| As exist objectively and one of the scarcity natural resources, land bred and carries all biotic and abiotic on Earth currently. Land provides a source of energy and material survival place for human survival. However, under the impact of the rapid development of the global economy and urbanization, human economic activity to bring a lot of negative impact on the land, resulting in a lot of environmental problems. As one of the precious and scarce natural resources, land’s rational use patterns and proper management plays an important role of the long-term survival and development of human health and the natural environment in the sustainable cycle. Land use/cover and land space allocation issues, environmental security not only has become an important part of global environmental change, but also become the core and hot spots of scientists from various countries. Yulin City is located in the northern of Shaanxi Province,as a major energy base, Yulin’s economic development ia rapid since the reform and opening up, however, its ecological environment is extremely fragile, ecological problems are many and prominent,land’s problem is increasingly grim and harsh, peoplego to tensions.In this paper, Yulin City as the study area, focuses on land use change and ecological security issues. The main methods are GIS, qualitative and quantitative, literature review method. Understanding of Yulin City’s natural resource conditions and exploring the ecological environment and land use/cover issues. Selected the 2000, 2005 and 2010 land use data and other geographic data, such as temperature and precipitation, using the land classification index, degree of land utilization model, showing the land use change; selecting the computing geographic, economic statistics, emergy ecological footprint model, calculating and analysising the 2000-2010 land footprint, ecological carrying capacity, ecological security of Yulin City. Finally, Comments and suggestions for the development of Yulin City’s environmental safety. Specific conclusion as follows:1 Yulin City’s land use structure is special and imbalance. The characteristics of various types of land use change in 2000-2010 are quite different. The highest proportion is grassland, accounted for 43.94%, the construction is minimum of 0.38% 。 in 2000. The three classes of meadow, woodland, arable land occupy as high as 91.06%. By 2010 the grass, farmland, forest decline in the proportion of 69.11%. The magnitude of arable land is small,6.35%, and small changes in haste,1.1%, and the trend has continued to decline; the woodland changed much,60.15%, but little change of speed, 0.98%, there is an increasing trend; building land not only changed much,9.35%, but also large rate of change,6.43%, there is also an increasing trend. Grassland’s variation width is small, of 2.21%, and small change rate,0.5%, there is a decreasing trend. The comprehensive dynamic degree of land is 0.36%, which proves that the overall change is not severe. Construction land into cultivated land, cultivated land into forest and grass grass out of proportion, mainly in the northern region.10 years land use index decreases, which proves that during this period, the land use is in recession.2The land use pattern is obviously different in Yulin City in the north and south. The rate of the change of land use is obviously regional. The vegetation cover in the south is better than the vegetation cover in the north, Medium degree of coverage of vegetation coverage is higher in the South, the northern vegetation covers with low vegetation cover. The land area ratios for every types in the northern county and southern county is, north/south of arable land is 2.19, north/south of forest land is 1.74, north/south of grass land is 4.81, north/south of water is3.94, north/south of building land is3.85, north/south of unused land is 65, respectively; The relative change rate of cultivated land in the northwest is far greater than it in the southeast, the maximum value is Zizhou County,the R in Zizhou County is 1.84,the R in Jingbian County, Hengshan County and Dingbian County is greater than 1.3.The R of grass land in Dingbian County is 0.98,and the R of grass land in the other counties is between 1 and 1.1;The R of building land in Shenmu County and Yuyang is larger,they are 2.02,2.62, respectively,;The R of building land in Fugu County is smaller,it is 0.3. The rate of change of land use degree is more than 0 both in Shenmu County and Yuyang District. That is say that only Shenmu county and Yuyang District are in the development stage,while the other ten counties are in the period of adjustment or recession in the Yulin City.(3) In Yulin City in 10 years,the SHDI rises to 1.2201 from 1.1863, the PD drops to 0.0512 from 0.0526,the FRAC_MN drops to 1.0221 from 1.023,the COHESION rises to 97.5458 from 97.363, this means that all types of the land use tend to be integrated, simple, compact, equalization.(4) In Yulin City, renewable resources ecological carrying capacity is relatively stable, the speed of the nonrenewable resources carrying capacity in 10 years is faster. Land ecological footprint of the production is more consistent trends, showing an increasing trend. Waste material footprint tends to be on the rise. The per capita GDP, average GPD growth was positively correlated with the ecological footprint. Footprint structure has no obvious change,it is all land footprint, fossil fuel footprint, land footprint building which occupies most of proportion, and grassland footprint, water footprint, woodland footprint which occupy a small proportion. The proportion of the first three plays to 93.465% in 2000,however,the proportion of the first three plays to 94.93% in 2010. During this period, from 2005, the building and fossil fuels generates weak contrast ratio of land, and building land occupancy ratio of land slightly larger than fossil fuels.In 2000,the ratio between the building land and fossil fuels is 39.85: 28.55,however,it is 39.22:40.84 in 2005 and 41.40:43.13 in 2013.(5) The renewable resources ecological deficit is serious from 2000 to 2010 in YuLin city,the renewable resources is insecurity;the nonrenewable resources ecological is surplus between 2000 and 2010,the nonrenewable resources is safe. But from the perspective of long-term sustainable development is concerned, Yulin city’s ecological is insecurity. The biodiversity ecological is insecurity between 2000 to 2010, except in 2004,2005,2007 ecological surplus belongs to ecological security.(6) Whether renewable or non-renewable resource system, the coordinated development of resistance is not high,the development is uncoordinated. The renewable resource coordination of 2000 was 1.2015 and in 2010 to 1.1190 in Yulin City. The nonrenewable resource coordination of 2000 was 1.2015 in 2010 to 1.1190 in Yulin City.The total resources of ecological coordination was 1.1980 in 2000 and to 1.1186 in 2010.The years of resources close coordination coefficient of 1.4 almost nothing in YulinCity.(7) capacity of systems development has gradually increased Yulin City. The capability value of systems development in 2000 was 20.9525,64.1975 in 2010 Descripte that the social development is rapid, and industrial development is more comprehensive in the ten years of Yulin city.The feature of this paper is respectively in Yulin City, and each county as the research scale, starting from the changes of land use characteristics, quantitative indicators to measure, to reveal the type change. On land use by the specific analysis of the model from the number and extent, is 5 years of interval comparison, show trends, and the contrast between the. According to the special characteristics of resource-based cities of Yulin City, using the improved emergy ecological footprint model, divided into renewable resources and can not be updated in two aspects of resources, the specific capacity and footprint and show trends, and ecosystem development level and degree of stability evaluation calculation using mathematical evaluation model. To reveal the ecological security change trend of Yulin city. |
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