Study Of Mountainous Rural Settlements Spatial Layout Based On Ecological Security ——A Case Study Of Yongchuan District

Since the 18 th national congress of the CPC,the construction of ecological civilization has been promoted to an unprecedented strategic height.Mountainous areas play an important role in ecosystem because of their large vertical gradient and diverse environmental sensitive zones.This not only challenges the ecological environment protection of mountainous rural settlements,but also provides a new vision for their sustainable development.With the deepening of urbanization,China’s rural areas have entered a transitional period of accelerated reconstruction.And spatial reconstruction is an important part of it.In the reality of the lack of scientific planning and guidance in the development of mountain rural settlements,all kinds of contradictions in the process of development emerge in the rural settlements space.In the context of mountainous areas,due to the particularity of their natural geographical conditions,mountainous rural settlements often face more severe problems in spatial development.Relations between man and land are increasingly tense,the spatial layout of the rural settlements is scattered,and the ecological environment was destroyed.At the same time,the spatial planning guided by ecological civilization strategy has become a new spatial guide for regional development in the new era.Maintaining regional ecological security is an inherent requirement of spatial planning,and the management of natural resources is an important part of it.In this context,it is particularly necessary to incorporate natural areas and rural settlements into the planning of spatial planning.How to guide the spatial layout of rural settlements from the perspective of maintaining regional ecological security has become an urgent problem to be solved in the development of mountainous rural settlements.In view of this,this paper sorts out the ecological characteristics and realistic difficulties of mountainous rural settlements based on the previous research results.It also analyzes the important value of ecological security concept to guide the development of settlement space in mountainous rural settlements.Based on the model of PSR framework,the ecological security evaluation system for mountain area is constructed in this paper.With the support of GIS spatial analysis technology,attribute data and spatial data are used to carry out an empirical study in Yongchuan district of Chongqing,a typical mountainous city.On the basis of understanding the characteristics of ecological security in Yongchuan district,this paper tries to explore the relationship between the spatial distribution of rural settlements and ecological security.Finally,based on the results of the analysis,some Suggestions are put forward to optimize the spatial distribution of rural settlements for the purpose of maintaining ecological security.In order to provide some guidance and reference for the construction of livable towns and villages and rural revitalization.The results of ecological security evaluation in Yongchuan district show that:（1）In terms of regional scale,the ecological security level of Yongchuan has been improved in recent years.From the grid scale,the change of ecological security level is more drastic.（2）The regional distribution of high ecological security level in Yongchuan is relatively stable,and the change of ecological security level is the lowest.While regions with low level of ecological security show more significant characteristics of agglomeration distribution,and this agglomeration has an increasing trend.（3）The high level of ecological security in Yongchuan is mainly distributed in three north-south bands,which are rich in ecological resources and less disturbed by human activities.The areas with low ecological security show the characteristics of expansion around the central urban area,while in other areas show leapfrog changes.（4）The high ecological security zone is not directly adjacent to the low ecological security zone.The distribution of low ecological security has a barrel effect,which has a significant influence on the overall level of regional ecological security.The results of the research on the correlation between ecological security and the spatial distribution of rural settlements show that:（1）The density and size of settlement patches in ecological security zones of Yongchuan decreased with the change of regional ecological security level from low to high.However,the agglomeration degree of rural settlements distribution is affected by the distribution range of different ecological security levels.（2）The influence mechanism of the spatial distribution elements of rural settlements on ecological security is different,the ecological pressure caused by the increasing number of rural settlements,the expansion of rural settlements scale changes the ecological state,while the degree of agglomeration reflects the ecological response of human behaviors.（3）In regions with different levels of ecological security,the influence of the three elements of the spatial layout of rural settlements on ecological security is different.The high ecological security zone is mainly affected by the change of rural settlements scale,the middle ecological security zone is significantly affected by the agglomeration of rural settlements,the change of the number of rural settlements in the low ecological security zone is the most obvious.Suggestions for optimization based on the correlation analysis of ecological security and the spatial distribution of rural settlements include:（1）Establish the overall layout principle of rural settlements to maintain ecological security,It includes the holistic principle of people-oriented and regional coordination,the adaptive principle of dynamic adjustment and strict control of the bottom line,and the principle of unified planning and compact layout.（2）Suggestions on space control based on ecological security include that: focus on the scale effect of ecological security,adopt partition and different space management method,pay attention to the dynamic changes in key areas of the ecological security pattern,Hold the structural integrity of regional ecological security.（3）According to the characteristics of each ecological security level area and its inner situation of rural settlements,this paper summarizes the spatial layout optimization of rural settlements in the high,medium and low ecological security areas under the guidance of the mode of migration,the mode of group integration and the mode of central agglomeration.At the same time,the paper expounds the important value of improving production mode,strengthening internal connection and enhancing the strength of towns for maintaining the ecological security level of different regions.Finally,five typical towns and streets in Yongchuan district are taken as examples to apply the optimization model,and guidance is put forward to optimize the spatial distribution of rural settlements in every towns and streets in Yongchuan district.