Land Use Optimization Based On Resource-environment Carrying Capacity In Karst Mountainous Area

With the deterioration of resources and environment,the evaluation of carrying capacity has gradually become a guiding content of land resources protection and development.Especially in karst mountainous areas,the fragile ecological environment and excessive use of resources caused decreasing natural vegetation,serious soil erosion,severe rocky desertification,reducing land productivity,insufficient water supply,so that human-land contradiction and resource-environment problems were very prominent.Therefore,it is urgent to scientifically understand the resource-environment carrying capacity and optimize the land development and utilization in karst mountainous areas.Following the basic idea of "background overview,research progress,methodology system,empirical analysis",consulting literature,inspecting the field situation,and considering the current resource-environment situation,socioeconomic conditions and land use structure in karst mountainous areas,this study put forward a methodology system for evaluating the resource-environment carrying capacity and optimizing the land use structure in karst mountainous areas.Guangnan County,a typical region,is taken as an example for empirical analysis.The main conclusions are as follows:(1)The major influencing factors of resource-environment carrying capacity in karst mountainous area are 12 aspects(water resources,land resources,mineral resources,tourism resources,regional resources,ecological environment,geographical environment,soil erosion environment,water environment,atmospheric environment,social status and economic condition)from the three subsystems of resources,environment and social economy;among them,tourism resources,regional resources,geographical environment and soil erosion environment are four special indexes for the evaluation of resource-environment carrying capacity of karst mountainous areas.(2)The resource-environment carrying capacity of study area,Guangnan County,was in the mid-carrying class as a whole in 2017,and mainly distributed with the low-carrying and mid-carrying region,accounting for more than 80.00%of the county’s total area.Urban construction land has the strongest resources-environment carrying capacity,which is the important land type supporting for human activities and socioeconomic development in karst mountainous areas.(3)The relationship between carrying capacity and land use types is analyzed.The average of carrying capacity of each subsystem is taken into the optimal objective function,which can effectively optimize the quantitative structure of land use in karst mountainous areas from the optimal perspective of the three sub-goals of resources,environment and social economy.(4)Based on the water supply situation in karst mountainous areas,three scenario models of "20%utilization rate of available water resources","30%utilization rate of available water resources" and "40%utilization rate of available water resources" were adopted to optimize the quantitative structure of land use in 2035 in Guangnan County.The scenario "30%utilization rate of available water resources" has the best optimization effect.Reducing the area of dry land,rural construction land and natural reserved land appropriately,and increasing the area of garden land,forestland,urban construction land,other construction land and waters at the same time will help to enhance the overall resource-environment carrying capacity,and promote the coordinated and sustainable development of human activities and resources and environment in karst mountainous areas.