Why the Oak Opening is Still Closed: the Problem of Nature in its Restoration

I wrote this essay as a “place paper” in Bill Cronon‘s Environmental History course in the fall of 2010. 

Aldo Leopold
Aldo Leopold

In June of 1934, a crowd of onlookers stood around the men whose visionary leadership had led to the purchase and creation of the University of Wisconsinʼs Arboretum. The Universityʼs newly appointed chair of Game Management, Aldo Leopold, spoke to the crowd: “This hill on which we stand was then an ʻoak opening.ʼ Our grandparents describe, sometimes with rapture, the beauty of these open orchard- like stands of oaks, interspersed with copses of shrubs, and the profusion of prairie grasses, and flowers which grew between.” He envisioned the new Arboretum as more than a collection of trees, but rather, “a sample of what Dane County looked like when our ancestors arrived here.”[1]

Prior to European settlement in the mid-19th century, oak openings were by far the most dominant ecosystem in Dane County.[2] They covered upland areas with white and bur oak trees characterized by their open-growth form, with branches extending perpendicularly from the trunks, making them wider than tall. These trees did not grow close together as in a forest, but widely spaced, so that sunlight reached the ground between, supporting a diverse mix of prairie grasses, shrubs, and wildflowers. This vegetation, along with the acorns of the oaks fed a diverse mix of herbivores, including bison, elk, deer, birds, and people. American Indian societies thrived in oak openings from their emergence 8000 years ago up until European settlement.[3] But the incoming Euro-American settlers did not value these ecosystems, only the soil underneath. The great openings were quickly converted into cropland, so that fewer than 500 of the 5.5 million acres present at the time of settlement remain intact today.[4]

Just what kinds of species had these landscapes contained? Nearly one hundred years of settlement had erased many traces of the past. It was the quest for this knowledge that led to one of the most comprehensive accounts of a regionʼs vegetation ever compiled. Newly appointed professor of plant physiology, John Curtis, was involved with the Arboretum from the start. Along with a slew of graduate students, he spent nearly two decades collecting data from around the state, resulting in the 1959 book, The Vegetation of Wisconsin.[5] This work organized vegetation into distinct communities such as prairie, savannah, forest, or sedge meadow. The plant species most commonly found in these communities were listed, along with a section on their origin and maintenance. Armed with these species lists and management techniques, Arboretum scientists were able to begin the process of restoration.

Curtis Prairie

The first known prairie restoration in history and the Arboretumʼs most successful, took place in what is now called the Curtis Prairie. This former pasture and cropland was planted with seeds collected at several prairie remnants near the Wisconsin River. The project was initiated under the direction of Aldo Leopold and botanists Norman Fassett and John Thompson starting in 1935. A camp of Civilian Conservation Corp men was set up at the Arboretum, and many of these men were employed on the project, experimenting with different seed mixes along with seeding and transplanting techniques.[6] Today, the Curtis prairie boasts well over 200 native species, and is the best-known prairie restoration in the world.[7]

Thanks to low land values at the height of the depression, the Arboretum quickly grew from its original purchase of 245 acres in 1934 to nearly all of its present size of 1200 acres by 1941.[8] By the time John Curtis completed The Vegetation of Wisconsin in 1959, the Arboretum had begun the establishment of most of the communities found there now. These include a floodplain forest and Ohio Valley forest at Galistel Woods, a northern Wisconsin coniferous forest at Leopold Pines, mesic deciduous forest in Noe Woods and the Lost City, northern Wisconsin deciduous forest in Wingra Woods, prairie at Curtis and Greene Prairies, and oak savannah and woodland in the Grady Tract. Through their work on these projects, Curtis and his his students developed the ordination techniques and plant community theory which came to be known collectively as the Wisconsin School.[9] Their pioneering work in the restoration of vegetation communities at the Arboretum set the stage for the development of restoration ecology, which emerged as a distinct discipline in the 1980s. Arboretum researchers such as William R. Jordan III and Joy Zedler played central roles in the disciplineʼs emergence and continue contributing to its evolution, authoring some of its foundational texts, and producing one of its defining journals.[10]

