The commercially valuable tree, white spruce (Picea glauca (Moench) Voss) has proven difficult to regenerate either naturally or artificially following harvesting. A strongly masting species, its small seeds require mineral soil or thin duff for germination. This study explored the possibility of increasing natural recruitment of white spruce and balsam fir (Abies balsamea (L.) Mill) following harvesting by coupling site preparation treatments with a masting episode in the boreal forest of northwest Quebec. Four treatments (on average 4604 m²) were applied to a seed tree retention cut, replicated in three blocks: 1) understory shrub and slash chipping, 2) ground scarification, 3) combination of chipping followed by scarification, and 4) cut with no prescribed site preparation (control). Cumulative seed density in seed traps (area: 1/2 m², made out of wood and mesh; 0.75 m high) located in the treatments was approximately 1000 seeds/m²for spruce and 50 seeds/m²for fir. Quantities of exposed mineral soil differed significantly between treatments, with 25% in the chipped & scarified treatment; however, this was not significantly greater than in the scarified only treatment (12%). There were no significant differences in adjusted germinant densities between mineral soil and decomposed wood in both the scarified and chipped & scarified treatments. The chipped & scarified treatment had the greatest mean recruitment densities for spruce, followed by the scarified treatment (?3.10/m²). In 2007, both species (lumped) attained full stocking (>60%) in all treatments, including the control. In 2008, full stocking of spruce was maintained in all treatments except the control, while no treatment attained full stocking of fir. Applying these results within an ecosystem-based and mixedwood management framework would require some degree of flexibility (and operational agility) in forest management planning that would allow adapting appropriate harvesting and site preparation treatments when a mast year occurs.

Les peuplements mélangés, caractérisés par une abondance de tiges résineuses prématures croissant sous un couvert dominant de peuplier faux-tremble mature, se prêtent bien à la coupe partielle qui favoriserait la croissan-ce des tiges supprimées et l'établissement de la régénération. Dans cette étude, nous décrivons la réponse initia-le de peuplements soumis à trois types de coupe où on a fait varié l'intensité de la récolte de la surface terrière du tremble par rapport à celle des peuplements témoins. Nous avons ainsi observé que la croissance des tiges inter-médiaires d'épinette blanche était favorisée par la coupe la plus sévère seulement. Après 5 ans, les coupes n'ont pas eu d'effet sur l'établissement et la croissance de la régénération résineuse. Un essai de scarifiage visant à favoriser l'établissement de semis a donc été réalisé. À la suite d'une année semencière, le taux d'établissement des semis d'épinette blanche sur le sol scarifié variait de 125 à 165 semis/m². En dépit de la mortalité élevée d'une grande proportion des semis, une régénération adéquate pourrait être assurée dans la zone scarifiée.