Effects of slope and tree position on soil properties in a temperate deciduous forest

This paper examines changes in soil physical and chemical properties in relation to tree proximity on different slopes. Topsoil and subsoil were sampled at 12 research plots on four slope types, the soil pits being placed at the base of a tree (near tree, NT) and between the test tree and an adjacent tree (between trees, BT). We observed a significant decrease in vertical topsoil response to slope on lower, middle and upper slopes, and a decrease in fine roots (R < 2 mm) on flat ground. Overall, middle and lower slopes showed the highest similarity, and upper slopes and flat ground the least, with the greatest subsoil changes observed mainly on middle slopes and least on lower slopes. There was clear topographic dependence between subsoil water stable aggregates (WSA) and C dynamics, with BT total carbon (Ctot) higher on flat ground and lower on middle slopes; unlike topsoil, where the strongest WSA correlation was with distance from the tree. The highest N : OM (organic matter) ratios occurred on middle slopes facing north-west, and lowest on lower slopes facing north and flat ground. Our findings confirm the influence of slope type on soil characteristics, with NT soil supporting soil formation by transporting water to deeper layers, especially on slopes > 5 degrees. These observations contribute to a better understanding of the dependence of soil properties on slope type and tree position when planning sustainable forest management.