Long-term fire-vegetation change: data-based challenges

Reconstruction of forest fires in the Nizhnyaya Tunguska river basin (Central Evenkia) in the middle and late Holocene from the data of the macroscopic charcoal analysis in peat

14 Feb 2023, 12:05

15m

MN09 (Faculty of Geoscience and Geography)

Online short talk Fire-vegetation interactions (Oral) Fire-vegetation interactions

Speaker

Anton Shatunov (Lomonosov Moscow State University, Faculty of Geography, Moscow, Russia)

Description

The periodicity of fires in the Middle and Late Holocene in the vicinity of the village of Tura (central Evenkia) is considered according to the analysis of the concentration of macroscopic coal particles in peat bogs: Gornoye (64°13'55.97"N, 100°02'5.21"E) and Nizhnyaya Tunguska (64 °10'49.74"N, 100°34'59.16"E). The depth of the deposit of the Gornoe swamp is 215 cm, radiocarbon dating at the base of the well is 7015±25 14С BP. (IGANAMS 9531), Nizhnyaya Tunguska 113 cm and 6785±25 14C BP (IGANAMS 9525), respectively.
Sample preparation for the analysis of coal macroparticles was carried out according to the standard procedure [1]. Samples from the Nizhnyaya Tunguska bog were also counted by analyzing photographic images using a program written in the R language. As a result, it was possible to determine particles > 250 µm2 with an accuracy of 71%. The Pearson correlation between the samples calculated by the standard and software methods was 84.5%. The tapas software package in R was used to highlight fire events.
A comparison of the data obtained on the frequency of fires and climatic reconstructions for the north of Siberia showed that the period with low fire activity in Central Evenkia in the interval between 7900 and 3700 cal. BP comparable in time with warming and an increase in moisture by more than 140 mm at a latitude of 60-65°N in the Middle Holocene. C 3700 to 2700 cal. BC, a high frequency of fires in the study region was revealed, which is in good agreement with the interval of precipitation decrease according to the reconstruction made according to palynological data from the lakes of Taimyr. Cooling and humidification of the climate of the Northern Hemisphere starting from 2500-2700 cal. BP led to a decrease in the frequency of fires in Central Evenkia in the Late Holocene. The accumulation of coal macroparticles in bog sediments increases in the 17th century, and may be due to the anthropogenic factor. According to data from the Gornoye swamp, several fires were identified, which occurred on average once every 105 years.
The study was supported by the Russian Science Foundation project 20-17-00043
1) Mooney S.D., Tinner W. The analysis of charcoal in peat and organic sediments. Mires and Peat, Article 09, 2011, 1–18.