Optimization of regionalization of territorial space function regions in typical karst areas of southwest China

Territorial space is the important carrier of urban construction, agricultural activities, and ecological protection. It is necessary to reasonably promote the coordination, moderation, and sustainable utilization of territorial space. The territorial development of different function types has posed serious conflicts on the regional economy and ecological system, especially in karst areas with fragile ecological environment and high poverty rate. Taking Guangnan County, a typical southwest karst area, as an example, this study aims to realize the coordinated development of territorial space in research regions. A series of geospatial modeling and statistical analysis tools were combined to propose the urban-agricultural-ecological functions coordination method, and the "dual evaluations" method of territorial space in karst areas. According to the environment situation of natural resource and regional planning, amendment rules was also formulated for conflict spaces, while a comprehensive optimization method was proposed for function areas of territorial space. This comprehensive method systematically combined the urban-agricultural-ecological functions coordination and the "dual evaluations", constructed comprehensive optimization patterns of territorial space function areas, and divided different types of territorial space function area in karst areas. The results showed that: 1) In the most suitable level and less, the ecological suitability was the maximum, accounting for 61.21%, which was mainly distributed in the north and east. The suitability of urban development was the minimum, accounting for 27.81%, which was mainly distributed in the middle and south. The suitability proportion of agricultural development was 49.80%, which was mainly distributed in the northeast and east. The carrying capacity of resource and environment was dominated the level VI and V, where the highest level of carry capacity distributed in the northeast and southeast, whereas, the lowest levels of carry capacity in the south, southwest, and northwest. 2) In the optimized function areas of territorial space, seven types of function areas were divided in karst areas. Specifically, the types of function areas related to ecological function dominated in the development of karst areas, accounting for 79.54%. The types of function areas related to urban function were the smallest, accounting only for 2.35%. The areas dominated by urban function were mainly distributed in the middle and southeast, whereas, the areas dominated by agricultural function were mainly distributed in the north, west, and east, as well as the areas dominated by ecological function were mainly distributed in the north and south. 3) Compared with the urban-agricultural-ecological functions coordination method and the "dual evaluations" method, the comprehensive method could more accurately and rationally construct the spatial patterns of territorial space for karst areas. This proposed method can provide an important decision-making support to delimit different areas in karst areas for territorial space planning and ecological restoration. The reasonable layout for different function types of territorial space can provide a sound reference to improve ecological environment, the management of rocky desertification, and the coordinated development of territorial space in karst areas.