Nonlinear Equations for Predicting Diameter Inside Bark at Breast Height for Young-Growth Red Fir in California and Southern Oregon

摘要

Inside bark diameters of young-growth red fir can be estimated from the relationship of inside bark diameter to outside bark diameter at breast height. Inside and outside bark diameters were obtained from stem analyses of 562 trees distributed across 56 sampling locations in the true fir forest type of California and southern Oregon. The resulting equation can predict inside bark diameter as a function of outside bark diameter. Because stand basal area and site index also influence the inside-outside bark diameter relationship, and additional equation that includes both of these independent variables is given. Weighted, nonlinear regression was used to estimate the equation coefficients. Application of the prediction equations in calculating past tree diameters is discussed.