Events that the Grande plée Bleue had to face in the past – Fires

Upper picture by Daniel THOMPSON Ph.D. – Forest Fire Research Scientist – Natural Ressources Canada – Wood Buffalo National Park of Canada in North Alberta.

FIRES

Photo par Daniel THOMPSON - Forest Fire Research Scientist

Picture by Daniel THOMPSON Ph.D. – Forest Fire Research Scientist – Natural Ressources Canada – Showing peat bogs with burnt sphagnum among green fens with sedges and hills covered with spruces – Wood Buffalo National Park, North Alberta

Two types of conditions causing fires

Fires are one among other perturbations affecting bogs. The fire regime went through important changes in the last decades. (Watch the video produced by the Northern Peat Fire Working Group of Guelph and Mc Master universities.)

Fires can be divided into 2 groups: first, fires lighted naturally under specific conditions, second, fires of anthropogenic origins, meaning caused by human activities. If the Grande plée Bleue has gone through fires all along its history till the present period, such events of the second category clearly appeared recently, in connection with the development of the territory. Fires during the pre-contact period (before European colonization) were less frequent then more difficult to be detected into peat samplings, while fires occurred during the contact period and subsequently have happened more often and so are more easily seen when samples are analyzed.

From a bog destruction threat to…

We may suppose, as proposed by Martin Lavoie, that the peat bog has known fires not too severe and rather located in the forest margin nearby. Except for samplings showing scattered charcoals, no layers of abundant ones have been found which could have revealed, by their surface and thickness, fires periods during the laurentian prehistory.

grapim-tourbiere-feu-pompiers-ssirdl-sq-004-620x348

Picture by François DROUIN (infodimanche.com) take on the 26th August 2014 – Fire in the commercial peatbog H. Théberge in Saint.Modeste, Qc, Canada

But some evidence of fires that happened during the 19th and the 20th centuries have been documented; they were related to an increase in human activities (draining, fires) creating conditions added to the climatic ones (drought) that were propitious to such events. An event recorded in the 19th century has been reconstituted and described in the book Écologie des tourbières du Québec-Labrador. Probably caused by anthropogenic activities, it left a significant layer of carbonized material.

… to the stimulation of peat growth

Yet, the destruction by fire of a forest besides or inside a peatland gives access to the light; such a new condition will help the growth of mosses like the sphagnum. Paradoxically, when a fire destroys trees which are keeping in the shade some areas of the forest, it will help the production of a new biomass. Similarly, the regeneration of a coniferous forest (during a drought) will facilitate more the ignition of a fire than a surface covered with mosses would do.

Photo par Daniel THOMPSON - Forest Fire Research Scientist

Picture by Daniel THOMPSON Ph.D. – Forest Fire Research Scientist – Natural Ressources Canada – Burn peat bog with lightly colored sphagnum mounds and burnt surface that was before covered with feathermoss. Wood Buffalo National Park, North Alberta

The example of a fire event located in a vegetal layer corresponding to the 19th century is well described in the book Écologie des tourbières du Québec-Labrador, in page 68, and illustrated on figure 2.19; types of woody vegetation and other plants growing before the fire are shown, also the ones that could grow after because of new conditions, different from the ones prevailing before in the bog.

Photo par Daniel THOMPSON - Forest Fire Research Scientist

Picture by Daniel THOMPSON Ph.D. – Forest Fire Research Scientist – Natural Ressources Canada – Where an area of burnt feathermoss meets a wetter sector of sphagnum with bushes untouched by fire – Wood Buffalo National Park, North Alberta

RED

TEXT: FRANÇOISE DE MONTIGNY-PELLETIER

REVISION: SERGE PAYETTE, professor Dept. Biology, curator of the Herbier (herbarium) Louis-Marie, University Laval, Qc, Canada

Special contributions

François DROUIN – http://www.infodimanche.com/blogues/fdrouin

Daniel THOPMSON – Ph.D. – Chercheur scientifique, chimie de l’environnement – Ressources Naturelles Canada

Courriel: danthomp@nrcan.gc.ca

References mentionned

Peatland carbon cycling in a fire prone landscape, a visual montage published by the Northern Peat Fire Working Group – Science, Management, and Policy, under the direction of Brian W. Benscoter and Merritt R. Turetsky from Guelph University and Dan Thompson and Mike Waddington from Mc Master University.

www.uoguelph.ca/peatfire

Écologie des tourbières du Québec-Labrador, under the direction of Serge Payette and Line Rochefort, Presses de l’Université Laval, 2nd ed. 2005.

Infodimanchehttp://www.infodimanche.com/actualites/faits-divers/138932/violent-incendie-dans-une-tourbiere-de-saint-modeste

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