DYNAMIC ASPECTS FOR THE DEVELOPMENT OF TH E FARNHAM BOG, QUEBEC

Pollen and plant macrofossil sequence of a core at the margin of the F arnham bog provide a local developmental record that can be subdivided into five main stages for this part of the peatland. Organic sediment ation began around 8500 year BP in a shallow pound at the centre of th e depression following the retreat of the Champlain Sea. Subsequent ce ntrifugal paludification caused the onset of peat accumulation at the sampling point about 8100 year BP. An initial forested fen dominated b y larch (1) has been rapidly followed by a treed fen (2) until 6900 ye ar BP. This stage was succeeded by a fen characterized by sparse trees and the development of open-water pools (3) until 5800 year BP. At th at time, the vegetation changed to oligotrophic bog (4) until the pres ent. Recently, the influence of external factors such as fire and anth ropogenic activity resulted (5) in the establishment of tree species t ypical of disturbed environments. Paludification and local development al trends are closely controlled primarily by continuous peat accumula tion, local hydrology, climate and fire. The formation of pools around 6900 year BP and the synchronous spread of Tsuga canadensis populatio ns in the surrounding forests suggest an increasing trend towards mois ter conditions with higher precipitation and/or reduced summer evapotr anspiration.