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Thermal Efficiency: A Possible Determinant of Height Growth Potential in Young Loblolly Pines

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Height growth of 10 loblolly pines (Pinus taeda L.) during one growing season ranged from 35.7 to 126.9 cm. Ninety-four percent of these tree-to-tree differences in height growth were accounted for by two thermal characteristics of each tree: (1) thresh-old temperature for growth and (2) growth rate per unit of heat above 40°F (4.4°C). These parameters were derived from the nocturnal growth of the first flush of three shoots per tree measured in late April and early May. Threshold temperature alone accounted for 62 percent of the differences in height growth. Growth rate alone had no significant effect. The parameters were more closely related to terminal shoot growth after the first flush (R² = 0.80) than to first flush lengths alone (R² = 0.66). Threshold temperatures ranged from 32.3°F (0.2°C) to 43.2°F (6.2°C) and averaged 38.5°F (3.6°C). Forest Sci. 22:279-282.

Keywords: Pinus taeda; heat units; plant growth; selection; temperature

Document Type: Journal Article

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

Publication date: September 1, 1976

More about this publication?
  • Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
    Forest Science is published bimonthly in February, April, June, August, October, and December.

    2015 Impact Factor: 1.702
    Ranking: 16 of 66 in forestry

    Also published by SAF:
    Journal of Forestry
    Other SAF Publications
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