LUCC And Ecological Safety Assessment In Xianyang City

As Land Use and Land Cover Change (LUCC) and ecological state are significant in regional sustainable development, it has important research significance to make use of land rationally, protect the limited cultivated land resource, ensure the safety of food supplies and maintain regional ecological safety.This paper takes Xianyang City in Guanzhong zone of Shaanxi as a study, through field surveys, integrating with related statistical data, quantitatively analyzing the Land Use and Land Cover Change(LUCC) in Xianyang City, and makes a cause analysis on the change. This paper makes a dynamic analysis on cultivated land as a sensitive part in the land use structure. By using Principal Component Analysis (PCA) and Multivariate Regression Analysis methods, this paper analyzes the socio-economic factors that affect the cultivated land's change. This paper analyzes the dynamic change safety of food supplies changes and cultivated land pressure in every part of Xianyang City. Based on the actuality of Xianyang's ecological environment, this paper makes a qualitative analysis on Xianyang's ecological safety, by using Analytical of Hierarchy Process(AHP) and "Pressure-State-Response"(PSR) model. This paper makes a quantitatively dynamic assessment in Xianyang's ecological safety and a ecological safety assessment in every administrative unit of Xianyang, and also analyzes the characteristics of different ecological safety region.This paper is divided into five chapters. The first chapter provides the research background of land utilization and ecological safety, the research's progress, the research's significance and the general situation of region under research. In the second chapter, the paper analyzes the land utilization's speed and range, the differences of spatial Change and the cause of this change. The third chapter makes a quantitatively analysis on the sensitive part of land utilization change, analyzing the dynamic changes and spatial differences of the safety of food supplies, and forecasts the safety of food supplies. The fourth chapter analyzes the change and spatial difference of the ecological safety, and makes a forecast for the safety of food supplies. Some advices on the ecological safety in Xianyang are put forward. The last chapter provides a summary and discussion of the paper.Conclusions drawn in the study are as follows:First, the cultivated land of 111127.84hm~2 decreased beween 1986 and 1996, but the land area of other types increased in different extent. The gardens, residential and industrial land have increased the most, the respective number of which are 83178.29hm~2 and 12683.43hm~2. The cultivated land continues to decrease, but the reduction rate reduced.The structure of land use changed sharply. The annual rate of changes of gardens area is the greatest, which reached 35.54%, but the period between1986 and 1996 is higher than that of 1996 and 2004. The main reason is that since reform and opening up policy, under the condition of market economic system, with the improvement of people's life, the demand of fruits increases correspondingly, which results in the enlargement of gardens. The cultivated land had been decreasing during this period. The annual average change rate is 3.29% between 1986 and 2004.Changwu's relative change rate of cultivated land is the greatest. The variations of cultivated land in the north of Xianyang is bigger than that of south. The variations of gardens in urban area is the greatest. The variations of grassland in Changwu is the greatest, and the variations of residential and industrial land and traffic land in urban area is the greatest. The variations of water area in Xunyi is the greatest, and the variations of unused land in urban area is the greatest. The changes of non-agriculture land in urban area and neighboring region is more than other areas. The changes of agriculture land in Changwu, Jingyang and Sanyuan is respectively greater than other areas.The spatial structure of land use in every administrative unit of Xianyang tends to be almost the same, and the area of the cultivated land decreased, while the area of gardens, residential and industrial land had increased. The diversity index of every counties tends to ascend except Xunyi, which shows that the situation of single type land dominated in the land use structure had been changed. The land use structure tends to be diversified, and the land use's diversity index in the north of Xianyang is greater than that of south. The diversity index in urban area changes the most, in contrast, the diversity index changes in Xunyi is the least, and the extent of the diversity index's change in the south is bigger than that of the north.Second, the area of cultivated land fluctuated a little in the past 55 years, which experienced the process of quick increasing, steep decreasing, slight increasing, slow decreasing and quick decreasing.With rapid development of society and economy, the cultivated land in Xianyang decreased rapidly from 1979 to 2004. This paper makes a anlysis on the reduction. The results show that the main reasons affected the area change of cultivated land are the factors of population, the urban expansion, environmental pollution, agriculture structural adjustment and regional industry structure adjustment. The counties of cultivated land area decreased sharply include QianXian, Xunyi and Chunhua. Although the decreasing of Cultivated land is of great difference among these cotmties, the changing process was similar. Counties with the arable land annual decline rate over one are mostly located in the north of Xianyang, which shows the north of Xianyang has ahigher speed of loss of arable land than the south.The food Self-sufficiency rate of Xianyang has been in a relatively high state, which plays a key part in the safety of food supplies of Xianyang. This paper forecasts food supplies of Xianyang will be still in a high state in the coming 10 years and in the following 20 years the food Self-sufficiency rate can still remain 90%.In terms of food safety distribution results, Binxian and the urban areas of Xianyang are unsafe districts; Changwu and Liquan are in relatively unsafe situation; Xunyi and Yongshou are in medium safe situation; Xingping city is in relatively safe situation; Chunhua, Sanyuan, Jingyang, Qianxian and Wugong are safe areas; which shows that most administrative units of Xianyang are in a relatively safe situation.The highest pressure of cultivated land in Xianyang is the urban area, and the lowest is Qianxian. The pressure of cultivates land in most counties distributes in an affordable area. The districts which have relatively high pressure of cultivated land and real per capita arable land area is lower than the lowest per capita cultivated land area are mainly located in the Loess hilly areas in the north of Xianyang.Third, ecological safety is improved, RES has been improved from 0.5951 in 1997 to 0.7749 in 2003.In terms of ecological safety partition, the Ecological safety high risk region includes Changwu and Xingping, whose respective Ecological safety value are 0.6568 and 0.6861. The Ecological safety relatively high risk region includes Qianxian and Sanyuan, and their respective Ecological safety value are 0.7049 and 0.7013. The Ecological safety medium risk region involves Liquan and Jingyang, whose respective Ecological safety value are 0.7263 and 0.7201. The relatively Ecological safety low risk region includes Binxian, Xunyi, Wugong and urban area of Xianyang, their respective Ecological safety value are 0.7432, 0.7427,0.7407 and 0.7414. The Ecological safety low risk region involves Chunhua and Yongshou, whose respective Ecological safety value are 0.7789 and 0.7618. Changwu has the highest ecological environment pressure, while Yongshou has the lowest. Chunhua has the best ecological environment and Qianxian has the worst. The urban area of Xianyang has the strongest ecological humanities response while Changwu has the weakest.The innovation of the thesis are as follows:First, this paper forcasts the safety of food supplies in Xianyang by building forcasting models of population, Grain Yield per Hectare, crop area and multi-cropping index.Second, this paper makes an ecological safety assessment spatially in Xianyang by administrative unit, analyzing the problems arousing among different security levels and also gives ways to improve ecological safety of Xianyang targeted.