Characterization of tree macroremains production in a recently burned conifer forest in northern Quebec, Canada

The production of plant macroremains was studied in a conifer forest two months after it burned in 1996 in northern Quebec. The proportions of various types of charred and uncharred pieces (needles, cones and wood) produced by black spruce (Picea mariana) and jack pine (Pinus banksiana) were determined by sampling around individual trees. Both species produced equivalent masses of charred material, but pieces of wood charcoal from jack pine are generally larger that those of black spruce. The proportion of charred versus uncharred needles is the best indicator of the species dominance in the forest. Although the fall of uncharred needles is delayed from the time of a fire, they contribute to more than half of all remains produced. Jack pine cones remain on the tree for a long time after a fire, while charred cones of black spruce are dehiscent (cones come off the branches easily). Trees are poor wood charcoal producers compared to undergrowth shrubs. As a result, the macroremains assemblage associated with a fire event is made up of large amount of uncharred material from trees and a large proportion of charred pieces produced by undergrowth vegetation. Modern assemblages of plant macroremains indicate that in order to reconstruct past vegetation associated with fire disturbance, it is important to distinguish between the various types of remains, because wood charcoal is mainly produced by material that is already dead.