Lori Daniels is an associate professor in the Dept. of Forest Science in the Faculty of Forestry. She uses tree rings to reconstruct the history of forests and better understand the effects of fire, pest outbreaks and climate change.
Every year Canadians fight wildfires that ravage forests and nearby communities. How does fire affect the forest?
Fire comes in a range of sizes, frequencies, severities and effects. Fires that burn near urban areas can be tremendously costly and traumatic to those impacted but they account for relatively few of the wildfires that burn every year in Canada.
The high-severity fires we commonly see in the news contribute to landscape diversity, creating patches of forests of a range of ages that provide a variety of habitats for plants and animals. It takes time for forests to regenerate and fuels to accumulate so there tends to be many decades to several centuries between fires in one location.
Equally important are low-severity stand-maintaining fires. These types of fires occur more frequently but do not kill mature trees. Historically, frequent surface fires “maintained” the forest, reducing fuels and stimulating native grasses and plants while sustaining some trees. Today, stand-maintaining surface fires are poorly understood because they have been eliminated during the 20th century. Very effective fire suppression has prevented many fires from burning.
What are the implications of trying to prevent forest fires?
We’ve tried to protect ourselves from fires and as a result, we’ve increased our risk. Our good intentions really backfired. We call this the “fire suppression paradox.” By trying to protect our forests and communities, we have made many dry forests in B.C. more susceptible to severe fires.
In the absence of low-severity stand-maintaining fires, tree density and surface fuels build up. Increased fuels increase the chance of a severe fire that is difficult to control and may threaten human communities. This may have been a factor in the Okanagan Park fire of 2003.