Growth and productivity of black spruce (Picea mariana) belonging to the first cohort in stands within and north of the commercial forest in Quebec, Canada

The managed area of the North-American boreal forest has been studied extensively. However, because of their inaccessibility, the growth and dynamics of trees at higher latitudes remain unknown, so precluding the possibility of quantifying their productive and economic potential and, if any, their exploitation. The aim of this paper was to assess individual growth patterns in dominant black spruces (Picea mariana (Mill.) B.S.P.) belonging to the first cohort and to compare growth dynamics within and north of the commercial forest in Quebec, Canada. Compared with stands located on 49th parallel, stands on 51st parallel showed thinner tree rings and 15% less growth in height, resulting in a 35% reduction in the stem volume attained at the age of 125 years (170 and 110 dm(3) for dominant trees in stands within and north of the commercial forest, respectively). At maturity, the annual increment in stem volume in northern stands was 28% lower than that measured in southern stands. These findings represent important information on tree growth in stands of high-latitude boreal forests and should be taken into account when evaluating the profitability of exploiting the remotest Canadian forests. Confirmation by more extensive and spatially-exhaustive inventories is desirable.