Past and future changes in Canadian boreal wildfire activity

Area of Science:

• Ecology and Environmental Science
• Climate Change Research
• Forestry and Fire Management

Background:

• Climate change in Canadian boreal forests is typically linked to increased drought and fire activity.
• However, future fire activity may remain within historical preindustrial ranges.

Purpose of the Study:

• To contrast 21st-century fire occurrence forecasts with the historical range of the past 240 years.
• To evaluate future fire activity in the southern Boreal Shield, Canada.
• To assess the impact of projected climate change on fire occurrence and forest management.

Main Methods:

• Developed a historical relationship between drought indices and fire occurrence (FireOcc) from 1959-1998.
• Utilized tree-ring data for drought reconstructions over the last 240 years.
• Employed global climate model simulations (CGCM3, ECHAM4) to estimate past and future FireOcc.
• Applied statistical time series analysis to evaluate changes in mean FireOcc and extreme fire years.

Main Results:

• Projected increases in precipitation are insufficient to offset rising temperatures and maintain evapotranspiration.
• Limited moisture availability is expected to increase fire occurrence (FireOcc).
• Future FireOcc is likely to reach the upper limit of the historical range, with a potential increase of over 34% by 2061-2100 in northwestern Ontario and eastern boreal Manitoba.

Conclusions:

• Projected fire activity increases could challenge forest management strategies based on historical disturbance dynamics.
• Forest management approaches may need adaptation to mitigate the adverse impacts of potentially elevated fire activity.
• The feasibility of management strategies depends on future fire activity remaining comparable to preindustrial levels.