THE VALUE OF WHAT’S BEEN LEARNED

with Steve Apfelbaum and Susan Lehnhardt

Ecologists Steve Apfelbaum and Susan Lehnhardt are frequent Studio Gang collaborators and led the Studio’s rooftop bioblitzes in 2016, 2017, and 2018. We spoke with Steve and Susan about the ecology of our rooftop, the concept of sky islands, and the importance of citizen science.

What is the ecological history of the Chicago region?

It all depends on what time period you look at, but within the past 12,000 years this landscape we live on has transitioned from a spruce and fir boreal forest system to a northern hardwood forest system to a savanna and prairie system. It has remained a savanna and prairie landscape for the past 7,000 or 8,000 years. Because of the

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young nature of the landscape, it’s very poorly drained. This is not just because the land is relatively level or flat but also because it was transformed by glaciers. The glaciers that moved across this part of the Midwest left behind heavy clay soils, and in their wake other heavy soils developed: mucks and peats. The result is that the Chicago region was historically a very wet, very productive, mineral-rich landscape primarily consisting of prairies, wetlands, and savannas before agricultural development and urbanization began.

What are the basic tenets of restoration ecology and how can we use them to establish and maintain our green roof?

The basic tenet of restoration ecology is to put back into the land what has been lost. This typically translates into encouraging native plants in existing degraded settings using management practices and/or reintroducing the seeds for native plant assemblages that will be attractive to pollinators, soil microbes, soil fungi, and a larger, diverse animal community: birds, mammals, reptiles, amphibians, insects, and others. A green roof designed with the right physical conditions can contribute to some of the biological life previously found in historic ecosystems. Your green roof addresses the basic requirements of this tenet and provides habitat for these communities.

By creating an elevated prairie environment you’re actually doing something that doesn’t exist in nature in your area. There are no cliff communities nearby, for example, that might be representative. So with your roof you’re not trying to duplicate nature—instead you’re trying to create plant and animal communities that emulate, that are similar to some of the structure and composition of the local plant communities like prairies and savannas. Planting native prairie and savanna plant species has been the primary strategy used to create the green roof, along with some cultivated grasses

and flowers that are not local. You even baked bread with the wheat cover crop that was grown and harvested that first year, demonstrating that green roofs can equally provide humans with food and enjoyment as it can provide environmental and ecological benefits.

You mentioned cliff communities. Can you talk about the sky island idea?

Sky islands are wonderful places on the planet—they’re high-altitude areas that are typically totally disconnected from the environment of the surrounding lowlands. So what you find on quite a few of these sky islands are species of plants and animals that aren’t found in the valley bottoms, including absolutely different species, new species, and rare species. Some examples are mesas in Utah that are 500 to 1,000 feet high and the tepuis in Venezuela that are nearly a mile high.

The idea of a sky island may therefore be symbolic of what you’ve done with your roof in Chicago. You haven’t created a sky island with the specific qualities of those found in Utah or Venezuela, which have cooler temperatures, receive more rainfall, and have shorter growing seasons than the valley below. But you’ve created functioning habitat that’s located 30 to 40 feet above the ground. And what’s so interesting, as demonstrated by our sampling is that—like the naturally occurring sky islands—there’s a completely different ecosystem on your green roof compared to what’s down below at street level.

Sky islands are considered hot spots of biodiversity. Can you talk about the benefits of biodiversity?

Biodiversity creates products and conditions that all life on the planet needs. Every organism uses resources differently and creates various waste products that become feed stock for other organisms. Plants photosynthesize differently and sequester more or less carbon, some of which can contribute to soil building (improving the quality of soil). Soil microbes, soil fungi, and insects respond to each plant species, and over time, as an ecological community diversifies, will provide secondary benefits that are often called ecosystem services. Think air quality cleansing, stormwater cleansing, soil building, pollinating by visiting insects, seed and spore dispersal by the wind and visiting birds, and many additional services. Rather than a typically hot and nearly lifeless rooftop, your green roof is alive, cool, and will continue to grow with life. In fact, be prepared for visits from wildlife that will provide a wonderful surprise.

The benefit of a diverse ecosystem is that you have redundancy, which means that there are multiple species and thus multiple pathways for carrying out the necessary ecosystem services. This makes for a much more efficient system that is capable of operating effectively under a broader range of conditions. Biodiversity thereby means a more resilient environment that can sustain itself in the face of change.

What are the ways in which we’ve lost biodiversity through human activities and what are the ecological consequences?

We’ve lost a lot of the species and the stability that a diverse ecosystem used to provide on a landscape scale, and there are many negative impacts of this loss.

One major result of reduced biodiversity, which is certainly an issue in Chicago, is the loss of natural stormwater management—an important ecosystem service. Historically, during an average year, more than 70 percent of the rainfall and snowmelt on the Chicago region would soak into the ground or immediately evaporate back into the atmosphere. Due to human activities like developing massive agriculture and building modern cities, now 70 to 80 percent of this water runs off the land. So we’ve lost a large percentage of the historic landscape’s ability to manage normal rainfall events, and this is an increasingly serious problem as rare storm

events and the excess water they deliver become more frequent because of climate change. Today, as a consequence, we have more destructive floods and deteriorated water quality. We also have much higher rates at which agricultural runoff— stormwater that is mixed with chemicals used to increase crop yields—spills off farmland and enters waterways, making its way downstream. This runoff can pollute drinking water supplies and recreational water bodies. It also harms aquatic life.

You led our rooftop bioblitzes in 2016, 2017, and 2018, where we used citizen science techniques to record and measure different aspects of our green roof, including the varieties of insects and plants found there and some seemingly wizardly measurements of the soil microbe and fungi species. Can you talk about the role of the citizen scientist?

Every human being who is sensitive to and becomes knowledgeable about nature becomes an observer, and as people hone their observation skills, they become very astute. The biological sciences are historically grounded in the work of skilled observers. Over the years, techniques of measurement have been developed to “capture” and attempt to “objectify” what can be observed. So transitioning from being a good observer to measuring nature is a wonderful way for people to become more in tune with what’s happening around them. Just the process of formalizing the way observations are made and recording them results in even more astute observation skills and helps us all communicate the world’s discoveries about nature. Many of biology’s most important discoveries have come from gardeners and others who make keen observations and share what they learn in very simple ways— and the people they share them with might be scientists who recognize the value of what’s been learned, what’s been observed. Especially in this day and age, when scientists don’t seem to be held in high political esteem, citizens may have a better chance of elevating the conversation and getting more attention from policymakers around the world. The more, the merrier.

Steve Apfelbaum and Susan Lehnhardt are senior ecologists with Taylor Creek Restoration Nurseries and Applied Ecological Services, Inc., an ecological science and restoration firm headquartered in Brodhead, Wisconsin. They are both actively involved in nonprofit conservation and citizen science efforts. Susan is President of the Lower Sugar River Watershed Association, and together with Steve, who is Board Chairman of the Southern Wisconsin Land Conservancy, has been sponsoring bioblitzes annually near Brodhead each June. These events have drawn several hundred citizen scientists who work with experts to survey butterflies, moths, mammals, fish, amphibians, plants, mushrooms, and anything else that grows, crawls, swims, flies, or slithers. Anyone wishing to participate should visit LSRWA.org.

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