Ecological Risk Assessment Of Farmland Desertification In Horqin Sand Land

Ecological risk assessment is a research field that arises gradually and develops continuously in the1990s at home. It is a new way of desertification evaluation and means of desertification quantitative research.Based on theoretical framework of ecological risk assessment, selected northern part of sandy area in Naiman Banner as typical area, this paper has carried ecological risk assessment for its different types of farmland.The procedure is as follows:The first step was problem formation. On the basis of regional analysis, the paper recognized main risk source of the farmland desertification, including man-made risk source (management methods and farming life), the natural risk sources (landform types) and determination of risk acceptor (farmland), end point of evaluation (desertification risk) and measurement end point (soil physicochemical properties).The second step was pressure-effect evaluation. Analysis of impact on soil physicochemical properties which effected by different risk sources and their bound forms were conducted and obtained the value of different types of farmland desertification risk,The third step was risk characterization. The paper carried on characterization of quantitative relationship between the different risk sources or their bound forms and farmland desertification risk and found the main risk source of farmland desertification risk.The last step was risk management. Farmland desertification risk management strategies were processed on the basis of evaluation resultsThe main conclusions were as follows:Desertification risk value of different risk acceptor was different under the effect of different risk source and risk bound forms.(1)landform types:Both lump farmland and meadow farmland, the desertification risk values of3samples was increased along the main wind direction and the value of meadow farmland was lower than the one of lump farmland.(2)Farming years:The desertification risk on windward slope lump farmland was enhanced after30years cultivations, and the risk on slopping top was also enhanced, however, the risk on leeward slope was reduced.(3) Risk bound forms:Under the protection of shelter forests, the desertification risk of the lump farmland and meadow farmland has decreased.(4) Landform type was the most important single risk source of farmland in the northern sandy area in Naiman Banner. Lump farmland which has farmed many years and no shelter forest that have the highest desertification risk.