Green infrastructure is defined as a “strategically planned network of high quality natural and semi-natural areas with other environmental features, which is designed and managed to deliver a wide range of ecosystem services and protect biodiversity in both rural and urban settings [1].”. Cities can have a wide range of green infrastructure types, including forests, a mix of natural and built elements, and parks, green street structures and green roofs in more built areas. Particularly in a dense urban environment, integrating green infrastructure into other urban infrastructure requires careful planning. By taking green infrastructure into account in the early planning phases, cities can be made into more pleasant and safer living environments that are both more sustainable and more ‘climate-wise’.
Green infrastructure is sometimes also discussed in connection with ‘blue infrastructure’, which refers to water, but more often water is included in the definition of green infrastructure. Together, green areas and water bodies provide ecosystem services that are a source of the benefits that people derive from nature.
Nature-based Solutions (NbS) is a distinct but similar term to green infrastructure, even though the terms are often used interchangeably. NbS are ‘solutions that are inspired and supported by nature, which are cost-effective, and simultaneously provide environmental, social and economic benefits and help build resilience. Such solutions bring more, and more diverse, nature and natural features and processes into cities, landscapes and seascapes, through locally adapted, resource-efficient and systemic interventions’ [2]. NbS and green infrastructure offer multiple co-benefits ranging from flood management to cleaner air and mitigating urban heat, while contributing to residents’ well-being.
Green infrastructure brings nature to the city and creates many benefits for residents. The urban structure of growing and densifying cities, such as Helsinki and Tallinn, is constantly being developed for future needs. Densification as a result of population growth can increase the severity of the impacts of climate change and the extreme weather phenomena it brings, such as heavy rain and hotter summers. Cities need to be designed in new ways that keep future changes in the climate in mind. This can be done through green infrastructure.
The planning of green infrastructure guides us to prioritise ecological provision and processes.
Ecosystem services are divided into three categories. Provisioning services are the food from agriculture and from forests, such as berries, mushrooms and other gathered goods, as well as wood and energy sources based on biomass. Regulating and supporting services are water regulation and flood protection, pollination by insects and the maintenance of soil capacity. These processes regulate or are necessary for the functioning of ecosystems and form the basis for other ecosystem services. In cities, plants absorb carbon and thus contribute to carbon neutrality goals. The third category is cultural ecosystem services, or nature as a recreational and educational environment.
Different green infrastructure elements can generate different types of ecosystem services and benefits for society and nature. For example storm and rainwater management structures will help mitigate flooding to a higher level than a green wall or a green roof. The levels, however, ultimately depend on the specific site as well as scale. Planning should consider all these aspects when deciding which green infrastructure to implement to tackle its societal challenges.
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