Ecological Risk Assessment Of Land Use Change In Northern Hebei

Ecological risk assessment is a new rising field of research after the 1990s.It is not only an important branch of environmental risk assessment, but also the scientific basis of environmental management and decision making. Ecological risk assessment is a process that evaluates the possibility that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors, and its research is involved in many subjects including environmental science, ecology,environmental and ecological toxicology, geography, disaster science etc. Regional ecological risk assessment is a significant branch of ecological risk assessment, and that is an integrated process of risk on studying many risk sources and risk receptors under the complex environmental background based on a large seale.Northern Hebei is located in the north of Hebei Province, which belongs to the farming-pastoral ecozone. Disturbance of human activities which is mainly reflected in the transformation of land use patterns on the northern Hebei is strong. Studying the ecological risk of land use change in this region, under the influence of human activities in this region can be concentrated reflection of the regulation of ecosystem characteristics and ecosystem change.In this paper, we have interpretation the TM data between 1988 and 2000 by 3S in North Hebei Province, and analyzed six kinds of major changes in the types of land during these 13 years. According to the definition of ecological risk assessment and characteristics,we use geographic information systems and modern mathematical methods in geography in the study.we select ecological impact caused by human activity as a risk source and cross-scale eco-system as receptor. we select habitat fragmentation, soil erosion, soil desertification as indicators of the risk source, at the same time select the soil organic carbon and NDVI, precipitation, temperature as indicators of ecosystem vulnerability,then we use AHP method and factor superposition method, superimpose the source of risk indicators and ecological vulnerability indicators,to gain a comprehensive evaluation level chart of ecological risk in Northern Hebei, and divided the level chart into six grades 1,2,3,4,5,6,the value indicate the degree of risk. The results show that there is more obviously regional differences of level ecological risk in the three geographical areas of bashang plateau, northwestern Hebei region and the inter-mountain basin in northern Hebei hilly area :the level of risk in bashang plateau is the highest,where the grade 1 and 2 is not exsit,but 90.36% of 4 and above risk areas in the total area,so the ecological risk is high;The next is the inter-mountain basin in northwestern Hebei Province, 3.44% of the whole region belonging to the grade 1 and 2, ,3 grades accounted for 35.10%,4 or more risk areas accounted for 53.46%;risk of the value is less at Risk hilly area in northern Hebei, 4 and above risk areas accounted for 33.87%,1,2,3 grades increased, respectively 2.09%, 19.99% and 44.05% of the total area.The degree of risk in different regions is different from the source because of the distribution of differences of the risk indicators and indicators of vulnerability ecosystems. By spss software, we do correlation analysis to risk values and these seven indicators of factors。By comparison we found that the greater impact factors are:soil erosion by wind, temperature, soil desertification.Risk value of three districts in Northern Hebei are different.Risk value of Bashang plateau is highest at 4.4,the main influence factor are soil erosion, rainfall, soil desertification;risk value of Inter-mountain basins in Northwest Hebei is higher, at 3.7,the main influence factor are soil erosion, vegetation NDVI, soil desertification;risk value of mountainous areas in northern Hebei is small at3.1, the main influence factor are soil erosion by wind, precipitation, temperature.The innovation of this paper lies: on the basis of land-use change, we construct ecological risk assessment index system of northern Hebei,which is useful for content and methods of land-use of ecological effects caused by human activities,making up for the deficiency of Ecological risk of forgetting, considering regional of ecological risk,reflecting the multiple receptors and cross-scale of risk receptor.