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

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.