Évolution de la structure diamétrale et de la composition des peuplements mixtes de sapin baumier et d'épinette rouge de la forêt primitive après une coupe à diamètre limite sur l'Aire d'observation de la rivière Ouareau
Using data from 41 plots, the diameter structure and composition of old-growth mixed stands composed mainly of balsam fir (Abies basalmea (L.) Mill.) and red spruce (Picea rubens Sarg.) were characterized. The stand table was organized in five groups of diameter classes, and we characterized the basal area of four tree species in each group. Analysis showed that diameter structure tends toward a reverse J-shaped curve. Red spruce and yellow birch (Betula alleghaniensis Britt.) were more abundant among large diameter trees while balsam fir was more abundant among saplings. A comparison with 18 permanent plots from a diameter-limit cutting showed that plots had come back to a structure similar to that of the old-growth forest 47 years after cutting. However, spruce ratios had decreased while those of balsam fir and paper birch (Betula papyrifera Marsh.) had increased. Red spruce decrease is not due to a lack of regeneration but to overcutting. Single-tree selection method would be a suitable treatment if aimed at protecting red spruce trees up to a given diameter.