THE ANIMAL BIODIVERSITY OF GREEN WALLS IN THE URBAN ENVIRONMENT

Over the last few decades, a substantial body of literature has highlighted the importance of the natural environment for human well-being and health. In the urban environment where, space is particularly costly, the abundance of plants can be increased by growing them vertically as ‘green walls’, rather than horizontally. Although green walls ecology is a rapidly growing science, large gaps remain in our knowledge as only few studies have investigated their ecosystem services, focusing mainly on their thermal values. This doctoral research is one of the first attempts to establish the value of varying vertical greening systems for animal biodiversity. To identify the animal populations of green walls, surveys were carried out on bird, snail, spider and insect communities in green façades and living walls of Stoke-on-Trent, Birmingham and London, UK. The study then focused on the effects of varying characteristics of green walls (e.g. vegetation surface area, plant density and richness, botanical composition, type of foliage) on these communities and also investigated if the local environment (e.g. pedestrian and vehicle traffic volumes, abundance of nearby vegetation) influenced the use of green walls by animals. The results showed that animal groups respond differently to the characteristics of green walls and the surrounding features. Importantly, the design and the maintenance interventions of green walls influence their use by animals and, as such, it is possible to modify these environments to make them more attractive to certain animal communities. Whether growing on independent self-supporting structures, or directly on or in buildings, plants can use largely underexploited vertical space allowing an additional type of ecosystem to be incorporated into the urban environment.