North American Pollen Atlas
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               World Data Center for Paleoclimatology, Boulder
                                  and
                     NOAA Paleoclimatology Program
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NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!!


NAME OF DATA SET: North American Pollen Atlas
LAST UPDATE: 12/2006 (Original receipt by WDC Paleo)
CONTRIBUTOR: Jack Williams, University of Wisconsin - Madison
IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2007-001

SUGGESTED DATA CITATION: Williams, J.W., et al.  2006. 
North American Pollen Atlas.
IGBP PAGES/World Data Center for Paleoclimatology 
Data Contribution Series # 2007-001.
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.


ORIGINAL REFERENCE: 
Williams, J.W., B. Shuman, P.J. Bartlein, J. Whitmore, K. Gajewski, 
M. Sawada, T. Minckley, S. Shafer, A.E. Viau, T. Webb, III, P.M. Anderson, 
L.B. Brubaker, C. Whitlock, and O.K. Davis. 2006. 
An Atlas of Pollen-Vegetation-Climate Relationships for the United 
States and Canada. 
American Association of Stratigraphic Palynologists Foundation, 
Dallas, TX. 293 pp. 


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.


GEOGRAPHIC REGION: North America
PERIOD OF RECORD: Modern



DESCRIPTION: 
An atlas of the geographic, climatic, and vegetational distributions for 
major and minor pollen and spore types from all of North America. 
The atlas is based upon a recent compilation of surface pollen samples 
that includes 4549 samples, 134 pollen and spore types (hereafter referred to 
as pollen types), and climatic and vegetational attributes at all locations.
The atlas is a series of visualizations of pollen-climate and pollen-vegetation 
relationships for 95 individual pollen types and 11 summed pollen types.
Each pollen type is represented by five kinds of maps and plots, 
spread across two pages.  

First, the percent abundance of each pollen type across North America is mapped. 
 
Second, plots of pollen percentages against a single climatic or bioclimatic variable 
(sensu Prentice et al. 1992) are employed to indicate the existence of unimodal or 
multimodal distributions in the pollen abundances, threshold climatic values where 
pollen abundances drop off steeply, and the existence of climatic envelopes.  
Plotted climatic variables include mean January temperature, mean July temperature, 
and total annual precipitation. Plotted bioclimatic variables include growing degree 
days on a 5°C base, mean temperature of the coldest month of the year, and the ratio 
of actual to potential evaporation, which is an index for the amount of moisture 
available for plant uptake. 

Third, plots of pollen percentages versus multiple climatic variables illustrate the 
operation of multiple environmental controls upon pollen and plant distributions 
(Bartlein et al. 1984, Anderson et al. 1991, Prentice et al. 1991, Webb et al. 1993a, 
Thompson et al. 1999b). 

Fourth, ternary diagrams show pollen abundances relative to the percent areal cover of 
broadleaf woody, needleleaf woody, and open/unforested vegetation at the pollen sample 
locations. 

Fifth, box plots show the distribution of pollen percentages within vegetation formations. 




DATA:
In the form of Adobe PDF files available from the WDC for Paleoclimatology:
http://www.ncdc.noaa.gov/paleo/pollen/atlas/