Studies On The Land Degradation Mechanism And Ecosystem Stability Of Agro-pastoral Ecotone

Over the past more than 300 years,with the influx of immigrants and the continuous increase of land reclamation area,Inner Mongolia grassland area plummeted,natural environment deteriorated.Especially in the last 70 years,in the context of population growth,global climate change and intense disturbance of human activity,land desertification,soil erosion and desertification were serious in agro-pastoral ecotone,and the ecological environment was obviously degraded.In order to clarify the mechanism of land degradation in Inner Mongolia agro-pastoral ecotone and the stability of ecosystem in the process of repair,using Landsat TM,ETM+ and OLI Remote sensing data and 3S technology integration,the land use/cover change of Siziwang Banner in Wulanchabu and Arong Banner and Yakeshi in Hulunbeier,the typical areas of the agro-pastoral ecotone in Inner Mongolia,have been studied,this paper revealed the spatial and temporal distribution characteristics and changing tendency of land use in Siziwang Banner in the past 30 years by using the spatial and temporal change characteristic model of land use;and the physicochemical properties of soil in three study areas were also determined,the driving mechanism of land degradation in typical areas of agro-pastoral ecotone in Inner Mongolia was analyzed by using ecological factors,the contribution of soil erosion to land degradation in Siziwang Banner was quantitatively analyzed,the characteristics of heavy metal pollution,ecological system vitality,organization,resilience and stability in the study areas were quantitatively analyzed by using pollution index method and ecosystem health index.The results of the study showed as blow:(1)In the past 30 years,the land use of Arong Banner and Yakeshi have changed slightly,but the land use of Siziwang Banner has changed greatly,the concrete manifestation is the increase of construction land,woodland,grassland and saline land,and the decrease of cultivated land,water and sand,and the land use structure presented the unstable situation,the land use degree continuously improve,land use type spatial transfer imbalance.(2)Unique climatic characteristics such as drought and windy,and the interaction between the characteristics of soil parent matter,types,nutrient,soil heavy metal pollution and vegetation cover in the regions,multi-factor comprehensive effect become an important factor driving land degradation in agro-pastoral ecotone.(3)The soil erosion condition of Siziwang Banner in the past 30 years was quantitatively studied by RUSLE model,the results show that soil erosion in this area shows a tendency to fall first and then rise,and soil erosion modulus has increased dramatically in recent years,soil erosion is getting worse.(4)Analysis of the health evaluation results of farmland ecosystem covered by different crops,wheat ecosystem health index is the highest,reaching up to 0.5800,the lowest rapeseed is 0.1050.Among them,conservation tillage farmland health index significantly higher than potato,rapeseed and oats,it shows that different tillage measures,planting structure and planting density are important factors affecting the health of farmland ecosystem.The results are aimed at providing scientific basis for the prevention and treatment of land degradation in agro-pastoral ecotone,to provide reference for ecological comprehensive management of agro-pastoral ecotone in northern China,and it provides case reference for returning farmland to forest and grassland,dropping grazing and grassland,and controlling wind and sand source in Beijing and Tianjin.