Analysis of Changes in the Chemical Composition of Lysimetric Water in the First Years after Logging (Middle Taiga, Komi Republic)

Changes in the content and composition of lysimetric water in podzolic soil (Albic Retisol) under mixed middle-taiga stand were studied in the Komi Republic before and after clearcutting. Gravity lysimeters were installed on the key plot at depths of 5 cm (O horizon) and 20 cm (EL horizons). Chemical analysis of lysimetric water and calculation of the removal of elements from the organic and eluvial soil horizons were carried out. It was found that pH, specific electrical conductivity, concentration of elements in the water, and their removal from the horizons after clear cutting did not change much in comparison with the initial values. Changes in the removal of water-soluble carbon (Cws) and nitrogen (Nws) compounds and phenols were revealed. A reliable sharp decrease in the concentration of of followed by its gradual increase after clearcutting (R2 = 0.94), and a decrease in the removal of Cws (R2 = 0.63) from the organic horizon were noted. The opposite pattern was observed for the upper mineral horizon, where a significant increase in both the Cws concentration (R2 = 0.94) and the its removal (R2 = 0.63) took place. An increased removal of Nws with lysimetric water was observed throughout the study period. Peak values were reached on the the second year after clearcutting. The impact of clearcutting on the composition of lysimetric water was largely determined by the removal of the forest stand, changes in the composition of ground-cover plants, and the decomposition of logging residues on the soil surface.