Three Minute Thesis [What role do green roofs play in biodiversity?]

The following is the transcript from my speech at Mississippi State University‘s Three Minute Thesis competition. I’m sharing for two reasons: 1) it was a fun activity that I would like to do again for a chance at redemption (that’s a story for another day…) and 2) I wanted to share my research because that’s what doing research is all about!


What role do green roofs play in biodiversity?

Imagine yourself in the middle of a city. Impervious surfaces are everywhere, and generalist species like pigeons forage trash discarded by motorists on the street. Oily stormwater refracts into thousands of colors as it joins the sewer and is swiftly piped away through decaying stormwater infrastructure to a polluted river nearby.

Now consider for a second how things got this way: land use and cover change AKA human settlement consumes space and natural resources, which cause both habitat loss and habitat fragmentation—which in turn pressures wildlife populations across our planet.

The world’s human population is on target to hit 10 billion by 2050. Once, unbroken forests and grasslands stretched for countless miles, bisected by clear waters and healthy wetlands that naturally cleansed pollutants from the environment. Thousands of species of diverse biota populated the earth’s ecosystems in abundance and harmony.

As human settlement continues to expand, increasing pressure is applied to wildlife populations through habitat fragmentation and habitat loss.

Today, scientists and researchers of diverse disciplines are scrambling to unlock the potential in various green technologies as a means to mitigate some of urbanization’s toughest problems.

Because impervious surfaces like parking lots, roads, and roofs are associated with habitat loss, green roofs are being explored to combat that habitat loss.

This study seeks to establish baseline data on avifauna’s response to green roofs in the humid subtropical climate region. Two local sites, one urban and one rural were observed for six months to determine: one, what species are visiting? And two, how are these species using the roofs? More specifically, we wanted to know if green roofs with native plantings were more attractive to birds than green roofs with drought-tolerant non-natives.

The two green roof types, representing applied technologies to combat habitat fragmentation, were compared to typical asphalt shingle control roofs, which represent habitat loss, to see if green roofs even had an impact on local habitat and biodiversity.

So. What did the data say?

We found on the landscape scale that both sites observed the same general suite of species. In terms of number of species interacting with green roofs, the urban site observed four species and the rural site observed 16 species on the green roofs. For the most part, birds used the roofs—both control and living—for resting, perching, foraging, and vocalizing. When we looked at the living roofs, we found no statistical difference between the avian response to the native versus non-native plantings. But what we did find was a statistical difference between the living and control roofs-or the habitat fragmentation versus habitat loss roofs. In this case, our evidence supports the theory that habitat fragmentation has less of an impact on biodiversity than habitat loss.

So, if we want to protect our natural capital and protect wildlife populations for future generations, we must encourage both new and old development to include green technologies which address the phenomenon of habitat fragmentation and loss. Doing this will support global biodiversity by promoting biodiversity on the local scale by returning habitat loss to habitat fragmentation.


Here is the original:


To see the publication this piece originated from, see my Master’s Thesis from Mississippi State University: Examining the relationship between avifauna and green roofs in Mississippi’s humid-subtropical climate, 2015 (penned under my maiden name: Sara Katherine Lamb).

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