Boreal mixedwood stand dynamics: Ecological processes
underlying multiple pathways.
Yves Bergeron, Han Chen, Norman C. Kenkel, Albanie Leduc, Ellen MacDonald.
The southern portions of the boreal region across Canada are dominated by boreal mixedwoods forests, which are characterized
by varying canopy dominance of boreal broadleaf and conifer trees. This forest region encompasses a large east-to-west
gradient of climate and disturbance regimes. Although the same major boreal tree species occur in all parts of the boreal
mixedwood region, they vary greatly in relative abundance. This is a reflection of the interactions among the different abiotic
and biotic components. As a result, there is considerable variation in post-disturbance stand development, producing a wide
variety of mixedwood forest conditions existing as a mosaic in time and space. Post-disturbance dominance by broadleaf species
followed by a transition to conifers is the “classic” pathway in all regions. However, there is wide variation in the transition
rate and the species sequence across the gradient depending on factors such as moisture, abundance of each species, fire cycle,
climate and secondary disturbances (mainly insect outbreaks). Future changes in climate and disturbance regime could influence
the nature of stand dynamics of boreal mixedwoods and the prominence of different pathways among regions. Focussing
on the commonality of processes in mixedwood stand development across the boreal is a promising way to address the management
of this important forest ecosystem.