What is a Biodiverse Roof?
A biodiverse roof is a type of green roof designed to provide a habitat for varieties of flora and fauna. Particularly in urban areas. Often these roofs are designed to recreate habitats lost when the building in question was erected.
Whilst a traditional intensive or extensive green roof don’t solely focus on supporting habitats – green roofs have multiple other benefits. Biodiverse roofs focus on one thing. Biodiversity.
Biodiverse Roof Diagram
A biodiverse roof – as shown above – is very similar in style to a typical green roof.
Really what gives the biodiversity angle away is the ‘rough and readiness.’ The roof is left to the elements and designed to encourage specific species. So plants, vegetation and debris is purposefully collected to provide the right conditions for specific animals and plants to thrive.
Green Roof vs Biodiverse Roof
Green roofs can be created with a multitude of different goals in mind.
- Reduce pollution – both air and noise
- Mitigate runoff
- Enhance mental wellbeing
- Reduce the urban heat island effect
Whereas biodiverse roofs are designed with one principle focus. To encourage biodiversity. To restore the imbalance created by urban development and create habitats for wildlife destroyed by urbanisation.
Brown Roof vs Biodiverse Roof
Whilst brown roofs and biodiverse roofs are commonly mistaken to be one and the same. They are not. There are subtle differences that separate the two.
Biodiverse roofs have seeds and / or plants introduced at the time of construction. They’re specifically developed to encourage certain species.
Brown roofs are akin to brownfield sites. Areas of land once developed that have been left to the elements (and are now commonly used for self-build projects). Instead of planting seeds and encouraging specific growth, they’re left to windblown or bird-carried seeds to develop naturally. So you could get anything.
Biodiverse Roof Pros & Cons
Whilst biodiverse roofs have some really tangible benefits – the potential to increase endangered flora and fauna population, alongside some standard living roof benefits – there are some potential downsides to them.
Roofs can be incredibly harsh environments. Much more so than ground level. And replicating that has its challenges.
Pros
- Encouraging specific flora and fauna development
- Pollution mitigation
- Runoff mitigation
Cons
- Roofs are stressed environments
- No guarantees wildlife will inhabit
- Can be left with a less effective version of a green roof
Biodiverse Roof Example - Black Redstarts
Perhaps one of the most famous examples of biodiverse roof success (in the UK at least) has been the Black Redstart – a small robin like bird that has grown accustomed to thriving in industrial areas and urban centres.
They came to particular prevalence during WWII, nesting in and amongst the rubble caused in The Blitz. But their numbers declined during the 60s and 70s as the industrial sector dwindled.
Fortunately, many biodiverse green roofs popped up specifically focused on restoring the population. With fewer than 100 breeding pairs in the UK (earning them a place on the red list), the success of these roofs in restoring Black Redstart numbers is paramount.
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