The maturation of ecosystem services: Social and policy research expands, but whither biophysically informed valuation?

1. The concept of ecosystem services (ES) has risen to prominence based on its promise to vastly improve environmental decision-making and to represent nature's many benefits to people. Yet the field has continued to be plagued by fundamental concerns, leading some to believe that the field of ES must mature or be replaced. 2. In this paper, we quantitatively survey a stratified random sample of more than 1,000 articles addressing ES across three decades of scholarship. Our purpose is to examine the field's attention to common critiques regarding insufficient credible valuations of realistic changes to services; an unjustified preoccupation with monetary valuation; and too little social and policy research (e.g. questions of access to and demand for services). 3. We found that very little of the ES literature includes valuation of biophysical change (2.4%), despite many biophysical studies of services (24%). An initially small but substantially rising number of papers address crucial policy (14%) and social dimensions, including access, demand and the social consequences of change (5.8%). As well, recent years have seen a significant increase in non-monetary valuation (from 0% to 2.5%). 4. Ecosystem service research has, we summarize, evolved in meaningful ways. But some of its goals remain unmet, despite the promise to improve environmental decisions, in part because of a continued pre-occupation with numerical valuation often without appropriate biophysical grounding. Here we call for a next generation of research: Integrative biophysical-social research that characterizes ES change, and is coupled with multi-metric and qualitative valuation, and context-appropriate decision-making.