COMPARATIVE ASSESSMENT OF THE DECOMPOSITION RATE OF PLANT LITTERFALL IN SPRUCE AND PINE FORESTS AT THE NORTHERN DISTRIBUTION LIMIT

A comparative assessment of the processes of initial stages of decomposition of plant residues (pine needles, spruce needles, leaves of boreal shrubs, moss thalli) in lichen-shrub pine forests and shrub-green-moss spruce forests formed under natural conditions at the northern limit of distribution was carried out. The characteristics of the litter initial composition, the rate of decomposition and changes in the chemical composition of plant residues in the process of destruction caused by the forest type were studied. The higher initial content of Corg in the plant tissues of pine forest is associated with favorable lighting conditions under the forest canopy, while the high content of Mn in the tissues of ground cover plants in spruce forests is due to the direct influence of spruce needle litter rich in this nutrient. The results of the study clearly demonstrated that the forest type has a significant impact both on the initial quality of the litterfall of the same plant species and on the rate of decomposition: in the spruce forest spruce needles and lingonberry leaves with a higher content of nutrients (Mg, Mn, P) and narrow ratios of elements (C:N, C:P) were characterized by more active decomposition processes. However, green moss litter, despite its high quality in spruce forests, decomposed more actively in pine forests, which may be due to a large amount of precipitation in pine forests. Thus, differences in the rate of decomposition of plant residues are influenced by a combination of the plant material quality, temperature conditions and precipitation amount associated with the forest type.