Plant Community Types And Functional Diversity Of Islands Forests In Eastern China

The mechanism of the formation and maintenance of biological diversity that is community assembly mechanism has been the core topics of ecology.At present,there are more comprehensive and detailed studies on the scales of terrestrial ecosystems,but there are few studies on island research,especially on large regional scales.Therefore,this paper is based on typical islands in eastern China.The region covers Shandong,Jiangsu,Shanghai,Zhejiang and Fujian provinces.It covers four ecoregions in the warm temperate zone,the subtropical Asia,the subtropics and the subtropical Asia.Of the large scale range.A comprehensive survey of vegetation and environmental factors was carried out for each island.The vegetation types of each island were not only divided into vegetation types,but also the vegetation scale of the eastern island of China.Based on the 15 functional traits of each species in the plot,the weighted average of the community and the Rao quadratic entropy index of each trait were calculated.By means of principal component analysis and linear regression analysis,the plant traits were diversified.Finally,in order to verify that the environment is the main source of variation of plant functional traits,the relationship between plant functional traits and environmental variables was examined by RLQ(environment,plant traits,species abundance matrix)and Fourth-corner method.Significance.The main results and conclusions are as follows:(1)In the classification of plant community types,the advanced units were divided into 13 types according to the appearance principle:evergreen broad-leaved forest,evergreen and deciduous broad-leaved mixed forest,deciduous broad-leaved forest,coniferous forest,coniferous and broad-leaved mixed forest,evergreen Deciduous broad-leaved mixed shrub,coniferous and broad-leaved shrub,coniferous shrub,evergreen and deciduous mixed shrub,evergreen broadleaf shrub,deciduous broad-leaved shrub,native grass,salt grass and sand grass.The intermediate units are mainly based on the principle of flora,taking into account the role of dominant species and identification species in classification.Among the 13 major types,84 community types are divided.Which comprehensively covers the vegetation types of the study area islands,and records the vegetation status of the islands in detail,which can be helpful for the future research work.(2)In the relationship between plant functional traits and environmental variables,In the forest community,the community weighted mean trait and mass leaf density was positively correlated with the first principal component of the environment(p<0.01).There was a significant negative correlation between the density of dry matter,the ratio of nitrogen to phosphorus,leaf nitrogen content,branch density,average leaf area and amber value to the first principal component(p<0.05).The Rao quadratic entropy index of mass leaf density was positively correlated with the first principal component(p<0.05).The Rao quadratic entropy index of mean leaf area,amber value and branch density was negatively correlated with the first principal component(p<0.05).In the shrub community,the weighted average of the community of mass leaf density was positively correlated with the first principal component(p<0.05).There was a significant negative correlation between the weighted average of the branch density and specific leaf area and the first principal component(p<0.05).The Rao quadratic entropy index of branch density was negatively correlated with the first principal component(p<0.05).There was a significant positive correlation between the weighted average of leaf phosphorus content and the second principal component(p<0.05).There was a significant negative correlation between the weighted average of the nitrogen and phosphorus ratios and the second principal component(p<0.05).The Rao quadratic entropy index of nitrogen/phosphorus ratio was negatively correlated with the second principal component(p<0.05).(3)Fourth-corner analysis showed that there were more species with high branch density and leaf nitrogen and phosphorus contents in the high latitudes with larger annual evaporation and higher wind speed.In the low latitudes,the climate is more humid,the soil moisture content is higher,wind speed is also lower.In this environment,the species with high leaf carbon-nitrogen ratio and branch,twig water content and low branch density are higher.The results showed that the leaf nitrogen and phosphorus content and branch density were significantly higher than that of branch lets,and the dry matter density,specific leaf area,leaf dry matter content,It is possible that the hydrothermal gradient and wind gradient caused by the latitude gradient in the island habitat are the main environmental factors that affect the spatial distribution of plant traits.