Ecological Research On Wetland Plant Community In Diecai District Of Guilin City

In this study,the ecological characteristics of wetland plant communities in Diecai District of Guilin were systematically studied by using conventional community survey methods.Using many field surveys,species composition,characteristics of the flora,classification system,community characteristics,distribution characteristics,biomass composition,and species diversity were quantified and combined with protection status of wetlands in Diecai District.The analysis provides options for the development,utilization,protection,and management of the wetland vegetation resources.The research results are as follows:1.Taxonomic diversity of wetland vegetation in Diecai District included 71 families,167genera and 251 species.Of these,bryophytes comprised 1 family,1 genus,and 1 species.Ferns comprised 5 families,7 genera,and 8 species.Gymnosperms comprised 1 family,2genera,and 2 species.Dicotyledonous angiosperms were the most common group in the wetland communities,comprising 51 families,98 genera,and 148 species.Monocotyledonous angiosperms comprised 13 families,59 genera and 92 species.The dominant families of monocots were Gramineae and Cyperaceae,which contain 31 genera and 36 species and 9genera and 27 species,respectively.There were 15 cultivated species and 25 invasive species.Of the ferns,3 families represented are globally distributed,and one family each are of tropical and temperate distribution;four genera are globally distributed,and two genera have a tropical distribution.The types of distribution of seed plant families can be divided into 6types and 1 subtype.Among them,33 families are globally distributed;18 families are from the tropics,accounting for 72%of the total number of families,while 7 families are from the temperate zone,accounting for 28%of the familes.The types of distribution of surveyed genera can be divided into 12 types and 8 subtypes.Among them,42 genera are globally distributed;73 genera are of tropical origin,accounting for 70.18%of the total number of genera,and 28 genera are of temperate origin,accounting for 27.87%of genera.Genera endemic to China include Eomecon and Sheareria,accounting for 1.92%of genera..In general,the wetland flora of Diecai District is characterized by obvious tropical and subtropical lineages and lacks endemic families.2.Wetland vegetation in Diecai District can be divided into four vegetation types:coniferous forest,broad-leaved forest,shrubs,and grasses.Deciduous coniferous forest wetland Vegetation type,deciduous broad-leaved forest wetland vegetation type,deciduous broad-leaved shrub wetland vegetation type,sedge grass wetland vegetation type,grasses grass wetland vegetation type,weed grass wetland vegetation type,emergent grass wetland vegetation type,floating grass wetland vegetation type,free-floating grass wetland vegetation type,submerged grass wetland vegetation type.There are 10 vegetation types and 82formation types of the wetland vegetation type3.Wetland vegetation in Diecai District is mainly distributed shallow waters,floodplains,river banks,paddy fields,and swamps of the Diecai section of the Lijiang River.The wetlands in Diecai District are dominated by weed-type grasses and emergent grasses,while the floodplain and Jiangxinzhou are dominated by deciduous broad-leaved forests,deciduous broad-leaved shrubs,grass-type grasses,and weed-type grasses.The main species are Form.Salix babylonica,Form.Salix chaenomeloides,Form.Celosia argentea,Form.Cynodon dactylon,Form.Polygonum capitatum,etc.Submerged grasses,emerging grasses,floating grasses,and floating leaf grasses are mainly distributed in the shallow waters of the Diecai section of the Lijiang River,as well as in paddy fields and ponds.The main species are Form.Ceratophyllum platyacanthum subsp.oryzetorum,Form.Egeria densa,Form.Halophial verticillata,Form.Nelumbo nucifera,Form.Typha angustifolia,etc.The wetland communities in Diecai District are often dominated by single species and,therefore,have simple community structure and low species diversity.4.A gradient in moisture among rivers in Diecai District results in a gradient of wetland communities:submerged plant community?floating plant community?wet plant community?semi-humid plant community.Similarly,a moisture gradient among natural ponds results in a gradient in wetland communities:submerged plant community,floating plant community?emerging water Plant community?wet plant community.Field marshes have fewer communities along moisture gradients:emergent plant community?wet plant community.5.Biomass differed among wetland vegetation types in Diecai District.Among the floating plant communities,the Eichhornia crassipes community had the highest biomass(479.62 g·dw/m~2)among the emergent plant communities;the Cladium jamacence subsp.chinense community had the largest biomass(3471.7 g·dw/m~2);in the submerged plant communities,the Ludwigia adscendens community had the highest biomass(407.1 g·dw/m~2);in the wet plant community,the Arundo donax community had the highest biomass(1169.41 g·dw/m~2).The main factors affecting the biomass of wetland vegetation are species composition,season,and water depth.6.Overall,wetland communities in Diecai District were relatively species-poor.The Simpson index,Shannon-Weiner index,and Pielou evenness index all varied greatly among different community types,indicating that communities have different species compositions,hierarchical structures,and habitat conditions.7.The main challenges confronting the wetland vegetation of Diecai District are:serious water shortage in the dry season,continuous reduction of wetland area,the over-utilization of wetland vegetation resources,and increasing competition from invasive alien species.For this reason,the following suggestions are put forward for the development,utilization,protection,and management of wetland vegetation resources:(1)Further improve wetland protection laws and regulations;(2)Strengthen the publicity and education of the importance of wetland vegetation;(3)Take effective measures to further control the excessive utilization of wetland vegetation resources;(4)Strengthen research and establish a dynamic monitoring system for wetland vegetation resources;(5)Strengthen the restoration and reconstruction of degraded wetland vegetation.