Characteristics and Species Diversity of Semi-Natural Plant Communities on Langqi Island

Simple Summary This study investigated the characteristics and species diversity of semi-natural plant communities on Langqi Island, a coastal island in Fujian Province, China. Additionally, we explored the environmental factors that influenced species diversity and community distribution. The results revealed that the semi-natural plant communities on Langqi Island had rich plant species diversity, with variations in diversity among different plant formations. The soil total potassium and nitrogen contents significantly affect the species diversity of the semi-natural plant communities, whereas the soil pH, soil total nitrogen content, organic matter content, available potassium content, and elevation significantly affect the community distribution. This study can provide important reference information for the construction of semi-natural or artificial plant communities on islands.Abstract (1) Background: Islands are relatively independent and fragile ecosystems with unique habitats. Studying the relatively stable semi-natural plant communities on islands can enrich island vegetation data and provide an understanding of the factors affecting species diversity and distribution. (2) Methods: The semi-natural plant communities on Langqi Island (LI) in Fujian Province were sampled, and the redundancy method was used to analyze the correlation between species diversity, community distribution, and environmental factors. (3) Results: (i) There were 432 species of vascular plants, with 306 genera and 110 families; (ii) the semi-natural plant communities consisted of three vegetation types, 10 formations, and 10 clusters; (iii) the species diversity indices of the semi-natural plant communities presented a trend of gradually decreasing along the shrub, tree, and herb layers. Different formations varied in terms of the species diversity index; and (iv) the soil total potassium and nitrogen contents significantly affected the species diversity of the LI semi-natural plant communities, whereas the pH, soil TN content, organic matter content, AK content, and altitude significantly affected the community distribution. (4) Conclusions: Selecting appropriate tree species for mixed forests based on plant characteristics and regional conditions, together with regulating the soil nutrient content, can improve the species diversity of semi-natural plant communities.