The Regeneration of a Highly Disturbed Ecosystem: A Mined Peatland in Southern Québec

Abstract

We studied the natural regeneration of an ombro- trophic peatland (Cacouna bog) located in southern Quebec that was disturbed by peat mining and other anthropogenic activities over a 200-year pe- riod. Using an extensive collection of historical doc- uments, as well as dendrochronological data, we reconstructed the history of the peatland. We also sampled vegetation and environmental variables, and integrated the data in a geographic information system. More than 60% of the total area of the bog was mined between 1942 and 1975, and 98 km of ditches were dug to drain the site. The peatland lost 34% of its initial peat volume between 1946 and 1998. Although the bog was severely disturbed, the spontaneous revegetation of the site by vascular plants was successful (90%-100% cover). How- ever, only 10% of the total mined area has been recolonized by Sphagnum species, mainly because drainage ditches are still operational and contribute to drying out the bog. Water table level, peat de- posit thickness, and pH are abiotic factors strongly influencing the vegetation composition in the bog. Spatial and historical factors are also important components in this study since they explain, either alone or in interaction with abiotic factors, 44% of the variation of the species data. The intensity of mining activities and the pattern of abandonment of mined sectors strongly influenced abiotic factors, which in turn affected the revegetation process. Even if the Sphagnum cover of the bog is low, the rapid "recovery" of the vegetation cover in the peatland indicates that after the reestablishment of an appro- priate hydrological regime, a highly disturbed peat- land has a considerable potential for regeneration.