Fill-planting maintains stand yield and can influence successional trajectories toward desired stand compositions: a 25-year retrospective study in black spruce forests of eastern Canada

Fill-planting, which may account for 25% of clear-cut areas, has been applied on nearly 400,000 hectares over the last 25 years in eastern Canada. Despite its operational importance, knowledge gaps remain regarding the long-term yield of fill-planted stands. We assessed whether fill-planting of black spruce (Picea mariana (Miller) B.S.P.) in skid trails increases stand yield. We compared yield in clear-cut stands fill-planted in skid trails (n = 40), established 15 and 25 years ago, with yield in nearby stands naturally regenerated after clear-cutting (n = 38). Fill-planting did not produce higher yields than natural regeneration; instead, it brought understocked stands to yields comparable to those of fully stocked naturally regenerated stands. We therefore recommend applying natural-stand yield curves to fill-planted stands, and using fill-planting to maintain yield where stands would otherwise remain understocked as well as for influencing successional trajectories toward desired stand compositions.