[Influence of vegetation on the accumulation of peat in southern Quebec]

Mirabel bog (southern Quebec) was studied with the aim of specifying the past influence of local vegetation on peat accumulation. This influence was essentially translated by the reduction of minerotrophic inputs and peat accumulation induced by the highering of the peatland surface. Extremely rich initial conditions allow to explain the very high accumulations of the beginning of the Holocene, observed in various plant communities, among which Larix forests with ferns and Carex without modern analogues. Moreover, the structure (forest density) and the composition (dominance of Cyperaceae or Ericaceae) of these communities have locally controlled the dynamic of peat accumulation. These results point out the interest of the confrontation between palynological and macrofossil data and the spatialisation of palaeoecological studies.