Abstract: By using a line sampling a total of 36 gaps were measured in the coumunity of Castanopsis eyrei in the nature reserve area of Zhawan located in south Anhui Province. The gaps were classified into three types based on it area,large gap with area of 300m²~400m²,middle 100m²~200m² and small <100m². 5 samples of (4×4m²) were set for each type of gaps and under canope,and results of sample investigation showed that there were 18 tree species in large gap,11 in middle and 13 in small one; for understory species there are 28 in big gap,21 in both middle and small one respectively. Based on species of important value,Alnus trabeculosa was listed at first in both big gap and middle one,but Meliosma veitchiorum and Castanopsis eyrei were at top in small gap; young seedling of Cyclobalanopsis myrsinaefolia and herb species Woodwardia japonica are dominant in understory in the 3 gaps of different size. This indicated that Cyclobalanopsis myrsinaefolia could grow up into canopy layer and will be dominant species in future.Both of the number of tree species and richness in gaps was higher than that in non-gap,but ecological evenness in gap was lower compared to that in non-gap,Its similar to shrub herb species. Species diversity of tree species was the highest in gaps of 300~400m² and the lowest in that of 100~200m². SW diversity index and evenness index for different gaps could be list in order as the follows:big gap > middle gap > small gap,for ecological dominance:middle gap > big gap > small gap. The species richness of the shrub tree and herb species was listed at top in gaps of 300~400m²,and in the smaller gap area the richness could be lower. The species diversity for both shrub herb species was at top in big gap,and ecological dominance index was the lowest in small gaps,but the highest in middle gaps.

Key words: gaps, species diversity, Castanopsis eyrei stand, Zhawan Nature Reserve, Anhui Province