Plant Community Characteristics And Related Environmental Factors Of 6 Islands In Pingtan

The related research on island plant communities has important guiding significance for the protection and rational use of island plant resources.In this paper,the plant community of six uninhabited islands in Pingtan was investigated by means of a combination of sample line method and sample method,and the soil and topographic factors in the sample were measured.The characteristics of plant resources,community characteristics and diversity were analyzed.Redundancy analysis(RDA)was used to analyze the correlation between species composition and diversity of island plant communities and soil and topographic factors,and to explore the influencing factors.In order to provide theoretical reference and data support for screening suitable plants in coastal cities such as Pingtan,optimizing local plant community allocation and creating landscapes with seaside features.Research indicates:(1)There are 208 species of 182 genera in 73 families(including 3 subspecies and 6 varieties)of vascular plants in 6 islands,ratio of genus and species was 87.50%.Among them,there are 164 species of 150 genera in 60 families of native plants,and 34 species of 32 genera in 22 families of exotic plants,including 21 species of 23 genera in 13 families of alien invasive plants,Monitoring and management should be strengthened.According to the survey,there are 29 families,54 genera and 55 species of plants with coastal or island characteristics,including the National Second-Class Protected Plants Glehnia littoralis of Dasong Island.At the level of families and genera,families with more than 10 species are Compositae,Gramineae and Leguminosae,and single family and genera are dominant.In floristic geography,the native plants and exotic plant families and genera are mainly tropical,which is consistent with the geographical distribution characteristics of Pingtan,and the alien plants have a certain influence on the geographical composition of the flora.(2)Among the texture characteristics of the island plant community structure: 64.90% of the growth form were herbaceous plants,and 87.02% of the life type were phanerophytes,hemicryptophytes and therophytes.In the characteristics of the leaves,the leaf size are mainly nanophyll and microphyll,accounting for 83.65%.The dominant leaf quality were sclerophyll,papery and succulent,accounting for 67.31%,and 49.04% of the leaves were hairy.Leaf margins and leaf types are dominated by whole leaves and single leaves.In the fruit type,mainly the capsule,achene,caryopsis,stone fruit,and berries,the way of transmission mainly relies on wind,birds and other few flying animals.(3)The plant communities of each island are divided into Formation according to the principle of vegetation.there is Form.Casuarina equisetifolia and Form.Pinus thunbergii in Guangyou Island.There is Form.Pinus thunbergii in Hongshan Island.There is Form.Acacia confuse+Casuarina equisetifolia in Beixianglu Island.there is Form.Casuarina equisetifolia,Form.Acacia confuse and Form.Pinus thunbergii+Eurya emarginata in Dasong Island.there is Form.Pinus thunbergii+Eurya emarginata in Xiaosong Island.there is Form.Casuarina equisetifolia in Huangmen Island.There are slight differences in the structural characteristics of each community type.The shrub layer dominated the diversity index of the five types of plant communities at all levels.Among the community types,the diversity index of Form.Pinus thunbergii+Eurya emarginata was more prominent in tree layer,while that of Form.Acacia confuse was more prominent in shrub layer and herb layer.In addition to the Pielou evenness index,the diversity index is lower than the uninhabited islands of Xiamen and Zhejiang,as well as the nearby inland areas.(4)Redundancy analysis of important values and environmental factors of island plant communities: soil pH,organic matter content,total nitrogen content,total phosphorus content,alkali nitrogen content,available phosphorus content,and aspect direction are the species distribution of island plant communities the main environmental factors.The species distribution of Form.Acacia confuse+Casuarina equisetifolia was positively correlated with the slope direction,soil alkali nitrogen content and available phosphorus content.Soil pH significantly affected the species distribution of Form.Pinus thunbergii+Eurya emarginata and Form.Pinus thunbergii.The soil factor and topographic factor explained 44.63% and 7.67% respectively,the common interpretation of environmental factors to species distribution was 13.49%,and 86.51% of undiscovered environmental factors and human disturbance factors still exist.