Regional Stem Profile Model for Cross-Border Comparisons of Harvested Red Pine (Pinus resinosa Ait.) in Ontario and Michigan

Abstract

Abstract In recent years, considerable attention has been paid to the problem of increasing the comparability of wood valuation across different markets (e.g., stumpage prices), highlighted in the ongoing softwood lumber dispute between the United States and Canada. One major thrust is toward standardizing measurement systems across markets such that volume estimation is more consistent and versatile. As part of the Great Lakes Stem Profile Modeling Project, established to improve the local timber production process and to enable cross-border comparisons of timber volumes, here we present results of a fitting taper (stem profile) model for red pine (Pinus resinosa Ait.) growing in Michigan and Ontario, Canada. Red pine is an important commercial species in both regions. We developed a joint stem profile model that predicts individual tree volume for red pine in Michigan and Ontario with a standard deviation (SD) of error of 10%, demonstrating the feasibility of providing regionally valid stem profile models for major commercial tree species. The stem profile model was fitted as a system of simultaneous equations using a three-stage least-squares regression method. Predictions were evaluated using an equivalence test. We believe that developing statistically and legally defensible estimates of timber product volume across political borders, as exemplified by the regional stem profile model presented here, will improve communication among the trade partners, such as the United States and Canada, by reducing uncertainty created by a lack of comparable estimates.