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Heat Accumulation: An Easy Way To Anticipate the Flowering of Southern Pines

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Accumulation of degree-day heat sums accounts for most of the year-to-year variation in dates of peak pollen shed by slash (Pinus elliottii Engelm.), longleaf (P. palustris Mill.), loblolly (P. taeda L.), and shortleaf (P. echinata Mill.) pines. During 19 years of observation for longleaf and 6 years for each of the other species, the average deviation of observed from predicted peak date was four days or less. Slash pine had the greatest range among years in date of peak flowering (45 days), followed by longleaf (40 days), loblolly (23 days), and shortleaf (20 days). Male strobili of slash pine developed without pause. except on cold days, after their emergence in late November or early December. Longleaf, however, had a period of winter dormancy that averaged about one month, and loblolly and shortleaf were dormant about two months during winter. Only the pollen shed periods of longleaf and loblolly pines overlapped during this study. Differences in heat and dormancy requirements apparently preclude overlap between longleaf and slush pines, or between shortleaf and any of the others.

Document Type: Journal Article

Affiliations: Principal Silviculturist at the George W. Andrews Forestry Sciences Laboratory, Auburn, Alabama, maintained by the Southern Forest Experiment Station, USDA Forest Service, in cooperation with Auburn University

Publication date: January 1, 1978

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  • The Journal of Forestry is the most widely circulated scholarly forestry journal in the world. In print since 1902, the Journal has received several national awards for excellence. The mission of the Journal of Forestry is to advance the profession of forestry by keeping forest management professionals informed about significant developments and ideas in the many facets of forestry: economics, education and communication, entomology and pathology, fire, forest ecology, geospatial technologies, history, international forestry, measurements, policy, recreation, silviculture, social sciences, soils and hydrology, urban and community forestry, utilization and engineering, and wildlife management. The Journal is published bimonthly: January, March, May, July, September, and November.

    2015 Impact Factor: 1.476
    Ranking: 22 of 66 in forestry

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