Fire History of Appalachian Forests of the Lower St-Lawrence Region (Southern Quebec)

Abstract

Sugar maple (Acer saccharum) forests are among the main forest types of eastern North America. Sugar maple stands growing on Appalachian soils of the Lower St-Lawrence region are located at the northeastern limit of the northern hardwood forest zone. Given the biogeographical position of these forests at the edge of the boreal biome, we aimed to reconstruct the fire history and document the occurrence of temperate and boreal trees in sugar maple sites during the Holocene based on soil macrocharcoal analysis. Despite having experienced a different number of fire events, the fire history of the maple sites was broadly similar, with two main periods of fire activity, i.e., early-to mid-Holocene and late-Holocene. A long fire-free interval of at least 3500 years separated the two periods from the mid-Holocene to 2000 years ago. The maple sites differ with respect to fire frequency and synchronicity of the last millennia. According to the botanical composition of charcoal, forest vegetation remained relatively homogenous during the Holocene, except recently. Conifer and broadleaf species coexisted in mixed forests during the Holocene, in phase with fire events promoting the regeneration of boreal and temperate tree assemblages including balsam fir (Abies balsamea) and sugar maple.

Sugar maple (Acer saccharum) at its northeastern range limit: a fire-resilient tree species

“…The same paleofire tendencies characterize the Bas-StLaurent region, situated west of the Gaspé Peninsula, and is highlighted by peaks in microcharcoal abundance in several lakes at the beginning of the Holocene (Richard et al 1992). The same fire frequency is again observable in macrocharcoal datings from the beginning of the Holocene in the region situated in the countryside around Rimouski, in the Saguenay, as well as in the greater Quebec City region (Talon et al 2005;Pilon and Payette 2015;Payette et al 2016;2017). The Mont-St-Pierre sugar maple site, also located in the northern part of the Gaspé Peninsula, shows a fire history resembling that of Forillon during the last millennium, where 6-8 fires occurred at an interval of 120-150 years (Pilon and Payette 2015).…”

Hedging at the rear edge: Intraspecific trait variability drives the trajectory of marginal populations in a widespread boreal tree species

“…Theory predicts that natural selection might foster evolutive strategies such as moderate level of serotiny if (1) the interval between fires approaches the species' lifespan, (2) fire return intervals are unpredictable, (3) interfire seedling recruitment is possible and (4) the fitness cost of serotiny creates a trade‐off between supporting structures and the number of seeds (Enright et al, 1998; Lamont et al, 2020; Lamont & Enright, 2000; Muir & Lotan, 1985). At the rear edge of jack pine distribution, natural wildfire return intervals are highly unpredictable but historically exceeded the mean lifespan of the species (Elzein et al, 2020; Payette et al, 2017) and rock outcrops with reduced competition support interfire jack pine seedlings establishment (Conkey et al, 1995). This meets conditions 1, 2 and 3.…”

The velocity of postglacial migration of fire-adapted boreal tree species in eastern North America

“…3 ; SI Appendix , Table S4 ; refs. 17 , 18 , 64 – 71 ). Fire activity was at its climax during the Pleistocene–Holocene transition and declined progressively during the mid-Holocene.…”