Shelterwood cutting in a red spruce – balsam fir lowland site: Effects of final cut on water table and regeneration development

Abstract

We evaluated the effectiveness of the regular shelterwood system in mitigating water table rise and regenerating a new cohort while favoring red spruce (Picea rubens Sarg.) in an 80-year-old, red spruce – balsam fir (Abies balsamea (L.) Mill.) lowland site. We used an experimental design established in 1994, with four completely randomized blocks and five treatments (uncut control, low, moderate, and heavy shelterwood cuttings, and clearcutting). In 2006, final overstory removal was carried out in the three shelterwoods and we monitored the first five growing seasons after treatment. Results showed that final cut did not lead to significant watering-up during the 2006–2010 period compared to levels measured in 1999, but water table levels did not fully recover from shelterwood cutting or clearcutting compared to precut levels measured in 1994. Under conditions of abundant seed supply, poor drainage, and low herbaceous and noncommercial woody competition, clearcutting (0.25ha patches) provided the best red spruce cohort in terms of regeneration density, stocking, and growth. Balsam fir and red maple (Acer rubrum L.) regeneration was abundant in both silvicultural systems. Regeneration density and stocking of red spruce, balsam fir, and all commercial broadleaf species were generally lower inside logging trails than between trails, likely due to disturbance by machinery. For poorly-drained lowland sites, findings indicate patch clearcutting may be more effective in regenerating red spruce than the regular shelterwood system.