Basal Area Increment and Growth Efficiency as Functions of Canopy Dynamics and Stem Mechanics
Abstract:Crown and canopy structure correlate with growth efficiency and also determine stem size and taper as described by the uniform stress principle of stem formation. A regression model was derived from this principle that expresses basal area increment in terms of the amount and vertical distribution of leaf area and change in these variables during a growth period. This model was fit to data collected from five studies analyzing various effects of cultural practices, atmospheric deposition, and stand density on the growth of loblolly pine (Pinus taeda), slash pine (P. elliottii), or lodgepole pine (P. contorta). For both southern pines, the model was fit to individual-tree data and plot totals measured on 1- to 4-yr-old trees and from 12- to 20-yr-old trees. The model was also fit to data measured on approximately 90-yr-old lodgepole pine trees in northern Utah. The model explained an average of 85% of the variation in individual-tree basal area increment and an average of 86% of variation in gross basal area increment per hectare. By comparison, leaf area alone explained an average of 54% of the variation in the increment of individual-tree stem volume and an average of 50% of the gross increment in stem volume per hectare. The value of the exponent in the model implicates stem mechanics in stem growth, and fitted exponents were all within 7% of the exponent derived from the uniform stress model. Isolines of basal area increment and basal area growth efficiency based on fitted equations indicate that increments in the product of leaf area and height to center of leaf area must increase yearly for either basal area increment or growth efficiency to be constant with age. FOR. SCI. 50(1):106–116.
Keywords: Leaf area; environmental management; forest; forest management; forest resources; forestry; forestry research; forestry science; growth; natural resource management; natural resources; stem mechanics; uniform stress principle; wood properties
Document Type: Regular Article
Affiliations: Associate Professor School of Renewable Natural Resources LSU AgCenter Baton Rouge LA 70803 Phone: 225-578-4216;, Fax: 225-578-4227, Email: email@example.com
Publication date: February 1, 2004
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