Assessment Of Land Use Suitability In Pingguo County Based On GIS

China,where karst area widely distributes,is one of the three most widespread areas of carbonate rocks in the world.With complex topography and barren soil,the karst region is extremely fragile eco-environment.Due to the irrational land use,vegetation was reduced and soil was eroded seriously in karst area,which led to the soil layer getting thin and the bedrock to expose,and rocky desertification took place.Therefore,the evaluation of land use suitability in karst area is essential to provide an important reference for the rational utilization of land resources and fragile ecological environment protection.The Pingguo County,a typical karst county,was selected as the study area.With the support of the GIS and RS technology,four aspects which include the soil(soil organic matter and soil type),the topography(landform type,elevation,slope and aspect),the ecology(rainfall erosivity,lithology,rocky desertification grade)and the traffic(road distance and settlement distance),can represent land use suitability evaluation indicators,and the hierarchical model for comprehensive assessment of land use suitability was established.The qualitative indicators and quantitative were quantized by the delphi method and ecological niche model,respectively.The weight of each indicator was determined by the analytic hierarchy process(AHP).The land use suitability levels of the Pingguo County were divided into four classes,such as the highly suitable,the moderately one,the marginally one and the inappropriate,by isometric method.The obstacles of land use suitability were sorted by the geo-detectors method.And finally,the main obstacles affecting the suitability of land use were selected,which could provide consults for the rocky desertification treatment and sustainable land use in karst region.The main results of the study are listed as follows:1.The average value of land use suitability composite index(LSI)of the Pingguo County was 0.646,ranging between 0.179 and 0.979.Overall,the high LSI responded to the non-karst areas which were mainly located in the northwest,central south,and southwest of the study area,while the low to the karst areas,mostly in the north,middle,and southeast.2.The land suitability in CountyPingguo could be divided into the highly suitable,the moderately one,the marginally one and the inappropriate categories.The areas of four categories are 449.17 km~2,1301.77 km~2,630.97 km~2 and 102.29 km~2,which accounted for 18.08%,52.40%,25.40%and 4.12%of the total area,respectively.Therefore,the land suitability of the Pingguo County is generally at a moderate to low level.As far as townships are concerned,the highly suitable grade mainly distributed in the Haicheng country and the Matou town;the moderate suitability grade in the Tonglao country,the Liming country,Taiping Town,Guohua Town,and Xin'an Town;the marginally appropriate grades in Fengwu town,Taiping town,and Bangxu country;and the inappropriate grades in Fengwu country and Sitang town.3.The factor detectors showed that the contribution of factors to land use suitability was in descending order as rainfall erosion,soil organic matter,rocky desertification grade,the slope,the lithology,the aspect,landform type,soil type,the elevation,the land-settlement distance,the land-road distance.The contributions of ecological factors and soil factors are relatively higher.The results of the interactive detectors showed that land use suitability impacting factors were not independent,but interactional.Their interaction was the most important among other factors,and the soil factors enhanced the contribution of ecological factors to land use suitability.