Spatial Variation of Modern Pollen in Oregon and Southern Washington, USA.
Thomas Minckley and Cathy Whitlock (2000).
Review of Palaeobotany and Palynology, 112: 97-123.

Abstract:-and-nbsp; Surface sediments from 95 lakes provide information on the spatial variation of modern pollen spectra in Oregon and southern Washington.-and-nbsp; Percentages for 13 pollen types were compared within and between vegetation zones to characterize regional patterns of pollen spectra.-and-nbsp; The percentage data were also compared with climate variables to determine relationships between pollen percentages and regional climate gradients.-and-nbsp; The composition of modern pollen spectra corresponds well with the distribution of the pollen producers.-and-nbsp; Most pollen assemblages were generally dominated by Pinus, but those west of the Cascade Range were dominated by Alnus.-and-nbsp; Low percentages of Pseudotsuga/Larix, Tsuga mertensiana, Abies, and Picea pollen coincided with local occurrence of the trees.-and-nbsp; The distributions of the pollen data were arranged along gradients of temperature and effective moisture.-and-nbsp; West of the Cascade Range, Alnus, Tsuga heterophylla, Pseudotsuga/Larix, and Cupressaceae pollen were abundant and correlate well with moderate temperature and high effective moisture.-and-nbsp; In the shrub-steppe and woodlands east of the Cascade Range, where effective moisture is low, Artemisia, Cupressaceae, and Pinus pollen were dominant.-and-nbsp; At high elevations, Pinus, T. mertensiana, Abies, and Picea were common pollen types in areas with short growing seasons and high effective moisture.-and-nbsp; Pollen percentages collected from lake surface sediments, moss polsters, and soils were compared within a number of vegetation types to assess their similarity.-and-nbsp; The three types of samples yielded similar results for forested areas, but lake sediment samples from upper- and lower-treeline sites captured a more regional picture of the vegetation.