Enhance Biodiversity
BioBerm™s are rounded mounds of growing media on an otherwise level vegetated roof. They offer a natural, seamless way to integrate extensive and intensive green roof systems. This not only adds visual interest but supports more varieties of plants and a wider range of wildlife. Biodiverse roofs can contribute up to 2 points under LEED v4.1 “Sustainable Sites – Protect or Restore Habitat”. See Portfolio of Green Roofs with Bioberms™.
Manage Structural and Cost Limitations
While intensive systems support greater biodiversity, they can be too heavy and/or expensive for many projects. BioBerm™ is a smart way to creatively manage structural and cost limitations. Designers can strategically add depth to those parts of roof that can support the added load, such as over a load-bearing beam or near a structural wall, while keeping weight and cost low with an extensive system on the rest of the roof.
Create Microclimates and Microhabitats
In addition, the transition between extensive and intensive systems creates localized hills and valleys on the roof. The hills favour drought tolerant plants while the valleys support taller and denser vegetation, which attract different insects, birds and wildlife. As a result, BioBerm™s can create different microclimates and microhabitats to support potentially higher biodiversity than an intensive system.
In Toronto, stormwater is often stored in underground cisterns to meet site runoff requirements. This water is reused through irrigation or toilet flushing to create storage space for the next rain event. BioBerm™s enable designers to combine plants with high and low irrigation needs on one roof, so the green roof will evapotranspirate more when water is available but perverse moisture when the tank is empty.
Steps How to Create a BioBerm™?
Although not necessary, a good way to create a BioBerm™ is to cover the entire growing substrate surface with a pre-vegetated sedum mat. Simply cut slits and plant plugs through the openings into the growing medium underneath. The pre-vegetated mat has many benefits to offer.
Sedum Mat is an Instant Green “Cover Crop”
While the native plant plugs grow, the sedum mat prevents wind and water erosion of the growing medium during establishment. It also acts as a “living mulch” to preserve soil moisture, reduce irrigation needs and minimize airborne weed encroachment.
Many native and adapted vegetation will thrive in 100-200 mm of growing medium in the BioBerm™. Select plants whose natural habitats are similar to the rooftops and avoid invasive species. Design plant palettes that offer longer bloom time to provide nectars for bees and butterflies and produce seeds and berries for birds. City of Toronto’s Design Guidelines for Biodiverse Green Roofs is an excellent resource in creating a successful biodiverse green roof.
Supplier of more than 2.5 M SQFT Coast-to-Coast
Canada’s leading supplier of pre-vegetated roofs, NLSM customizes to local requirements, offers warranty & maintenance support, provides stormwater calculations specific to location and building/roof type, stormwater test data & related innovative hydrologic modeling. Click here to get started on your next green roof.