Succession in the Hudson Bay Lowland, Northern Ontario, Canada

The hypothesis that successional pathways converge onto climax bog communities is tested in the Hudson Bay lowland of Canada using both chronosequence data and paleoecological reconstruction. A chronosequence of different age surfaces has resulted from land emergence out of Hudson Bay due to isostatic rebound during the late Holocene. The chronosequence results, based on remote-sensing data and ground surveys, indicate that successional pathways beginning on moist sites (mesoseres) and on dry sites (xeroseres) support quite different vegetation types on the youngest age surfaces, but ultimately converge onto Sphagnum bog communities which dominate the older (>4000 yr) surfaces. The vegetation changes based on paleoecological reconstruction of a peat profile from a Sphagnum bog on a 4100 yr BP surface in the Hudson Bay lowland shows strong similarities to the present day vegetation along the regional chronosequence.The development of the Hudson Bay lowland appears to be primarily under the control of succession coupled with surface hydrology and, perhaps, climate. This result suggests that the pollen record may be more a reflection of a coupling of successional and environmental processes rather than externally forced climate changes. This work points to the critical need for understanding the contribution of succession (coupled with climate, soils, and hydrology) in the interpretation of paleoecological data.