Abstract

Maplehurst Lake, situated in a former interlobate zone that was deglaciated relatively early compared to adjacent areas of southern Ontario, provides one of the more complete pollen records for the region.Five radiocarbon dates allow determination of sedimentation rates and hence pollen influx rates. Both relative percentage and pollen influx values outline a vegetational history that began prior to 12 000 years BP with a herb pollen zone representative of tundra conditions. This was followed by invasion of spruce that culminated in a spruce woodland environment which peaked about 11 200 years BP and then declined, to be replaced, beginning about 9500 years BP, by a closed mixed conifer–hardwood forest dominated by pine species. Hemlock replaced pine as the most abundant coniferous species about 7200 years BP. Hardwoods completely dominated the forest after 6400 years BP and beech, maple, oak, elm, and ash were prominent, associated with a wide variety of other deciduous genera. The deciduous hardwood forest prevailed without major change until recent times when the forests were largely removed for agriculture. Ragweed, grasses, and other weed taxa indicative of agricultural activity characterize the pollen spectra of this most recent interval. This sequence of events parallels those found at sites throughout the Great Lakes region, New England, and Maritime Canada and adds to the knowledge of migration rates, succession, chronology, and climate of northeastern North America.

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