Retrospective study of the diameter growth of balsam fir(Abies balsamea (L.) Mill.) and red spruce (Picea rubens Sarg.) in mixed stands after diameter limit cutting.

摘要

Diameter growth at breast height of 341 balsam fir (Abies balsamea) and red spruce (Picea rubens) stems has been reproduced over a time lapse of 50 years following a diameter limit cutting. The available information has been analysed with a statistical model in which the effects of time, species (two levels), ecological type (three levels) and diameter at harvesting have been tested. The study site is on River Ouareau, which is now in the Mont-Tremblant National Park, Quebec, Canada. Results indicate that balsam fir saplings have higher diameter growths than red spruce saplings, but only in the case of better ecological types. The differences between both species are smaller for stems having a merchantable diameter (>9.0 cm) at harvesting time. On poor ecological station, red spruce diameter growth is more important than for balsam fir and this, whatever the diameter at harvesting time. On the other hand, as indicated by this analysis, stem diameter at the time of silvicultural treatment constitutes a significant variable in the prediction of diameter growth for red spruce stems, while the effect of this variable is less identifiable for balsam fir. Even if significant, the growth differences between the two species are small. The competition created by the balsam fir regeneration on red spruce saplings is definitely not the cause of the depletion of red spruce in second growth stands..