Assembly of understory woody communities during the close-to-nature restoration of a Pinus massoniana lamb. plantation in the southern subtropical region of China: From environmental filtering to competitive exclusion

In Pinus massoniana Lamb. plantations, the understory plant community has a major role in close-to-nature restoration. However, investigations of the processes that create and maintain understory plant community assemblages on plantations are relatively rare. In this study, we used the method of space instead of time to study the assembly methods of woody communities at different strata in the subtropical P. massoniana plantation in China, in an attempt to discover the driving force of plantation community assembly. We found that soil water content, soil organic matter, and soil temperature were key environmental factors affecting community species composition across strata. The evolution of plant leaf traits was conserved in the shrub stratum and convergent in the tree stratum. While the nearest taxon index (NTI) of plant leaf traits did not change significantly as the close-to-nature restoration progressed, NTI did generally trend towards being dispersed. The phylogeny NTI in the shrub stratum decreased, meaning the community changed from clustered to dispersed. In the tree stratum on the other hand, an increasing phylogeny NTI meant the community changed from dispersed to clustered. Although the aggregation patterns of shrub and tree communities were opposite, the driving force of community assembly was the same, shifting from environmental filtration to competitive exclusion.