Hickory and dead White Oak surrounded by Maple trees in Wingra woods

Because of its unique vision of recreating the former landscape and significant academic success in restoration ecology, the Arboretum should be covered in restored oak openings, just as they would have once appeared. But these openings are practically non-existent. One of the last remaining signs of the landscapeʼs open history can be found at Wingra Woods, a 52-acre upland rising out of the marsh just south of Lake Wingra. The large stand of open-grown oaks here were one of the Arboretumʼs few remaining remnant oak openings. Instead of plowing for crops, the former owners had kept the area a pasture, burning each spring to renew the grasses for cattle. Immediately following purchase by the Arboretum, burning ceased, and a woody understory including invasive honeysuckle quickly developed. Arboretum scientists then decided to “give Mother Nature a boost.”[11] Between 1943 and 1961, over 3000 sugar maple, red maple, ash, birch, and hemlock seedlings were planted underneath the oaks together comprising the Arboretumʼs most successful northern Wisconsin deciduous forest restoration.[12] Unfortunately, this success necessarily came at the expense of the oaks, which have since been crowded out, their skeletons one of the Arboretumʼs few reminders of its open history. The closed canopy of the forest suppressed the grasses that once held stable the hillsideʼs soil making way for the shade-tolerant invasive shrubs honeysuckle and buckthorn which have continued to dominate.[13] Every year, Arboretum staff and volunteers spend hundreds of hours armed with saws and herbicide, trying to eradicate these unwelcome invaders.[14] The only decent size purposeful savanna restoration occurs on the Grady Tract, where bur oaks were planted and fire has been used to try to recreate native ground cover. This section bears little resemblance to an oak opening as it also struggles with the same invasive species, requiring many hours and much energy to combat.[15]

What happened to Aldo Leopoldʼs vision for the Arboretum? Why didnʼt Curtis and his students recreate “a sample of what Dane County looked like when our ancestors arrived here?” Most of the Arboretumʼs currently restored communities were not found in Dane County prior to settlement. Some of them occurred in the state, such as the northern coniferous and deciduous communities, but others, like the Ohio Valley flora, are not even native to Wisconsin. The most egregious example was a pet project of one of John Curtisʼs students, Grant Cottam. Cottam was from Utah, and his failed attempt to create a western ponderosa pine community in the Grady tract is sometimes affectionately referred to as “Cottamʼs Folly.”[16] The Arboretum was successful in establishing many different vegetation communities, especially forests. Yet the oak openings mentioned in Leopoldʼs speech, the only of these communities that actually existed here before Euro-American settlement, are conspicuously absent. Paradoxically, the institution which has been so successful, leading the world in the science of restoration ecology, has seemingly failed in its most primary purpose of restoring historic vegetation.

In addition to Leopoldʼs vision, there was another strand of thought influencing the thinking of the Arboretumʼs founders. In 1928, prominent attorney Michael Olbrich gave a speech to the Madison Rotary Club providing the first public plans for the Arboretum. He concluded that an arboretum that was not also a refuge was of little purpose; quoting Thoreau, he argued that “In wildness is the preservation of the world – hope and future for me are not in lawns and cultivated fields, not in towns and cities, but in the impervious and quaking swamps.”[17] Olbrichʼs vision of the Arboretum was thus to create a place where wilderness could be preserved in perpetuity.

On the surface, Olbrichʼs vision seems perfectly compatible with Leopoldʼs. The Arboretum could simply restore the natural wilderness existing prior to settlement. This was exactly the reasoning behind the 1949 Arboretum master plan created with John Curtis as director, to revalue the Arboretum project as a whole. The Arboretumʼs main objective was defined as “an outdoor demonstration and research area in which native plants, animals, and landscapes can be studied under natural or nearly natural conditions.” The Arboretum was also to serve an educational function, providing “living models or dioramas of the pre-settlement Wisconsin landscapes.”[18] It was this master plan that lay behind the diverse, if strange, plant community restoration projects that proliferated in the 1950s. But there is a major problem with the idea of restoring the pre- settlement landscape so they can be studied under “natural or nearly natural” conditions. The oak openings were not natural ecosystems, and setting them aside as wilderness leads directly to their demise.

The climate of southern Wisconsin has been sufficiently moist for the past several thousand years to support deciduous forest as its climax vegetation.[19] This means that left alone under “natural” conditions, trees like maple and basswood gradually shade out and replace the oaks and grasses, creating moist conditions suitable only for the replacement of the newcomersʼ own offspring. But just as they help create conditions suitable for their own replacement, oaks and grasses can too, but only with a little help from friends. In autumn, the leaves of the oak fall to the ground, and unlike their moister cousins whose leaves decompose rapidly, oak leaves remain dry on the ground. At the same time, the perennial grasses and flowers of the understory, having completed their annual task of pollination, germination, and seed production, leave mounds of dead and drying material sitting on top of the ground. Along with the oak leaves, this material creates perfect conditions for fast-moving, relatively cool ground fires that pose no threat to the thick-barked fire-tolerant oaks towering above. Frequent burning of the oak opening understory by Indians allowed it to persist for millennia despite the wetter climate. So the forests of fire-intolerant maple and basswood that now cover uncultivated areas of southern Wisconsin, including in the Arboretum, sprang up only after settlement, when fires ceased to annually clear and renew the openings. John Curtis and others recognize fire as necessary for maintenance of oak openings, but fire is only half of the equation.[20]

Following a ground fire, grasses and wildflowers grow rapidly with the pulse of carbon and phosphate to the soil. This new growth is high in nitrogen, and eagerly sought by grazing animals. Oak trees also provide a cool environment in the hot summer months, not only by the shade underneath the canopy, but also from the massive amount of transpiration pulling water from the ground and pumping it into the atmosphere, actively cooling the ground underneath. The desirability of this cool environment in the summer would have made the land under the oaks popular places to eat, rest, and wallow for many herbivores, including bison, elk, deer, and people. It was thus a combination of fire and grazing that was responsible for the ecosystems encountered by the first European settlers – ecosystems that had sustained the Indian societies who maintained them for millennia.

