Ecosystem services (ES) are increasingly included in conservation assessment worldwide to sustain their ability to fulfill human needs. Due to the instrumental value inherent in ES, priority areas for their conservation should be selected based on their capacity to both ensure an available supply and meet beneficiary demands. However, such a methodology has yet to be developed. Aiming to adopt systematic conservation planning procedures to include ES, we conducted a case study in eastern Canada focusing on ten ES for 16 wetland types. We first delimited the ES supply accessible for human use from the total biophysical supply and mapped demand for each ES. Secondly, we assembled conservation networks targeting the accessible supply and demand and compared them with networks targeting either ES biophysical supply or accessible supply. We found that targeting only ES supply resulted in selecting sites that are not in demand and maybe up to three times less efficient in fulfilling the demands of beneficiaries for local flow ES. Thus, not considering demand in ES conservation assessment fails to position reserves where ES supply is likely to be most useful. Setting conservation targets for ES supply and demand could therefore help to achieve ES conservation objectives
