On the risk of systematic drift under incoherent hierarchical forest management planning

In theory, linkages between hierarchical forest management planning levels ensure coherent disaggregation of long-term wood supply allocation as input for short-term demand-driven harvest planning. In practice, these linkages may be ineffective, and solutions produced may be incoherent in terms of volume and value-creation potential of harvested timber. Systematic incoherence between planned and implemented forest management activities may induce drift of forest system state (i.e., divergence of planned and actual system state trajectories), thus compromising credibility and performance of the forest management planning process. We describe hierarchical forest management from a game-theoretic perspective and present an iterative two-phase model simulating interaction between long- and short-term planning processes. Using an illustrative case study, we confirm the existence of a systematic drift effect, which we attribute to ineffective linkages between long- and short-term planning. In several simulated scenarios, the planning process fails to ensure long-term wood supply sustainability, fails to reliably meet industrial fiber demand over time, and exacerbates incoherence between wood supply and fiber demand over several planning iterations. We show that manipulating linkages between long- and short-term planning processes can reduce incoherence and describe future work on game-theoretic planning process model formulations that may improve hierarchical planning process performance. Resume: En theorie, les systemes de planification hierarchiques integrent des mecanismes de liaison efficaces, assurant ainsi une desaggregation coherente de l'attribution de volumes aux usines lors de la planification detaillee des operations de recolte. En pratique, les mecanismes de liaison entre la planification a long-et a court-terme peuvent etre inefficaces, menant donc a des plans incoherents en termes du volume recolte, de la representation des essences, et du potentiel de creation de valeur des billes livrees aux usines. Cette incoherence entre la planification et l'execution de la recolte peut induire une derive systematique de l'etat du systeme forestier (c.-a-d. divergence entre les trajectoires projetees et realisees), compromettant donc la credibilite et la performance du processus de planification de l'amenagement forestier. Nous decrivons le processus de planification forestiere en termes de la theorie du jeu, et nous simulons l'interaction entre la planification de l'approvisionnement et la planification de la recolte a l'aide d'un modele iteratif a deux phases. Nous presentons une etude de cas, et nous montrons l'existence d'un effet de derive systematique, que nous attribuons a l'innefficacite des mecanismes reliant la planification long- et court-terme. Nous montrons qu'il est possible d'ameliorer la coherence des plans en manipulant les mecanismes de liaison, et proposons des avenues de recherche futures pouvant potentiellement ameliorer la performance du processus de planification hierarchique a l'aide de nouvelles formulations de modeles bases sur la theorie du jeu.
1. Introduction Hierarchical forest management (HFM) on public land may currently be failing on two levels. At the top level, HFM may not be providing credible assurance of long-term sustainability [...]