The Relationship Between Plant Community Structure And Soil Erosion In Loess Hilly Area

The Loess Plateau is one of the most areas suffered most from soil erosion in China and even in the world.In order to control soil erosion and improve the ecological environment,a series of vegetation restoration programs have been carried out to restore vegetation.However,the situation of soil erosion has not been fundamentally curbed.The reason is that the current vegetation restoration overemphasizes the increase of vegetation coverage and neglects the vegetation structure.In the study of the relationship between vegetation and soil erosion,vegetation cover is still the most widely used vegetation parameter,and the information of vegetation structure is not fully reflected,and to a certain extent,it also limits the understanding of the mechanism of reducing water and sediment by vegetation.Therefore,this study intends to explore the response relationship between different vegetation structure and soil erosion from the perspective of plant community hierarchy,species diversity and functional diversity,and provide a basis for selecting suitable vegetation parameters.The main conclusions obtained are as follows:1)The functional diversity of plant community has a significant response relationship with the process of runoff and sediment production.The fitting results is y=368.62 x+93.08,R~2=0.55,this means the functional richness of communities has a significant negative correlation with the characteristics of time variation of runoff on slopes.That is,when more niche space is occupied in a community,the function of water storage and sediment reduction is more obvious to the rainfall.The greater the role of closure.At the same time,there is also a negative correlation between the functional richness of the community and the sediment yield of the community.2)Comparative analysis of functional diversity,species diversity index,and sensitivity to runoff and sediment production.Compared with the Simpson index,Shannon-Wiener index,Pielou index that characterize the species diversity of the community.The fitting result with the Simpson index is y=-24.75 x+82.78,R~2=0.11.The fitting result with Shannon-Wiener index is y=-32.96 x+79.73,R~2=0.08.The fitting result with Pielou index is y=40.21x+57.09,R~2=0.14.The R~2 of the regression result between the community functional richness index(FRic)and the slope output is>0.5,and the R~2 of other indexes results are at about 0.1,the functional richness is more sensitive than the species diversity to the response of runoff and sediment production,and it can better reflect the benefits of soil and water conservation in the community.3)The relationship between hierarchical structure of plant community and community production and sediment production was analyzed.The result is that the monolayer community structure's accumulated runoff and cumulative sediment production is 66.87L,78.16L,76.73L,81.74L and 10.52g,102.98g,10.92g,6.13g.The cumulative net flow of the two-layered community structure was 72.48L,64.27L,94.47L,89.69L,and the cumulative sediment yield was 4.98g,26.06g,29.15g,12.07g.The cumulative runoff and cumulative sediment yield for the multi-layer community structure were 16.01L and 5.87g.Compared with the monolayer and two-layered community structure,the multi-layer community structure was significantly reduced compared with the other two communities,with 20.1%and 21.2%.The plant community structure is divided into single layer,double layer and multi-layer structures,and analysis the runoff and sediment production shows that,compared with the multi-layer community structure,the single-layer and double-layer structure of the plant community reduces the flow benefits with the community level.The decrease in structure and continuous reduction,there is no obvious pattern of changes in the benefits of sand reduction,but in general,the benefits of the other two structures have been reduced to varying degrees.The average sand reduction benefit of different levels of structure is less than the average flow reduction benefit,indicating that the hierarchical structure of the community has more role in reducing flow and sand storage.