Soil Heterogeneity Along The Airdity Gradity Gradient Of Grassland Communities In Mongolia And Its Correlation With Vegetation

The relationship between vegetation and climate and soil is an important part of vegetation ecology research.The relationship between vegetation and environment is usually concerned with the relationship between vegetation and climate,while ignoring the relationship between soil and vegetation.The Mongolian Plateau is located in the hinterland of the Eurasian continent,and from the northeast to the southwest,the rainfall is reduced and the temperature is improved.It is not only the difference of water and heat,but also the heterogeneity of the soil.It is an ideal place to study the spatial distribution of large scale vegetation and environment.In this study,we investigated the transects along the dryness gradient in the Mongolian steppe area,and analyzed the changes of soil physical and chemical properties along the dryness gradient and their relationship with community productivity and species diversity using measurement method,to explore the impact of plant community formation and spatial differentiation mechanism from the perspective of climate and soil.To provide a theoretical basis for studying the spatial dynamics of terrestrial ecosystems and the response to global climate change.The main conclusions are as follows:1.The vegetation biomass,Shannon-Winner index,Simpson index and Gleason index of the Mongolian plateau are slightly decreased after the increase along the rise of the de Martonne aridity index(IdM).The Pielou index increase along the increase of de Martonne aridity index(IdM)and represent linear rise;IdM = 35mm/? is the dividing line for the changes of productivity and diversity index.2.The contents of soil total nitrogen,total carbon and organic carbon increased along the rise of IdM.The soil content sand,soil density and pH increase along the rise of IdM.3.The effects of aridity(temperature and precipitation conditions)on the soil physical properties(soil density,mechanical composition)were concentrated in the soil surface of 0-10 cm.The effects of aridity on soil chemical properties(pH,total nitrogen,total carbon,inorganic carbon,Organic carbon content)though surface and deep,which affected the pH and total nitrogen content basically through 0-100 cm soil layer,the impact on whole carbon and organic carbon concentrated in the soil 0-30 cm.4.Soil total nitrogen and organic carbon contents were negatively correlated with soil pH,bulk density and sand content.Soil total nitrogen and organic carbon contents were positively correlated with silt content.The effects of pH and bulk density on soil total nitrogen and organic carbon were concentrated in soil 0-30cm.The effects of soil mechanical composition on total nitrogen and organic carbon were throughout the soil.5.Soil total carbon content,organic carbon content,sand content and plant community productivity and diversity were significantly positively correlated;Soil density,pH,clay content,and plant community productivity and diversity were significantly negative correlated;The soil total carbon content,organic carbon content and sand content were significantly correlated with plant community productivity and diversity.,PH,total nitrogen,total carbon and organic carbon on the plant community productivity and diversity have a certain vertical differentiation,the impact were concentrated in the 0-5cm,10-70cm,20-70cm,0-70cm,0-50 cm,0-10 cm,0-100 cm.6.There was a significant difference in the pH value of 0-50cm soil layer between different types of plant communities.There was a significant difference in soil pH between the populations and the other communities.There were significant differences in the contents of sand and grain in 30-100 cm soil layer between different types of plant communities.There were significant differences in sand content and grain content between other communities.