A 12,000-year perspective of fire and vegetation history in Northern Cape Breton, Nova Scotia, Canada

Fire has influenced age stands and forest composition in boreal ecosystems over millennia. The Cape Breton Highlands National Park in northern Nova Scotia encompasses a unique mixture of Boreal, Taiga and Acadian ecosystems. A sediment record from Paquette Lake within the park spans the initial development of the lake to the early 20 th century and is the first well-dated Holocene record of vegetation and fire history from this region. Vegetation history based on analysis of pollen grains, and fire history based on accumulation of macrocharcoal particles (>125 µm) and identification of charcoal morphotypes, provides information on millennial-scale changes in forest composition and on the frequency and size of local to regional fires. Forest composition follows the inferred fire regime zones over the Holocene, supporting the strong interconnections between climate, vegetation, and fire. The early Holocene fire regime (ca. 11,000–7000 cal yr BP) was characterized by large and frequent fires under warming conditions and high fuel availability when Picea and Pinus were most abundant. The mid-Holocene (ca. 7000–5000 cal yr BP) was characterized by a lower frequency of smaller fires than in the early Holocene and some large local fires when Quercus and Tsuga reached their highest abundances. The lowest fire frequency over the Holocene occurred between ~5000 and 2000 cal yr BP when Fagus increased, and Pinus and Quercus declined. The early 20th century composition of forest and fire regime in Paquette Lake was established ca. 2000 cal yr BP. This period had a higher fire frequency and larger local fires than between ~5000 and 2000 cal yr BP but a lower magnitude in comparison to the early Holocene. Records of ecosystem change over millennia provide critical baselines for modeling future scenarios of vegetation and climate change.