E-mail : stefanie.pollock.1@ulaval.ca

The origin and dynamics of the spruce-moss forests at their northern limit of distribution in Québec, Canada
Supervisor : Serge Payette

Closed spruce-moss forests occupy the southernmost boreal forest in Québec. The extent of these forests diminishes gradually towards the north where they are replaced by open spruce-lichen woodlands. The spruce-moss forests are dominated by black spruce (Picea mariana) and are dependent on fire for their regeneration. Two hypotheses have been suggested to explain the long-term evolution of these closed forests. The first hypothesis stipulates that the spruce-moss forests are the end stage of succession after fire. The second hypothesis postulates that the moss forests can be transformed into open forests once affected by several disturbances that significantly reduce tree regeneration. The principal objective of this research is to characterize the structure of the northern closed forests and evaluate their stability as a function of both time and disturbance (fire, insect epidemics, climate, etc.). The study region extends from 51˚ N to the northern spruce-moss forest limit at around 54°N (James Bay). The spruce moss forests in the study are grouped into 1 km wide bands between 70˚ and 72˚ W at each 15 minutes of latitude, i.e., 12 bands between 51˚ and 54˚ N. The sites will be randomly selected with the aid of aerial photographs and verified in the field. The spruce moss forest in the study sample are composed primarily of black spruce and balsam fir (Abies balsamea), with a total tree cover greater than 60%. The role of fire, along with stand characteristics (age and height), will be evaluated through stem and annual growth rings analysis, regeneration estimates, soil analysis, and the carbon dating of wood charcoal.

Pollock, Stefanie L. & S. Payette, 2010. Stability in the patterns of long-term development and growth of the Canadian spruce-moss forest. Journal of Biogeography, 37: 1684-1697.

Feller, M. C., Pollock, S. (2006). Variation in surface and crown fire hazard with stand age in managed coastal western hemlock zone forests in southwestern British Columbia. USDA Forest Service Proceedings RMRS-P-41.