| With the rapid development of the reform and opening up,land space problems such as imbalance in the development and utilization of land and space in China,and tightening constraints on resources and the environment have become increasingly prominent,mainly manifested in the relatively backward space governance capabilities that are not compatible with the territorial space pattern in the drastic changes.To this end,it is a major and urgent task to build and improve the national land space governance system with the national land space planning as the starting point,and vigorously improve the national space governance efficiency and capabilities.Among them,rural settlements have received great and continued attention from the government and academia as the shortcomings of land and space management and the focus of solving urban-rural land conflicts and stimulating rural vitality.Based on different discipline backgrounds such as geography,economics,demography,and sociology,combined with government macro policies,the academic community has conducted a large number of studies from different perspectives such as land use,urban-rural relations,rural sustainable development,population migration,and community governance,the types,structures and functions of rural settlements,evolution rules,driving mechanisms,and remediation strategies have been clarified,and the overall and systematic results of the research on rural settlements have been initially formed.However,as far as rural settlements in specific areas are concerned,their spatial pattern characteristics,evolution process,change trend and optimization strategies are still lack of pertinence,and need to be deepened in the construction of theoretical framework,application of analytical tools,and design of utilization strategies.In practice,the mountainous urban fringe area,which carries important industries and urban development,must not only meet the development needs of industrial land and improve the production and living conditions of farmers,but also dig and play the ecological function of the rural landscape to provide land protection and ecological barriers for urban expansion.Thus,studying the direction,model and technology of the layout optimization of rural settlements in the region will not only help enrich the basic theory of the research on the evolution of rural settlements and layout optimization,but also help to optimize the urban-rural land use pattern for the region,promote urban-rural integration and ecological civilization construction.Therefore,this article aims at its rural settlements under the pressure of urbanization and industrialization.Based on the perspective of land and space governance,it takes the relatively unique geographical characteristics of the mountainous urban fringe as the type area and its representative Chongqing Liangjiang New District as the research area.The research is based on the land use change survey database,using ant colony algorithm,cellular automaton and other spatial measurement analysis methods,following the logical of "current status characteristics-evolution process-simulation prediction-layout optimization" to explore rural settlements of this distribution pattern,evolution mechanism and optimization path,expecting to provide a reference for studying the morphological characteristics,evolution rules and optimization strategies of rural settlements in the mountainous urban fringe area.The main conclusions of this study are as follows:(1)The theoretical analysis shows that the spatial distribution of rural residential areas in the mountainous urban fringe shows different distribution patterns due to the influence of special landform and many natural and human factors.The analysis of the spatial distribution characteristics of rural settlements must consider both the natural factors and the impact of economic and social development.The site selection of rural residential land under special landforms is affected by factors such as elevation,slope,ground disasters,water sources,formed towns,roads,etc.,and many irregular land forms on the microscale,which further lead to spatial differentiation and spatial pattern disorders.There are four spatial distribution patterns,which are agglomeration,band distribution,free-style and radial.In addition,various modes and patterns have certain advantages and disadvantages,which are well adapted to the special landforms of low mountains and hills.By using Arc GIS spatial statistical analysis and constructing the index system of spatial differentiation characteristics of rural settlements,the analysis results show that urbanization has a certain impact on the scale of land use in rural settlements;the level of township urbanization near the urban area is high,and the scale of rural settlements is relatively reduced;however,due to the elevation,slope,geological disaster,water system,urbanization and traffic conditions,the scale of residential land varies greatly in different regions.8% of rural settlements are located in mountainous areas with an altitude of more than 500 m,38% of rural settlements are located in areas with a slope of more than 15 °,5% of rural settlements are located in areas with high incidence of geological disaster,40% of rural settlements are located in1000 m buffer zone of river system,24% of rural settlements are distributed outside the urban 2000 m buffer zone,and 47% of rural settlements are more than 2000 m away from the main road.Combined with the fractal dimension measurement,it shows that the poorer the natural and location conditions are(such as Gulu Town,Shichuan Town,Mu’er Town,etc.),the more complex the spatial form of rural settlements is.On the contratry,the more adjacent the urban areas are(such as Shimahe Street,Tiangongdian Street,etc.),the more regular the patches of rural settlements are;under the constraints of terrain,the rural settlements in Liangjiang New Area are generally distributed in strips.The terrain is the leading factor,but the effect of location conditions gradually becomes prominent,and thus breeds a diversified spatial distribution pattern.