A Functional Framework for Improved Management of Western North American Aspen (Populus tremuloides Michx.)

Michx.) forests occur in highly diverse settings across North America. However, management of distinct communitieshas long relied on a single aspen-to-conifer successional model. We examine a variety of aspen-dominated stand types in the western portion of its range as ecologicalsystems, avoiding an exclusive focus on seral dynamics or single-species management. We build a case for a large-scale functional aspen typology based on the existingliterature. Aspen functional types are defined as aspen communities that differ markedly in their physical and biological processes. The framework presented heredescribes two “functional types” and seven embedded “subtypes”: seral (boreal and montane), stable (parkland, Colorado Plateau, elevation and aspect limited, andterrain isolated), and a crossover seral-stable subtype (riparian). The assessment hinges on a matrix comparing proposed functional types across a suite of environmentalcharacteristics. Differences among functional groups based on physiological and climatic conditions, stand structures and dynamics, and disturbance types and periodicityare described herein. We further examine management implications and challenges, such as human alterations, ungulate herbivory, and climate futures, that affect thefunctionality of these aspen systems. The functional framework lends itself well to stewardship and research that seek to understand and emulate ecological processesrather than combat them. We see advantages of applying this approach to other widespread forest communities that engender diverse functional adaptations.Keywords: forests, climate, landscape, classification, biodiversity, adaptive management