since its introduction in the psah has been adjusted several times to improve its costeffectiveness by targeting areas with high biodiversity benefits areas with high risk of loss to ensure additionality and areas with low opportunity costs given that there were million hectares enrolled in the programme its conservation impact has been fairly low this can be partly explained by the low weight given in the design of the programme to environmental criteria visavis social and administrative criteria such as complementarities with other programmes environmental criteria represented of the weight in and in