Careful plant choice can deliver more biodiverse vertical greening (green façades)

Abstract

Plants growing against walls (green façades) are an important part of urban greening. We report on an experiment that used a set of replicated mini model building plots designed to quantify and compare potential biodiversity benefits associated with three plant species commonly grown as green façades in temperate climates: Hedera helix (common ivy) (either as a straight species, or a mix with H. helix ‘Glacier’), Parthenocissus tricuspidata (Virginia creeper) and Pileostegia viburnoides (climbing hydrangea). We assessed the relative abundance of invertebrates collected from green façades in Reading (UK), over two growing seasons. The abundance of invertebrates increased with wall vegetation depth and cover, where considerably more invertebrates were collected from vigorous/deeper leaf wall cover by Hedera helix compared to the other treatments. A combination of two ivy taxa showed a higher invertebrate abundance compared to H. helix alone. The experiment demonstrates that green façades on buildings provide resources for invertebrates; the more vegetation resources there are, and the more varied they are, the more invertebrates are supported. It is clear that green façades can add to the value of invertebrate abundance on buildings and that plant choice is a strong determining factor to that value.