Impacts Of Land Use Change On Landscape Pattern And Ecological Security At Watershed Scale

Land is the base of human survival and development. In recent decades, the way and degree of land use has been changed profoundly, with the rapit growth of population and the development of science. The changes have decisive influence on the land cover of the earth, as the source and collection of material and the energy flows, supporting the biosphere. The changes of the land cover will change the climate, biogeochemistry circulation, hydrology and biodiversity on the earth. Land use and land cover change (LUCC) is one of the main drive forces, changing global environment. The rivers and these basins are the origin of human culture. There are lots of attentions paid on the impacts of human activity on rivers and basins. It is of important theoretic and practical significance to analyze the relationship of LUCC, landscape pattern and ecological security in basin, on the scale of landscape.Models to assess landscape pattern index and regional ecological surcurity have been built in this study, in the case of the middle and lower reaches of Hanjiang. Combined with the data of Landsat TM images, statistic and other maps of this study area, the indexes of land use intensity, colligate landscape pttern and regional ecological security have been discussed, during the years from 1995 to 2000. And the distributing and changes of the indexes in the middle and lower reaches of Hanjiang have been showed in this article. Then the conjugate evolutive rule on space-time of LUCC-landscape pattern-ecological security has been opened out, in the way of statistical methods. The productions are follows.(1) A spatial database of land use in this study aere of the year 1995 and 2000 has been built in this article, by using softwares of RS and GIS. Then the land use in the case area is overlapped to pick-up the mutative data. The main kinds of land use changes are mapped in this article.(2) On the base of the spatial database, the land use and land cover change in this case is analyzed. And it is showed on the maps about spatial distributing of land use intension index and bidirectional direction changes index in 1995 and 2000.(3) A model of landscape pattern index assessment has been built in this article. The model of landscape pattern assessment has appraised the landscape pattern and its changes of every county in the area.The maps of studying area are showing the spatial distributing of landscape pattern index in 1995 and 2000.(4) The model to assess regional ecological security has been built, in the scale of landscape. Then the ecological security of this region and its cuontries is estimated. The changes of regional ecological security are discussed. The maps of ecological security spatial distributing in 1995 and 2000 are maked by ARCGIS.All of the maps above show this: The physiognomy controlles spatial pattern. The index of land use intension increases from mountanious, knap to the plain regions; and the indexes of landscape patter and ecological security are highest in knap regions, lowest in plain regions and middle in mountainous. Although the physiognomy controles spatial pattern, it is economy to decide differences inside and determining the direction of changes.(5) The indexes of land use, landcape pattern and ecological security has been analyzed in the way of correlating, by using statistic softwares like Access, Excel, SPSS etc. The space-time conjugated rule of LUCC - landscape pattern - ecological has been opened out in this paper. It shows this: the land use intension is negative correlated obviously with indexes of landscape pattern and ecological security; The indexes of landscape pattern and ecological security are positive correlated obviously; In spatially, the correlation of the indexes is dependent on physiognomy; They are correlated obviously in regions of mountainous and plain, witch means that the configuration of land use and landscape pattern is inconsequent, the region ecosystem is not safe. They are correlated hazily in knap regions, because the configuration of land use and landscape pattern is reasonable, the region ecosystem healthy. And the correlation of all the indexes is more obviously when the time goes by.