FACTORS AFFECTING GERMINATION AND EARLY SURVIVAL OF YELLOW BIRCH (Betula lutea Michx.) IN QUEBEC

Abstract

Three stations were established in 1943 for the purposes of this study: (1) in an uncut 70-year-old stand, (2) in a similar stand from which 40% by volume had been removed, and (3) a dear-cut area. The resulting variations in microclimate were reflected in considerable differences of germination, growth and survival of the seedlings. More seed germinated under canopy than in the open, probably owing to higher soil moisture, but germination in all 3 sites was much lower on litter than on mineral soil. The physical structure and its wide variations in temperature and moisture are held responsible for this. The average germination value per quadrat was 15 seedlings in full shade, 62 in part shade, and 2 in the open; on mineral soil, in the same order, the values were 233, 273, and 92. After 2 growing seasons, no seedlings remained on the litter surface except at the partial-shade station (13% survival). Survival percentages on mineral soil were 2% in full shade, 27% in part shade and 69% in the open. The height reached by the seedlings at the end of the 2nd growing season in the open, part shade, and full shade stations was 10.86, 3.52, and 1.47 in. respectively. Seedling losses were relatively high during the first growing season. The main factors responsible were high surface temperatures, drought, late frosts, mechanical injuries, insects and rodents. It is concluded that the best system for obtaining good regeneration of Yellow Birch is partial cutting, removing 30-50% of the stand volume. A group selection system might be better still. Mechanical logging, which tends to expose the mineral soil, should encourage plentiful germination. With clear cutting, lopping and scattering of the slash is desirable in order to prevent the soil from drying out too quickly. KEYWORDS: Betula lutea natural regeneration, Litter, effects, natural regeneration, Logging, natural regeneration, natural regeneration, influence, logging methods, natural regeneration, influence, seedbed conditions, natural regeneration, influence, soil moisture.