Determining appropriate goals for restoration of imperilled communities and species.
Conservation and restoration practitioners often struggle to define appropriate targets for restoration. Frequently, 'pre-settlement conditions' (the conditions that are believed to have existed prior to European settlement) are used. In this review, we draw on our experiences working with land-managers to restore native ecosystems in the Pacific Northwest (USA) to discuss some of the challenges in using pre-settlement conditions as a restoration target. We have found that information on the structure and composition of pre-settlement communities does not exist in sufficient detail to set quantitative restoration targets. The systems we work in have been so altered from the historic condition (as we best understand it), that mimicking the anthropogenic and 'natural' disturbances that shaped these communities is both difficult and unlikely to guarantee success. Furthermore, the pre-settlement condition may not be an appropriate restoration goal given on-going global changes, including species invasions, habitat loss, and climate change. Synthesis and applications. We suggest that rather than focusing on historic benchmarks, restoration goals should be based on ecological principles that will lead to resilient, functioning ecosystems. We provide real-world examples for how scientists and managers can work together to define and test appropriate and effective restoration methods and targets.