滇东岩溶断陷盆地地表/地下不同侵蚀场土壤的可蚀性

Soil Erodibility of Different Surface and Underground Erosion Fields in Karst Rift Basin of Eastern Yunnan

以滇东海峰岩溶盆地土壤复合侵蚀过程为研究对象,分析综合土壤可蚀性指数(CSEI)的分布特征,探讨地表、地下土壤可蚀性的关联性、变化趋势及其影响因素,以期深入认识岩溶地区土壤侵蚀机理,治理石漠化现象。通过野外调查取样结合土壤比重计法、团聚体湿筛等方法,分析了滇东岩溶断陷盆地地表、地下不同侵蚀场土壤的理化性质及可蚀性变化特征。结果表明:(1)土壤理化性质随侵蚀过程发生变化。土壤中黏粒、SOC、大团聚体(>0.25 mm)呈递减趋势,粉砂、小团聚体(<0.25 mm)呈递增趋势。不同侵蚀过程土壤特征存在显著差异,地表侵蚀过程土壤黏粒(20.91%~45.62%)、砂粒(44.96%~64.59%)、SOC(4.93~88.72g/kg)、大团聚体(17.82%~99.86%)含量>地下漏失过程(15.30%~30.86%,43.63%~64.59%,3.57~19.05 g/kg,16.81%~85.94%);粉砂(4.85%~30.84%)、小团聚体(0.14%~82.18%)含量<地下漏失过程(16.03%~25.86%,14.06%~83.19%)。(2)CSEI与土壤理化性质密切相关,CSEI与黏粒、砂粒、大团聚体、SOC、MWD、GMD呈极显著负相关(p<0.01),与粉砂、小团聚体呈极显著正相关(p<0.01),CSEI的主要影响因素为SOC和土壤团聚体的稳定性。黏粒、砂粒、SOC、水稳性团聚体含量对地表侵蚀过程CSEI影响更大,其他因素对地下漏失过程CSEI影响更大。(3)CSEI对岩溶盆地地表、地下侵蚀过程土壤可蚀性的评价具有适用性,CSEI_(地下)>CSEI_(地表),二者随侵蚀过程和土层深度的变化而上升,地下漏失过程存在二次侵蚀影响。其土壤侵蚀过程是地表、地下复合、持续进行的过程,植被-土壤的协同恢复能增强土壤抗侵蚀能力。

Taking the soil composite erosion process of Haifeng karst basin in eastern Yunnan province as the research object,the distribution characteristics of comprehensive soil erodibility index(CSEI)were analyzed,and the correlation,variation trend and influencing factors of soil erodibility between surface and underground soil were discussed,so as to deeply understand the soil erosion mechanism in karst area and control rock desertification.Through field investigation and sampling,soil hydrometer,wet screening of aggregates and other methods,the physical and chemical properties and erodibility change characteristics of soils in different erosion fields on the surface and underground of karst fault basin in eastern Yunnan were analyzed.The results showed that:(1)Soil physical and chemical properties changed with the erosion process.Clay,SOC and large aggregate(>0.25 mm)in the soil showed a decreasing trend,while silt and small aggregate(<0.25 mm)showed an increasing trend.There were significant differences in soil characteristics among different erosion processes.The content of soil clay(20.91%~45.62%),sand(44.96%~64.59%),SOC(4.93~88.72 g/kg)and large aggregate(17.82%~99.86%)in surface erosion process was higher than that in underground leakage process(15.30%~30.86%,43.63%~64.59%,3.57~19.05 g/kg and 16.81%~85.94%).The content of silt(4.85%~30.84%)and small aggregates(0.14%~82.18%)was less than that of underground leakage process(16.03%~25.86%and 14.06%~83.19%).(2)CSEI was closely related to soil physical and chemical properties.CSEI was negatively correlated with clay,sand,large aggregates,SOC,MWD and GMD(p<0.01),and positively correlated with silt and small aggregates(p<0.01).The main influencing factors of CSEI were SOC and soil aggregates stability.Clay,sand,SOC and water-stable aggregate contents had greater influence on CSEI of surface erosion process,while other factors had greater influence on CSEI of underground loss process.(3)CSEI had applicability to evaluate soil erodibility in the process of surface and underground erosion in karst basin,the CSEI of underground leakage was higher than that of surface erosion,both of which rose with the change of erosion process and soil depth.And the underground leakage process had secondary erosion effect.The soil erosion process was a compound and continuous process of surface erosion and underground leakage.The synergistic restoration of vegetation-soil could enhance soil erosion resistance.