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

Abstract

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) threshold 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 385°F (3.6°C).

Citation

Boyer, William D. 1976. Thermal Efficiency: A Possible Determinant of Height Growth Potential in Young Loblolly Pines. Forest Sci. 22:279-282