The multiple benefits of (urban) green infrastructure

Green or blue areas in the city, such as parks, green roofs, green walls, vegetated road verges, trees, urban (care) farms, rivers, ponds, and ‘tiny forests’ are hypothesized to, and sometimes shown to, contribute to solving many urban problems. They are shown to have a positive impact on both physical and mental health, and moreover can stimulate social cohesion and local economy. Apart from effects on human health and wellbeing, this green or blue infrastructure also enhances biodiversity, stores water, and has a cooling effect (and thus combats the urban heat island effect). Effects on noise (reduction) and clean air are under debate. When it comes to clean air it is known that vegetation can absorb particles, but trees can also prevent air circulation in ‘street canyons’. Other negative effects exist too: blue and green infrastructure can enhance pests such as mosquitoes, rats, ticks and oak processionary caterpillars and pollen can cause allergic reactions.

The term Nature-based solutions is used, mainly by policy makers, when discussing these multiple benefits of (urban) green infrastructure for humans. In regeneration projects of degraded urban areas, nowadays often this “greening” is used with the idea that it will enhance human wellbeing, although the knowledge base is still thin – and negative effects are often neglected.

More research is needed to unravel the complex relations between the different types of urban green infrastructure and their benefits to society (ecosystem services). For example: do the new ‘tiny forest’ enhance biodiversity and/or social cohesion? Do they stimulate children to play outside? Do they make neighbourhoods safer or less safe? Can they store water and cool the neighbourhood?

If you are interested in these issues, we can discuss a possible concrete thesis subject.