IngentaConnect 1200 years of fire impact on biogeochemistry as inferred from hig...

Abstract:

The consequences of fire on water chemistry are important considering that major changes in the frequency and intensity of forest fires are anticipated as a result of global warming. Due to the important differences in succesionnal vegetative trends after fire between mixed-wood and coniferous-dominated forests in Quebec (Canada), we undertook a long-term paleoecological study of the impact of fires on the biogeochemistry of Lac à la Pessière, a small lake located in a conifer-dominated boreal forest ecoregion (Picea mariana-moss domain). The paleolimnological study was carried out using diatom assemblages (class:Bacillariophyceae) to reconstruct changes in environmental variables of limnological interest [pH, total phosphorus (TP), total nitrogen (TN), dissolved organic carbon (DOC) and, epilimnetic carbon dioxide (CO₂)] potentially associated with fire over the last 1200 calendar years. Diatom composition and related reconstructed limnological variables were compared before and after fire events. No significant changes were systematically observed in lake chemistry associated with fire events. However, diatom-inferred epilimnetic CO₂showed a clear decreasing trend over the last sim 400 cal. yrs BP. The results suggest that fire-induced changes in lake chemistry are limited in catchments dominated by black spruce (Picea mariana). We hypothesize that this fact result of excess moisture associated to the thick humus layer, which likely limits the mobilization of nutrients and major ions even during a fire event.

Keywords: CO₂; Coniferous forest; Diatoms; Fire; Paleolimnology; Quebec (Canada)

Language: English

Document Type: Research article

Affiliations: 1: Université du Québec à Montréal-UQAM, P.O. Box 8888, station Centre-Ville, Montréal (QC), H3C 3P8, Canada 2: Université du Québec à Montréal-UQAM, P.O. Box 8888, station Centre-Ville, Montréal (QC), H3C 3P8, Canada (e-mail: prairie.yves@uqam.ca) 3: Laboratoire de Paléobotanique et Paléoenvironnement, École Pratique des Hautes Études, et Centre de Bio-Archéologie et d prime Ecologie (CNRS UMR 5059), Institut de Botanique, Université de Montpellier 2, 163 rue Broussonet, Montpellier, F-34 090, FranceEcologie (CNRS UMR 5059), Institut de Botanique, Université de Montpellier 2, 163 rue Broussonet, Montpellier, F-34 090, France">

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1200 years of fire impact on biogeochemistry as inferred from high resolution diatom analysis in a kettle lake from the Picea mariana-moss domain (Quebec, Canada)