Analysis of α Diversity in Artificially Assisted Regeneration Castanopsis carlesii Secondary Forest

In 2022，the secondary forest of Castanopsis carlesii，which has been artificially assisted regeneration by different thinning intensities(heavy thinning，moderate thinning，low thinning) for 40 years in the state-owned forest farm of Youxi County，Fujian Province，was taken as the research object to explore the characteristics of community structure and species diversity of artificially assisted regeneration of Castanopsis carlesii. The results showed that：the analysis of species-area accumulation curve showed that the sampling was sufficient in the study area，four mathematical models were selected to fit the species-area accumulation curve of the community as a whole，and the logarithmic square function was selected as the optimal fitting model，the equation was S=(2. 9804+1. 7418logA)². The species composition is relatively rich，and the community has a total of 39 families，58 genera and 102 species；Castanopsis carlesii has the highest important value and forms the dominant tree species in the tree layer；with the increase of directional interference intensity，the impact on the important value of the target species increases gradually. There were no significant differences in species richness，Shannon index，Simpson index and different thinning intensity；and there were significant differences in tree，shrub and herb layer，the order of species richness，Shannon index，Simpson index and rarefy was shrub layer＞tree layer＞herb layer. The results can provide reference for vegetation restoration and species allocation of zonal evergreen broad-leaved forest in this region.