Research For The Response Relationships Of Habitat Factors To Community Structure And Spatial Pattern Of Vegetation In The Horqin Sandy Land

The type and structure of vegetationcommunityin this region were investigated in relation to environmental factors using MRT and DCCAbased on the 19 natural vegetation samples' data of vegetation and habitat factors,which area were 50 m×50 m,and the relationships between environmental factors and distribution pattern of vegetationin the Semi-arid Desertification Area were verified by establishing SEM firstly,such as terrainconditions,hydrology conditions,surfacesoil conditions.The main conclusions were as follows:(1)Taking vegetation community of Agriophyllum squarrosum in mobile sand dunes as the starting point of vegetation restoration,combined with the research result of the different sampling scales shows that the advantages of natural vegetation in the study area are:Agriophyllum squarrosum?Setaria viridis?Eleusine indica,Bassia dasyphylla and Artemisia halodendron?Medicago sativa,Polygonum divaricatum and Hedysarum fruticosum?Leymus chinenis and Caragana microphylla.(2)The plant communities in this region could be divided into 4 types by MRT,which was named vegetation community of Artemisia halodendron,vegetation community of Leymus chinensis,vegetation community of Caragana microphylla and vegetation community of Phragmites australis.The Shannon diversity index,vegetation coverage and biomass of the Artemisia halodendron community were different from the others,and its living environment were worst among the four communities.There was similar living environment in Artemisia halodendron community and Caragana microphyllacommunity.The Phragmites australiscommunity distributed in the edge of the lake,in these regions,the groundwater level depth were less than 1 m,the water-holding capacity of soil was best,the vegetationgrowed well,but due to severe salinization,the community vegetation diversity was low.(3)Using underground water level depth as the observation variables of "hydrology condition" was batter than using underground water level as the observation variables of"hydrology condition" and height as the observation variables of "terrain condition" to the model simulation result.(4)In order to verifiy the direct and indirect relationship among terrain,hydrology,soil.and vegetation succession,we established SEM.The simulation results showthat:The "surface soil condition" had bigger direct influence on the "hydrologic conditiont"and "vegetation spatial pattern",and the direct influencing coefficients were 0.91 and 0.66,respectively."Terrain conditions" had an indirect influence on the "spatial pattern of vegetation" and "hydrological conditions" mainly through affecting the "surface soil conditions" directly,and the indirect influencing coefficients were 0.46 and 0.63,respectively.Due to the limitations of the data acquisition time and the study area,the"hydrological conditions" that only response to underground water level depth and soil volumetric water content had a little effects on the spatial pattern of vegetation,and the total influencing coefficient was 0.22.