Study On Spatial Structure Of Urban Greenbelt Landscapes Of Nanjing City Based On RS And GIS

An urban greenbelt map of Nanjing city was made in this paper though the process of image correction, merging, distilling and classifying using the SPOT-5 image in 2003.7 as the data source, and the work was done with the help of some software such as ENVI, ERDAS, ARCGIS, AutoCAD and so on. Based on the urban greenbelt map, with the help of Fragstats and Excel soft, the current greenbelt structure index, fragmentation index, Fractal dimension index and whole landscape pattern index were calculated. By the analysis of the indexes, the problems of urban greenbelt landscape pattern were pointed out, which could provide scientific foundation for perfecting greenbelt special framework and pattern of Nanjing city. The research findings are as follows:(1) The distribution of greenbelt landscape's type is uneven. Scene forest is in the majority in the total greenbelt area, while the appertain greenbelt and residence greenbelt occupy utterly predominance by the proportion of each type patch accounts for the total number of patch. The mini type and middle type patches are widely distributed, which mostly fasten on affiliated greenbelt and residence greenbelt. And the proportion of great type patch just takes up 3.01 percentages.(2) Fractal dimension of six types of patches are between 1.35 and 1.45, indicating a low degree of perimeter complexity as whole. The calculated fractal dimension of scene forest is only 1.411, showing that its' nature zoology succession was interfered by human. Fragmentation values of six types of patches is between 0.0302 and 0.7365, indicating a commonly degree of fragmentation as whole. The degree of affiliated greenbelt fragmentation is the most serious, secondly is residence greenbelt, and scene forest is the lightest because of its' concentrated distribution.(3) The analysis of whole landscape pattern, using landscape diversity index, max diversity index, landscape richness density, relative richness density index, landscape dominance index and landscape evenness index, showed that the distribution of greenbelt of Nanjing city is uneven, the dominance of each type greenbelt has great different, the degree of whole diversity is low and the richness is less.(4) The problem of urban greenbelt pattern of Nanjing city was found by the analysis of the type's structure distribution of urban greenbelt landscape, urban greenbelt fragmentation index, fractal dimension and whole structure pattern indexes. Some methods were put forward to solve this problem:?Developing urban virescence vigorously and enhancing urban virescence mantle ratio, at the same time, making the distribution of urban greenbelt more even and improving the proportion of public greenbelt. ?Depressing fragmentation degree and increasing great patch appropriately, the pattern of "making areas either sparse or bushy" should be taken in changing residence and affiliated greenbelt of main city district. ?Reducing the destruction to scene forest by the human, resuming nature zoology succession of Zijin Mountain and Mufu Mountain and so on. (4) Increasing the landscape diversity and the complexity of the grade of greenbelt system structure, which can enhance spatial heterogeneity of landscape.