Summary
Published in Forest Ecology and Management, 485: 118954.
The dynamics of the boreal forest have followed several successional trajectories during the Holocene caused by recurrent stand-scale, abiotic and biotic disturbances. Under stable environmental conditions, site disturbances should favour the regeneration of forest communities enabling the recovery process to produce forests similar to the pre-disturbance states. However, a failure in the post-disturbance recovery process can also occur to shift the forest communities to alternative states. Although fire is the main disturbance factor affecting the dynamics of the boreal forest, long-term resilience of most forest ecosystems remains poorly understood because of lack of stand-scale paleoecological evidence.
To evaluate the fire resilience of boreal forest ecosystems, we reconstructed their Holocene fire histories and documented their successional pathways at the stand-scale in two climatically contrasted regions (western continental versus eastern humid climates of boreal Québec, Canada) based on botanically identified and ¹⁴C-dated soil charcoal remains. Since the mid-Holocene, western closed-crown conifer forests were resilient to fire disturbance, but hardwood trees declined substantially. In the eastern region, closed-crown conifer forests were similar to those that are still observed today. In both regions, moderate fire frequency leads to recurrence dynamics that favour renewal of forest stands with the same composition. Yet, balsam fir–paper birch stands follow a successional pattern characterized by the establishment of paper birch, with subsequent increasing abundance of balsam fir. This allows the maintenance of forests composed of these species, the dominance of which fluctuates according to the time elapsed since the last fire. The succession from black spruce to balsam fir stands seems to be an uncommon process that requires a prolonged fire-free period. Although most closed-crown forests are resilient post-fire ecosystems that have persisted over several millennia, their resilience is precarious as evidenced by the transformation of some forests into lichen woodlands after fire.
File
Sector(s):
Forests
Categorie(s):
Scientific Article
Theme(s):
Forest Ecology, Inventory
Departmental author(s):
Author(s)
COUILLARD, Pierre-Luc, Serge PAYETTE, Martin LAVOIE and Mathieu FRÉGEAU
Year of publication :
2021
Keywords :
Resilience, Succession, Fire disturbance, Soil charcoal, Lichen woodland, Boreal forest
