Dynamics of North American boreal mixedwoods

Boreal mixedwoods (BMWs) are the most productive and diverse forest ecosystems in North American boreal forests. A good understanding of BMW stand dynamics is a prerequisite for sustainable management of these vital resources. In this review, we describe the patterns and processes of BMWs created by natural disturbances, examine the biotic and abiotic factors that influence these patterns and processes, and discuss forest management implications related to stand development. Based on distinct structural and developmental features, BMW stand development is characterized by four stages: stand initiation, stem exclusion, canopy transition, and gap dynamics. These four stages of stand development provide a conceptual model of complex developmental processes. However, multiple pathways are possible during BMW stand development depending on disturbances, neighbour effects, and stand condition. Boreal mixedwood management at the stand level needs to emulate the natural development process and target a specific stand structure and species composition. Alternative silvicultural techniques are available to achieve the multiple objectives of BMWs. Further considerations at various temporal and spatial scales and at the operational level are required to ensure sustainable BMW management. Key words: stand dynamics, boreal mixedwoods, natural disturbance, stand structure, developmental process, management implications.