Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (173 KB bytes)

Title: Air Temperature, Heat Sums, and Pollen Shedding Phenology of Longleaf Pine

Author: Boyer, William D.;

Date: 1972

Source: Ecology, Vol. 54, No. 2

Publication Series: Miscellaneous Publication

Description: Between 1957 and 1966, pollen shedding by longleaf pine (Pinus palustris Mill.) in southwestern Alabama peaked at dates ranging from February 23 to April 3. January 1 and 50°F was the combination of starting date and threshold air temperature that minimized annual variations in heat sums before the trees flowered. The heat sum required for peak pollen shedding declined as the season advanced. The regression Y = 19009 -89.26X, in which Y is the degree-hour heat sum above 50°F and X is days from January 1 through date of peak pollen shedding, accounted for nearly all observed annual variations in peak date. For the data from which the regression was computed, deviation of observed from expected date of peak pollen shed averaged 0.3 day. For eight subsequent observations, including two in North Carolina and one in northern Alabama, the deviation averaged 1.6 days.

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • You may send email to to request a hard copy of this publication. (Please specify exactly which publication you are requesting and your mailing address.)



Boyer, William D. 1972. Air Temperature, Heat Sums, and Pollen Shedding Phenology of Longleaf Pine. Ecology, Vol. 54, No. 2


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.