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Sapwood taper models and implied sapwood volume and foliage profiles for coastal Douglas-fir

Maguire, D.A., Batista, J.L.F.
Canadian journal of forest research = 1996 v.26 no.5 pp. 849-863
Pseudotsuga menziesii, sapwood, volume, leaf area, mathematical models, equations, Oregon, Washington, British Columbia
Sapwood dimensions lend insight into the functional and ecophysiological structure of trees and can therefore be profitably applied in various types of growth analyses and simulation models. Ten taper models were fitted to sapwood data from the stems of 134 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees and were compared by various fit statistics, residual behavior, and validation performance on 21 additional trees. The recommended model was a variable exponent model with six parameters and three basic tree-level predictors: diameter, height, and height to crown base. The resulting equation can be applied for estimating sapwood area at crown base, leaf area, sapwood volume, and vertical foliage distribution on standing trees. Ten sample plots are examined to demonstrate that sapwood taper models allow more explicit portrayal of stand structure in dimensions that have a direct functional link to various growth and developmental processes.