The paleoecology of a peatland in the Laurentian Highlands (Quebec): Identifying the role of climate on peat accumulation.

The paleoecology of a peatland in the Laurentian Highlands (Quebec): Identi fying the role of climate on peat accumulation. Microscopic (pollen, rhizop ods, charcoal) and plant macrofossil analyses were carried out on three cor es for a peatland in the Laurentian Highlands (Quebec). The objectives were to reconstruct the developmental history and the past hydrological conditi ons of the peatland, and to inter paleoclimatic conditions, notably for the moisture balance. The peatland was characterized by contrasting hydrologic al conditions between the sampling points during its history. Except for th e late Holocene, no clear regional hydrological control was revealed by pal eobotanical analyses. Feat inception began in a smalt pond around 10 300 ca l. years BP in a shrub tundra, more than 2000 years after the ice retreat. The peatland dynamics during the early Holocene likely reflects increased b iological productivity caused by the continuous warming of the climate afte r initial harsh conditions. From 8000 to 3000 BP, a general decrease of the net peat accumulation rate for all cores is in part attributed to the acti vity of nitrogen fixing cyanobacteria which promotes an important decomposi tion of the organic matter. An important vertical peat increment occurred d uring the last 3000 years probably in response to wetter and colder climati c conditions.