Montane Alternative Silvicultural Systems (MASS) Conifer Growth and Understory Vegetation Response to Alternative Silvicultural Treatments and Systems - 15 Year Results

This comprehensive 15-year report details the Montane Alternative Silvicultural Systems Project, which tested the efficacy of different harvesting treatments, including clearcutting, patch cutting, and various forms of retention, on forest health and regeneration in coastal British Columbia. Key findings reveal that while conifer survival remained consistent across treatments, tree height and volume growth was generally slower in the shelterwood environment due to reduced light, and the single most effective way to boost planted tree growth was through intensive vegetation control. Conversely, the shelterwood system successfully maintained the greatest understory species diversity and composition most similar to the uncut old-growth forest, minimizing the loss of shade-loving plants. The long-term data emphasizes a crucial trade-off: maximizing early conifer growth favors more open treatments, but retaining pre-harvest biodiversity values is best achieved with substantial canopy protection.