Impact of Depression Areas and Land-Use Change in the Soil Organic Carbon and Total Nitrogen contents in a Semi-Arid Karst Ecosystem

Background: Depression areas are essential structural components of Karst ecosystems. Their influence in the carbon and nitrogen dynamics under different land uses, which could be effectively used to define management strategies aiming to combat global warming, however, is not clear. This study investigated the changes in selected soil attributes across four land use types (forest, degraded forest, rangeland and cropland) both in depressed and non-depressed areas in a karst ecosystem in Kahramanmaras, Turkey. Soil attributes investigated in this study included soil pH, soil moisture (SM), soil organic carbon (SOC), total nitrogen content (TN), available water (AW), hydraulic conductivity (HC), root rate (RR) and C/N ratio. Results: Discriminant analyses showed that N, AW, SOC, pH and landuse were the most effective variables affecting the distinction between depression and none-depression areas in karstic ecosystems. According to the structural matrix, the most important single factor affecting the distinction between depression and none-depression areas was SOC, with a correlation coefficient of 0.62. Highest values for SOC, TN and other attributes were found in forest and rangeland land use types, while minimum values were found in cropland land use in most comparisons. Depression areas reduced the negative effects of land use in terms of C, TN, C/N, SM, and RR. Conclusion: As a result, while constructing restoration plans, the study area should be evaluated from a geo-ecological perspective. Ecological capabilities of depression areas should be considered especially in karst environments.