Analysis Of Landscape Gradient Based On GIS

Land is the important resource and basic material on which human's survival and development depend. With the rapid expansion of the world's population,urbanization,industrialization,constantly deepening of the extent and depth of land utilization,led to the great land cover changes,causing a series of resources, environment,social and economic problems.In recent years,land utilization had been caught widespread attention in academic field.It is great significant to maintain region ecosystem balance,to improve entironment,to strengthen land resource conservation,to achieve sustainable development of land resource by combining landuse changes and landscape patterns research,by the depth study on landscape patterns dynanfic changes.With the development of landscape ecology,using landscape pattern analysis method to study landuse structure and its evolution has become effective technical means at present.The Hechuan district,Chongqing was chose for the study area in this paper.Based on the GIS technology support,landscape pattern index and city gradient belts methods were used to analyze characteristic of landuse patterns and gradient changes from the view of landscape patterns and types in Hechuan district.The driven factors to landscape patterns distribution and changes were further studied to provide reference for landuse planning and industrial composition and adjustment in Hechuan district.The results were as follow:1.Analysis of landuse patterns changes(1)The landuse patterns had changed greatly under human activities.At landscape patterns aspect,the number of landscape patches and patch density increased,the border shape of the whole landscape became complex,fragmentation degree increased.Landscape diversity and heterogeneity degree increased as well, landuse was toward the direction of diversity.But discrete degree of landscape patch area decreased,the predominant patch types proportion declined,the control function to whole landscape weakened,patches tend to uniform size.(2)At the landscape types aspect,farmland,water and water conservancy facilities landscape decreased,but the patch number and density increased.The patch became broken.However,forest,garden and other landscape area,patch number and density increased,but patch mean area decreased.Residential landscape patch area,number,mean area and density,increased,all landscape shape became more complex, and the maximal extent change was forest landscape.(3)There was great transfer among landscape types.Farmland,water and water conservancy facilities landscape had decreased compared to that of 1993.Farmland mainly transferred to forest,residential and garden land,water and water conservancy facilities landscape mainly changed to farmland,forest and other landscape.The rest landscape increased,residential land mainly transferred from farmland and garden land. Garden land mainly change from farmland and forest land.Forest land mainly transferred from farmland, garden land and other land.2.Analysis of landscape gradient changes(1)At landscape pattern level,patch total area and number increased outward from the center of the gradient.In 1993,the difference of mean patch area and shape to each gradient was little.The more predominant farmland was,the farther away from the city center.In 2006,the patch number increased significantly,patch density increased,shape landscape structure was more complex,landscape fragmentation degree increased in each gradient belt.The 1-5 gradient belts changed most,their urbanization degree was very high,patch density increased,residential land was dominant,and patch shape was simple.The mean patch area significant declined along the gradient from the city center.(2)in the view of landscape types,farmland landscape area declined;patch area and number increased outward from the urban center along the gradient belts.The patch shape became complex,with fragmentation degree increasing.The expansion of residential landscape mainly occurred in the 1-5 gradient belts.The patch shape was more regular and compact.The large area patches increased, distribution was more centralized;shape was more complex in the 6-20 gradient belts.Forest landscape area,patch number and patch density increased,mainly distributed in the 7-20 gradient belts.The patches were more fragmental,shapes more complex in the original built-up area with 6-20 km.Garden landscape concentrated in the 2-8 gradient belts with 2-8 km.Water and water conservancy facilities landscape decreased,other landscape's development was to a large extent,patch shape was more regular,especially in the 1-7 gradient belts.(3) Based on the characteristic of landscape distribution.Landscape in Hechuan would be divided into three landscape zones:urban landscape(with gradients 1-5),urban and rural transition landscape(with gradients 6-9) and village-town landscape(with gradients 10-20).3.Analysis of landscape changes driving forcesThe gradient changes of landscape patterns were common drove by natural and socio-economic factors.The natural factors mainly were elevation and slope.Slop factor significantly influenced farmland and other landscape.Forestland,water and water conservancy facilities were common influenced by elevation and slope factors.Garden and residential landscapes which were semi-natural and man-made landscape,elevation and slope factors influenced some extent;the function of socio-economic factors was significant.Government's macro regulation and control which was one of socio-economic factors played a important role,including Chongqing resumed a municipality,Hechuan evacuated the city to the district,the western region development strategy,the determination that Hechuan was the northern part central city, Hechuan overall city planning,the implementation of the policy of returning farmland to forest,the work of eco-environmental protection and governance,Hechuan citrus industry "158"strategy,new rural development policy.At the same time,the acceleration of urbanization process,urban population increase, the size of city expanding,traffic conditions improvement and industrial structure adjustment and so on all affected the distribution and changes of landuse landscape patterns.In recent years,the landuse landscape patterns had changed greatly in Hechuan.Landscape pattern index and city gradient belts were applied to analyze the characteristic of landuse landscape patterns and gradient changes in Hechuan district.The study conclusion would provide scientific basis for landuse overall planning and industrial adjustment,also for further study on the dynamic change of urban form,the cological process of urbanization and quantitative modeling.But due to limited data,how to use the quantitative method to study the driving factors to gradient changes need further explore,requiring synergy of multi-disciplinary experts and scholars.