Challenges and implications of incorporating multi-cohort management in northeastern Ontario, Canada: A case study

Abstract

In northeastern Ontario, the natural fire cycle is long, resulting in large areas of forest in an uneven-aged condition. Under Ontario forest legislation requiring emulation of natural disturbance regimes, extended rotations and multi-cohort management present options that may meet landscape targets. We used a forest management wood supply model to compare scenarios of current even-aged management, extended rotations, and multi-cohort management (adds partial harvesting). Because science-based information to incorporate late successional forest stages into wood supply modeling is lacking in boreal Ontario, we adjusted the current even-aged inputs to account for mid-and late-seral conditions. Based primarily on expert opinion, adjustments were made to the Forest Resources Inventory age, yield curves, and succession rules; and partial harvesting was added. For modeling, we specified three broad succession groupings (even-aged, two-to three-aged, and all-aged) and established targets of 50%, 25% and 25% of the landscape area, respectively. The current even-aged scenario met even-aged targets but not multi-aged targets. Extended rotations and multi-cohort management scenarios met all the succession grouping targets over the long term. Wood supply was highest for the even-aged scenario, slightly lower for multi-cohort management scenario, and much lower for the extended rotations scenario. Road usage and relative cost was highest for the extendedrotations scenario and lowest for the even-aged scenario. Multi-cohort management may represent a compromise between maximizing harvest levels using even-aged management and retaining mid-and late-succession habitat structures.Keywords: emulation of natural disturbance, sustainable forest management, multi-cohort, variable rotations, extended rotations, wood supply résumé Dans le nord-est de l'Ontario, les longs cycles naturels de feux font que de vastes zones de forêt deviennent inéquiennes. Comme la législation forestière de l'Ontario oblige à imiter les régimes de perturbations naturelles, il est envisageable d'atteindre ces objectifs au niveau du paysage par l'allongement des rotations et l'utilisation de l'aménagement multi-cohortes. Nous avons utilisé un modèle d'approvisionnement en forêt aménagée pour comparer scénario d'aménagement équienne avec ceux comportant un allongement des rotations et un aménagement multi-cohortes (incluant la coupe partielle). Puisque les informations scientifiques pour intégrer les stades de succession écologique tardifs dans la modélisation de l'approvisionnement faisaient défaut pour la région boréale de l'Ontario, nous avons ajusté les paramètres du modèle équienne pour tenir compte des conditions de succession moyenne et tardive. En nous inspirant surtout de l' opinion des experts, nous avons ajusté l'âge, les courbes de rendement et les règles de successions provenant de l'inventaire forestier provincial; nous avons ajouté la coupe partielle. Pour effectuer la modélisation, nous avons spécifié trois grands groupes de succession...

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