Intermediate ecosystem services: the origin and meanings behind an unsettled concept

Some ecosystem services (ES) bestow society with obvious tangible benefits such as nourishment from food and water (i.e. final ES), whereas other ES benefit society through complex pathways such as maintaining the resilience of ecosystems and the final ES they provide (i.e. intermediate ES). However, the term 'intermediate ES' has remained loosely defined and some authors are now questioning the term's applicability. To uncover the meaning and origin of the intermediate ES term, we reviewed the literature from 2000 to 2016. We found that the term originated in economics (early 2000s), shifted into ecology in the late 2000s, and its use has grown since. Intermediate ES have been commonly defined as indirect benefits, less commonly as types of ecological components, and occasionally as supporting and regulating ES. We explore these analogies, provide a timeline of the term's use, and discuss pros and cons of the terminology. We recommend that intermediate ES should be defined in specific (often local) contexts considering social factors such as demand for ES and if the service is a key step along an identifiable pathway toward final ES delivery - considerations we illustrate using coastal temperate forests as a case study. EDITED BY Matthias Schröter