Objective To analyze the interspecific relationship of primary coastal plant communities in Pingtan Island and further understand the structural characteristics and coexistence mechanism of coastal plant communities.

Method Based on community survey, the interspecific association and correlation analysis of dominant species (importance value ny) of plant community in four typical habitat types (bedrock shrub, hilly shrub, sandy meadow and bedrock grass) in Pingtan Island were carried out by the variance ratio method (VR), in Pingtan Island were carried out by the variance ratio method (lysis of dominant specie(CCA sorting), and the ecological species groups were divided.

Result The coastal plant communities of the four habitats were significantly positively correlated (VR > 1, W > χ²_0.05(N)), and the community was relatively stable as a whole. The association and correlation between most species pairs were not significant (P > 0.05), and the interspecific independence was strong. Overall positive and negative association and correlation ratio was greater than 1, showing a positive association and positive correlation trend.

Conclusion Spearman rank correlation coefficient test has higher significance rate of interspecific correlation and higher sensitivity than χpearman rank correlation coefficient test has higher significance racan be divided into 4 ecological species groups according to the results of R language CCA sorting and interspecific correlation analysis. These 4 groups correspond to 4 habitats. In the restoration and protection of native coastal vegetation in Pingtan Island, the interspecific relationship and environmental adaptability of species should be fully considered, and the appropriate ecological species groups should be selected for planting. In the bedrock habitat with high soil salinity, the ecological species group I: Peucedanum japonicum, Crepidiastrum lanceolatum, Vitex trifolia, etc. The ecological species group II is suitable for planting in the low mountains and hills with large soil volume, high altitude and high rock exposure rate: Eurya emarginata, Elaeagnus pungens, Ficus pumila, etc. On the coastline of sandy soil with low soil salinity and loose soil, ecological species group III is selected for planting: Oenothera drummondii, Calystegia soldanella, Glehnia littoralis, etc. In the soil with relatively high water content, ecological species IV is selected for planting: Berchemia sinica, Heteropappus ciliosus, Lycoris radiata, etc.