Late Quaternary vegetation dynamics and hydroseral development in a shrub swamp in southern Ontario, Canada

Using a multiple-core paleoecological approach, we studied the development of a small kettle-hole wetland (informal name Spiraea wetland) in southern Ontario. The sedimentary record begins at around 11 700 BP, when Picea and herbs characteristic of a disturbed environment were the principal componen ts of the upland vegetation. These were replaced by ca. 9500 BP by Pinus do minance, which persisted until at least 6300 BP. Mixed deciduous forest com munities then developed and were only disturbed by Euro-Canadian settlement in the last few hundred years. Initially, the basin contained an open lake , which was progressively colonized by a range of aquatic plants, becoming a shallow open water wetland community by 9500 BP. A marsh community spread rapidly from the edge of the basin, and a mat of aquatic mosses filled the central area of open water before marsh vegetation became established ther e. Between 6300 and 1500 BP, there is a marked decrease in sedimentation ra tes, and the paleoecological data imply that the vegetation communities at the coring points varied between marsh, shrub swamp, and conditions where n o net sediment accumulation occurred. Sedimentation rates increased in the upper part of the core, as the modern tall-shrub swamp developed.