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Allometric equations predicting individual branch and total crown leaf area, leaf mass, and branch wood mass were developed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca), ponderosa pine (Pinus ponderosa Dougl. ex Laws.), and western white pine (Pinus monticola Dougl. ex D. Don) on the Priest River Experimental Forest in northern Idaho. Whole crowns were weighed fresh in the field by crown quarter. Two antithetic random branches were sampled from each crown quarter, weighed fresh in the field, and returned to the laboratory for detailed analysis. Nonlinear weighted regression with the general allometric equation was used to estimate all parameters. For the branches, branch diameter and length, foliated length, and position in the crown explain 82-97% of the variation. Specific leaf area (leaf area/mass) differs significantly among species and increases with distance from the tree top. For whole trees, sapwood area at breast height, crown ratio and length, and crown competition factor (CCF) explain 94-99% of the variation. The assumption of linearity and constant ratio between leaf area and sapwood area held rather generally. Differences between two alternative estimators (branch summation vs. crown weighing) of total crown biomass and leaf area were not statistically significant. For stands, stand totals were estimated from the whole-tree equations and stand-inventory data. Generally, these stand estimates were intermediate between coastal forests west of the Cascades and drier forests in the rain shadow of the Rocky Mountain crest.
Monserud et al. (Sat,) studied this question.