Selection cutting in a yellow birch-conifer stand, in Quebec, Canada: Comparing the single-tree and two hybrid methods using different sizes of canopy opening

We experimented three selection cutting patterns using different sizes of canopy opening, including single-tree (SIN, <100 m2 in area), hybrid single-tree and small groups of trees (HGR, 100-300 m2), hybrid single-tree and one larger gap (HGA, 700 m2), and an uncut control (CON) to regenerate tree species with a range of shade tolerance in a yellow birch (Betula alleghaniensis Britt.)-conifer stand, in Quebec, Canada. In this paper, we are presenting the 10-year effects on regeneration dynamics, seedbed coverage and light availability. During the six summers of monitoring, incoming solar radiation increased with canopy opening at a rate of 1.5, 3.9, 4.9 and 8.9 MJ/m2/day in microsites distinctive of the CON, SIN, HGR and HGA, respectively. Yellow birch established well in the three cutting patterns (including the matrix and openings), which contained 5-6 times more seedlings >5 cm in height than the control (2400/ha) after 10 years (all p < 0.001). Raspberry (Rubus idaeus L.) coverage was also higher in the three cuts (9-15% at year 10) than in the CON (<1%, p ⩽ 0.001). Pin cherry (Prunus pensylvanica L. f.) rapidly emerged independently from the cutting pattern (6000-7000 stems/ha, year 2), but had almost disappeared by year 10 (100-300 stems/ha). The 100-300 m2 groups and 700 m2 gap were favourable niches for yellow birch development. The gap, where light blade scarification was carried out in areas without conifer advance growth, was by far the worst niche for both red spruce and balsam fir (Abies balsamea [L.] Mill.). Therefore, the hybrid method that removed small groups of trees revealed the best option to maintain yellow birch and conifer species in the study site.