Recent Crown Thinning in a Boreal Black Spruce Forest Does Not Reduce Spread Rate nor Total Fuel Consumption: Results from an Experimental Crown Fire in Alberta, Canada
Dan K. Thompson,
Dave Schroeder,
Sophie L. Wilkinson,
Quinn Barber,
Greg Baxter,
Hilary Cameron,
Rex Hsieh,
Ginny Marshall,
Brett Moore,
Razim Refai,
Chris Rodell,
Tom Schiks,
Gregory J. Verkaik,
Jessica Zerb
Affiliations
Dan K. Thompson
Canadian Forest Service, Natural Resources Canada, Northern Forestry Centre, Edmonton, AB T6H 3S5, Canada
Dave Schroeder
Alberta Agriculture and Forestry, Wildfire Management Branch, Government of Alberta, Edmonton, AB T6H 3S5, Canada
Sophie L. Wilkinson
School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
Quinn Barber
Canadian Forest Service, Natural Resources Canada, Northern Forestry Centre, Edmonton, AB T6H 3S5, Canada
Greg Baxter
FPInnovations Wildfire Operations Research Group, Edmonton, AB T6H 3S5, Canada
Hilary Cameron
Alberta Agriculture and Forestry, Wildfire Management Branch, Government of Alberta, Edmonton, AB T6H 3S5, Canada
Rex Hsieh
FPInnovations Wildfire Operations Research Group, Edmonton, AB T6H 3S5, Canada
Ginny Marshall
Canadian Forest Service, Natural Resources Canada, Northern Forestry Centre, Edmonton, AB T6H 3S5, Canada
Brett Moore
Canadian Forest Service, Natural Resources Canada, Northern Forestry Centre, Edmonton, AB T6H 3S5, Canada
Razim Refai
FPInnovations Wildfire Operations Research Group, Edmonton, AB T6H 3S5, Canada
Chris Rodell
Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
Tom Schiks
Department of Forestry, University of Toronto, Toronto, ON M5S 1A1, Canada
Gregory J. Verkaik
School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
Jessica Zerb
Canadian Forest Service, Natural Resources Canada, Northern Forestry Centre, Edmonton, AB T6H 3S5, Canada
A 3.6 ha experimental fire was conducted in a black spruce peatland forest that had undergone thinning the year prior. After 50 m of spread in a natural stand at 35–60 m min−1, the crown fire (43,000 kW m−1 intensity using Byram’s method) encountered the 50% stem removal treatment; spread rates in the treatment were 50–60 m min−1. Fuel consumption in the control (2.75 kg m−2) was comparable to the treatment (2.35 kg m−2). Proxy measurements of fire intensity using in-stand heat flux sensors as well as photogrammetric flame heights had detected intensity reductions to 30–40% of the control. Crown fuel load reductions (compensated by higher surface fuel load) appear to be the most significant contributor to the decline in intensity, despite drier surface fuels in the treatment. The burn depth of 5 cm in moss and organic soil did not differ between control and treatment. These observations point to the limited effectiveness (likely reductions in crown fire intensity but not spread rate) of stem removal in boreal black spruce fuel types with high stem density, low crown base height and high surface fuel load. The observed fire behaviour impacts differ from drier conifer forests across North America.
