Évaluation de la coupe avec protection de la régénération et des sols comme méthode de régénération de peuplements mélangés du domaine bioclimatique de la sapinière à bouleau jaune de l'est du Québec, Canada

Abstract

valuation de la coupe avec protection de la regeneration et des sols comme methode de regeneration de peuplements melanges du domaine bioclimatique de la sapiniere 2 bouleau jaune de l'est du Quebec, Canada The effect of careful logging to preserve advance growth was studied in mixedwood stands of the balsam fir (Abies balsamea (L.) Mill.) -yellow birch (Betula alleghaniensis Britton) eco-climatic domain in eastern Quebec, Canada. The study is based on 19 sites harvested five years earlier. In each cutover, 50 sample plots have been established to quantify the abundance of regeneration five years after logging. This cutting method proved to be ineffective in limiting the invasion of competiting species such as mountain maple (Acer spicatum Lam.) and pin cheny (Prunuspensylvanica (L.), which fully occupied the sites with 25 092 and 5619 stems ha-' respectively. Balsam fir was abundant after five years in the study area with 13 500 stems ha-' but two thirds of the seedlings were smaller than 30 cm. Soil disturbance was minimal, probably limiting the establishment of yellow birch, which reached a density of 1416 stems ha-' five years after logging. Height growth projection of regeneration over five years showed that competiting species should still dominate the sites. Commercial species should improve their position but would still account for only 40 % of dominant stems. It is therefore unlikely that this regeneration method will be successful in bringing back the initial stand composition in a short period of time. The next stands will probably contain a high proportion of intolerant species with a dominance of paper birch (Betula papyrifera Marsh.) over yellow birch. In the near future, cleaning operations should be conducted to reduce the impact of competing vegetation and make sure that balsam fir will remain in the main canopy.

Are clearcuts appropriate for the mixed forest of Québec?

“…In comparison, paper birch was relatively abundant with a mean density of more than 4700 stems/ha. Paper birch was taller five years after harvesting, since almost 50% of its stems attained a mean height between 1 and 3 m. Paper birch also grew more quickly than yellow birch (Laflèche et al 2000). In clearcuts, arborescent colonizing species are more likely to form the next canopy than climax species (Fig.…”

“…In the mixed forest, Vallée et al (1976) found that five years after a clearcut in a balsam fir-yellow birch stand, mountain maple density was of 8870 stems/ha. Also five years after harvesting, Laflèche et al (2000) found that mountain maple density was of 29 730 stems/ha. In another study, Bédard et al (1978) found that eight years after clearcutting, mean density of mountain maple was 10 600 stems/ha.…”

“…Post (1970) reported that the height of the mountain maple stand at 8,11,13,16,18,21,23 and 26 years after harvesting was 1.9, 2.7, 3.2, 3.4, 4.7, 5.5, 5.3 and 5.4 m, respectively. In the mixed forest, Laflèche et al (2000) reported that mean height of mountain maple was 1.7 m five years after harvesting. Bédard et al (1978) reported that it varied between 1.3 and 2.2 m from eight to 12 years after harvesting.…”

“…Sugar maple was clearly not a part of the current canopy, with a mean height of about 0.5 m. De Grandpré et al (2000) also confirmed that sugar maple was not likely to form the next forest. Finally, Laflèche et al (2000) reported that in most cases, yellow birch had regenerated poorly five years after harvesting and had a mean density less than 1500 stems/ha. In comparison, paper birch was relatively abundant with a mean density of more than 4700 stems/ha.…”

“…In fact, 20 years after harvesting, balsam fir mean height was approximately 1 m (Archambault et al 1998). Laflèche et al (2000) reported that balsam fir was under the cover of all other species five years after harvesting, even if it had regenerated very well. Mountain maple frequently forms pure, dense stands that hinder the establishment of balsam fir and spruce regeneration (Post 1970).…”