Dr. Ze'ev Gedalof presents the "two cultures" in our understanding of fire in the Canadian boreal forest and how a new concept of "mixed severity" is changing our understanding of how complex forests develop. High frequency, low severity fires are the fires that remove underbrush and reduce the fuel in the forest. Native people were responsible for these types of fires on boreal forest/prairie boundaries. High severity, low frequency fires are more typical of the boreal forest and tend to be large, stand replacing fires. High severity fire science has led to stand origin mapping. Low severity fire science have led to fire scar analysis. He then shows how these two techniques are done in the field. Understanding mixed severity fires bumps up against our historical suppression of fire.
Dr. Gedalof describes how some of our management techniques combined with fire suppression introduce complications to the fire regime of Alberta's boreal forests, e.g. ladder fuels that turns underbrush fires into crown fires. Mixed severity fires introduces variability in severity and changes the minimum sample size. Where did mixed severity fires occur? Aspect and elevation are components; drought is less a factor than in large stand replacing fires. Dr. Gedalof finishes by talking about the management challenges and opportunities that come from an understanding of mixed severity fires as a natural disturbance on Alberta's boreal landscapes. Climate change will increase the likelihood of fire; mixed severity fires may be a consequence. Some species (e.g. woodland caribou) may prefer mixed severity fire landscapes.
Dr. Ze'ev Gedalof is an Associate Professor of Forest Science at the University of Guelph. His presentation was part of the 2013 Workshop and Field Tour on "Burning Issues in Alberta`s Forests" with the Forest History Research Team part of the Healthy Landscapes program at the Foothills Research Institute.
