Optimization Of Rural Settlement Distributions In Typical Ecologically Fragile Areas

In the process of rapid industrialization and urbanization,the"village disease"has emerged in the rural areas in China,which is characterized by the weakening of the old population,the empty-waste of villages and the deterioration of the ecological environment.As the most basic unit of rural regional space,rural settlement is the geographic spatial carrier of agricultural production,peasant's life and rural ecosystem,and its spatial distribution has obvious regional characteristics.Western Jilin Province is located in the farming-pastoral ecotone of Northern China,the economic development of this region is relatively backward and the problems of the agricultural ecological environment are prominent,mainly manifested in the serious land salinization,grassland degradation and land desertification.Compared with rural settlements in traditional agricultural areas,the spatial distributions of rural settlement in ecologically fragile areas are significantly affected by the availability of resource elements and regional natural environment conditions.Therefore,optimizing the spatial distributions of rural settlement in typical ecologically fragile areas through human intervention measures based on the correct value orientation is of great significance to improve the level of intensive and economical utilization of rural land and alleviate the pressure of resources and environment in ecologically fragile areas.This paper takes Da'an City,located in the ecologically fragile area in Western Jilin,as the research area.Firstly,the landscape pattern index and GIS spatial analysis technology are used to analyze the quantitative morphological characteristics and spatial distribution characteristics of rural settlements in Da'an in 2015,focusing on the impacts of location conditions,production conditions and policy systems on the spatial distribution of rural settlements,and then summarizing the distribution characteristics and problems of the current situation of rural settlement.Secondly,the soil and water conservation security pattern,water resources conservation security pattern,land salinization prevention security pattern and biological protection security pattern are constructed in the research area based on landscape ecology theory and minimal cumulative resistance(MCR)model.The comprehensive ecological security pattern is generated by overlaying the four individual security patterns and is taken as the ecological constraint condition for the optimization of rural settlement distributions in Da'an City.Thirdly,selecting relevant evaluation factors from the natural geographical factors and economic and social factors that affect the spatial distribution of rural settlements,and then studying the suitability of land distribution of rural residential areas by using analytic hierarchy process and multi-factor comprehensive evaluation method.Finally,considering the results of ecological security pattern and the suitability subareas of rural settlements,the research area is divided into four ranks:ecological relocation zone,limited development zone,key development zone and priority construction zone.The main conclusions are as follows:(1)The results of the analysis of the status quo characteristics and the influencing factors of rural settlements showed that the spatial distribution of the rural residential areas in Da'an city was the agglomeration type.The Voronoi diagram's Cv value of all the towns except Fengshou Town was more than 64%,among which Dalai town and Anguang town had the highest concentration of rural settlements.From the perspective of quantitative and morphological characteristics,the differences in size,number and shape of rural settlements in different towns were significant,which were mainly manifested as large number,small scale,simple patch shape and insignificant boundary effect.From the perspective of influencing factors,the closer the area was to the town and the traffic line,the denser,more and smaller the rural settlements were,and the scale of rural settlements was relatively large in areas with superior production conditions.Generally speaking,the rural settlements in Da'an City belonged to the typical distribution mode of"small settlement and large dispersion".(2)The comprehensive ecological security pattern of Da'an City was constructed according to four single ecological processes:soil and water conservation,water resources conservation,land salinization prevention and biological protection.The results showed that the area of the low security zone,general security zone,moderate security zone and extreme security zone was 395.65km~2?3212.80km~2?1246.23km~2 and 23.91km~2respectively,accounting for 8.11%?65.86%?25.54%and 0.49%of the total area of Da'an City.Among them,the area with low security level was the most fragile ecological environment and the most sensitive to human activities.The area with extreme security level had the lowest sensitivity to human development and utilization,and was the most suitable area for the site selection and construction of rural settlements and human development and utilization.(3)Six indexes including slope,distance from saline-alkali land,tillage radius,distance from water source,distance from traffic line and distance from township were selected from two aspects of natural geographical factors and social and economic factors to construct an evaluation index system for the suitability of land distribution in rural settlements.According to the results calculated by the multi-factor comprehensive evaluation method,the study area was divided into four ranks:highly suitable area,moderately suitable area,lowly suitable area and unsuitable area.The areas were respectively 374.82km~2,1175.83km~2,1889.96km~2 and 1437.98km~2,accounting for 7.68%,24.10%,38.74%and 29.48%the total area of Da'an city.(4)Combined with the results of ecological security pattern and suitability subareas,the target area was divided into four ranks:ecological relocation zone,limited development zone,key development zone and priority construction zone,which were the basic zones for the optimization of rural settlement distributions.Among them,the area of ecological relocation zone was 2449.92km~2,the area of existing rural settlements in this zone was 48.27km~2,accounting for 39.95%of the total area of such settlements.It was suggested to guide these settlements to move to the nearby key development zone or priority construction zone.The area of limited development zone was 483.34km~2,the area of existing rural settlements in this zone was 14.62km~2,accounting for 12.10%of the total area of such settlements.It was suggested that rural settlements in this zone should tap their internal potential of development and curb the trend of rural settlements expansion.The area of key development zone was 483.34km~2,the area of existing rural settlements in this zone was 14.62km~2,accounting for 12.10%of the total area of such settlements.The development plan of these settlements should be formulated to promote the integration and co-construction of the resettlement residential areas and the existing residential areas.The area of key development zone was 392.12 km~2,the area of existing rural settlements in this zone was 20.29km~2,accounting for 16.80%of the total area of such settlements.This zone had the basic conditions for the large-scale and intensive development of rural settlements.