| Intensive and efficient use and the development of potentials of regional land resources is one of the hot issues that people are concerned about. And that is also the key and core issue of regional ecological security and sustainable development. Loess Platform region is the major grain production base of Loess Plateau, and is also the important industry and population agglomerations of Loess Plateau in the future. Shaanxi Loess Platform region lies in the Guanzhong Basin. Guanzhong-Tianshui area has been identified by the country as the Third Economic Development Zone of the west. With the rapid development of economic industry as well as the rapid increase of the population pressure, the pressure has been directly radiated and transferred to the loess platform area surrounding Guanzhong. Therefore, loess platform area is facing the exploitation of high strength. There exist potentially enormous ecological risks. In this dissertation the loess plateau area acts as the main research object; based on the support of GIS and RS, multi-source data have been colleted and processed; Geodatabase has been established to conduct integral management of spatial data and attribute data; from the analysis of the process and pattern of land use, the pressure of the soil and water resources of the land system and the intensive utilization degree of agricultural land along with the exploitation potentials of land resources have been quantitatively evaluated. And land ecological risk has been analyzed to put forward countermeasures and advice on the sustainable use of differentiated land resources. The main conclusions are as follows:(1) The proportion of the functional land of ecology is low and continues to decrease. And there is a serious shortage of arable land reserve resources. Arable land occupied78.91%in1985, woodland2.04%, grassland12.19%, water0.51%, the unused land0.02%, the land for construction6.33%. With growing urbanization, the problem that construction land occupies the land resources of high quality is becoming more serious. Within1985-2010, construction land expanded as32.37%, while arable land reduced1.29%, the woodland area4.59%, the grassland7.18%, water area11.64%.(2) Pressure on land and water resources continue to increase. As for the pressure of land, though the land capacity was being increased by3.05%of the average annual growth rate during1985-2010, the relation between people and food in some counties and regions gradually became strained. Up to2010, seven of the34counties and regions in Shaanxi Loess Platform were in the state of severe overloading, three overloading state, six near overloading state. As for water resources pressure, it mainly demonstrated the problems of lack of the total water resources, poor spatial matching of soil and water resources, the prominent structural water shortage, etc. During1985-2010, the load index of water resources continued to increase and water resources pressure was increasingly becoming serious. By2010, approximately2/3of the counties and regions were in the state of serious overloading.(3) Intensive utilization degree of agricultural land is not high, and economic returns are low. The land of high quality of Shaanxi Loess Plateau covers56.50%, yet intensive utilization degree of54.61%of the agricultural land is on the middle and lower level, and the utilization efficiency of51.72%of the agricultural land is low. In space, the basic pattern shows the matching characteristics of equal quality-equal use-equal economy. The areas with the same quality, the same utilization, the same economy mainly distribute in the primary and secondary platform sub-regions, the areas with the value lower of the three indicators mainly distribute in the sub-areas of platform of Level three in Weibei.(4) Owing to water restrictions, most of the counties and regions exploitation potential of land resources is limited and the difference between the counties and regions is much larger. Among all the counties and regions, the production potential of the two counties, Zhouzhi County and Lantian County can reach the maximum potential of climate; in the four counties of Chang’an District, Lintong District, Yanliang District and Fengxiang County the production potential is3.0-5.0t/hm2; in the nine counties of Hua county, Fufeng County, Qishan County, Sanyuan County, Yongshou, Jingyang, Liquan dry county and Fuping County, the production potential is2.0-3.0t/hm2; in the three counties and regions of Baqiao District, Yanta District and Wangyi District the production potential is0.4-0.75t/hm2, the production potential of the other16counties are1.0-2.0t/hm2.(5) The land ecological risk indicates a tendency of increase. It increased from0.47in1990to0.67in2010. In space it demonstrates Weibei loess platform of Level3is the highest. Qinling northern hillfoot sub-regions of Level2and urban region system are higher; Weibei loess platform of Level1and2is lower. However, types of risk sources and intensity of different regions of space are quite different. The risk of land structure of Weibei platform sub-areas of Level2and1and is higher; in the crossing zones of urban and rural pastoral areas, including Weibei loess platform sub-areas of Level3the risk of vegetation degradation is higher; in the loess platform and valley slope zones there is a high risk of soil erosion; except the fact that it indicates carbon sink within the very small range of the edge zone of north-east of loess platform, the carbon source effect of land of the other areas is obvious.(6) The land utilization structure is to be adjusted; the construction for ecological functions of land is to be strengthened; the control strategies of differentiated sustainable land utilization are to be adopted. land utilization and ecological coupling state of loess platform can be divided into four types, among of them, the proportion of woodland and the ecological service function of land for grass in those typed areas with low potential of land utilization and a high ecological risk should be raised; in those typed areas with low potential of land utilization and a high ecological risk, as for Weibei loess platform sub-areas of Level3and Qinling northern hillfoot sub-areas of Level2, part of the steep slope area of it can be used for returning farmland to forest; more emphasis should be placed on optimizing the planting structure of agricultural land in the contiguous distribution areas of central Xianyang loess platform; there should be a strict control of the expansion of construction land in the coupling regions with higher utilization rate of the potential of land and a low ecological risk; in the coupling regions with higher utilization rate of the potential of land and a lower ecological risk, part of woodland and grassland can be changed into arable land.Major creativity:(1) The concept of land transfer flow and its model has been put forward; the reflection of the vector properties of land change has been highlighted.(2) Density mapping method has been applied in the clustering feature recognition of land utilization space so that it has made up for the shortcomings of visualization of smaller land change by the commonly used method of overlay analysis.(3) Township-scale accounting data have been abtained via bottom-up and top-down methods. And the management and analysis of space data of land system and attribute data of the loess tableland have been carried out by establishing Geodatabase database. |
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