This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999
Fire is the dominant stand-renewing disturbance through much of the Canadian
boreal forest, with large high-intensity crown fires being common. From 1 to 3
million ha have burned on average during the past 80 years, with 6 years in
the past two decades experiencing more than 4 million ha burned. A large-fire
database that maps forest fires greater than 200 ha in area in Canada is being
developed to catalogue historical fires. However, analyses using a regional
climate model suggest that a changing climate caused by increasing greenhouse
gases may alter fire weather, contributing to an increased area burned in the
future. Direct carbon emissions from fire (combustion) are estimated to
average 27 Tg carbon year–1 for 1959–1999 in
Canada. Post-fire decomposition may be of a similar magnitude, and the
regenerating forest has a different carbon sink strength. Measurements
indicate that there is a net carbon release (source) by the forest immediately
after the fire before vegetation is re-established. Daytime downward carbon
fluxes over a burned forest take 1–3 decades to recover to those of a
mature forest, but the annual carbon balance has not yet been measured. There
is a potential positive feedback to global climate change, with anthropogenic
greenhouse gases stimulating fire activity through weather changes, with fire
releasing more carbon while the regenerating forest is a smaller carbon sink.
However, changes in fuel type need to be considered in this scenario since
fire spreads more slowly through younger deciduous forests. Proactive fuel
management is evaluated as a potential mechanism to reduce area burned.
However, it is difficult to envisage that such treatments could be employed
successfully at the national scale, at least over the next few decades,
because of the large scale of treatments required and ecological issues
related to forest fragmentation and biodiversity.
simulating carbon dynamics along the Boreal Forest Transect Case Study (BFTCS) in central Canada: 2. Sensitivity to climate change