(2)The spatial-temporal evolution of rural residential areas in the mountainous urban fringe is extremely intense,driven by the economic and social development,urban planning,industrial layout and natural factors of special geomorphic units in the study area.The evolution of rural settlements in the fringe areas of mountainous cities has the general succession process of scattered villages → central clustering → deep clustering → urban fringe.In the early stage of evolution,the layout of residential areas was mainly affected by natural factors,but in the later period,it was more affected by economic and social elements.Under the current control of the "three red lines" of the government,the channels for urban fringe areas to obtain urban construction land can only be achieved through "increasing,decreasing,and suspending",inevitably requiring more inefficient utilization of rural residential settlements,which further changes spatial land use patterns in rural settlements.In addition,the coordinated advancement of land urbanization and population urbanization will inevitably require the increase of urban construction land to coordinate with the transfer of rural population,thereby achieving equal exchange of urban and rural land elements.In the process,the spatial layout of rural residential areas will have a significant effect.In the rural settlements in the mountainous urban fringe,the terrain slope is the most important natural driving force,but the leading driving force lies in the improvement of traffic conditions and the promotion of urban expansion.Based on land use spatial data,social and economic data,landscape ecological analysis technology,nuclear density estimation method,land use dynamic transfer degree and other methods,this paper analyzes and depicts the spatiotemporal evolution characteristics of rural residential land in Liangjiang New Area from 2010 to 2018.The spatial error model and spatial lag model are used to identify the driving force of rural residential land evolution in the study area.The results show that the overall distribution pattern of rural settlements is relatively stable in this period;most of the settlements are within 4000 m of the road buffer zone,both around the city and 4000-5000 m away from the city,but completely disappeared beyond 5000 m,while the average patch area of rural settlements shrinks dramatically within 1000 m of the urban buffer zone and 1000-2000 m of the road buffer zone.After the establishment of Liangjiang New Area,the dynamic change of rural settlements in the area is intense,fragmentation and reduction are prominent,the shape of land is regular,the density of patches is stable,the degree of aggregation is improved,the trend of being replaced by other land types is increasingly significant,and the proportion is gradually reduced.From 2010 to 2018,the dynamic degree(K)of rural residential land transfer in Liangjiang New District was negative,and the transfer-out degree was higher than the transfer-in degree;The natural driving force mainly acts on areas with poor terrain conditions,high terrain,far from the waters,and rural residential settlements with a high degree of landscape dominance.The traffic road conditions and urban expansion are the leading forces to promote the regularization of the patch shape of rural settlements,while the uncertainties of economic driving force and social driving force leads to the complexity of the patch shape of settlements.(3)The spatiotemporal evolution of rural settlements in the fringe areas of mountainous cities is a comprehensive system of the spatial pattern and function of rural settlements formed in time and space.The evolution of rural settlements is affected by many factors such as economic and social development.Rural settlements in different regions show different evolutionary states in time and space,and their laws and processes can be scientifically predicted.The gradual decrease of rural settlements in urban fringe of mountainous region is the main trend of land use change.In the next2030,rural residential settlements will shrink faster with the expansion of the city,the overall land use scale,per capita land use scale will decrease,and the degree of land intensification will increase.Based on the perspective of urban-rural coordination,a transfer area matrix and land suitability atlas were established,and the MCE-CA-Markov model was used to simulate the land-use change trend in Liangjiang New District.The results show that from 2010 to 2018,the construction land in the Liangjiang New District continued to increase,arable land and forest land gradually decreased,and rural settlements gradually decreased.Simulating the size and spatial distribution of rural settlements in 2030,the number of rural settlements decreased by172.895 hm2 from 2018,accounting for a decrease of 1.47%,and the distribution became denser with economic development,especially in the central and western parts of the area,the regional patches are highly concentrated.The verification results show that the MCE-CA-Markov model is used to simulate the spatiotemporal evolution of rural settlements,which will provide an optimized layout for rural settlements in the Liangjiang New District,adjust land use structure,rationally allocate urban and rural land resources,and coordinate urban and rural development.For reference,this method is reasonable and effective.