E-mail : pitre_n@hotmail.com

Black spruce growth along a subarctic toposequence

Supervisor: Serge Payette

The growth of 40 black spruce (Picea mariana) seedlings and 24 mature individuals were monitored at four sites with different edaphic conditions. The four sites included a hill summit, north and south facing slopes, and an east-west orientated valley bottom. The growing season started earlier in the south facing spruce lichen woodland and later in the peatland located in the valley bottom, as well as for the north facing spruce lichen woodland. Light tree rings, which indicate cold growth seasons, tended to be more abundant at the sites with a shorter growing season. Light ring frequency is inversely proportional to the photosynthetic activity at any given height along a tree stem. Frost rings, which form in young trees that are less resistant to frost, were more frequent at the less elevated sites and near the ground, as these locations are favourable for the accumulation of cold air masses.


Payette, S., Boudreau, S., Morneau, C., Pitre, N., 2004. Long-term interactions between migratory caribou, wildfires and Nunavik hunters inferred from tree rings. Ambio, 33: 482-486.

Laberge, M.-J., Payette, S., Pitre, N., 2001. Development of stunted black spruce (Picea mariana) clones in the subarctic environment: A dendro-architectural analysis. Écoscience, 8: 489-498.