out of 106 species were shown significant associations with microtopographical variation (P<0.05). We also employed canonical correspondence analysis (CCA) and permutation test to analyze the species distributions constrained by habitat factors. The results of CCA and permutation test showed that most of species display high correlation with different habitat types. Using chi-quared test to analysze the most dominant ten species and all the 60 rare species(individuals≤24), both dominant and rare species showed important correlation with different habitat types. However, most dominant distributing to all kind of habitats in despite of habitat preferences showed that habitat specialization is not the only key factor. Rare species have shown strong habitat preference. These results indicated that the species in Gutianshan plot had strong differentiation of microtopographic niche. We therefore conclude that the community was niche structured and species coexistence in this case. However, we can not provide the evidences to refuse neutral theory because many species including some common and rare species are generalist species.