A prairie roof at Freedom Field — exploring new horizons

The prairie roof at Freedom Field. (Photo provided)

By Drs. Robert & Sonia Vogl
President and Vice President, Illinois Renewable Energy Association

Little remains of the original prairie vegetation that greeted the Europeans upon their arrival in Illinois. Given their existing knowledge, they saw little practical use in the native landscapes and proceeded to lay waste to them to live as they saw fit. They began building a new society of farms, cities and industries that provided them with many comforts and conveniences unknown to previous generations.

In the process, they destroyed almost all of the existing prairie vegetation that had been thriving with only limited human intervention for nearly 10,000 years following the retreat of the glaciers. Prairies grew on the glacial deposits of rock, sand, gravel and clay. When the plants died and their parts decomposed, they contributed to the development of some of the richest agricultural soils in the world.

The plants adapted to the extremes of weather — floods, droughts, heat waves and frigid temperatures — characteristic of Illinois. They thrived in a variety of settings, including wet, mesic and dry habitats, and benefited from periodic fires.

In the 1930s, Aldo Leopold, through experimentation, successfully restored prairies as functioning communities to preserve local plants and their diversity.

In the 1960s, Ray Schulenberg began growing prairie plants from seeds and rootstock in a greenhouse at the Morton Arboretum. Schulenberg felt it was important to learn how to grow the plants and encourage their use in prairies and prairie gardens to build up broadly-scattered sources of prairie plants and seeds to increase their survival opportunities and to stimulate public interest in prairies.

We continue our involvement in protecting natural areas and prairies, and have two sand remnant prairies and two restored prairies on our farm.

A few years ago, Dave Smith of Simply Prairies designed and installed a prairie roof on a small building on his property. His prairie of potted plants has thrived in a base of aged locally-obtained woodchips roughly 8 to 10 inches deep. While we knew prairies live in a range of soil types, depths and moisture regimes, we were pleasantly surprised by how well his prairie roof grew. We usually think of prairie plants as deep-rooted, but prairies can thrive nested on top of limestone formations in very shallow soils. In such settings, the plants send their roots out horizontally rather than vertically. The plants also flourish in dry, thin, sandy soils overlaying sandstone outcroppings.

Insects feeding on the plants pass on their wastes, enriching the woodchip base. As plants die back and decompose, they, too, enrich the woodchips. The plants attract insects and birds, increasing survival opportunities for these natives.

At our suggestion, the board of Freedom Field agreed to place a test rooftop prairie on their building.

About 1,300 plants of more than 40 species were placed on the roof. Plants with eye appeal were selected as we wanted something of beauty available for showing at last fall’s International Bioenergy Conference in Rockford. Over time, the plant composition may change as the species adapt to the microclimate of the roof.

A prairie roof needs very little maintenance, as the genetics of the plants are well adapted to the rigors of our Midwest climate. Some weeding is necessary; the first year’s plants were periodically watered during this past summer’s heat wave. Limited fertilization may be required. As expected, some plants died, but they were easily replaced. A flexible maintenance plan is being developed.

In addition to the benefits of water retention, reduced summer heat gain, and cleaner air, a prairie roof helps to preserve rapidly disappearing local genetic diversity and offer habitat for insects and birds.

Although beauty could be reason enough for its being, some perceive a prairie roof of limited practical value, which denies the possibility of new understandings that could prove useful to us. For example, the Pacific Yew was seen as useless until extracts from it proved useful in treating breast cancer. Additionally, Wes Jackson’s experimental work on perennial food crops from prairie plants, if successful, could revolutionize agriculture.

Drs. Robert and Sonia Vogl are founders and officers of the Illinois Renewable Energy Association (IREA) and coordinate the annual Renewable Energy and Sustainable Lifestyle Fair. E-mail sonia@essex1.com.

From the Sept. 14-20, 2011, issue

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