ARBORETUM NEWS (NATURALISTSNOTES)

What Dane County Looked Like in 1834

SATURDAY, AUGUST 20, 2011

Oak openings or savannas, marshlands, and prairies – that’s what our Arboretum and the lands of present day southern Wisconsin looked like before the land became available for sale in the mid 1830’s. Farmers with steel plows, citizens with fire hoses, and entrepreneurs with ever more effective earth moving equipment, and several generations of extensive road and city building have dramatically changed the landscape within a relatively short period of time.

I say, “relatively short” because a landscape that slowly evolved over thousands of years has been altered beyond recognition in just over a few hundred years. Our population size, legal/land owning practices, economic and social systems, etc. lead to some very practical reasons why we would not do well to allow or encourage fires to regularly march through Madison. These periodic fires (as often as yearly or possibly overlapping areas of fire in a single year), along with some dry and drought periods were the main drivers in the development and maintenance of oak savannas and prairies. So, I’m not offering my house, or yours, as tinder to go back to these days. However, it is a challenge to imagine the landscape of the early 1800’s and earlier. And, that is in part, what the Arboretum is about: re-creation, maintenance, and study of historic landscapes and biotic communities. In the 1940’s, the Arboretum staff were pioneers in the practice of using fire to imitate how the prairies and oak savannas were formed and persisted before the eras of farming, city building and fire suppression.

It is great to see that people are learning about and planting prairie grasses and plants. These prairie plants are still well adapted to our climate. While they require some care to get started, once established they have their own capabilities to weather droughts, floods, and the vast range of weather we get here – including lighting your yard periodically on fire (you need a permit for that).

The largest prairie area at the Arboretum is just to the south and west of the Visitor Center and parking lot. It is 73 acres, and it is named after the botanist, John Curtis. Published in 1959, his book, The Vegetation of Wisconsin, describes the various plant communities of historic and present day Wisconsin. Inside the front cover is a vegetation map of Wisconsin from about 1840 drawn from various types of seed and soil analysis, as well as survey, journal and oral histories. Along the Mississippi River and throughout the southern half of Wisconsin oak savanna is the most extensive plant community, with zones of oak forest, especially towards Lake Michigan. Looking a bit like abstract art are fingerlike projections and significant splotches of prairie amongst the oak savanna. One thing that isn’t shown on the map are the fairly extensive marshlands that existed around Lake Wingra and many of the lakes in the area.

This is what John Curtis (1959:262) wrote about the landscape before the era of European settlement of the landscape:
The prairie is a plant community dominated by grasses rather than by trees as in a forest. Growing with the grasses are many other species of non-grassy herbs which are known by the collective name “forbs.” Many woody shrubs are present in the prairie as well, and under certain circumstances, tree seedlings may also be found. The prairies frequently grade imperceptibly through an oak savanna to a denser oak forest, although on occasion there may be a rather abrupt boundary between grassland and forest, particularly at rivers or at places of rapid topographic change. On moist soils, the prairies blend into marshlands dominated by sedges rather than by grasses. Since these transitional boundaries are present, it is necessary to establish the criteria by which a prairie may be recognized. For purposes of the present discussion, a prairie is defined as an open area covered by low-growing plants, dominated by glasslike species of which at least one-half are true grasses, and with less than one mature tree per acre.

As Curtis writes, the plant communities may have boundaries that both contain the some of the same species and gradually grade into one another. As we have some old oaks in the central part of Curtis Prairie and along Arboretum Drive to the north end of the prairie, we walked along both of these areas and got some of the feel for this transition from open prairie the dapled shady environs of the oaks.

The oak openings of the past were described as “park like,” open areas with oaks that look as if they were planted, similar to a classical arboretum planting such as we have in Longenecker Gardens. Similar to the definition of prairies, there isn’t an exact definition of an oak savanna. The oak part is clear – oak savannas have oak trees. How many? What kind? That’s where the variety begins. The type and amount will depend on moisture conditions, location, soil type, and other weather and climate conditions, such as the frequency of fire. Typically, the oak savannas had more than a few oak trees per acre, but less than 50% tree cover. More than half of the landscape covered with oaks would be an oak forest. You can also get a feel for a mixture of oak opening and prairie plant communities on the south side of the Arboretum property in the Grady tract.

Paul Borowsky
Naturalist

Located between Lake Wingra and the West Beltline Highway at 1207 Seminole Highway, the University of Wisconsin-Madison Arboretum features the restored prairies, forests and wetlands of pre-settlement Wisconsin. This 1,260-acre arboretum also houses flowering trees, shrubs and a world-famous lilac collection. Educational tours for groups and the general public, science and nature-based classes for all ages and abilities, and a wide variety of volunteer opportunities for groups, families and individuals are available.