Effects Of Different Slope Positions On Community Characteristics And Functional Traits Of Dominant Plants In Desert Steppe

Desert steppe is an important part of grassland.Because it is a desert steppe ecosystem in transition from grassland area to desert area,its productivity and species diversity are low.And with the deterioration of the ecological environment,the degree of desertification is increasing.Therefore,it will have an important impact on the growth of plants and the distribution of communities.In this study,Xilamuren desert steppe was selected as a typical research area,and the effects of different slope positions on plant community structure and functional traits of desert steppe were analyzed through field investigation and laboratory experiment.The main findings are as follows:(1)Different slope positions affect the physical and chemical properties of soil.Soil moisture content,organic matter,total carbon,total nitrogen and total phosphorus contents were in the order of lower slope > upper slope > middle slope.Soil gravel and silt contents were the highest on the upper slope,and clay contents were the highest on the lower slope.In the 0-30 cm soil layer in the study area,with the increase of soil depth,soil water content gradually increased,soil gravel and silt contents first increased and then decreased,soil clay contents first decreased and then increased,and soil organic matter,total carbon,total nitrogen and total phosphorus contents gradually decreased.Overall,soil total carbon,total nitrogen,total phosphorus content and soil water content were most significantly affected by slope location.(2)The characteristics of plant community were affected by different slope positions.A total of 39 species belonging to 22 families and 33 genera were counted in the field investigation.The life forms were mainly perennial herbs,34 species,accounting for87.18% of the total species.The main water ecological types were xerophytes,with a total of 27 species(69.23%).The geographical composition is mainly distributed in the Eastern Arctic,with a total of 17 species,accounting for 43.58% of the total species,which fully reflects the temperate nature of desert steppe plant community.Affected by the micro-topography,vegetation coverage,species height,community productivity,Shannon-Wienner index and Simpson index showed the order of down slope > middle slope > up slope,and Pielou index showed the order of up slope > middle slope > down slope.(3)Different slope positions affected the functional traits of plants.Under the influence of microtopography in the study area,plant height,fresh weight,biomass per plant,leaf length,fresh weight,leaf biomass,leaf number,leaf area and dry matter content of the four dominant plants were lower slope > middle slope > upper slope.The thickness of the blade is in the upper slope > middle slope > lower slope.The specific leaf area of Daurissima and Spiroconvolvula was lower slope > middle slope > upper slope,and that of Leymus chinensis and Stipa clanneri was higher slope > middle slope >lower slope.There was significant correlation between functional traits of dominant plants and slope position in the study area.