The Characteristics Of Typical Island Vegetation And Its Relationship With Environment In Eastern China

The environmental conditions of the islands are special and the ecosystem stability is poor due to the influence of geographical isolation in the sea area.Vegetation is the main part and the structural basis of island land ecosystem,which plays an important role in maintaining the structural stability of the ecosystem and preventing soil erosion and so on.Therefore,it is of great significance to understand the island vegetation status for the utilization of island plant resources and ecological environment protection.Taking typical islands in eastern China as an example,this paper discusses the relationship between vegetation and environment in different aspects,including vegetation types,community types,species and plant functional traits,based on the plant community survey.It is helpful to understand the distribution characteristics of island vegetation and the adaptation of plants to the special environment of islands.This research is mainly put into practice in the following three parts:Firstly,the vegetation types and community types in 7 typical islands,including North Changshan Island,Miao Island,South Changshan Island,Qinshan Island,Dajinshan Island,Fenghuo Island and Dayu Island,were investigated and the vegetation types and community type in 61 other islands were collected through literature.Based on the environmental data,including latitude,mean annual temperature(MAT),island area,distance to the continent,the highest elevation,and mean annual precipitation(MAP),the distribution characteristics and environmental interpretation of the vegetation types in the eastern islands of China are discussed.Secondly,6 functional traits,including diameter at breast height(DBH),tree height(H),mean leaf area(MLA),specific leaf area(SLA),twig wood dendity(TWD)and twig water content(TWC),were measured in 7 typical islands.We analyzed the numerical range of each functional trait and their differences among different islands and climatic zones.Finally,the correlation between the plants functional traits and climate(MAT,MAP and mean annual wind speed/MAWS)and soil factors(soil total carbon/TC,soil total nitrogen/TN,soil total phosphorus/TP and soil water content/SWC)was analyzed.The main influencing factors were discussed from species and community level respectively.The results of this study are as follows:(1)The vegetation types of islands in eastern China are mainly affected by climatic conditions(MAT and MAP).The change of vegetation type from north to south is basically consistent with the change of land forest vegetation type,showing the evolution from coniferous forest,conifer-broadleaf forest,broadleaved deciduous forest,evergreen deciduous broadleaved mixed forest to evergreen broadleaved forest.The theory of island biogeography can influence the vegetation types and plant community types indirectly by species richness.And the large area of the island is easy to form an arbor-oriented community,while the smaller area of the island vegetation is mainly shrub and grass.(2)The mean values(±standard error)of DBH,H,MLA,SLA,TWD and TWC of typical islands in eastern China are 17.27±1.43cm,3.07±0.17m,43.77±5.52cm~2,151.99±6.68cm~2/g,172.55±33.48g/cm~3 and 0.58±0.01g/g.The ranges of variation are1.62-100.56cm,0.70-8.64m,1.08-331.51cm~2,24.79-559.18cm~2/g,1.58-3671.71g/cm~2and 0.23-0.88g/g.The degree of variation of TWD is the highest and the variation of TWC is the least.There are significant differences in the DBH,H,MLA,TWD and TWC among some islands,and there is no significant difference in SLA.Compared with the southern islands such as Fenghuo Island,Miao Island and other northern islands have higher MLA,and the TWC of southern island plants is obviously higher than that of northern islands.The functional traits of evergreen and deciduous plants are different in different climatic zones which showed that the degree of response and adaptability of plants to the environment varied with life forms.(3)The plant functional traits in typical islands of eastern China have different responses to climate and soil factors at community and species levels respectively.And responses of the same trait to environmental factors at community and species levels are different.At community level,plant functional traits were mainly influenced by climatic factors,and the hydrothermal condition is the dominant factor,which is consistent with the results of the study on the functional traits of terrestrial forest plants on similar scales(such as North-South Transect).At species level,plant functional traits are significantly affected by soil factors.In addition,the plant small-branch traits are significantly influenced by the wind conditions in the islands.