Optimization Of The Spatial Layout Of Rural Settlements In Ecologically Fragile Areas

As urbanization and industrialization continue,rural development factors such as population and land flow in one direction to developed regions and central cities,triggering a rural disease characterized by the non-agriculturalization of rural production factors,the ageing and weakening of the rural population,the pollution of the ecological environment,the impoverishment of the social economy and the disorganization of village governance.The rural base in ecologically fragile areas is thin,and the obstacles to rural development are relatively prominent.Due to a combination of factors such as ecological fragility and sensitivity,poor infrastructure,weak agricultural foundations and loss of rural population,the problem of external disorderly expansion and internal idleness and abandonment of rural settlements in ecologically fragile areas has become prominent.As an important living space and dwelling place for rural residents,rural settlements are the core of human-land interaction in the rural areas and the basic unit of rural construction.In the context of comprehensively promoting rural revitalization,the optimization of the spatial layout of rural settlements is considered an important means to alleviate the relationship between human and land in ecologically fragile areas,improve the efficiency of land resource utilization,and achieve sustainable rural development and common prosperity for people in ecologically fragile areas.This paper takes the ecologically fragile area in western Jilin as the study area,and takes three typical towns,namely,urbanized township(Kaitong town),agricultural development township(Gashigen township),key ecological township(Momoge township),as case areas.With the research idea of “current situation characteristics-type identification-intelligent model simulation-optimization and control”,a framework for optimizing the spatial layout of rural settlements in ecologically fragile areas is constructed.Firstly,the basic characteristics,problems and influencing factors of rural settlements in ecologically fragile areas are systematically reviewed.Based on the problems faced by the rural territorial system in ecologically fragile areas,and relying on the macro development policies formulated by the government,the external environment of rural settlements is comprehensively assessed from both the socio-economic and ecological subsystems,and the development types of rural settlements in ecologically fragile areas are identified from a top-down perspective.On this basis,the multi-agent model is used to simulate the spatial decision-making behaviors of different types of agents and their interactions with the external environment,so as to achieve dynamic intelligent optimization of the spatial layout of rural settlements based on microscopic subjects.The main conclusions can be summarized as follows:(1)Rural settlements in the ecologically fragile areas of western Jilin are characterized by fragmented patches,scattered layouts and complex morphology.There are significant differences in the current characteristics of rural settlements in different development types of townships.In terms of patch area,rural settlements in urbanized townships are generally more fragmented than those in key ecological townships and agricultural development townships.In terms of patch density,rural settlements are denser in agricultural development townships than in urbanization townships and key ecological townships,with all three townships showing a high density and large-scale agglomeration distribution.In terms of patch shapes,the urbanized townships have the most regular rural settlement patches,followed by the key ecological townships,while the agricultural development townships have the most complex rural settlement patches.(2)The spatial layout of rural settlements in the three townships is analyzed in terms of both the external environment and the entities,and the results show that the spatial layout of rural settlements in different development types of townships is influenced by different factors.The spatial layout of rural settlements in all three townships is influenced by locational factors such as road distance or distance to the central town/village,while rural settlements in agricultural development townships and key ecological townships are also influenced by natural geographical factors and ecological environmental factors respectively.In addition,the spatial layout of rural settlements is also changed by governmental entities and rural residents through macro policies and individual migration behavior respectively.Therefore,to optimize the spatial layout of rural settlements,it is necessary not only to make a comprehensive assessment of the external environment in which they are located,but also to take full account of the decision-making behaviors of rural micro-entities under the guidance of the macro-policy.(3)There is a significant spatial dislocation in rural development potential and ecosystem resilience in the different development types of townships in the ecologically fragile areas.Among them,only 40% of the administrative villages in urbanized townships are of high or higher potential,distributed along both sides of the transit roads,while areas of high and higher ecosystem resilience account for about 65%,concentrated on both sides of the central towns.About 70% of the administrative villages in the agricultural development type townships have high development potential,while the high value areas of ecosystem resilience only account for 13% of the total area of the townships.The high value areas of development potential in the key ecological townships are the central villages,while the high value areas for ecosystem resilience are concentrated to the north and south sides of the central villages.(4)Based on the spatial combination of different levels of rural development potential and ecosystem resilience,rural settlements are classified as key development type,aggregation and promotion type,in-situ remediation type and relocation and merger type,and differentiated development paths are formulated for different types of rural settlements.Key development type rural settlements should consolidate their existing development advantages,and annex the relocation and merger type rural settlements for synergistic development.Aggregation and promotion type rural settlements should further optimize the spatial structure of rural settlements and promote the clustering of development factors.In-situ remediation type rural settlements are prohibited from expanding in scale,and the number and scale of scattered and fragmented rural settlements should be reduced.The only type of rural settlement that needs to be relocated is the relocation and merger type,which is also the focus of subsequent spatial layout optimization of rural settlements,and should be actively guided to move to key development areas or agglomeration and promotion areas.According to the rural settlement development type identification method,three typical rural settlement types within townships are identified.In the Kaitong town,34.54%,36.51%,3.64% and 25.31%of the rural settlements are of the key development type,aggregation and promotion type,in-situ remediation type and relocation and merger type respectively.In the Gashigen township,36.00%,5.82%,39.28%and 18.90% of the rural settlements are of the key development type,aggregation and promotion type,in-situ remediation type and relocation and merger type respectively.In the Momoge township,19.76%,39.59%,27.33% and 13.32% of the rural settlements are of the key development type,aggregation and promotion type,in-situ remediation type and relocation and merger type.(5)The multi-agent model can achieve dynamic and intelligent optimization of the spatial layout of rural settlements by simulating the spatial decision-making behaviors of micro-agents.In the Net logo simulation platform,different types of agents can be initialized and their spatial decision-making behaviors can be set based on the initialization of rural settlement development types,and the external environment of agents’ activities can set by integrating the attribute information such as land use type data,residential suitability data and spatial zoning data,and the spatial decision-making behaviors of agents can be constrained by random utility model and discrete choice model,with living suitability and spatial compactness are used as the comprehensive utility evaluation criteria.The spatial layout optimization model based on multi-agent system is constructed,and the spatial layout optimization process of rural settlements in three townships was simulated separately.The results show that after optimization,the average patch size and aggregation degree of rural settlements in the three townships have increased,while the total number of rural settlement patches has decreased significantly.All the relocation and merger type agents were relocated to key development areas and aggregation and promotion areas.Key development areas,aggregation and promotion areas,in-situ remediation areas are where scattered and fragmented rural settlements are moderately clustered to form relatively large-scale patches,different types of rural settlements are efficiently and orderly integrated,and the spatial layout of rural settlements is more compact.The application of the multi-agent model extends the process of spatial optimization of rural settlements from a single static to a dynamic intelligent one,which can effectively solve the problems faced by rural settlements in ecologically fragile areas,such as scattered layout and inefficient use,while the moderate clustering and large-scale development of living space not only facilitate the common construction and sharing of rural infrastructure,but also further provide spatial support for large-scale management of arable land and ecological environment restoration.