Regional variations in peatland ecosystems of west-central Canada through time

Zoltai, S.C. 1995. Regional variations in peatland ecosystems of west-central Canada through time. Gunneria 70: 35-42. Peatland ecosystems respond to major changes in their environment induced by prolonged changes in climate. In the western boreal region of Canada, permafrost occurs only in Sphagnum-dominated peatlands. In the north, the palsas and peat plateaus are associated with well-defined, circular collapse scars. Further south, the collapse scars are replaced by indistinct, roughly circular internal depressions in bogs and fens with or without remnant permafrost bodies. In the most southern areas, no internal depressions occur in the fens and bogs. Peat macrofossil analyses show that in many collapse scars several permafrost development and subsidence cycles have taken place, beginning about 3700 yrs B.P. In the internal depressions, a layer of forest peat occurs below the fen or bog surface, indicating the presence and ultimate collapse of a permafrost peat landform. This collapse began about 150 years ago and is proceeding at the present. In the southern peat bogs, the peat stratigraphy shows that bog formation was initiated long after the original fens were established, about 2000 to 3000 years ago. Basal dates of fen peat along the southern margin of the boreal zone indicate that fen development began only about 6000 years ago, covering marsh and shallow pond deposits.