Research On Spatial Expansion Of The Plateau Mountainous Town Based On Ecological Security

In recent years, with the further implementation of the western development strategy, the economy increases rapidly in the western region of China, the process of urbanization and industrialization accelerates gradually,the population scale and urban scale grow quickly. However, the eco-environmental problems have become increasingly serious. Especially in the plateau mountainous area of Southwest China, the contradiction between urban expansion and ecological environment is more obvious under the special geographical environment. The disorder of urban expansion will not only occupy a large number of agricultural land and ecological land, may also break the original balance of natural ecosystem, even threaten the ecological security of the town. How to balance the ecological effects and economic effects, and chieve sustainable development of plateau mountains town has become the focus of the domestic scholars and the government.The research of optimal adjustment of the existing urban space expansion mode from the perspective of ecological security can provide theoretical basis for the sustainable development strategies of towns,meet the requirements of environmental protection in plateau mountainous cities.The research has important practical significance.According to the complex natural geographical features of Dali city, this paper constructs the ecological security pattern of urban spatial expansion in Dali city from the perspective of maintaining urban ecological security as the main basis for the Dali city Urban Expansion.Then the paper studies the spatio-temporal evolution and characteristics of urban expansion in Dali city from the aspects of expanding scale, expanding space shape and expanding direction. What’s more, the paper analysis the rationality of current urban spatial expansion by combining with the ecological security pattern;Finally, based on the,urban ecological security,the paper puts forward the optimization and control strategies of urban spatial expansion in Dali city.The main conclusions of the study are the following:(1) According to the ecological security pattern of urban spatial expansion in Dali City, the total land area of Dali city which can be used for urban expansion and construction is about 481km2. Among them, the area of land which are giving priority to the construction accounts for about 281km2.The land are mainly distributed in Xiaguan town and Fengyi town which are located in the southern region of Erhai Lake,and the scattered plots which are divided by basic farmland in the towns of the western and northern region of Erhai Lake;The area of land which are suitable for construction is about 200km2.The land are mainly distributed in Erhai lake coast,the foothills and the mountainous area with gentle slope;The area of land which are limited to construction is about 173km2. The land are basically located between the land forbidden for construction and the land suitable for construction.It can effectively alleviate the contradiction between urban expansion and ecological land;The area of land which are prohibition for construction is about 1161km2.The land are mainly including the Cangshan-Erhai scenic area, the mountains region where the slope is more than 25 degrees in the southern and northeastern region of Erhai Lake,the basic farmland distribution area,major rivers, reservoirs,large pools and the disaster-prone areas.(2) During the period of 1995-2015, the main features and the changing trend of the urban spatial expansion in Dali city include that the scale of the urban space is expanding. The degree of the spatial dispersion of the urban land becomes larger.The level of intensive use of the urban land is declining.The urban space mainly adopts the denotative extended way to expand,along the highway, river and lake. The Urban Spatial Morpholog have non-balanced circle type, radial type, strip type and enclave type.The expansion of urban space begins to shift from the dam to the mountain.(3) After analyzing the relationship between urban extension in Dali city and ecological security pattern space, the study finds that the current urban space expansion pattern is not completely helpful to maintain the ecological security of the Dali city, And it needs to be regulated and optimized.(4) Based on the ecological security pattern, the paper put forward some optimization and control strategies about the future urban space of Dali city from the aspects of expanding mode, expanding direction and expanding scale.