Impacts of land use/cover change on soil hydrological properties, runoff, and erosion: results from micro-plots in Western Iran

In Iran, particularly in the Zagros forests, natural land uses are increasingly being converted into agriculture, which can negatively influence soil hydrological processes. To study this, three replicate micro-plots were installed on similar slopes in the forest (FO), rangeland (RA), and vineyard. under the canopy (VUC) and in the inter-row space (VIR) - to measure soil loss and surface runoff. Top- and sub-soil samples were randomly taken in three replicates from three sites for each land use/cover (LUC). Standard laboratory methods were utilized to measure the designated soil properties. According to the results, soil organic matter (SOM), aggregation indices, residual (theta(r)) and saturated water content (theta(s)), water content at field capacity (theta(FC)), and saturated hydraulic conductivity (Ks) showed a significant decreasing trend as follows: FO > RA > VUC > VIR, whereas EC, pH, CaCO3, bulk density, and K-factor significantly showed an increasing opposite trend. LUC did not affect permanent wilting point (theta(PWP)), available water content (AWC), and alpha and n van Genuchten's parameters. It was also found that RA and FO exhibited a higher repellency index than VUC and VIR. The forest had the lowest soil loss and runoff due to its higher porosity, SOM, aggregate stability, infiltration rate, water storage capacity, and surface cover. The highest soil loss and runoff were observed in VIR because of the vineyard's management operations and the bareness of soil between the vine rows. Conservation measures, such as no-tillage, mulching, or cover crops in the inter-row spaces, are recommended to mitigate these negative effects.