Larch forests of Middle Siberia: long-term trends in fire return intervals

Abstract

Fire history within the northern larch forests of Central Siberia was studied (65+°N). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRI) were found to be 112 ± 49 years (based on fire scars) and 106 ± 36 years (based on fire scars and tree natality dates). FRI were increased with latitude increase, and observed to be about 80 years at 64°N, about 200 years near the Arctic Circle, and about 300 years nearby the northern range limit of larch stands (~71°+N). Northward FRI increase correlated with incoming solar radiation (r = − 0.95). Post Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase.

Surface forcing of non-stand-replacing fires in Siberian larch forests

“…NSR fires are a key element of the Siberian larch forest functioning. They support larch dominance by increasing soil temperature and drainage and eliminating competition (Shorohova et al 2009, Sofronov and Volokitina 2010, Schulze et al 2012, Kharuk et al 2016. Because of the differences in spatial coverage, a direct comparison of the total burned area estimated by this project and those by previous studies is not feasible.…”

“…This is similar to the mechanism for the albedo-induced cooling observed in the forests that experienced SR fires, which is likely a result of canopy damage and sub-canopy mortality caused by NSR fires. Although NSR fires have been known to be of lower severity than SR fires, they can still lead to a certain level of canopy loss by killing the juvenile trees which are less resistant to fires than the mature trees (Conard and Ivanova 1997, Shorohova et al 2009, Schulze et al 2012, Kharuk et al 2016, which may also cause increases in forest albedo. Another potential reason is that although NSR fires do not cause significant damage to the canopy of mature trees, they consume shrubs in the understory which also create a shading effect similar to the canopy.…”

Evidence for fire in the Pliocene Arctic in response to amplified temperature

“…Given the similar climate to BP on the Central Siberian Plateau and some key aspects of the floras in Siberia such as the dominance of larch, we considered the fire regime of the larch forests of Siberia. Kharuk et al (2016Kharuk et al ( , 2011 studied MFRIs across Siberia, from 64 to 71 • N, the northern limit of larch stands. They found an average MFRI across that range of 110 years, with MFRI increasing from 80 years in the southern latitudes to ∼ 300 in the north (Table 1).…”

The role of elevated atmospheric CO<sub>2</sub> and increased fire in Arctic amplification of temperature during the Early to mid-Pliocene

“…Given the similar climate to BP on the Central Siberian Plateau and some key aspects 10 of the floras in Siberia such as the dominance of larch, we considered the fire regime of the larch forests of Siberia. Kharuk et al (2016;2011) studied MFRIs across Siberia, from 64°N to 71°N, the northern limit of larch stands. They found an average MFRI across that range of 110 years, with MFRI increasing from 80 years in the southern latitudes to ~300 in the north (Table 1).…”