| The ecological environment of karst area is fragile,affected by the unique geological and geomorphic features,forming a unique karst regional system,in which a variety of regional functions play their respective roles.With the development of social economy,the acceleration of urban and rural construction and the intensification of human activities,the fragile karst ecological environment is damaged,and even the degree of rocky desertification is aggravating,which seriously restricts the sustainable development of social economy in karst areas.In recent years,the state has paid more and more attention to the ecological and environmental problems in karst areas,and the rocky desertification control project has also been strengthened.Many rocky desertification areas have achieved good results.However,the contradiction between regional economic development and ecological environment protection is still sharp.The differences and changes of regional natural resource endowment and economic and social development level lead to the continuous changes of regional functions in karst areas.It is an inevitable requirement for ecological environment protection,sustainable development and Rural Revitalization to clarify the multi-function theory of karst region and carry out the multi-function research of karst region,which is also an important content of regional multi-function research and rural geography research.Based on the basic data of natural environment,social economy,land use and remote sensing,this study adopts GIS,RS,ecosystem services and trade-off,machine learning,geographic detector and other related technologies and research methods,systematically analyzes the regional system of karst man land relationship and the multi-functional research of rural area,and combines theoretical and empirical research,The typical karst area northwest Guangxi is divided into 3046 5km × 5km grid,and systematically carried out the research on regional multi-functional identification of grid scale,long time series(20years)and high efficiency(Clusteringby fast search and find of density peaks)in Northwest Guangxi,as well as the research on spatial-temporal change mechanism and pattern optimization of regional multi-functional with multi factors(natural environment and socio-economic factors),multi mechanism(various regional functions and regional comprehensive functions)and multi mode(five optimization modes).The key issues to be addressed include(1)The multi-functional connotation of karst region is analyzed,and the multi-functional classification and evaluation index system of karst region is constructed.(2)The paper explores the characteristics,main influencing factors and mechanism of the multifunctional spatial and temporal changes in karst region in Northwest Guangxi.(3)The paper diagnoses the problems of the multi-function spatial pattern in karst region of Northwest Guangxi,clarifies the spatial optimization layout of different regional functions,and explores the development and utilization mode of regional multi-function optimization in Northwest Guangxi.The main conclusions are as follows:(1)The multi-function of karst region is a regional system with karst landform distribution,which is beneficial to the natural environment and human social and economic development,including ecological security,economic production and social life functions.In the classification,the differences between ecological protection function and other regions are mainly considered,which are divided into biodiversity protection,soil conservation,water conservation and rocky desertification control function.The comprehensive indexes such as water yield,soil conservation and rocky desertification sensitivity are selected as the evaluation indexes,especially the rocky desertification sensitivity indexes,which reflect the characteristics of karst areas.The study of karst regional multi-function theory can not only provide theoretical guidance for the study of regional multi-function,the improvement of urban-rural pattern and the reconstruction of urban-rural relationship,but also an important content of regional multi-function theory and rural geography.(2)The density clustering algorithm CFSFDP is used to cluster the multi-function index data of karst area in Northwest Guangxi.The CFSFDP algorithm is efficient and does not need to specify the category,which realizes the efficient recognition of multi-function of grid scale area.From 1995 to 2015,the distribution range of biodiversity protection and water conservation functions in Northwest Guangxi changed the most,and became the dominant function in the eastern and southern regions with more rocky mountains and more karst landforms,while the regions with more earth mountains and less karst landforms in the north of the West were gradually dominated by biodiversity protection and rocky desertification control functions.The overall level of economic production and social life functions has been significantly improved,and two high-level gathering areas have been formed in Youjiang River Valley in the south of the west,Jinchengjiang River and Yizhou in the East.The regional comprehensive function has gradually formed a pattern that the ecological security function is dominant in the north of the west,and the economic production and social life function are dominant in the East and south.(3)The dominant factors of ecological security function change in Northwest Guangxi are natural environment factors such as vegetation cover index,topographic relief and karst landform.The dominant factors of economic production and social life function change are social economic factors such as urban and rural population and fertilizer application.The dominant factors of regional comprehensive function change are karst geology,landform and karst landform Total retail sales of social consumer goods and other factors.The influence of karst geology and geomorphology on economic production and social life is weak,but the interaction with other factors is significantly stronger.The spatial-temporal change of regional multi-function in Northwest Guangxi is the result of the combination of internal factors of natural environment and external factors of social economy,and the interaction of leading and basic factors.The interaction of various influencing factors has significantly enhanced the impact on the spatial-temporal change of regional function.(4)There are great differences in the spatial distribution of multi-functional karst regions in Northwest Guangxi.Different spatial patterns and optimization modes for different functional types and spatial regions are conducive to carrying out regional ecological protection and promoting regional economic and social development.Based on the principle of problem orientation and controllable factors regulation,five development and utilization modes are put forward,including comprehensive guarantee mode of ecological town,promotion mode of green ecological industry,urbanization transfer and resettlement mode,land consolidation and restoration mode and driving mode of ecological characteristic town,which can increase the operability of optimizing the layout of multi-functional space in karst region of Northwest Guangxi.In addition,the county scale regional multi-functional optimization zoning can provide more effective guidance for ecological protection and spatial optimization in Northwest Guangxi. |
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