Biodiversity And Endemism Pattern Of Subtropical Evergreen Broadleaf Forest In China

Evergreen broadleaf forest is the most representative vegetation type of subtropical zone in China. But human activity has damaged vegetation and ecological environment in the zone and hence many species face extinction. Concerns over loss of biodiversity have led to biological conservation. Using 1×1 degree grid system of subtropical endemic species range of representative families in subtropical evergreen broadleaf forest, I performed biogeographic research at regional scale to analyze their diversity pattern, endemism pattern, the relationship between these two patterns and the effect of biodiversity-related random effects on endemism pattern. Based on these works, I reached 4 main conclusions as follows:(1) The biodiversity pattern of subtropical endemic species spatially exhibits a gradient of center to sides and a monomial distribution at latitudinal and longitudinal gradient. On the respect of range size structure, a minority of widespread species exerts much more effects on overall diversity pattern than that of a majority of range-restricted species. Furthermore, large-scale climate factors, such as moisture and temperature, cannot explain biodiversity pattern while topography-related elevation difference is significantly correlated to the pattern.(2) The endemism centers of subtropical evergreen broadleaf forest are located at following regions: north-west Yunnan, south-east Yunnan, west Guangxi, west Guangdong and east Guangdong. The endemism centers of representative families also cluster in these five regions respectively. Among those centers, north-west Yunnan and south-east Yunnan to west Guangxi are the most significant regions. Species turnover is intensely focused around those centers of endemism.(3) The correlation between the richness pattern of total endemic species of tropical evergreen broadleaf forest in China and endemism pattern is dim. But a minority of range-restricted species highly correlates with endemism pattern. The degree of correlation between these two patterns varies in accordance with the range size of research objects.(4) After tests by two models, the five centers of endemism cannot be explained by two kinds of random effects. Furthermore, grids with significantly high level endemism score mainly centers in the south-west region while grids with significantly low level endemism score mostly centers in the north-east region. This gradient of endemism could not be attributed to random effects. Because large-scale environmental factors still cannot well explain endemism pattern, the historic progresses and events of this region become one of important determinants of this pattern.