ИСТИНА

The present study aimed to the reconstruction of forest fire history for the area of the Mordovia State Nature Reserve (European Russia). This area is located at the border between mixed forest and forest-steppe vegetation zones and particularly sensitive to environmental changes including forest fires. The Quaternary deposits in the study area is represented by fluvioglacial sands which contribute to the increasing the role of pine in the forest composition due to the edaphic factor. High pine abundance determines the relatively high activity of forest fires. Two main methods were used for reconstructions of the fire history: analysis of the macrocharcoal (particle size >125 µm) concentration in the peat and pedoanthracological analysis. The rate of macrocharcoal accumulation and identified peaks of fire activity were calculated on the base of macrocharcoal analysis and radiocarbon dating of 3 peatbogs using the CharAnalysis software. Also we compare this data with results of other proxy methods (pollen analysis, LOI, peat humification). Pedoanthracology analysis included radiocarbon dating of charcoal fragmens from soil (70 samples), their species identification and the study of anthropogenic impact traces in the soil morphology. The obtained results show that the frequency of fires was caused by both climatic and anthropogenic factors. The study area was characterized high-fire activity during the in the first half of Holocene thermal maximum (9–7 ka BP), obviously due to the relative warmer and drier climatic conditions. No evidences of human impact were detected for this period. Frequent fires (4-5 local fire events per 1 ky for each peatbog) during the Holocene thermal maximum may have led to the persistence of birch and pine forests in the study area. The subsequent decreasing of the forest fire frequency could contribute the expansion of broadleaved forests (Qurecus, Tilia and Ulmus) and Picea, which reached their maximal role between 2.3 and 1.5 ka BP. The second peak (2-3 local fire events per 1 ky) of increased forest fires activity occurred in 1.2 – 0.2 ka BP and probably coincided with the beginning of intensive human-induced change of the area. Most of the charcoal fragments from soil are dated in the range of 0,2-1.5 ka BP. The presence of plowing traces in the most soil pits also confirms the fact of active human impact during the last 1.5 ka BP. The identification of species composition of the soil charcoal showed that more than 80% of all charcoals fragments are represented by Pinus. Remains of Picea, Quercus and Betula were also found. The evidences of active human influence during the last 1.5 ka BP are consistent with the data on archaeological findings and historical studies in this region.