Study On Landscape Pattern Of Land Use And Ecological Security Evolution Based On Grid GIS In Huailai County

Huailai County is the important ecological barrier for Beijing and northern region. The ecological security situation of land use in Huailai is not important to the environment of land use and life itself, but also significant to sustainable development of land resources around Beijing. In recent years, the rapid development of urbanization changes the original ecosystem and environment, which becomes big challenge to ecological security. Lots of researchers have studied the evaluation of ecosystem security. When the evaluation system of ecosystem security built, features of different aspects should be considered, including the status of the study area, reflecting causality of the main ecological problems and taking both time and space scale into account, which is inadequate for now. So it is of great importance to maintain the environment protection mechanism and establish the ecological civilization system to build the reasonable evaluation system to analyze the evolvement rules of land use ecological security.This article analyzes the land use changes, the feature and changes of landscape spatial pattern systematically and comprehensively during 1996-2012 on the basis of land use interpretation map in 1996, 2004 and 2012 using RS and GIS. Then analyze the factors that impact the landscape pattern changes by introducing sequencing analysis method. On this basis, Building the evaluation system from three aspects of land carrying capacity, land stability and landscape spatial patterns, taking 3km×3km grid as evaluation unit, to analyze the evolution and forecast of land use security in Huailai County, and getting the conclusions below:(1) Unused land and forest are the main land types of Huailai County during 1996-2012. The areas of garden plot, forest and construction land increase, while cultivated land and water decrease. The decreasing cultivated land mainly turns to construction land and increasing most comes from garden plot, forest and unused land. The sources of added construction land are cultivated land and unused land. The center of gravity of water and forest basically unchanged, while garden plot changes most and moving distance is 3394 km, and other land types after it.(2) Calculating and analyzing landscape indexes from two aspects of time and spatial scales and the results show that: the area of once the dominant landscape types, for example forest and unused land, reduce during 1996-2012, thus drives landscape form becomes simple and fragmentation increases. The high values of SHDI, SHEI and IJI mainly locate in central region and decrease systematically towards south and north, while contagion index appears the opposite trend, which means the landscape types diverse in middle areas of Huailai County, but the connectivity is low because of the large number of small patches. The intraregional changes of landscape indexes are imbalance by comparative analysis of time and space.(3) Selecting indexes from two aspects of nature and socio-economy to discuss the formation law of landscape patterns by introducing sequencing analysis method. The results show that population aggregation, density of population and topography are the important drive factors to landscape changes.(4) The land area of biological production decreases during 1996-2012 in Huailai County and land carrying capacity index reduces 4.44×104ghm2. At the same time, the average value of land system stability turns to 0.5914 from 0.6257 and the middle regions reduce obviously; the average value of landscape index reduces to 0.43 from 0.53 and south central area has clear reduce; the average value of ecological security index of comprehensive land use reduces to 0.65 from 0.68. The variability degree of security index rises and change rate increases, while the spatial association decreases. The total ecological status of land use in Huailai County appears download trend during 1996-2012 under the influences of kinds of factors and the regional changes becomes obvious and complex. The prediction result shows that the ecological security of most regions turn to decrease except that the southwest hilly areas will maintain the status quo.