Relaxing even-flow constraints to avoid infeasibility with the Timber Resources Allocation Method (RAM)

Abstract

When inflexible rotation ages for regenerated timber are coupled with a strictly interpreted policy of nondeclining or even flow of timber volume, a mathematically feasible harvest schedule often does not exist. This problem of infeasibility can be avoided by relaxing the definition of even or nondeclining flow used in the postconversion period of the Timber Resources Allocation Method (RAM). Relaxed flow policies can lead to scheduled harvest volumes which fluctuate greatly from decade to decade in the postconversion period. Explicitly planning for these fluctuations seems to violate the principle of sustained yield and some believe it may lead to a poorly regulated forest. However, when frequent review and reassessment of harvest schedules for two Alberta forest management units were simulated, undesirable fluctuations in future harvest volumes did not occur and the resulting forest structures were reasonably regular.

Aggregating forest harvesting activities in forest plantations through Integer Linear Programming and Goal Programming

“…In difficult forest planning problems, as harvest scheduling including spatial relations, the relaxation of timber flow constraints is a common strategy applied for obtaining feasible solutions (Armstrong et al, 1984;Bettinger et al, 1999). In our study, it was necessary to apply a management and production flow flexibilization for obtaining feasible solutions.…”