Plant and animal macrofossils (vascular plant, moss, fungus, bryozoan, cladoceran and coleoptera remains) were analyzed to reconstitute the development of a palsa peat located at the northwestern forest limit of subarctic Quebec (57deg;45prime;N., 76deg;15prime;W.) and to detect any black spruce (Picea mariana) remains older than the presumed time of arrival of the species in the study area (4560ensp;BP), after the deglaciation. The oldest peat deposits were formed in a fen with many shallow pools between 5850 and 4500ensp;BP. The flora was mainly composed of aquatic taxa (Ranunculus trichophyllus,Potamogetonspp.,Hippuris vulgaris). Around 4500ensp;BP, there was a shift from a very wet fen to a sedge fen withPotentilla palustrisandMenyanthes trifoliata. From 3700 to 1950ensp;BP, most plant remains were wood fragments of dwarf birch (Betula glandulosa). The formation of the palsa occurred after 1950ensp;BP. The development of this peatland is similar to that of other palsa peatlands of subarctic Quebec, except that it is characterized by the presence of a thick peat layer composed ofBetula glandulosafragments at the top of the palsa. There were no black spruce remains older than 4560ensp;BP. Three peaks of coleoptera abundance were identified at 4400, 3800, and 2700ensp;BP, respectively. Most of the coleoptera taxa being hygrophilous, it was not possible to infer structural changes in the peatland from their fragments.Key words: palsa peatland, macrofossil analysis, subarctic Quebec,Betula glandulosa,Picea mariana, beetles.
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