The Pinus massoniana forest represents the most extensive type of evergreen needleleaf forest vegetation on the islands of Fujian Province. The diversity of plant species and the regeneration of trees in these forests played a decisive role in determining the path of community succession. Dicranopteris pedata,a prevalent understory species in Pinus massoniana forests,exhibits both beneficial ecological functions and characteristics of invasive plants. Exploring its potential impacts on Pinus massoniana forests not only aids in devising effective strategies for plant community conservation but also enhances our understanding of the parallels and differences between native species with invasive characteristics and non-native invaders. This study conducted quadrat surveys about the communities where Dicranopteris pedata and Pinus massoniana coexist on six islands within Sandu Gulf,Fujian Province. We calculated the α and β diversities of herbs,shrubs,trees,and tree seedlings,and decomposed the β diversity into the components of species abundance differences and species turnover. Through regression analysis,we investigated the relationship between the importance value of Dicranopteris pedata and the α diversity of all layers. Furthermore,we used redundancy analysis(RDA) and multiple regression on dissimilarity matrices (MRM) to identify the factors that have significant effects on the α and β diversities across all layers. Finally,path analysis was used to infer the direct and indirect effects of Dicranopteris pedata and environmental factors on plant diversity,as well as their relative significance. The results indicated that: (1) Dicranopteris pedata influenced the α diversity of the grass,shrub layer,and tree seedlings,with explanation rates ranging from 0.45 to 0.90,0.49 to 0.61,and 0.19 to 0.48,respectively. Interestingly,its impact on the Pielou index of tree seedlings differed from that on other layers,showing a positive correlation trend. (2) The decomposition of β diversity revealed that the species turnover dominanted in all layers of the surveyed plots,accounting for over 70% of the total β diversity. Dicranopteris pedata significantly affected the total β diversity of the grass layer,shrub layer,and tree seedlings,with MRM regression coefficients of 0.089,0.034,and 0.051,respectively. It also affected the species turnover of the tree,shrub,and grass layers and the species abundance difference of tree seedlings. (3) The results of the redundancy analysis (RDA) showed that soil pH,distance from the mainland,and the importance value of Dicranopteris pedata jointly affected α diversity,and the total explanation of the first and second axes was 33.03%. The results of the MRM analysis showed that soil factors,canopy closure,geographic distance between plots,and the importance value of Dicranopteris pedata jointly affected β diversity. (4) Correlation and path analyses suggested that soil pH indirectly affected the α and β diversity of the community by fostering an environment conducive to the growth of Dicranopteris pedata. The direct impact of Dicranopteris pedata on diversity was generally greater than that of soil pH,yet soil pH serves as a prerequisite. The direct influence of geographical distance on β diversity was comparable to the importance value of Dicranopteris pedata,with path coefficients exceeding 0.30,and it can indirectly affect β diversity by influencing environmental factors. In conclusion,Dicranopteris pedata significantly affected the α and β diversity of the shrub and grass layers,along with tree seedlings. Environmental factors such as soil pH served as important prerequisites for the influence of Dicranopteris pedata on community diversity. Analogous to invasive plants,the influence of Dicranopteris pedata on α diversity also showed a unimodal trend and had an impact on tree regeneration.