Aggregate effects on ecosystem services from certification of tea farming: powerpoint

Agriculture sustainability standards and certification are considered a promising approach to incentivize and support environmental conservation and improved livelihoods in rural areas. However, evidence of impact is limited by methodological challenges that hamper the quantification of certification-induced changes, especially at an aggregate, cross-farm, level. Responding to this evidence gap, this paper aims to estimate the aggregate watershed level changes to ecosystem services from the adoption of Rainforest Alliance tea certification in the Upper Tana River watershed in Kenya. The concept of ecosystem services bridges natural and social systems, and is therefore a suitable measure to evaluate impacts on people and nature with one single measure. In this study we: i) apply ecosystem service models to estimate the effect of adopting farm-level practices prescribed by certification on the watershed-level delivery of selected ecosystem services, and; ii) evaluate the spatial modelling applications for their ability to quantify impact with the objective to guide future decision making. To inform model development and parameterization, we visited tea growers in the study area and collected information on management practices before and after certification. We also evaluated model outcomes for their sensitivity to input data and model choice. We found that adoption of agricultural practices prescribed in the certification standard substantially reduces sediment export into watercourses, with certification resulting an estimated vast reduction of sediment load compared to a without -certification scenario. However, certified farmers’ increased use of fertilizer to boost productivity is estimated to result in greater nitrogen and phosphorous loads post-certification.