Study On Land Use Changes And Evaluation Of Land Ecological Security In Fengdu County

Land is the basis for human survival and development, to achieve long-term human development necessary to obtain material wealth through the development of land use. In the pursuit of development and meet the needs of. In the process, changing the way land use, land cover changes accordingly, the constituent elem ents changes in land ecosystems causing land ecological security changes, therefore, to understand the relationship between change and land ecological security of land use becomes important for future regional sustainable land use planning and provide reasonable scientific basis.This paper based on the theory of man-land relat ionship and sustainable development, analyzed land use/cover change of Fengdu County using land-use change model number, land use structure model and the extent of land use models. Based on the concept of land ecological security, 20 indicators from the three aspects(pressure, state, response) were selected to build land ecological security assessment index system in the Three Gorges Reservoir region based on PSR model, and the entropy weight method and improved TOPSIS method were used to evaluate the land ecological security situation of Fengdu County from 2003 to 2012. and then for the land ecological security situation propose appropriate adjustment of land use. The results are as follows:(1) By doing some preprocessing like geometry correction, radiometric calibrat ion, image cropping and image enhancement on the remote-sensing images of six periods, using the way of supervised classification and unsupervised classification to interpret image data and doing a post classification processing on interpreting results, and finally interpreting eight kinds of land types including cultivated land, residential and industrial land, water areas, transportation land, grassland, garden and the other land. And its interpretation accuracy reaches over 80%,which can meet the research standard.(2) In 2003- 2014, the land-use types of Fengdu County changed, the number of forest land, cultivated land, residential and industrial land, water areas and land and transportation land was increased, while grassland, garden and the other land was reduced. From the angle of quantity variat ion, the area of other land and grassland rangeland show a decreasing tendency year by year. And the area of residential and industrial land and transportation land show a increasing tendency year by year, and the area of forest land, garden and water areas and land first icreasing and then ruducing change. Residential and industrial land changed fast, showing a net increase trend. The other land reduced fastest, showing a net decrease trend. Land use degree deepening, but there is still room for development. From the angle of landscape change, landscape diversity index changed slowly and was reduced, the degree of land use order was increased; landscape dominance has been in a gradual upward trend, showing the proportion of land use types difference becomes larger, which states that the difference of the proportion of land-use type in Fengdu largen controlled by four kinds of land types forest land and cultivated land.(3) Fengdu County land use change had a large effect on land ecological security. As the number, structure, extent of the land use types and landscape dominance changing, land ecological security changed. The security situation of land ecosystem was affected mainly from the climate, soil, hydrology, biodiversity, natural disaster.(4) Land ecological security in Fengdu showed a rising trend in volatility as a whole, from insecurity state transition to less security state, but the distance is still a wide gap between the security state. From each subsystem, the pressure system of land ecological security in Fengdu is decreasing, the state system is basically in steady state from 2003 to 2010, improved in 2011 to reach safer state, and in 2014 they dropped to critical security status, the response system fluctuating rising trend.The main factors affecting the ecological security of land Fengdu County, including the proportion of arable land, environmental management investment share of GDP, per capita net income, populat ion density, the proportion of tertiary industry, economic density, per capita arable land, the level of agricultural mechanization, construction of urban green coverage rate and other factors.(5)Under the basic of the study on the land use and land cover change and driving force and conbining the existing problems of Fengdu’s land use, Fengdu district should optimize the sustainable land use in the future from adjustment of industrial structure, the implement and revision of integrated land-use planning, harmonious development between land use and ecological environment and promoting environmental monitoring system.