重庆溶洼—丘峰区土地利用类型对土壤抗蚀性的影响

以重庆鸡公山耕地、果园、撂荒地、灌草坡和林地5种土地利用类型为研究对象，通过野外采样调查与室内分析，采用主成分分析法对与土壤抗蚀性密切相关的11个常用指标进行筛选和综合评价，探讨不同土地利用类型下土壤抗蚀性能的变化状况和差异性。结果表明:研究区表征土壤抗侵蚀能力最优指标为:>0.25 mm团聚体破坏率、>0.25 mm水稳性团聚体含量、团聚度、<0.01 mm物理性黏粒含量、结构性颗粒指数和<0.001 mm黏粒含量。依据提炼出的3个主成分，建立土壤抗蚀性综合评价模型，即Y（综合指数）=0.712Y1+0.157Y2+0.131Y3，由此计算出土壤抗蚀性由强到弱为:林地> 灌草坡>撂荒地>果园>耕地。建议区内适当退耕还林还草，减少人为扰动，以利于提高土壤的抗蚀性能和水土保持能力。 

Effects of different land use types on soil anti-erodibility in Chongqing karst depression and karst-hill peak areas

The karst area in southwest China is the largest one,which is mainly located in Yunnan Province, Guizhou Province and Sichuan Province. Beibei district of Chongqing belongs to subtropical monsoon humid climate,and is controlled by the brush fold of Huayin mountain.Its geological structure is the parallel ridge valley landform of "one hill three ridge two valley",which is composed of karst depression-hills in eastern Sichuan.The carbonate rocks are mainly Triassic Jialingjiang formation (T1j), Feixianguan formation (T1f) and the Permian Maokou formation (P2m). The developed soil is yellow and brown calcareous soil. Under the influence of geology and climate, the soil is seriously eroded by chemical dissolution, gravitational and fluvial erosion.In order to explore the changes and differences of soil anti-erodibility under different land use types,and provide scientific basis for soil erosion control and ecological reconstruction in karst area of Chongqing. The topsoils of 5 land use types,including cultivated land, abandoned land, shrub-grass slope land, forest land and orchard,were selected in depression-hill peak area of Jigong karst mountain in Chongqing.Through the combination of field survey and lab analysis,11 common closely indexes related soil anti-erodibility were screened and comprehensive evaluated using the principal component analysis method.The results show that: the soil in the study area belongs to clayey to loamy soil, and the most easily eroded particles ranged from 0.05 to 0.25 mm. The optimal indexes on behalf of soil anti-erodibility are >0.25 mm aggregate destruction rate, >0.25 mm water stable aggregate content, degree of aggregation, <0.01 mm physical clay content, structural particle index and <0.001 mm clay content. That is, the lower the aggregate destruction rate >0.25 mm, the higher the content of water stable aggregates content of >0.25 mm, the degree of aggregation, the physical clay content <0.01 mm, the structural particle index and the clay content of <0.001 mm, the stronger the anti-erodibility of karst soil. According to the synthetic index analysis, 3 principal components are extracted and the comprehensive evaluation model of soil anti-erodibility was established.The order of evaluation of soil anti-erodibility was， forest land > shrub-grass slope land >abandoned land> orchard> cultivated land. It is suggested that appropriate returning cultivated land to forest or grassland in the karst area will help to reduce water and soil loss, and reasonably human activities can improve soil anti-erodibility and capacity of water and soil conservation.