Planting the Seeds of Science to Grow Better Green Roofs
A bird’s-eye view of most cities captures the barren landscape of asphalt-covered rooftops, sprawling from one high-rise structure to another. As the sunshine makes its way across the city, the intense rays bake the dark roofs; and when the sun turns to rainfall, it floods the concrete sidewalks below.
Urban architecture in most areas across the United States is not ecofriendly - after all - many buildings date back generations, long before the green movement started making its way from Europe to America. But a new trend is starting to emerge throughout the country – green roofs.
Just like its name implies, green roofs are man-made green spaces on the top of buildings. Besides the decorative benefit, they can grow produce, catch storm water, control temperature, provide habitats for wildlife, and simply turn an unusable rooftop into a recreational haven.
What some call a sustainable answer to urban flaws, Anna Droz calls research. As a biological sciences’ doctoral student in Kent State University’s College of Arts and Sciences, Ms. Droz’s curiosity has developed into a passion, maybe even an obsession to discover the best green roof combinations with the best plants, best soil and best micro-organism communities.
“Design is limited,” says Ms. Droz. “Roofs are not meant to support a lot of weight. So, a lot of times these designs end up being this very thin layer of non-native plants. They are still good, and can catch storm water, but they’re not as sightly to look at and don’t provide many benefits such as thriving habitats for pollination and things like that.”
Ms. Droz asks one question: is there a way to make roof top gardens better? Her quest for the answer took her to the heart of the Midwest where she toured nearly 50 roofs. In Minnesota, Ms. Droz explored the rooftop of the American Swedish Institute in Minneapolis, the St. Paul Fire Headquarters and another on top of the Minneapolis Central Library. She also toured the gardens atop the Peggy Notebaert Nature Museum and the Hyatt Regency building in Chicago.
What she learned, she brought with her to the top of the Cleveland Industrial Innovation Center where she built 48, one-meter square plots out of wood. In the summer of 2015, she brought in the soil and started planting.
Each plot boasts a unique ecosystem. Some plants are randomly selected, others are from a prairie community based on observations made in a nature preserve in Toledo, Ohio.
The soils range from compost to artificially engineered blends of clay and shale, as well as sandy soils found in a rain garden. Ms. Droz also added microbes, or fungi, in hopes it will colonize and boost the health and functioning of the plants within.
As she collects data, she is comparing the plots to see which looks the best and which are the healthiest. Her next step will be to look at the soil and water quality and ultimately share her research findings.
“I’m hoping that by answering these ecological questions, we can add a bit of realism to green infrastructure and environmental architecture,” Ms. Droz says. “The field is growing and people are optimistic, but there isn’t a lot of science going into it. If this is going to be everywhere, we want to make sure that we know what works and why. My hope is to bridge this gap between design ecology and hard science.”
Ms. Droz plans to continue collecting data over the next two years until graduation. She hopes her research makes a difference in the biological make-up of green roofs, and opens doors to turn her passion into a life-long career.
“It would be really nice if I could enter the field of architecture as a scientist, which I have been exploring that possibility,” Ms. Droz says. “It would be nice to be in a position to tell people that their ideas are ecologically sound. It’s so new, you want every application to be as sound as possible, because it’s trailblazing.”