Based On The Ecological Security Pattern Of Urban Space Expansion

Extensive urban expansion leads to a series of urban diseases,such as the decline of eco-environment carrying capacity,low land use efficiency and loss of cultivated land and ecological land.At present,less research on urban space expansion is combined with ecological protection and resource carrying capacity.Taking Xi'an city as a case,this paper makes a systematic study on urban space expansion on the basic of ecological security pattern.First of all,the spatial analysis method and land transfer method were used to analyze the spatial and temporal evolution rules of land use in Xi'an from 2000 to2015.And after,the ecological"source"was defined based on the red line of ecological protection,and the comprehensive ecological security pattern was constructed by using the minimum cumulative resistance model,and three different levels of ecological security patterns were divided according to the grid"mutation point".Last,the FLUS model was used to simulate and predict the urban land use in Xi'an in 2020 and 2030.The research results show that:(1)during the whole research period,the expansion of urban construction land is mainly in the direction of northeast,west and southwest;The newly-added construction land mainlycomes from cultivated land and grassland,and mainly expands outward around the built-up area,showing a general trend of spreading outward from the central city.(2)based on the MCR model,the ecological security pattern of Xi'an is constructed.Among them,the low-level safety pattern area is 4876.64 km~2,accounting for 48.27%of the area;the medium-level safety pattern area is 6336.45 km~2,accounting for 62.73%of the area;the area of high-level safety pattern It is 8972.63 km~2,accounting for 88.82%of the area.(3)based on the FLUS model,the urban land expansion in 2020 was simulated and predicted,and compared with the overall planning of Xi'an(2004-2020).The results showed that the two were basically consistent with the expansion direction,but there was a big difference in the scale of land use.(4)in order to guide reasonably urban space development and make planning and early warning,Xi'an city 2030 urban land use simulation and prediction,and finally determine the urban space expansion under the medium level ecological security pattern is the best development model to solve the coupling between urban development and ecological protection.When constructing the pattern of ecological security,this paper chooses the red line of ecological protection as the ecological"source",which fully integrates the restricted development zone and can better protect the regional ecological security.Meanwhile,the simulation accuracy of FLUS model is higher,it not only made considerable improvement to the traditional model,and based on ANN was carried out on the probability of mutual conversion of various types of land suitability evaluation.Which can simulate more objectively the future land use status,application prospect,is of great significance to guide the direction of urban development.