Modelling the effects of surface and crown fire behaviour on serotinous cone opening in jack pine and lodgepole pine forests

Abstract

A methodology has been developed for defining the various threshold conditions required for the opening of serotinous cones and viable seed release in the overstorey canopies in jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta var. latifolia) forests on the basis of fireline intensity and, in turn, rate of fire spread and fuel consumption. The extent of the effects to the overstorey canopy (i.e. crown scorch height and flame defoliation) and the type of fire (i.e. low- to high-intensity surface, intermittent crown and active crown) vary at any given fireline intensity level and are principally a function of foliar moisture content, canopy base height, stand height and canopy bulk density. The viability of the seed stored in serotinous cones of the two pine species begins to decreases once the flame-front residence time at the ground level of an active crown fire exceeds 50 s.