The cost-effectiveness of agri-environment schemes for biodiversity conservation: A quantitative review

Agri-environment schemes (AES), where farmers receive payments in exchange for providing public goods and services such as biodiversity, account for a major proportion of conservation expenditure in agricultural landscapes around the world. The variable effectiveness of such schemes and increasing recognition of the importance of cost-effective conservation - maximizing conservation benefit for a fixed cost or minimizing cost of achieving a specific conservation outcome - has prompted calls over the past decade for integration of economic costs into evaluation. We reviewed the global agri-environmental evaluation literature to determine what proportion of studies evaluating biodiversity conservation effectiveness consider costs and cost-effectiveness and whether there has been an increase in this integration over time. Less than half of the studies reviewed made any reference to the costs of AES, and fewer than 15% included any measure of cost-effectiveness. Despite steady growth in the number of published AES evaluations over the past 15 years, and a gradual increase in the number of studies that acknowledge costs, the proportion of studies published annually that integrate economic data into evaluation remains largely unchanged. Various reasons have been identified for this poor integration, including limited understanding of, and access to, economic evaluation tools, data and training, and a philosophical aversion to the mixing of economics and conservation. We argue however that these reasons are no longer justified, and highlight several examples of the effective integration of economic and ecological data in evaluations to assist researchers and decision-makers in addressing this deficiency.