The Late-Quaternary History of the Boreal Forest of Central Canada, Based on Standard Pollen Stratigraphy and Principal Components Analysis

Abstract

(1) Pollen stratigraphic data from four 14C-dated sections of Holocene sediment at sites in the boreal forest region of central Canada were analysed by standard relative frequency pollen diagrams and by principal components analysis (PCA). Ordination of the 173 pollen samples on the second and third components of the PCA facilitated comparison between zones and sites. (2) Modern pollen samples from 1 10 sites throughout the modern vegetation zones of the Western Interior of Canada were ordinated onto the same principal component axes as the sub-fossil data, to provide a further comparative, graphical description of the data. (3) The two northern sites revealed a stratigraphic sequence from a treeless Artemisiawillow-sedge zone, through a Picea-Juniperus-Artemisia zone, to zones dominated by mixtures of pine, spruce, birch and alder. (4) At the two southern sites, by contrast, an early treeless zone was lacking; there were comparable early spruce and final mixed-forest zones, but the intermediate zones were dominated by herb and non-coniferous tree types.