North American Pollen Atlas, Picea
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Atlas of Pollen-Vegetation-Climate Relationships
for the United States and Canada
American Association of Stratigraphic Palynologists
Contribution Series No. 43
December 2006
John W. Williams, Bryan Shuman, Patrick J. Bartlein, Johanne Whitmore, Konrad Gajewski,
Michael Sawada, Thomas Minckley, Sarah Shafer, Andre E. Viau, Thompson Webb III,
Patricia Anderson, Linda Brubaker, Cathy Whitlock, and Owen K. Davis
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ABSTRACT:
This atlas displays the distribution of modern pollen abundances in North America,
both geographically and relative to various climatic, bioclimatic, and vegetational variables.
It is intended to aid analyses of modern pollen-environment relationships as well as
the climatic and ecological interpretations of fossil pollen diagrams.
The atlas is based upon a recent compilation of pollen samples from surface sediments
and polsters that includes 4549 samples, 134 pollen types, and independent climatic
and vegetational attributes for all locations. Atlas pages are presented for 106
pollen types, representing all of the major and many minor pollen types found in
North America. Ten pollen types are split into eastern and western regional groups,
using the corresponding species range maps as a guide. The pages are designed to show
in detail the distribution of pollen abundances with respect to key climatic and
vegetational variables; each set includes a map of modern pollen abundances plus
a series of visualizations of pollen-climate and pollen-vegetation relationships.
The relationship between pollen abundances and indices of fractional broadleaf and
needleleaf areal cover is consistent with the ecological associations of the plant taxon,
and biomes can be distinguished by the characteristic frequencies of various
pollen abundances, although abundances for individual taxa may vary widely
within a given biome. Pollen-abundance distributions with respect to environmental
gradients are usually characterized by an upper-limit unimodal distribution,
except where the representation of multiple species by a single pollen
morphological type results in multimodal distributions. Consequently,
high pollen abundances are usually more climatically informative than
low pollen abundances. Although individual pollen types are rarely diagnostic
of a particular climatic regime or vegetation type, assemblage-level information
about the abundances of many pollen types provides a strong basis for
paleoenvironmental inference.
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