Identifying impacts of land use change on soil redistribution at different slope positions using magnetic susceptibility

Abstract

Clear-cutting of Oak forests and intensive cultivation on the hilly regions of the Zagros Mountains has led to plausible threats on the natural ecosystem and catastrophic floods in western Iran. This study was conducted to explore the effects of clear-cutting of natural forests in different slope positions on some soil chemical and physical properties as well as quantification of soil redistribution using magnetic susceptibility. Two adjacent sites, including natural forest and cultivated lands, were selected and a total of six transects at three soil depths (0–10, 10–20, and 20–30 cm) and a total of seventy-two soil samples were examined. Soil properties such as particle size distributions, bulk density (ρb), calcium carbonate equivalent (CCE), soil organic matter (SOM), and magnetic susceptibility at low and high frequencies were measured. Results indicated that clear-cutting and cultivation for 50 years significantly (p < 0.05) increased ρb and CCE and reduced SOM and TN. Moreover, magnetic susceptibility at four slope positions was significantly (p < 0.05) lower compared with the natural forest. Using a simple proportional model to estimate the soil loss or gain and comparing the mean χlf in any given point confirmed a high rate of soil loss in cultivated sites. In the forest soils, low soil loss in shoulder position and high rate of deposition in footslope and backslope positions were obtained. In general, it is revealed that magnetic measures could provide valuable estimates of mid-term soil erosion and sedimentation in the hilly region following land use changes.