Study On Woody Species Biodiversity And The Spatial Pattern Of Dominant Species In Ever-Green Mid-Subtropical Broad-Leaved Forest Of Gutianshan Forest Plot

A central issue in community ecology is how biodiversity can be maintained in a forest and how spatial pattern of biodiversity can be shaped. Many theories such as density-dependence effect, niche theory and neutral theory have been evaluated in tropical rain forest. However, there are only a handful of similar studies on subtropical broad-leaved evergreen forest. Based on the operation guide of center for tropical forest science(CTFS), four 20-25hm~2 large, long-term monitoring forest plots have been established in China. In order to reavel community structure and the mechanism of their formation and maintenance, and how different species coexist in subtropical broad-leaved evergreen forest, we examine the diversity, structure and spatial pattern in the 24 hm~2 permanent plot in the mid-subtropical broad leaved evergreen forest at Gutianshan, Zhejiang Province, China. The main results are as follows:We analyzed theα-diversity of 159 wood species(DBH≥10mm) in the permanent plot. The result shows that: In the vertical structure of community, the various indices of diversity between the canopy layer and the sub-tree layer have slight diferences. The species richness and species diversity index of the canopy layer and sub-tree layer are obviously larger than those of the shrub layer. The minimal areas determined by species-area curve were consistently around 4-6.25hm~2, being too large to be applied in the mountainous areas with complex topographies. Compared to the species-area curve, the important value-area curve could fully and objectively reflect the positions and roles of different species playing in the plant communities. So it was more helpful to determining the minimum area of plant communities. Consequently, the minimal sampling area for subtropical evergreen broad-leaved forest in the Gutianshan forest plot was determined to be 2.25hm~2.The DBH size structure of dominant species shows a reversal J type. Ripley K(d) statistics was used to analyze the spatial patterns of dominant species. The results showed that clustering distribution across a range of scales(0～100m). The small-trees tend to be more clumped than mid- and large-trees. Spatial patterns of Neolitsea aurata var. chekiangensis, Camellia chekiang-oleosa, Chimonanthus salicifolius and Eurya rubiginosa var. attenuate vary greatly. Castanopsis eyrei and Schima superba are positively associated at smaller scales and negatively associated at larger scales, so are Castanopsis eyrei and Pinus massoniana, Schima superba and Pinus Massoniana; Rhododendron ovatum and Neolitsea aurata var. chekiangensis, Rhododendron ovatum and Camellia chekiang-oleosa are negatively associated at smaller scales and positively associated at larger scales. Neolitsea aurata var. chekiangensis and Camellia chekiang-oleosa are positively associated at smaller scales and negatively associated at larger scales; Chimonanthus salicifolius and Rhododendron simsii, Rhododendron simsii and Eurya rubiginosa var. attenuate are negatively associated at smaller scales and positively associated at larger scales. Rhododendron simsii and Eurya rubiginosa var. attenuate are negatively associated at 0～100m scales.Density-dependence effect, seed dispersal limitation and niche differentiation might act as a structuring force to maintain the spatial pattern of dominant species in the community.