Revealing the role that epikarst fissures filled with soil play in soil erosion and nutrient loss in karst rocky desertification region of Guizhou, China
Bailian Xiong, Yang Gao, Junlong Liu, Xiong Yan
Abstract
Karst region in Guizhou Province, China. Epikarst fissure filled with soil (EFS) is an important pathway connecting the karst surface with karst underground pipelines, and a vital soil resource bank in rocky desertification regions. Being buried underground, EFS is difficult to study, and the characteristics and control mechanism of soil erosion and nutrient loss in EFS need to be further investigated. In this work, we constructed a simulated experimental device that separated the EFS from the whole karst slope, and studied the role of EFS in soil erosion and nutrient loss in karst rocky desertification region. Sediment erodes from the bottom of EFS. The scouring effect surpasses the dilution effect, and dominating the process of carbon and nitrogen loss in the EFS. The 0–30 cm soil layer of EFS profile intercepts part of carbon and nitrogen in slope runoff, with a higher interception rate for carbon compared to nitrogen, thereby reducing the C/N ratio in underground runoff. EFS is an important pathway for dissolved total carbon (DTC) and dissolved total nitrogen (DTN) loss. These results reveal the important roles of EFS in soil erosion and C and N loss in karst rocky desertification region, and are promising to provide a theoretical basis on the application of EFS to the ecological restoration in this region.