EU report outlining the ideas and science behind current green infrastructure policy.
(2012) By the European Union Science for Environment Policy DG Environment Alert News Service. This report describes the different functions that GI seeks to execute and explores the scientific evidence behind its ability to perform these functions, using case studies where available. The functions are described in terms of four broad roles that GI performs:
• Protecting ecosystems state and biodiversity
• Improving ecosystem functioning and promoting ecosystem services
• Promoting societal wellbeing and health
• Supporting the development of a green economy, and sustainable land and water management
The roles of GI are highly interdependent, for example, societal wellbeing in coastal and river areas depends on flood retention by wetlands or natural drainage systems, which in turn depend directly on the provision of ecosystem services, such as soil and water regulation. These, in turn, are highly reliant on biodiversity to uphold the health of the ecosystems to provide ecosystem services.
Evaluating the many aspects and functions of GI is a complex process. Although some elements with clear functions and objectives can be easy to measure, such as the ability of green roofs to reduce stormwater runoff, it can be challenging to identify one overall measurement encompassing all the different GI objectives. As such, the evaluation of GI may require a combination of qualitative or descriptive assessments with quantitative measures, using input from both ecological and social sciences. For example, quantitative measures of changes in ecosystem services could be combined with descriptive measures of existing political infrastructure to support policy measures and stakeholder participation.