Relationships Between The Community Characteristics And Topography Parameters Of Evergreen Broad-leaved Forest In Tiantong's 20 Ha Dynamic Plot, Zhejiang Province, Eastern China

The vegetation in Tiantong national park is the typical subtropical evergreen broad-leaved forest in China, which is preserved with Tiantong temple. In addition, this type of vegetation is particular in the same latitude of the world, leading to its important role as a ideal place for ecological research. In this research, a 20 hectare forest dynamic plot which is one of plots in Chinese forest biodiversity monitoring network is studied, we analyze the relationship between community characteristics (species diversity, parameters of biomass, sprout and branch) and topography factors (altitude, convexity, slope),and get three main conclusions as following:(1) The sum of basal area and stem density were deemed the biomass index; species richness, Shannon-Wiener index, Jaccard index etc. were regarded as species diversity index. It was found that stem density was significantly positive correlated with species richness. As the number of species increased intensity of interspecific competitive exclusion would rise, this could induced the decreasing of the amount of stems, while the niche differentiation might have the opposite effects. The latter one played a greater role in the present example—species enhanced their competitive ability by raising the number of respective individuals. The unimodal relationship between the sum of basal area and species richness, which is coincided with the results of previous studies that maximum productivity occurred at intermediate levels of species richness.(2) Plots with strong topographic and environmental heterogeneity have higher species diversity, because the micro-environment of such habitats tend to be varied in microclimate, different species get the resources they need, leading to a moderating interspecific competitive exclusion. The correlation rusults between biomass (basal area; stem density) and terrain factors show that the habitat with higher topographic heterogeneity is more conducive to the growth of plants, which is also the result of different plant species share different niche differentiation in the community. Due to less interference, the area in the middle altitude of the dynamic plot have more mature community and the highest biomass. From the point of life form, evergreen species grow well in the higher ground, while the deciduous species in the valley lowlands.(3) As regeneration and growth strategy of plants, sprouting and branching commonly grow well in two habitat types:one is the habitat with higher extent and frequence of disturbance, and the other is the habitat with higher heterogenicity. It is obvious to explain this. When plants face to severe environment, they need to occupy the favourable niche by sprouting and branching, which is a shortcut to maintain its fast growth and development, then the branch can get resource through physiological and morphological adjustment in the completion. The highly positive relationship between mean no. sprout and species richness also fully prove the conclusion above.