Fire behavior in black spruce-lichen woodland: the Porter Lake project.

Abstract

The behavior of single point-ignition and line-ignition experimental fires was studied in upland black spruce (Picea rrulriana [Mill.] B.S.P.)-lichen (Stereocaulon paschale [L.] Hoffm.) woodland stands at Porter Lake in the Caribou Range of the Northwest Territories (N.W.T.) from June 26 to July 8, 1982. The experimental burning project objective was to relate the head fire rate of spread (ROS) in this fuel type to the Initial Spread Index (lSI) component of the .Canadian Forest Fire Weather Index System. The experimental fire plots varied from 0.02 to 0.65 ha in size. The live tree overstory averaged about 1200 stems Iha and 5.0 m in height. The lichen layer averaged about 3.5 em in depth. Three point-ignition fires, seven line-ignition fires, and one wildfire (CR-6-82) were documented over a wide range of burning conditions. The ensuing fire behavior varied from creeping surface fires to full-fledged crown fires. Head fire spread rates from 0.6 to 51.4 mlmin were observed and frontal fire intensities of nearly 33 000 kW 1m were attained. A relationship for equilibrium fire spread in black spruce-lichen woodland stands was established. The experimental fire data gathered during the Porter Lake project presently forms the basis for the quantitative prediction of fire behavior in the spruce-lichen woodland fuel type as currently incorporated into the system of forest fire danger rating used in Canada.