(4)The adaptability of the layout of rural residents in the mountainous urban fringe area has obvious spatial difference characteristics,so it is necessary to design different strategies for the renovation and optimization of residential areas.The suitable areas for rural residential land use in the study area are mainly located in the northwest of Shuitu Town,Fuxing Town,Shijialiang Town,Caijiagang Town,Mu’er Town,and southeast Longxing Town,Fusheng Town,and Tieshan Ping,Guojiabang Town and Yuzui Town,generally suitable areas are mostly concentrated in Shuangfengqiao Street,Yufengshan Street and Shuanglonghu Street in the middle of Liangjiang New District.Unsuitable areas are mainly distributed in Shichuan Town,Gulu Town,and northern Mu’er Town.From the results of layout optimization,the total area of rural residential areas have been reduced by only 132.75 hm2 after the optimization,but it has replaced the previous scattered distribution state,showing a high concentration trend,and is mainly distributed in Shuitu Town and Fuxing Town,Caijiagang Town,and Shijialiang Town,Cuntan Street and Tieshanping Street,Yuzui Town and Fusheng Town in Jiangbei District,and Longxing Town in Yubei District.Although the plan tends to be idealized,they have relatively concentrated the layout of rural settlements and improved rural living environment,which provides a strategic direction to promote the integration of urban and rural areas.Based on this,with the guidance of rural rejuvenation and the integration of urban and rural areas,full consideration should be given to the impact on resources,industry,location,and transportation conditions of the layout of residential areas.The optimization of rural residential areas in urban fringe of mountainous region can follow the the following five strategies: urbanization optimization strategy,the transportation element-led optimization strategy,the rural tourism driving optimization strategy,the optimization strategy for the relocation of villages,and the industry promotion-driven strategy.The urbanization optimization strategy is mainly to gradually incorporate residential areas into built-up areas and transform them into urban construction land.The transportation element-led optimization strategy is mainly to sort out the residential areas along the main transportation line to make the residential areas more orderly.The rural tourism driving optimization strategy is to take advantage of the natural ecological environment and location conditions,make full use of the unique landscape effects of rural residential layout,reasonably delimit the residential "three lives space",and create a distinctive rural complex.The optimization strategy for the relocation of villages is to expand the size of existing settlements,collect small settlements around it,and sort out neighboring similar settlements as a means to focus on building large-scale residential communities and improve infrastructure and public service facilities to achieve continuous development of rural settlements in the region.The industry-driven optimization strategy is based on serving the development of secondary and tertiary industries,rebuilding or rationally developing the current villages,and making the space more intensive through appropriate infrastructure construction and adjustment.In summary,although constrained by the original terrain of the mountain fringe area,the spatiotemporal evolution of peasant settlements is extremely fierce.The main driving force comes from the improvement of traffic and road conditions and the promotion of urban expansion,resulting in the morphology of its patches.The urban area tends to be more complex,and the area closer to the city tends to be relatively regular.With the expansion of the city,the overall land use scale and per capita land use scale have decreased,and the degree of land intensification has increased.The MCE-CA-Markov module of IDRISI software was used to explore the characteristics of the aggregation and spatial evolution of rural settlements under the influence of various influencing factors,and to determine the suitability function according to the influencing degree and spatial distribution of influencing factors to develop ArcGIS.Spatial analysis and ACO ant colony optimization in Geosos can provides regional reference and research reference for systematically revealing the morphological characteristics,evolution rules and optimization strategies of rural settlements in the edge of mountainous cities. |
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