Stem profile equations can estimate stem diameters using two standing tree measurements (or model predictions): diameter at breast height and total tree height. These diameter predictions are used in established scaling algorithms to estimate merchantable volume under different merchantability standards and scaling rules. This provides more flexibility than merchantable volume equations that must be revised whenever standards or scaling rules change. Estimates of merchantable wood volume are

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... wood volume are needed for timber sale preparation and administration, forest inventory, and strategic planning. The profile equation of Max and Burkhart was fit to eight tree species in the Pacific Northwest Region (Oregon and Washington), but overestimated stem diameters by an average of 0.06 to 0.24 inch. These biases were reduced using second-stage models that empirically correct for bias and weak patterns in the residuals. Most estimates of merchantable volume from the profile and second-stage models had an average error less than 10% when applied to independent test data for three national forests, and were usually within 6.5% of volume estimates from the hyperbolic profile equation of Behre, which has been used for decades in the Pacific Northwest; however, the Max and Burkhart equation does not require a standing tree measurement of Girard form class, as does the Behre equation. l~eadquarters is in Fort Collins, in cooperation with Colorado State University.