For us, biodiversity and sustainable materials are not fashionable words, but intrinsic to everything we are and do.
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.
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.
‘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.
Much of the materials in a Green Roof Shelter are reclaimed, re-used, or recycled. From the re-use of shipping containers, to reclaimed timber used as cladding & roof fascias, reclaimed aggregates & substrates for planting, and recycled plastic ‘lumber’ for rotproof retaining plates. Habitat panels combine a mix of found materials for invertebrate nesting & overwintering.
Re-used materials vary greatly as to what is recovered, be it re-used decking from seaside piers, cedar planking from school buildings, or granite from railway tracks. They’re all great materials to re-use. For anything exposed the the elements that would be liable to rot, we use recycled plastic ‘lumber’, made from collected waste plastics.
We try to be intelligent about using new materials (and have considerable material experience), sourcing those which have the lowest environmental impact long term.
Many ‘new’ materials are already part recycled. Mill steel and aluminium contain significant proportions of recycled material (usually dependent on current metal values/prices; the higher the world price, the more economical it is to collect & reintegrate recycled metals).
Most of the new timber we use is European softwood, and all the new timber we use is FSC certified.
Our re-used shipping containers have usually traveled in excess of 50,000 miles. The life to date of the container is inscribed in the registration and payload information on the container doors. As part of the container’s refurbishment, the whole has been repainted, and the container data reapplied.
We can also take existing containers away and replace with a completely refurbished container with planted green roofs and habitat walls.
Our green roofs keep the container interior cool in hot weather, and because the container has two roof layers protecting it from the elements, it’s life is considerably extended.
We use growing mediums that are made from recycled secondary wastes – recycled crushed brick, organic green waste compost, recycled ceramics. We do not use imported material such as pumice.
A low nutrient level is necessary to allow wildflowers to thrive without grasses and other plants out-competing them. Grasses will often colonise with time.
In most cases a green roof won’t be green all the time. It is important to understand that a green roof will vary through the seasons. In long hot dry summers no natural grassland will be green we can’t expect a green roof to be. With the right approach it is possible to ensure that there is flowering from March through to October.
Patience can be important. Many of our roofs have been around for a number of years and each year we look forward to seeing how they have changed. What new plants have arrived? What is going to flourish this year?
The green roof shelter system uses recycled plastic supplied by Filcris.
90% of our habitat walls come from a reclaimed source, whether it be reclaimed cedar for the frames, local logs, rocks, sheeps wool and other materials. Materials that get taken by birds for nesting, will need to be replaced over time. Locally found materials will always be the ideal for creating habitat panels.
We promote the use of native plants, especially in terms of meeting local and region biodiversity targets for butterflies, insects and other invertebrates. We would normally include some non-native flowering plants to extend the nectar season for solitary bees, hoverflies, butterflies and moths. We can obviously plant according to your needs, and are very happy to give advice.
We source our small plant plugs and seeds from recognised native suppliers as certified by FloraLocale.
Our roofs can be planted responsively to target species, so pocket habitats can be established with particular plants identified as food sources.
When used in public spaces, the wild plants on roofs tend to be free from accidental or mismanaged herbicide spraying.