Study On Species Diversity Of Vascular Plants In Dongting Lake Wetland

Dongting Lake wetland,located in the middle and lower reaches of the Yangtze River,is an important resource bank of wetland in China.It is rich in natural resources and functional in water storage,flood control and maintenance of ecological diversity.Therefore,it is necessary to carry out a comprehensive and systematic survey on plant diversity in Dongting Lake wetland.Based on the field investigation,collection and identification of specimens,reference to previous collection of specimens and relevant literature collection,this paper sorted out the list of vascular plants in Dongting Lake wetland,categorized the ecological types,analyzed its floristic composition,listed the rare and endangered plants in the study area,put forward the protection strategies,analyzed the alien invasive plants,and raise the control strategies.The main research results are as follows:(1)There are 130 families,399 genura,759 species of vascular plants in Dongting Lake wetland(including infraspecies).Excluding exotic and cultivated species,there are 632 famalies,347 genera and 125 families of wild vascular plants,including 18 families,21 genera and 28 families of pteridophytes which account for 4.43%of the total species.And there are 107 families,326 genera and 604 families of seed plants,accounting for 95.57%of the total species.It can be seen that the seed plants in Dongting Lake wetland are absolutely dominant.Gramineae,Compositae,Cyperaceae,Labiatae and Polygonaceae are the dominant families in this area.There are 427 species of wetland plants,which can be divided into 25 species of semi hygrophytes,311 species of hygrophytes,13 species of amphibians,12 species of leaf floating plants,10 species of floating plants,20 species of submerged plants and 36 species of emergents.(2)In Dongting Lake wetland,there are 14 species of rare and endangered plants and 7 endemic genera found in China.The protected plants are rare and the endemic genera are scarce.The characteristics of Dongting Lake flora are not obvious,which shows the hidden domain of wetland vegetation.The phenomenon of single species and genera is prominent,with 226 genera,accounting for 65.13%of the total genera(3)At the familial level,there are 7 distribution types of vascular plant in Dongting Lake wetland,most of which are widely distributed in the world.At the familial level,there are 14 types of distribution areas of vascular plant,including 142 genera of tropical genera(t2-t7 types),accounting for 40.92%of the total genera,135 genera of temperate genera(t8-tl4),accounting for 38.90%of the total genera,and the R/T value is 1.05.And the proportion of temperate genera and tropical genera is close,indicating that the region is deeply affected by temperate floristic elements and tropicelements has.The area has a strong transition at the genus level,which is in line with its subtropical regional characteristics.(4)There are 60 quadrats,including 12 arbor quadrats,14 shrub quadrats and 34 herb quadrats.By calculating the data of quadrat diversity,it is found that the species diversity of arbor forest in Dongting Lake wetland was higher,followed by shrub and grass.(5)The wetland vegetation of Dongting Lake can be divided into 2 groups of vegetation type,7 vegetation types and 91 formations.The most common types are Populus × canadensis formation,Salix matsudana formation,Phragmites australis formation,Triarrhena lutarioriparia formation,Carex formation and Artemisia selengensis formation;The vegetation of Dongting Lake wetland shows three different laws:1)concentric circle distribution under specific habitat;2)Zonal distribution according to the terrain change;3)Block and mosaic distribution according to regional variation.(6)During the investigation,five new records were found in Hunan Province,including Potentilla limprichtii,Cynanchum sublanceolatum,Cyperus odoratus,lipocarpa chinensis and rotboellia laevispica.(7)There are 89 species of alien invasive plants in Dongting Lake wetland,among which Compositae,Amaranthaceae and Gramineae are the most,with a total of 36 species,accounting for 40.45%of the total invasive species.In terms of the origin of invasive species,the species native to America are the most,most of the life forms are herbs,and the breeding mode is seed reproduction.The invasion way is mainly introduced intentionally.This paper introduces the most serious invasive species of Dongting Lake Wetland,such as Eichhornia crassipes and Alternanthera philoxeroides,and puts forward the control strategies for the harm of alien invasive plants.