Canadian Forest Service Publications
Regional paleofire regimes affected by non-uniform climate, vegetation and human drivers. 2015. Blarquez, O.; Ali, A.A.; Girardin, M.P.; Grondin, P.; Fréchette, B.; Bergeron, Y.; Hély, C. Sci. Rep. 5:13356.
Issued by: Laurentian Forestry Centre
Catalog ID: 36210
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Climate, vegetation and humans act on biomass burning at different spatial and temporal scales. In this study, we used a dense network of sedimentary charcoal records from eastern Canada to reconstruct regional biomass burning history over the last 7000 years at the scale of four potential vegetation types: open coniferous forest/tundra, boreal coniferous forest, boreal mixedwood forest and temperate forest. The biomass burning trajectories were compared with regional climate trends reconstructed from general circulation models, tree biomass reconstructed from pollen series, and human population densities. We found that non-uniform climate, vegetation and human drivers acted on regional biomass burning history. In the open coniferous forest/tundra and dense coniferous forest, the regional biomass burning was primarily shaped by gradual establishment of less climate-conducive burning conditions over 5000 years. In the mixed boreal forest an increasing relative proportion of flammable conifers in landscapes since 2000 BP contributed to maintaining biomass burning constant despite climatic conditions less favourable to fires. In the temperate forest, biomass burning was uncoupled with climatic conditions and the main driver was seemingly vegetation until European colonization, i.e. 300 BP. Tree biomass and thus fuel accumulation modulated fire activity, an indication that biomass burning is fuel-dependent and notably upon long-term co-dominance shifts between conifers and broadleaf trees.
Plain Language Summary
In this study, the researchers determined the impact of three factors that influence forest fire in eastern Canada, namely climate, vegetation, and human activity.
• In the tundra and in dense coniferous forests, fire has decreased because of the less and less favourable climatic conditions over the last 5,000 years.
• In the mixed forest (composed of hardwood and softwood), even though climatic conditions are less favourable to fire, there has been an increase in fires caused by the more predominant presence of conifers, which are more likely to burn.
• In the temperate deciduous forest, climatic conditions do not have any impact on fire. The main influencing factor would be the variations in the vegetation type that occurred until the European colonization approximately 300 years ago. From that point on, there was a dramatic increase in forest fires that is presumably related to humans’ use of the land.
These results are based on the analysis of coal buried in lakes.