Population structure and community characteristics of Pseudotsuga sinensis Dode in Badagongshan, Hunan Province, China

Pseudotsuga sinensis is a National Class Ⅱ protected plant species. To understand its population dynamics and underlying mechanism, we investigated the P. sinensis communities in the largest distribution area in Badagongshan, Hunan Province, China, and analyzed the species composition, vertical structure, size structure, and species diversity. Results showed that:(1) A total of 132 vascular plant species were recorded, belonging to 89 genera in 48 families. The canopy was divided into distinct tree, shrub, and herb layers. Pseudotsuga sinensis was the dominant tree-layer species, with Loropetalum chinense, Pinus massoniana,and Vernicia fordii as companion species. Loropetalum chinense was the dominant shrub-layer species and Dryopteris setosa was the dominant herb-layer species;(2) Most species in the community were subtropical to temperate zone transition species; (3) The P. sinensis population was divided into two types:stable to decaying stage and declining population stage; (4) Species diversity in the P. sinensis and Castanopsis tibetana mixed forest was higher than that in the P. sinensis forest. The highest species diversity was found in the shrub layer, followed by the tree and herb layers. Seedlings and saplings were lacking in the six study plots, thus potentially affecting population stability. This may be due to high canopy closure, which can inhibit seedling regeneration. We suggest that creating canopy gaps and long-term monitoring may help species regeneration and population stability.