A review of climate change effects on the regeneration dynamics of balsam fir

Abstract

Balsam fir (Abies balsamea) is one of the most abundant softwood species in eastern Canada but is projected to be adversely affected by climate change. Balsam fir decline could occur due to a combination of reduced germination and regeneration, lower growth and competitive ability, and higher rates of mortality. However, tree regeneration represents one of the most vulnerable stages to climate-induced stress. In this paper, we synthesize potential and observed effects of climate change on balsam fir regeneration. Recent studies have shown no detrimental effects of increased temperatures on either germination or seedling growth of balsam fir, but clear deleterious effects of decreased water availability. Balsam fir seeds require 28–60 days of cold stratification to become germinable, and such conditions should still be met under climate change across most of the species’ range. Sampling along a north-south climatic gradient throughout the Acadian Forest Region of eastern Canada indicated effects are complex and do not suggest a clear decline under warmer, drier conditions for the species. Thus, effects of global warming on balsam fir may be more gradual than projected in modeling studies and occur primarily via reduced competitive ability and/or higher mortality in overstory trees, rather than regeneration failure.