An evidence assessment tool for ecosystem services and conservation studies.

Reliability of scientific findings is important, especially if they directly impact decision making, such as in environmental management. In the 1990s, assessments of reliability in the medical field resulted in the development of evidence-based practice. Ten years later, evidence-based practice was translated into conservation, but so far no guidelines exist on how to assess the evidence of individual studies. Assessing the evidence of individual studies is essential to appropriately identify and synthesize the confidence in research findings. We develop a tool to assess the strength of evidence of ecosystem services and conservation studies. This tool consists of (1) a hierarchy of evidence, based on the experimental design of studies and (2) a critical-appraisal checklist that identifies the quality of research implementation. The application is illustrated with 13 examples and we suggest further steps to move towards more evidence-based environmental management.