Paleoenvironmental analysis of three bogs in Northeastern European Russia: Peatland development and fire influence

To elucidate the relationship between vegetation, fire regime, and the composition of peat soil organic matter, we conducted a paleoenvironmental analysis of three bogs in the Komi Republic, northeastern European Russia. This analysis integrated data from radiocarbon dating, botanical composition, macroscopic charcoal counts, and organic matter analysis. Our findings reveal the age and rate of peatland development during periods of the Holocene, with peat accumulation rates being higher in the Holocene Thermal Maximum (HTM) (∼0.6 mm year−1) compared to the post-HTM period (∼0.4 mm year−1). Analysis of pyrogenic remains content indicates the presence of charcoal particles throughout the depth of peat deposits, with the most frequent fires occurring at the Early Holocene, and at the end of Late Holocene periods. The beginning of Late Holocene period is characterized by the lowest content of post-pyrogenic residues, with the exception of one bog. Local pyrogenic events are evident throughout bog development, with up to 12 occurrences. During the HTM, local fires occurred every ∼ 340 yr, while in the beginning and ending of Late Holocene periods, local fires occurred every ∼ 1870 and ∼ 940 yr, respectively. Throughout the Holocene, local fires affected the studied bogs once every ∼ 790 yr. Horizons marking shifts in botanical composition stages exhibited elevated charcoal macroparticle concentrations. Samples with the highest post-pyrogenic residue content were concentrated at depths with high carbon aromaticity (fa; r = 0.71, p < 0.05). Analysis revealed weak but significant positive correlations between charcoal macroparticles and polycyclic aromatic hydrocarbons such as naphthalene (r = 0.38, p < 0.05) and pyrene (r = 0.40, p < 0.05). These findings align with previous research indicating increased fire frequency during the late Early Holocene, leading to the formation of stable, decomposition-resistant carbon forms.