Estimating fire emissions and disparities in boreal Siberia (1998–2002)

Abstract

[1] In the biomass, soils, and peatlands of Siberia, boreal Russia holds one of the largest pools of terrestrial carbon. Because Siberia is located where some of the largest temperature increases are expected to occur under current climate change scenarios, stored carbon has the potential to be released with associated changes in fire regimes. Our concentration is on estimating a wide range of current and potential emissions from Siberia on the basis of three modeled scenarios. An area burned product of Siberia is introduced, which spans from 1998 through 2002. Emissions models are spatially explicit; therefore area burned is extracted from associated ecoregions for each year. Carbon consumption estimates are presented for 23 unique ecoregions across Siberia, which range from 3.4 to 75.4 t C ha À1 for three classes of severity. Total direct carbon emissions range from the traditional scenario estimate of 116 Tg C in 1999 (6.9 M ha burned) to the extreme scenario estimate of 520 Tg C in 2002 (11.2 M ha burned), which are equivalent to 5 and 20%, respectively, of total global carbon emissions from forest and grassland burning. Our results suggest that disparities in the amount of carbon stored in unique ecosystems and the severity of fire events can affect total direct carbon emissions by as much as 50%. Additionally, in extreme fire years, total direct carbon emissions can be 37-41% greater than in normal fire years, owing to increased soil organic matter consumption. Mean standard scenario estimates of CO 2 (555-1031 Tg), CO (43-80 Tg), CH 4 (2.4-4.5 Tg), TNMHC (2.2-4.1 Tg), and carbonaceous aerosols (4.6-8.6 Tg) represent 10, 15, 19, 12 and 26%, respectively, of the global estimates from forest and grassland burning. Accounting for smoldering combustion in soils and peatlands results in increases in CO, CH 4 , and TNMHC and decreases in CO 2 emitted from fire events.

The Drivers of Effectiveness of Prescribed Fire Treatment

“…Most of the other well-studied fire-prone biomes in the world have relatively low fire incidence. For example, is it about 1.4% per year in the chaparral of California (Minnich and Chou 1997); 6% for shrub-lands and 2% for pine forests in Spain (Pausas et al 2008); 1% or less for the boreal forests (Flannigan et al 2005;Gray 1995) and taiga (Burton et al 2008) in Canada; and 1% for the boreal forests and taiga of Siberia (Soja et al 2004). All of these biomes will have leverage values well below 1, and for most of them, probably lower than the values as found in Australian forests.…”

Ozone-CO Correlations in Siberian Wildfire Plumes Observed at Rishiri Island

“…Biomass burning is a major source of trace gases and aerosols to the atmosphere (Andreae and Merlet 2001). Boreal forest fires commonly occur in May through September across Siberia, Alaska, and Canada (Kasischke et al 2005), although fire activities have large interannual variations (Soja et al 2004). A number of studies reported huge enhancement of CO due to boreal forest fires in Zhao et al 2002;Novelli et al 2003;Yurganov et al 2004;Edwards et al 2004;Yurganov et al 2005).…”

Uncertainties of fluxes and <sup>13</sup>C ∕ <sup>12</sup>C ratios of atmospheric reactive-gas emissions

“…Unfortunately, the representation of the combustion stages in the emission data is limited; hence, one can provide only a qualitative estimate of the isotope effect (depletion). The quantitative estimates of the contributions from various stages (for instance, in the modelling study by Soja et al, 2004) could be improved with the use of the isotopic composition in this case. Conclusively, in contrast to the primary biomass burning sources, the emissions from the sector L43 induce a minor influence on the average CO emission signature, accounting for a total of 16.3 Tg(CO) yr −1 (less than 3 % of the total anthropogenic emission).…”