Surface pollen spectra from southern Vancouver Island, British Columbia, Canada

Abstract

Analyses of surface samples of 84 sites from southern Vancouver Island were used to characterize pollen and spore spectra of modern vegetation types. Xeric Quercus garryana Dougl. and grassland associations can be identified by Quercus pollen and abundant nonarboreal pollen, respectively. Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) forests are distinguished by high proportions of Pseudotsuga and low Pseudotsuga to Tsuga heterophylla (Raf.) Sarg. ratios. Coastal Western Hemlock zone forests have abundant Tsuga heterophylla pollen. Dry Coastal Western Hemlock subzones have diagnostically abundant Pseudotsuga and Tsuga heterophylla pollen, and intermediate Pseudotsuga to Tsuga heterophylla ratios. Moist Coastal Western Hemlock variants are characterised by little or no Pseudotsuga pollen and high Pseudotsuga to Tsuga heterophylla ratios. The Mountain Hemlock zone exhibits abundant Tsuga mertensiana (Bong.) Carr. pollen percentages and notable nonarboreal pollen and spore values. Relatively high Alnus values are not necessarily indicators of dominant alder stands, especially when obtained from open communities. Pseudotsuga to Tsuga heterophylla ratios are useful as a proxy measure of mean annual precipitation between 700 and 2700 mm.Key words: pollen and spores, surface spectra, Vancouver Island, biogeoclimatic zone, vegetation, precipitation.