PREDICTING THE HEIGHT TO LIVE CROWN BASE IN PLANTATIONS OF J BOREAL FOREST SPECIES

A critical parameter for the initiation and propagation of a crown fir e in the boreal forest is the height to the base of the live crown. Th e initiation of a crown fire requires that the surface fire intensity must be sufficient to ''jump'' the gap between the forest floor and th e live crown and ignite crown fuels. The greater the height of the liv e crown base, the more intense the surface fire must be to induce a cr own fire. Plantation forest fuels tend to be more structured and have less variability than naturally regenerated areas, allowing prediction of the height of the live crown base to be made from commonly availab le stand parameters. Plantations of four commonly planted boreal fores t species were sampled over a variety of age classes to determine a pr edictive relationship for height to live crown base. Height to live cr own base can be predicted from stand height and density for Pinus bank siana (jack pine), Pinus resinosa (red pine), Picea mariana (black spr uce), and Picea glauca (white spruce). In addition to predicting the h eight to live crown base, parameters within the equations lead to othe r observations. Crown foliar fuel loading does not change with stand h eight following crown closure in red pine but in the other three speci es crown fuel load increases as the stand grows taller.