Fires of the Last Millennium Led to Landscapes Dominated by Early Successional Species in Québec’s Clay Belt Boreal Forest, Canada

Abstract

This study presents the long-term (over the last 8000 years) natural variability of a portion of the Picea mariana-moss bioclimatic domain belonging to Québec's Clay Belt. The landscapes are dominated by mesic-subhydric clay and early successional forests composed of Populus tremuloides, Pinus banksiana and Picea mariana. The natural variability (fires and vegetation) of one of these landscapes was reconstructed by means of pollen and macroscopic charcoal analysis of sedimentary archives from two peatlands in order to assess when and how such landscapes were formed. Following an initial afforestation period dominated by Picea (8000-6800 cal. Years BP), small and low-severity fires favored the development and maintenance of landscapes dominated by Picea and Abies balsamea during a long period (6800-1000 BP). Over the last 1000 years, fires have become more severe and covered a larger area. These fires initiated a recurrence dynamic of early successional stands maintained until today. A decline of Abies balsamea has occurred over the last centuries, while the pollen representation of Pinus banksiana has recently reached its highest abundance. We hypothesize that the fire regime of the last millennium could characterize Québec's Clay Belt belonging to the western Picea mariana-moss and Abies balsamea-Betula papyrifera domains.

Long-term and recent ecohydrological dynamics of patterned peatlands in north-central Quebec (Canada)

“…y BP) in its deepest section. The amount of charcoal fragments found at its base coincides with high fire occurrence in the surrounding regional forests (Asselin et al, 2016;El-Guellab et al, 2015) and confirm the warm and dry conditions at that period. Likely influenced by the local basin topography, peat initiated at the Misask site under minerotrophic conditions but shifted rapidly to ombrotrophy due to the warmer summer conditions (Fréchette et al, 2018) that influenced the growing season length and promoted rapid peat accumulation.…”

Spatiotemporal evolution of paludification associated with autogenic and allogenic factors in the black spruce–moss boreal forest of Québec, Canada

“…2) (Lecomte et al, 2005, 2006; Simard et al, 2007, 2009; Terrier et al, 2014). Profiles at Villebois have multiple charred layers until the top of the peat basal section (Table 3), suggesting that many fires occurred since peat inception, as observed in other peat deposits of the same region by Ali et al (2008) and Asselin et al (2016). Our data also show that with a residual organic layer ( ∼ 5 to 30 cm) fire triggered peat accumulation by favoring Sphagnum spp.…”

“…forest with Alnus crispa (Aiton) Pursh and Alnus rugosa (DuRoi) Spreng. are also well represented (Asselin et al, 2016). Fire interval was 135 yr between AD 1850 and 1920 and since has increased to ca.…”

A Holocene landscape dynamic multiproxy reconstruction: How do interactions between fire and insect outbreaks shape an ecosystem over long time scales?

“…Thus, existing boreal landscapes represent a combined inheritance of natural disturbance history and climate conditions occurring over the Holocene [ 19 , 20 ]. While the interactions between fire activity and climate at different time and space scales are relatively well understood for the boreal forest [ 21 – 23 ], the interactions between insect outbreaks, fire and climate remain uncertain.…”