Spatial Variation Of Grassland Community Biomass And Its Influencing Factors In Loess Hilly And Gully Region

Loess Plateau is one of the regions with most serious soil erosion in China,restoration and rehabilitation is one of the effective measures to control soil erosion.Plant biomass as an important carrier of material circulation in the ecosystem,is the embodiment of plant productivity,and an important evaluation index of the structure and function of ecological system.There are a lot of researches on relationship between biomass and environment,but it is difficult to carry out the research because the accumulation of plant biomass is a continuous process of a long-term,changes of biomass is small in short-term.Using the functional traits as the medium to study the relationships between plant biomass and environment,is propitious to elucidate the ecological strategy of plants in different environments and the effects on plant biomass accumulation.Researching the relationship between functional traits,plant biomass,and the environment,can provide the basis for the selection of plant species under specific environment and ecosystem stability evaluation,and to provide theoretical basis for fragile habitats of restoration and reconstruction.In view of this,this study in Yanhe River Basin as the study area,to study the relationship between functional traits,plant biomass and the environment,analysis of the impact of environmental changes on plant biomass.Analysis the relationship between biomass and environmental factors,and then combined with the plant phylogenetic to analysis the variation of biomass.Analysis the relationship between functional traits,explore the strategies of plant to respond to environmental changes.Analysis of the relationship between plant biomass and plant functional traits,using the fuctional traits as the medium for exploring plant biomass change to respond to environmental change.The research conclusions are as follows:(1)The community biomass and elevation was negatively correlated,the community biomass and the average temperature was significantly positively correlated,the community biomass and soil moisture content was positively correlated.Different slope positions or aspects will cause differences in plant biomass,Upper slope> Tableland> Middle slope> Lower slope;Tableland > North slope >South slope.(2)Environmental factors and genetic background are the main source of community biomass variation,which is the primary source of heat and water factors of community biomass variation,the genetic background is caused by the main source of community biomass variation,topographic factors are the factor resulted in the lowest impact to community biomass variation.(3)In different phytoformations,no significant difference in community functional traits,but there are significant differences in biomass.Biomass in Stipa bungeana phytoformation and Artemisia sacrorum phytoformation were significantly higher than Heteropappus altaicus phytoformation,Thymus mongolicus phytoformation and Stipa grandis phytoformation.Biomass in Bothriochloa ischcemum phytoformation and Artemisia giraldii phytoformation had no significant difference with other phytoformations.(4)There is a significant positive correlation between plant biomass and plant functional traits.Community height and community biomass are significantly positive correlated.The community biomass was significantly positively correlated with specific leaf area,leaf phosphorus content,root phosphorus content.Plant functional traits can explain some effects of environmental changes on plant biomass accumulation.(5)Functional traits and environmental factors correlation exists.Leaf traits is mainly influenced by rainfall and slope.Root traits,stem traits and biomass are mainly influenced by climate factors and topography factors.