Living walls boost biodiversity by providing safe spaces for urban wildlife

Living walls – structures housing flowers and plants fitted to the outside of new and old buildings – can significantly enhance the biodiversity within urban environments, a new study has shown.

The research monitored activity involving pollinating insects, spiders, soil invertebrates, birds and bats at three locations spread across the city centre and outskirts of Plymouth.

Over three survey periods, hundreds of creatures were observed including 12 different types of bees, hoverflies and other pollinators as well 19 types of soil invertebrates and 12 species of spiders.

There were also 32 bird species recorded across the locations, with three species – house sparrows, blackbirds and robins – observed nesting within the living walls.

Living walls with plants in soil attracted more wildlife than those with plants grown in artificial substrates, and the type of plant was also important with ivy, Mexican daisy and honeysuckle attracting the highest number of pollinator species.

Writing in the Journal of Urban Science, researchers say their findings indicate that appropriately designed soil-based living wall systems can deliver meaningful urban biodiversity benefits when integrated with strategic plant selection.

With the world’s cities expanding at an ever-increasing rate, with an estimated 68% of the world's population projected to live in urban areas by 2050, they believe living walls could help to preserve biodiversity at a time when it is increasingly being lost.

The project involved scientists and students from the University of Plymouth’s School of Geography, Earth and Environmental Sciences and School of Biological and Marine Sciences.

They used a range of observation techniques and acoustic monitoring surveys to assess the different animal species frequenting the living walls at the University’s Sustainability Hub, the Genesis Building on Union Street and in the Sherford new town development.

Dr Paul Lunt, Associate Professor in Environmental Science at the University of Plymouth and the new study’s lead author, said: “We’re in the middle of a global biodiversity crisis where wild species are increasingly being threatened by the changing climate and habitat loss. We need to do everything we can to support our wildlife, and it is one of the reasons why living walls are becoming an increasingly visible feature of UK urban design. Our work provides one of the clearest assessments to date of their biodiversity benefits, as well as a policy challenge with current legislation meaning their ecological contributions are being undervalued in planning assessments. Based on our research, we feel there is a case for revisiting that if we are to fully realise the extent to which living walls can benefit our urban flora and fauna.”

The University has been advocating for the greater use of living walls – and other environmental building techniques – for many years, with the one analysed in this research added to the Sustainability Hub on its main campus in 2019.

Since then, it has been pursuing research to monitor the structures’ effectiveness, including research published in 2021 which demonstrated that retrofitting an existing masonry cavity walled building with a green or living wall can reduce the amount of heat lost through its structure by more than 30%.