Point-source fire growth in Jack Pine slash

Abstract

A series of experimental fires was conducted to document point-source fire growth burning on full-tree harvested jack pine (Pinus banksiana Lamb.) sites with a feathermoss (Pleurozium schreberi (B.S.G.) Mitt.) duff layer. Results showed that the time for any of the fires to reach equilibrium spread rates was constant despite the fuel moisture codes and fire behavior indices of the Canadian Forest Fire Weather Index (FWI) System calculated at the time of the fires. Two relationships were developed (linear and nonlinear) for average (wind lulls included) and peak wind conditions. The linear prediction for peak wind conditions estimates that equilibrium spread rates may be achieved as quickly as 22.3 minutes after ignition. The fire depended upon a continuous feathermoss duff layer, and not the slash fuel component, for its spread. Hydraulic (moisture dependent) and thermal properties of the feathermoss surface layer contributed to the rapid drying experienced even after large amounts of precipitation had fallen.