Natural dynamics-based silviculture for maintaining plant biodiversity in Populus tremuloides-dominated boreal forests of eastern Canada. (Special Issue: Poplar research in Canada (part 2 of 2).)

摘要

Southern boreal forests dominated by trembling aspen (Populus tremuloides Michx.) are notable for the biological richness of their plant communities. We used 12 plant community and plant functional group indicators to test the hypothesis that natural dynamics-based silvicultural systems better maintain biodiversity in aspen plant communities than conventional clear-cutting. Using CA ordination, box-and-whisker diagrams, and ANOVA, we compared the range of variability of our 12 bioindicators among five experimental stand types of the sylviculture et amenagement forestier ecosystemiques (SAFE) project: mature (78 years) uncut; mature 1/3 partial-cut; mature 2/3 partial-cut; young (3 years) unburned clear-cut; young burned clear-cut; and three closely matched aspen stand types of northwest Quebec and northeast Ontario: old (105 years) uncut; young unburned clear-cut; young wildfire. Burned clearcuts partially emulated wildfires by reducing tall shrub abundance and regenerating post-fire specialists, but snags were lacking. The dual disturbance also retarded aspen regrowth and caused a 7-fold increase in non-native plants. Partial-cuts retained most attributes of mature uncut stands, but after 3 years showed little evidence of accelerating development of old stand characteristics. We concluded that SAFE natural dynamics-based silviculture better recreated the range of variability of naturally disturbed aspen plant communities than conventional clear-cutting. Improvements, including alternative burn prescriptions and snag or green tree retention in clearcuts, are nonetheless warranted.