A comparison of numerical and qualitative methods of separating pollen of black and white spruce

Abstract

Separations of pollen of black spruce from that of white spruce were made for sediment samples from two lakes in southeastern Labrador, Canada, by linear discriminant analysis of size measurements. Finding spruce grains in optimal condition and exact equatorial view was difficult and size distortion caused by cover-slip pressure occurred in some of the fossil samples. The latter problem was eliminated by adding fine sand to slide preparations. An alternative method of differentiating black and white spruce pollen was established using four morphological characters: saccus shape, saccus attachment to the corpus, density and arrangement of the internal reticulate structure in the saccus, and the area ratio of saccus to corpus. Qualitative separations of spruce pollen by these morphological characters were made for the same samples analyzed by numerical methods and for sediments from a third Labrador lake. The qualitative and numerical methods produced similar results within each level of a single core, as well as stratigraphically among the three sites.