STUDIES ON SPECIES DIVERSITY IN THE SECONDARY SUCCESSION OF THE EVERGREEN BROADLEAVED FORESTS IN JINYUN MOUNTAIN OF SICHUAN PROVINCE

The stratal species diversity of the secondary serial communities of the evergreen broadleaved forests in Jinyun Mountain is measured by the method of a grid contiguous quadrat along a transection. From the stratal diversity-area curves it is illustrated that the species richness (S) is higher, but the equitability and individual density are lower, and the minium diversity area size is also larger, and that the H_A and H_N-area curves are similar to S-curve and relatively flatten, while the H_C and H_D-area curves somewhat fluctuate. H_N and H_A in terms of individuals and abandance of species could express the information content of diversity for communities. It is statistically shown that the variability of diversity for communities with higher J is lower, while those with smaller J is higher. During succession, S of each stratum increases constantly; J is higher and H is associated positively with S at the initial phase of the shrub and herb strata, and later J decreases and H relates to J positively. However, H of tree stratum is always not negatively correlated to J. Mainly the variation in the life form composition are characterized by the decreasing of herbs, particularly of annuals, and by the decreasing of tree species, both in tha amount and in the role played in the communities. The diversity of climax communities situated in diffrent sites differenetiates according to the reducing sequence from herb to shrub to tree strata. The dominance-diversity curves based on Ⅳ could be represented from a straight line with no steep slope p ogressively to a typical sigmoid curve. Two questions, on the measurement of diversity and on the stability-diversity during succession, are also discussed in detail.