Reconstruction of Holocene local fires according to the macrocharcoals content from the peat deposits in the Dubches river valley

Abstract

The results of the local fires reconstruction based on the stratigraphic analysis of the peat deposit in the right-bank part of the Dubches River valley (middle taiga of the Yenisei Siberia) in the Holocene are presented. The object of research was the raised pine-shrub-sphagnum bog with a well-developed tree layer with Scots pine (Pinus sylvestris L.). The deposit thickness was 4.15 m, its age was interpreted by 11 radiocarbon dates. The bottom peat layer age was 11802 ± 52 14C years ago. In a peat core at depths of 3.25, 3.15, 2.90, 2.65 m, traces of fires were found in the form of pyrogenic layers. Reconstruction of the fire dynamics was carried out according to the method of counting macroscopic particles of charcoal “Charcoal”. The time, periodicity and intensity of fires on dry areas surrounding the bog have been established. Four periods were identified in the dynamics of local fires: about 12000–10000, 8250–7250, 6300–4000, 2400 cal. a BP (calibrated age before present). The reliable peaks of charcoal inflow occurred on the following dates: 11600, 11150, 10500, 7800, 5900, 5450, 4600, 1900, 1200 and 250 cal. a BP. It is noted that the highest fire activity was observed in the early Holocene, as evidenced by the increased content of macrocharcoals in peat. The main cause of the fires was probably the abnormally dry spring-summer seasons due to the dry and warm climate. The bog was traversed by fire during: 7790, 7030, 5610 and 4890 cal. a BP. The pyrogenic destruction of peat was minimal, which indicated a weak or medium intensity of the peat fire. Fires in the bog contributed to the activation of the forest formation process. In the late Holocene, the effect of fires on the bog ceased and forest phytocenoses were replaced by heavily watered ridge-hollow complexes.

Keywords

• mire
• macrocoal analysis
• pyrogenic layers
• charcoal inflow peaks
• fire dynamics.