Forest-steppe ecosystems possess unique biodiversity and contribute significantly to the regional carbon balance. However, the degradation of oak forests, accompanied by shifts in tree species composition, as well as the increasing risk of wildfires in pine stands, complicates the prediction of their climate-regulating functions. The aim of this study was to determine the patterns of carbon distribution and formation of carbon pools in the Usman Pine Forest and the Voronezh Upland Oak Forest. The study was conducted in ripe and overripe coniferous and broadleaf forests. A detailed inventory of carbon pools was carried out across the most widespread forest site types. The obtained data confirmed significant spatial heterogeneity and forest-type differences in carbon storage within ecosystem components. In the Usman Pine Forest, a substantial portion of carbon is concentrated in the litter layer, whereas in oak forests, carbon accumulation is predominantly in the soil and coarse woody debris. The aboveground biomass of oak forests contains an average of 92.5 t C/ha, which is 10% higher than in the Usman Pine Forest (84.4 t C/ha). Notable differences were observed in coarse woody debris: in oak forests, carbon stocks in this pool reach 49.2 t C/ha, which is twice as much as in pine forests (25.7 t C/ha). Conversely, in pine forests, carbon storage in the litter layer amounts to 12.5 t C/ha, whereas in oak forests, it is only 2.1 t C/ha, reflecting more intensive organic matter mineralisation in broadleaf stands. The soil carbon pool (0—100 cm) in upland oak forests (91.0 t C/ha) was found to be 58% higher than in pine forests (57.6 t C/ha). The degradation of oak forests is accompanied by a redistribution of carbon from the aboveground biomass to soil and coarse woody debris, while in pine forests, the biomass and litter layer are particularly vulnerable to wildfires and extreme climatic events. The results highlight the necessity of considering ecosystem structural specificity when assessing carbon balance dynamics.
Sheshnitsan et al. (Wed,) studied this question.