A 3.6 ha experimental re 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 re (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 re intensity using in-stand heat ux sensors as well as photogrammetric ame 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 signi cant 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 di er between control and treatment. These observations point to the limited e ectiveness (likely reductions in crown re 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 re behaviour impacts di er from drier conifer forests across North America.
Fire behaviour; boreal; crown re; fuel treatment; thinning; black spruce