The effect of land classification and stratification on derivation of timber supply and allowable cut in harvest scheduling

Abstract

The effects of boundary designations of timber management units on the allowable cuts were examined, and a new approach to derive marginal-cost curves for timber supply was developed. The maximum even-flow allowable cut from the whole forest as a unit was 1.33–2.13% larger than the sum of the five maximum even-flow allowable cuts from the five working circles. Maximum even-flow allowable cuts found with linear programming using stand aggregation were 1.31–2.10% larger than allowable cuts using area aggregation. Maximum per period cost constraints were found, on average, to increase predicted differences from unconstrained stand-based versus area-based analysis. Use of the maximum cost constraints led to the ability to develop curves for the marginal cost of allowable cut for both stand-based and area-based analyses. By incrementally examining increases in the allowable cuts generated on the independent management units at different cost constraints, a curve for the average marginal cost of allowable cut was derived. Careful use of this curve will allow woodland managers to select the least costly method of analysis for any particular desired allowable cut. As well, the selected curve can aid managers in determining the marginal cost of timber supply at any production level and to set upper limits on external wood purchase prices. While biological data were easier to derive for stand-based aggregation, area-based aggregation led to smaller linear programming models, which were thus cheaper to solve, and it was much easier to develop location-dependent economic data for these type models than for stand-based models.