Evaluation of biodiversity policy instruments: what works and what doesn't?

We review and confirm the claim that credible evaluations of common conservation instruments continue to be rare. The limited set of rigorous studies suggests that protected areas cause modest reductions in deforestation; however, the evidence base for payments for ecosystem services, decentralization policies and other interventions is much weaker. Thus, we renew our urgent call for more evaluations from many more biodiversity-relevant locations. Specifically, we call for a programme of researchConservation Evaluation 2.0that seeks to measure how programme impacts vary by socio-political and bio-physical context, to track economic and environmental impacts jointly, to identify spatial spillover effects to untargeted areas, and to use theories of change to characterize causal mechanisms that can guide the collection of data and the interpretation of results. Only then can we usefully contribute to the debate over how to protect biodiversity in developing countries.