Distribution Patterns and Environmental Determinants of Invasive Alien Plants on Subtropical Islands (Fujian, China)

Abstract

Plant invasions threaten the biodiversity of islands, causing serious impacts on their ecosystems. To investigate the distribution patterns of invasive alien plants on subtropical islands, the environmental determinants of species richness, and the growth forms of invasive alien plants, this study analyzed the composition and origin of invasive alien plants on 77 islands in Fujian. The similarity in the distribution of invasive alien plants between islands was assessed using the UPGMA. Moreover, feature selection, best-subset regression, and variance decomposition were performed using 19 environmental variables characterizing climate, anthropogenic disturbance, and landscape/geography, as well as the species richness and growth forms of invasive alien plants. Through the analysis, the main environmental factors affecting the species richness and growth forms of invasive alien plants on the Fujian islands were identified. The results showed 142 species of invasive alien plants in 38 families and 102 genera on 77 islands in Fujian. Annual herbs constituted the most representative growth form of invasive alien plants and tropical America was the main origin of invasive alien plants. The distribution of invasive alien plants across the 77 islands in Fujian showed a high degree of similarity, suggesting a nested pattern in their distribution. The proportions of building and farmland area (BFA), island area (A), and maximum elevation (ME) were the main driving factors of species richness and growth forms for invasive alien plants. In particular, BFA played a key role in driving plant invasion. The results of this study can help establish an early warning mechanism for invasive alien plants and better implement island ecological management, which are important for the protection of subtropical island ecosystems.