Restoring forest ecosystem services through trait-based ecology

Restoration is moving towards a more mechanistic approach that emphasizes restoration of ecosystem services. Trait-based approaches provide links between species identity and ecosystem functions and have been suggested as a promising way to formally integrate ecosystem services in the design of restoration programs. While practitioners have been routinely using informal knowledge on plant traits in their practices, these approaches are underutilized as operationalization remains challenging. The goal of this paper is to provide guidance for applied scientists and restoration practitioners looking to apply a trait-based approach to restore forest ecosystems. We present a five-step framework: (1) selection of services to be restored, (2) trait selection, (3) data acquisition, (4) analytical planning, and (5) empirical testing and monitoring. We use three Canadian case studies to illustrate the applicability of our framework and the variety of ways trait-based approaches can inform restoration practices: (1) restoration of urban woodlots after an insect outbreak, (2) restoration of a smelter-damaged landscape surrounding an urban area, and (3) reclamation of remote upland forests after oil- and gas-related disturbances. We describe the major mechanisms and traits that determine vegetation effects on ecosystem services of importance in each case study. We then discuss data availability, methodological constraints, comparability issues, analytical methods, and the importance of empirical testing and monitoring to ensure realistic prediction of service restoration. By outlining issues and offering practical information, we aim to contribute to a more robust use of traits in ecological restoration.