FOREST-FIRES IN RUSSIA - CARBON-DIOXIDE EMISSIONS TO THE ATMOSPHERE

Boreal forests of Russia play a prominent role in the global carbon cycle and the flux of greenhouse gases to the atmosphere. Large areas of Russian forest burn annually, and contributions to the net flux of carbon to the atmosphere may be significant. Forest fire emissions were calculated for the years 1971-1991 using fire frequency and distribution data and fuel and carbon density for different forest ecoregions of Russia. Both direct carbon release and indirect post-fire biogenic carbon flux were estimated. From 1971 to 1991 the annual total forest area burned by wildfire ranged from 1.41 X 10(6) to 10.0 X 10(6) ha. Approximately 15 000 - 25 000 forest fires occurred annually during this period. Mean annual direct CO2-C emissions from wildfire was approximately 0.05 Pg over this 21 -year period. Total post-fire biogenic CO2-C emissions for 1971-1991 ranged from 2.5 to 5.9 Pg (0.12-0.28 Pg annually). Forest fires and other disturbances are expected to be a primary mechanism driving vegetation change associated with projected global climate change. Future forest fire scenarios in Russia based on general circulation model projections suggest that up to 30-50% of the land surface area, or 334 x 10(6) to 631 x 10(6) ha of forest, will be affected. An additional 6.7 x 10(6) to 12.6 x 10(6) ha of Russian boreal forest are projected to burn annually if general circulation model based vegetation-change scenarios are achieved within the next 50 years. The direct flux Of CO2-C from future forest fires is estimated to total 6.1-10.7 Pg over a 50-year period. Indirect post-fire biogenic release of greenhouse gases in the future is expected to be two to six times greater than direct emissions. Forest management and fire-control activities may help reduce wildfire severity and mitigate the associated pulse of greenhouse gases into the atmosphere.