Summary
Voluntary certification standards (VCS) in agriculture and forestry typically include the protection of biodiversity among their objectives or requirements. This outcome is advanced through a range of mechanisms, from prohibitions on destroying certain types of natural ecosystems to requirements to conserve native species co-occurring in production systems to controls on negative externalities that can harm biodiversity, such as polluted runoff. Conservation results may be achieved at a range of scales-from smallholder farms to large landscapes-and as either direct or indirect consequences of implementing VCS. These myriad considerations point to the need for nuanced evaluation frameworks to understand effects on biodiversity across large certification portfolios while also evaluating the causality of VCS interventions on changes in biodiversity attributes. Here, we synthesize experience and perspectives from the VCS community to present a generalized assessment framework for understanding effects of VCS on biodiversity. We then use the example of the Sustainable Agriculture Network (SAN)/Rainforest Alliance certification system to illustrate the application of this framework to an agricultural standard covering about 3.5 million hectares and 1.2 million producers across 42 countries. The framework integrates evidence from multiple data sources, including basic attributes of certified operations, data on the adoption of biodiversity friendly practices as revealed by annual audits, and research studies assessing biodiversity outcomes at farm and landscape level. Based on experience from evaluating biodiversity effects of the SAN/ Rainforest Alliance system from 2011-2014, we reflect critically on challenges, opportunities, and future priorities for evaluating and improving the biodiversity conservation benefits of VCS more broadly.