Influence of root systems of different tree species and their exudates in formation of properties of forest soils

Abstract

The root systems of trees, through the production of biomass and through their exudates, affect the properties of forest soils. There is a lack of basic knowledge about the influence of root systems of basic forest-forming tree species on the properties of forest soils. The purpose of our study was to determine the influence of the roots of six tree species and their root exudates on shaping the physicochemical and biochemical properties of soils. The study included deciduous tree species (ash, hornbeam, oak, beech) and coniferous trees (pine, European larch).  The survey was conducted in 2022 in the Miechow Forest District (southern Poland). Each tree species was represented by 5 study plots. The research included analysis of root systems and analysis of surface properties of soil horizons. Exudates were collected using a culture-based cuvette system. Additionally, we determined the morphology, and production of fine roots.  Basic physicochemical properties and the activity of enzymes involved in the cycling of C, N, and P were determined in the soil samples. The tree species studied have different morphological characteristics of roots and differences in the exudates secreted. In addition, the studied species differ in the rate of growth of root systems.  Significantly higher amounts of secreted carbon from roots were recorded in ash, which had a positive effect on the increase in enzymatic activity.  The amount of C from exudates showed a positive correlation with CB, BG and PH activity. The activity of the enzymes studied also correlated with the morphological characteristics of the roots. Root systems also influenced the formation of basic physicochemical properties such as C and N content.