Late Holocene deforestation and peat formation in Charlevoix highlands: Onset of the subalpine and alpine belts

Late Holocene deforestation and peat formation in the Charlevoix highlands: Onset of the subalpine and alpine belts. Fire history based on C-14 ages of soil charcoal in the Charlevoix highlands was reconstructed for the late Holocene. The subalpine and alpine belts developed after 3000 BP. Fire occurred sporadically and contributed to forest fragmentation and reduction in tree regeneration likely in relation to climate deterioration. The subalpine and alpine vegetation is thus a response to ecological changes induced by recurrent fires, rather than a direct response to a climatic gradient associated with topography. Differences found in highland vegetation (forested or open) at similar altitudes resulted from differential fire influence among sites. Feat formation on slopes started after 1250 BP and intensified after 600 BP. The delay between fire occurrence and peat formation indicates that peat actually started to accumulate when a general trend toward climate cooling occurred after the Little Climatic Optimum period, a thousand years ago. In spite of this delay, it is likely that shallow ombrotrophic peat formed over steep slopes in reponse to postfire forest opening on the highlands.