The effect of slope position in Catena landform on soil physical and chemical features in the Asalem Beech forest

The beech (Fagus orientalis Lipsky) stands in the Hyrcanian region of Iran occur on a wide range of soils in a relief row with valley and ridge structures called Catena. This affects soil features and plant species distribution due to its topographic shape and different slope positions. The aim of this study was to compare changes in soil characteristics across V-shaped Catena in the two harvested and non-harvested beech stands in the Asalem region, Guilan Province. We selected three Catena landforms in each non-harvested and harvested stand. In each stand, a 400-m2 plot along each Catena and slope position was designed, in which soil samples were taken from the center and four corners as well as from 10-0 cm, 20-10 cm and 30-20 cm depths. The samples were mixed to obtain a single soil sample for each depth and slope position. Soil samples were transferred to the laboratory to study physical and chemical properties. Based on our results, the variability of soil features was significantly influenced by different depths and forest management plans, whereas they were poorly affected by the different positions of the Catena. The highest amounts of pH and Ec were measured in the harvested stand, while the highest phosphorus and potassium contents were measured in the non-harvested stand and toe slope position, respectively. Absorbable potassium was the only parameter that had a significant difference in management, slope position, and depth of soil interactions. Generally, foot and toe slope positions contained more nutritious soils, which can be attributed to the leaching and erosion of soil from higher to lower slopes.