Analysis On The Urban Landscape Pattern Of Xi'an Based On GIS And Study On Landscape Pattern Optimization

Landscape pattern analysis is beneficial to inquire the correlation between the landscape pattern and process. And it is the core problem of the landscape ecology. The rapid urbanization in Xi'an city is changing deeply the natural landscape and affecting the city's ecology process. Then the whole landscape pattern of the city is changed. At the same time, the problems such as city transportation, pollution of the environment and living environment deteriorated. Those problems reduce the comfort of the city to be the environment of producing and living, and go against sustainable development. The influence to the function of ecosystem and the ecological effect, which is caused by the out-of-order extending of constructed land introduced by urbanization, is the key problem that needs to resolve urgently in Xi'an. The research of city landscape pattern in Xi'an has important meaning to the reasonable proceeding of land-use plan and management, and ameliorating the city ecology and environment.This paper choosed the RS imagery of Three Circles of Xi'an by QuickBird as the research area, combined with the theories of Landscape Ecology and the technology of GIS, the appropriate grain was choosed based on the sensitivity analysis of landscape pattern indices with different grain, and thus the current landscape pattern of Xi'an was analyzed. Some landscape indices were computed along a 16km long and 2km wide west-east transect and another 19km long and 2km wide south-north transect, crossing at the urban center, with a moving window. The landscape gradient analysis could commendably validate the theory of urban form.1,In the research, the grain changed from 5 to 20 metre was tiny. When the grain exceeded 80 metre, the landscape pattern was totally altered, and the results differed from the fact. Between the 20 and 80 metre, the smaller the grain was, the more visible the landscape pattern diversity was. According to sensitivity analysis of landscape pattern indices with different grain, under the precondition of avoiding jumbled data and expressing the special heterogeneity well, the paper take the 20 metre as the appropriate grain.2,Use the landscape indices combined with gradient analysis, the paper showed the landscape indices pulsive process from suburb to the centre of the city, which behaved the obvious gradient trend both on class-level and landscape. The intensive urbanized region manifested the higher landscape fragmentation and complication. The landscape gradient analysis could commendably validate the theory of urban form, also can set gist for the measurement of urban centre. The study showed that, with the further urbanization in Xi'an, the current urban form, which maintains the bell tower as the single centre is unchanged. The gradient analysis which used the landscape indices, can clearly show the annular structure of Xi'an, and the diversification of the landscape indices were related to the different landscapes pattern among the three circles.3,The result indicated that the ecological processing was influenced by the result of conglomeration of artificial landscape, such as: residential area, industrial area; the fragmentation and distribution of green area and water body are high; the landscape structures within the 1st circle were unreasonable, the distribution of landscape types between 1st and 2nd circles are not uniform, the potential of economic and ecological effects of land use within 2nd and 3rd circle are high also.4,The optimization was presented that the improvement of urban space distribution and structure was needed, and the continuity of the landscape ecological processing and pattern should be maintained form the desirable point of view, such as the construction of green area landscape and the protection of the wet land system.