Ecosystem Services across US Watersheds: A Meta-Analysis of Studies 2000-2014

Despite increasing awareness on the importance of rivers in maintaining human wellbeing, there has not been a comprehensive inventory of watershed-scale ecosystem services across the USA. Here, we analyze and summarize the scientific literature within the context of the supply and demand for ecosystem services across 18 major watersheds of the continental US. We reviewed 305 articles and found that 68 provided information on both the biophysical delivery (supply) and the sociocultural and economic values (demand) of ecosystem services. Maintaining populations and habitats, water filtration, and nutrient sequestration/storage were the most extensively assessed services, while educational and aesthetic values were the least frequently studied. Biophysical assessments were the most frequent valuation followed by economic approaches. The majority of the studies were conducted in the eastern US, while the region least studied was the southwest. In addition to identifying the knowledge gaps in watershed-scale ecosystem services, we highlight the need for a common framework for assessing ecosystem services that includes both the assessment of the supply and demand of ecosystem services provided by US watersheds. There is an urgent need to incorporate the role that cultural services and values can play in water resources management and planning in the USA.