Assessment of carbon stocks in litter and soils of undisturbed and zoogenically damaged Siberian pine forests (Pinus sibirica Du Tour) in the southern taiga zone of West Siberia

The aim of the study. Assessment of soil and litter carbon stocks, as well as the study of the initial stages of organic matter decomposition of plant litter under conditions of undisturbed and dendrophague-invaded forest stands. Location and time of the study. The research was conducted in the zoogenically disturbed Luchanovo-Ipatovsky suburban cedar forest and in the undisturbed cedar forest near the village of Kolomino, both sites located in the Tomsk District of the Tomsk Region. Methods. Plant residue decomposition rate was studied using the partially isolated sample method. Litter bulk density was determined using the monolith method, and soil bulk density in mineral horizons was determined by the cutting ring method. Standard methods were used to determine actual and non-exchangeable acidity in soil, and actual acidity and ash content in litter. The content of total and water-soluble carbon and nitrogen was assessed using elemental analyzers for solid and liquid media. Results. The carbon stocks in the upper 50 cm soil layer of undisturbed cedar forests exceeded those in disturbed forests by 1.4 times. The contribution of litter in the total carbon stocks under zoogenic transformation was 9% higher than in the undisturbed cedar forests. In zoogenically disturbed forest ecosystems (Ips amitinus Eichh.), the intensity of decomposition slowed down at the initial stages of decomposition (depending on the type of litter, 4-14%). The leaves of Aegopodium podagraria are characterized by high availability for decomposition and the lowest contribution in carbon sequestration by the soil (organic matter losses reached 94% in 2 months). The litter demonstrated significantly lower decomposition rate, which may indicate that it was not readily available for utilisation by microorganisms. Conclusions. Degradation of wood during zoogenic transformation resulted in complex changes in understorey vegetation, litter and soil layers, affecting the availability of organic matter for decomposition and soil sequestration potential.