Regional paleofire regimes affected by non-uniform climate, vegetation and human drivers.
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.
Département de Géographie, Université de Montréal, Montréal, Québec, Canada.
Olivier
O
Blarquez
Institut des Sciences de l'Evolution de Montpellier, CNRS-IRD-Université Montpellier 2-EPHE, Montpellier, France.
Adam A
AA
Ali
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Quebec, Québec, Canada.
Martin P
MP
Girardin
Ministère des Forêts, de la Faune et des Parcs, Direction de la recherche forestière, Québec, Canada.
Pierre
P
Grondin
Centre de recherche en géochimie et géodynamique, Université du Québec à Montréal, Montréal, Québec, Canada.
Bianca
B
Fréchette
Centre d'étude de la Forêt, Université du Québec à Montréal, Montréal, Québec, Québec, Canada.|Natural Sciences and Engineering Research Council of Canada Industrial Chair in Sustainable Forest Management, Forest Research Institute, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec, Canada.
Yves
Y
Bergeron
Institut des Sciences de l'Evolution de Montpellier, CNRS-IRD-Université Montpellier 2-EPHE, Montpellier, France.
Christelle
C
Hély
D018533:Biomass; D002170:Canada; D002606:Charcoal; D057231:Climate Change; D005390:Fires; D005843:Geography; D006802:Human Activities; D006801:Humans; D016018:Least-Squares Analysis; D010163:Paleontology; D010944:Plants; D011058:Pollen; D011891:Rain; D012621:Seasons; D018709:Statistics, Nonparametric
D002606:Charcoal