The interrelationship of green infrastructure and natural capital

•There is a spectrum of environments ranging from natural systems to built systems.•Natural capital forms key components of green infrastructure.•Green infrastructure projects allow humans to protect, restore or create natural capital.•Natural capital and green infrastructure highlight the value of environmental assets.•Humans can enhance local ecosystem services through symbiotic relationships. The terms green infrastructure and natural capital are interrelated. Natural capital as a concept is focused upon environmental assets which can provide ecosystem services, either directly or indirectly to humans; the concepts of natural capital and ecosystem services emphasize the benefits humans obtain from the natural environment. Green infrastructure is a concept with a wide range of definitions. The term is sometimes applied to networks of green open spaces found in or around urban areas. In other contexts green infrastructure can describe alternative engineering approaches for storm water management, with co-benefits of temperature control, air quality management, wildlife habitats and/or recreation and amenity space. No environments are completely free of human influence and therefore no environments are entirely natural. Rather, there is a spectrum of degrees of ‘naturalness’ ranging from environments with minimal human influence through to built environments. A trio of case studies presented herein illustrates how green infrastructure projects are a practical application of the natural capital concept in that they seek to preserve and enhance natural capital via a management approach which emphasizes the importance of environmental systems and networks for the direct provision of ecosystem services to human populations. Natural capital forms critical components of all green infrastructure projects.