HR: 17:30h
AN: B54A-07    [Abstracts]
TI: Variations in the fire regime in the North American boreal forest between 1990 and 2004 and their potential impacts on terrestrial carbon storage
AU: * Kasischke, E S
EM: ekasisch@geog.umd.edu
AF: Department of Geography, University of Maryland 2181 LeFrak Hall, College Park, MD 20742 United States
AU: Turetsky, M R
EM: mrt@msu.edu
AF: Department of Plant Biology, Michigan State University, East Lansing, MI 48824 United States
AU: McGuire, A D
EM: ffadm@uaf.edu
AF: Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: French, N H
EM: nancy.french@altarum.org
AF: Alaturum Institute, PO Box 134001, Ann Arbor, MI 48113 United States
AB: Fires in the North American boreal region play an important role in regulating the the levels of carbon stored in the terrestrial ecosystems of this region, both directly and indirectly. Biomass burning not only consumes carbon present in the aboveground vegetation and litter layers of boreal forests and peatlands (as is common during fires in temperate and tropical ecosystems), but also large amounts of carbon present in the organic layer that lies on top of mineral soil (consisting of moss, lichen, dead woody debris and organic soil). Understanding the factors controlling consumption of ground-layer organic matter during fires in boreal ecosystem is central to quantifying the terrestrial carbon budget in this region. The 1950-2004 period can be divided into 3 distinct epochs in terms of fire activity in the North American boreal region. The early epoch of 1950-1968 experienced the lowest fire activity, 1.2 million ha or Mha per yr, and increased to 2.1 Mha per yr during 1969-1986 epoch and 3.0 Mha per yr during 1987-2004 epoch. The end result of this steep rise in fire activity is an increase in the average amount of carbon released during fires. A key question that needs to be addressed is how much carbon has actually been released through the burning of ground-layer organic matter. The observed increases in average area burned are due to a combination of increases in the frequency of large fire years, as well as increases in average area burned during large fire years. Analyses of fire databases show that as the burned area increases during a given year, the percent of area burned in large fire events increases as well. The amount of fires occurring later in the growing season also increases. Recent and ongoing studies have integrated field observations with satellite observations on fire location and fire severity to provide more detailed assessments of how fires impact carbon budgets of boreal systems. These studies, along with theoretical models, indicate that organic layers common in boreal forests and peatlands burn deeper and release more carbon during large fire events and during late season fires. In this paper, we will present the results of a study on how recent changes in the North American boreal fire regime have influenced carbon storage in the ground-organic layer in this region based on different assumption regarding levels of consumption of organic layer burning.
DE: 1610 Atmosphere (0315, 0325)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting