Fire regimes in Russia and their impacts on major biogeochemical cycles

Abstract:

The warming trend in Russia for period of 1976-2014 was more than two times higher than the global one. Change of precipitation was regionally diverse, but on average not enough to compensate the high warming rate. Variability of seasonal weather increased with long dry and warm periods. Severe heat waves are regularly observed in different regions of the country. Three available remote sensing products of spatially explicit distribution of burnt area in Russia (GFED4; Institute of Forest SB RAS, Krasnoyarsk; and Space Research Institute, RAS, Moscow) reported rather consistent average burnt areas for the period of 2000-2010 (from 8.3 to 9.4 x 10⁶ ha year^-1); however, the differences for individual years, particularly for 2011-2012 are large. Of the total fire area, about 2/3 were on forest land. A typical feature of fire regimes of recent decades is increasing frequency and severity of mega-fires, which envelope vast regions (up to millions of hectares) with numerous simultaneously burning areas, cause large ecological, economic and social losses and often provide irreversible impacts on forest ecosystems. Such fires occurred in different regions of Russia in 1998 (7.7 x 10⁶ ha of burnt areas), 2002 (8.2), 2003 (16.6), 2005 (8.5), 2006 (12.4), 2007 (8.9), 2008 (16.8), 2009 (10.4), 2010 (7.9), 2011 (8.8 x 10⁶ ha), 2012 (15.8 x 10⁶ ha). We present a full fire carbon budget for 2000-2012 as a proxy of severity of fire regimes, based on 1) a country’s Integrated Land Information System, which contains georeferenced land cover, amount of fuel by types and annual burnt areas at resolution of 1km; and 2) regionally distributed models of fire severity. The amount of fuel consumed by fire is estimated at 135 Tg C yr^-1 with large interannual variation and uncertainties ~25%. We discuss ecological consequences of fire, its impact on successions, health and productivity of forest ecosystems as well as predicted dynamics of fire regimes over 21^st century.