Different responses of ecohydrological processes in the re-vegetation area between the dip and anti-dip slope in a karst rocky desertification area in southwestern China

Abstract

Rocky desertification is an economic, social, and environmental problem, which refers to the processes and human activities that transform a karst area covered by vegetation and soil into a rocky landscape. The effects of different types of soil cover on ecohydrological processes during the revegetation of areas undergoing karst rocky desertification remain unclear. Taking different measures for different ecohydrological situations will benefit re-vegetation in karst rocky desertification areas. Monthly/heavy rainfall hydrochemical data and the δ13C of dissolved inorganic carbon (DIC) in karst water samples from January 2017 to December 2019 were obtained. This revealed the controlling mechanisms on hydrochemical processes by δ13CDIC under different soil cover conditions in the dip/anti-dip slopes of a karst trough valley in Ganxi Town, Chongqing City, southwestern China. Hydrochemical variations are controlled by climate, soil, and vegetation and show clear seasonality. The δ13CDIC values (−16.88‰ to −3.49‰) in the study area were higher than the theoretical value (−14.00‰). In addition, it was observed that rain accelerated soil erosion (R2=0.7) in the karst trough valley and human activities (exogenous acid) resulted in DIC loss. The slopes, soil, and bare rock cover on the dip slope were different from that on the anti-dip slope, leading to the difference in their re-vegetation statuses. In this study, we found that different vegetation restoration schemes and treatment measures should be implemented between the dip and anti-dip slope. The protection of soil and water resources, especially soil, is the key to ecological restoration in rocky desertification areas.