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absolute pollen frequency
absolute pollen frequency (APF) The expression of pollen data from sediments, expressed in terms of the absolute numbers (for each species, genus, or family) per unit of volume of sediment and, where deposition rates are known, per unit of time. In certain circumstances this approach gives clearer information than does the traditional way of expressing pollen data as relative pollen frequencies (RPF). APFs are particularly useful in site comparisons in which one or more high pollen producers vary. For example, when trees first appear in the regional pollen rain their prolific pollen may, in an RPF method, give the impression of declining herbaceous species, whereas examination by an APF method will show constant values for herb species.
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Cite this article
MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Ecology. 2004. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O14-absolutepollenfrequency.html MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Ecology. 2004. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-absolutepollenfrequency.html |
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absolute pollen frequency
absolute pollen frequency (APF) Pollen data from sediments, expressed in terms of the absolute numbers for each species, genus, or family, per unit volume of sediment and, where deposition rates are known, per unit time. In certain circumstances this approach gives clearer information than does the traditional way of expressing pollen data as relative pollen frequencies (RPF). APFs are particularly useful in site comparisons in which one or more high pollen producers vary. For example, when trees first appear in the regional pollen rain their prolific pollen may, in an RPF method, give the impression of declining herbaceous species, whereas examination by an APF method will show constant values for herb species.
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Cite this article
AILSA ALLABY and MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O13-absolutepollenfrequency.html AILSA ALLABY and MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Earth Sciences. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-absolutepollenfrequency.html |
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absolute pollen frequency
absolute pollen frequency (APF) The expression of pollen data from sediments in terms of the absolute numbers (for each species, genus, or family) per unit volume of sediment and, where deposition rates are known, per unit time. In certain circumstances this approach gives clearer information than does the traditional expression as relative pollen frequencies (RPFs). APFs are particularly useful in site comparisons in which one or more high-pollen producers vary. For example, when trees first appear in the regional pollen rain their prolific pollen may, in an RPF method, give the impression of declining herbaceous species, whereas examination by an APF method will show constant values for herb species.
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Cite this article
MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O7-absolutepollenfrequency.html MICHAEL ALLABY. "absolute pollen frequency." A Dictionary of Plant Sciences. 1998. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-absolutepollenfrequency.html |
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