SUCCESSION IN THE HUDSON-BAY LOWLAND, NORTHERN ONTARIO, CANADA

The hypothesis that successional pathways converge onto climax bog com munities is tested in the Hudson Bay lowland of Canada using both chro nosequence data and paleoecological reconstruction. A chronosequence o f different age surfaces has resulted from land emergence out of Hudso n Bay due to isostatic rebound during the late Holocene. The chronoseq uence results, based on remote-sensing data and ground surveys, indica te 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 c ommunities which dominate the older (>4000 yr) surfaces. The vegetatio n changes based on paleoecological reconstruction of a peat profile fr om a Sphagnum bog on a 4100 yr BP-surface in the Hudson Bay lowland sh ows strong similarities to the present day vegetation along the region al chronosequence. The development of the Hudson Bay lowland appears t o be primarily under the control of succession coupled with surface hy drology and, perhaps, climate. This result suggests that the pollen re cord may be more a reflection of a coupling of successional and enviro nmental 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 interp retation of paleoecological data.