Germination and establishment of natural red spruce (Picea rubens) seedlings in silvicultural gaps of different sizes

Abstract

Red spruce (Picea rubens Sarg.) is difficult to regenerate from natural seeding following silvicultural treatment. In order to study its germination and establishment, we monitored the dynamics of new seedlings over 10 years in silvicultural gaps of different sizes (small: < 100 m2, medium: 100-300 m2, large: > 700 m2). Seedling density was higher in small gaps but survival rate did not exceed 40%, leaving few live seedlings after 10 years (< 200 ha-1). Mounds were the best microtopography for seedlings. Our results confirm the important role of decaying wood and moss for understory germination and establishment. Decaying wood was important for the establishment in large gaps while humus was more favourable in medium gaps. In small gaps, germinants and established seedlings were found as much on moss as humus and decaying wood. However, low observed densities suggest that planting in small or medium gaps should be explored for accelerating species renewal, especially if advance regeneration is deficient.