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Air Temperature, Heat Sums, and Pollen Shedding Phenology of Longleaf Pine
Author(s) -
Boyer William D.
Publication year - 1973
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934351
Subject(s) - pollen , phenology , pinus <genus> , air temperature , environmental science , biology , botany , ecology , zoology , horticulture , atmospheric sciences , geology
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 degrees 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 degrees 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 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.