Biological diversity really comes down to ‘natural variety’, and every space, on the ground or on a roof, however large or small, can support wildlife, both animals and plants.
The type of green roof planting and habitat creation we provide is designed to enrich an area or structure with biological diversity.
We encourage the use of a variety of growing substrates and substrate depth to ensure that a range of plants can grow, but as importantly, a range of different bugs can find refuge on the roof.
Some bugs like bare and very dry habitats and roofs are ideal to create this type of habitat. Certain bee species rely on flowers with special sepals, such as the Trefoils, Toadflaxes and Vetches.
It is also important to ensure that there are flowers in bloom from April to September. This provides a food source for bees throughout their foraging season. Plants, like Toadflax, which flower mid to late summer and early spring bulbs, such as Grape Hyacinth help at either end of the season.
Toadflax is also important for a rare UK moth, the Toadflax Brocade. The Common Blue butterfly feeds on bird’s foot trefoil and medicks. The Small Blue feeds on Kidney Vetch. The Dingy Skipper’s caterpillars also feed on Bird’s Foot Trefoil as well as Horseshoe Vetch. Rock-rose, Crane’s and Stork’s-bill species are good for the Brown Argus. As some grasses colonise the roof, other butterfly species, such as the Meadow Brown and Small Heath might find food plants on the roof.
It is also good to have a mind for the bugs, which though small and unassuming find refuge on derelict/brownfield sites and dry grasslands. The increasingly rare small black beetle (name?), depends on Autumn Hawkbit; as this plant flowers late in the year, it also provides an ideal nectar source for bees and butterflies.
Creating Different Microhabitats.
The importance of providing larger stones and pieces of timber as give added humidity on the roofs for spiders and beetles. Birds make use of these structures for perching while searching food.
Logs, both dried and rotting, are important for a whole range of bugs. Some like the sun beaten logs to nest in, while rotting logs can host a range of invertebrates that include stag beetles. Boulders and bare areas can be very important too. There are a number of spiders that like to hunt in these areas, such as money, wolf and crab spider species. Small mounds of coarse sand can be habitat for a number of mining and solitary bees to nest on the roof.
To read further research….
‘Study of invertebrates on green roofs – How roof design can maximize biodiversity in an urban environment.’ Research undertaken by Gyongyver Kadas.
We can always try to answer questions about plants and wildlife, but for local expertise your local Wildlife Trust is a great place to start. Local soil types, corresponding native plants, and feeding and nesting wildlife all vary greatly around the country.