We need to halt the loss of species, right? Right. We should start building more sustainably to both reduce habitat destruction and create new habitat. It would be a giant waste of energy and resources to tear down and rebuild unsustainable buildings. BUT it is worth the effort to modify those buildings in ways that make them more “green”. One way to do this is to turn the roof into a green space. We need to start seeing the available roof space as potential habitat, not just for smoke breaks.
There are already thousands of acres of available roof space in cities around the world. In a paper by Dr. Gyongyver Kadas on the use of green roofs by rare insects in London, she estimates that there is about 65,000 acres of available roof space that would be easy to green- that’s like 50,000 football fields! The paper documents the insects and spiders on current green and brown roofs in London. That’s right, brown. Brown roofs are like green roofs but instead of adding plants, brown roofs are created with local soil and rocks. They are then left alone for plants to colonize themselves- if you build it, they will come.
Dr. Kadas found thousands of invertebrates on the roof tops- including nationally rare species of spiders and beetles- on both the green and brown roofs! Because some of the roofs are only 1-2 years old and the fact that she found more species in the second year of her study, as the roofs age, they have potential to support a vast assemblage of invertebrates and their avian predators.
A lot of these rare invertebrates have a limited range- meaning they don’t live in many places- so the roof tops can offer important habitat and maybe even the only habitat in highly urban areas. If we study the habitat needs of these rare species, we can add certain food plants or wood piles for nesting sites and enhance green roof potential even further!