The extent and dominance of the oak openings at the time of settlement is testament to the magnitude of Indian management in the area. Their main tool was fire. United States Forest Service scientist Gerald Williams reviewed hundreds of studies documenting dozens of major uses for fire, including hunting, crop management, and improving the growth and yields of plants for animal grazing. The overall purpose of burning, he suggests, was to “promote a diversity of habitats…which gave the Indians greater security and stability to their lives.”[21] One of this subjectʼs most prominent scholars, Henry T. Lewis, came to a similar conclusion, arguing that purposeful burning was done to establish or keep “mosaics, resource diversity, environmental stability, predictability, and the maintenance of ecotones.”[22] The oak openings were created and maintained by Indians because of their high functionality and the magnitude and diversity of goods they provided.

The oak tree represents the obvious keystone of the opening ecosystem. Their abundant seeds create a pulse of food for many different animals. Not only were the acorns themselves a staple of Indian diets, but they also contributed to high quality protein sources as transformed into the flesh of the deer, elk, and birds. The oaks also provided a stable source of high quality wood for fuel and building material. But the real benefit of opening over woodland is the diversity of understory vegetation that can thrive in the increased sunlight reaching the ground. These grasses, flowers, and shrubs supported populations of many animals including bison, elk, deer, bear, prairie chickens, grouse, rabbits, skunks, and badgers. These plants also provided valuable food and medicine for Indian peoples.[23] Sweet crabapples, prairie plums, and raspberries are just a few of the native fruit bearers. Bee populations thrived, navigating between their tree- bound hives and the floral nectar growing underneath.[24] By bringing together the benefits of the forest and the prairie to the same place, Indians created oak opening ecosystems producing more abundance than either alone could provide. Through their continued maintenance, Indians provided themselves a cornucopia of high quality meats, vegetables, fruits, nuts, medicines, honey, fuel, and building materials.

An 1852 Seth Eastman illustration of a Winnebago family encampment. Source: Wisconsin Historical Society

It was this ecosystem that had been formerly maintained and used by Indians on the Arboretum lands. There had been several Ho-Chunk families remaining camped on the Lake Wingraʼs shore up until 1910 when their traditional practices were finally no longer possible in the civilized farming and urban landscape. Archeologist and curator a the State Historical Society, Charles Brown was a member of the first Arboretum Committee, and held controversial views of the Arboretumʼs future. He advocated a return of the Indians themselves, along with their homes and former means of subsistence. He also wished to display on the shore of Lake Wingra a dugout canoe that had surfaced during dredging operations. The rest of the committee, however, disagreed. Arboretum historian Nancy Sasche writes that “the scientists did not care for any such clutter of historical relics living or dead, which might intrude upon the restoration of the land.”[25] It was decided early on that good objective science would be the key to proper restoration. This kind of science relies on a rigid distinction between the human and the natural world, observer and observed; a distinction not present in the landʼs original inhabitants who, as archeologist Robert Birmingham suggests, “traditionally perceived themselves as an integral part of the natural world and active participants in maintaining cosmological order.”[26]

The distinction between ʻhumansʼ and ʻnatureʼ is the curse of the ecological sciences so successfully developed in the Arboretum. It insists on studying the natural world – the world as it would be without human interference. We have seen, of course, the absolutely destructive power of human civilization driven by capitalistic markets toward the conversion of all natural resources into sellable commodities. So it makes sense that the discipline of ecology seeks to study the world without these harmful anthropogenic impacts. Yet this philosophy simply strengthens the divide between humans and nature, crushing creativity, and preventing scientists from actually valuing and utilizing the goods produced or produceable by those ecosystems they wish to restore. Aldo Leopold was well aware of this problem, writing that “The hope of the future lies not in curbing the influence of human occupancy – it is already too late for that – but in creating a better understanding of the extent of that influence and a new ethic for its governance.” Unfortunately, it seems Leopoldʼs words were left unheeded, as ecologists insist on stepping away, graciously giving the land “back to nature.” It is no surprise then that the Arboretum contains no functional oak opening ecosystems. For these are not natural ecosystems at all, but the result of persistent and intentional human use. This philosophical blunder is by no means constrained to the Arboretum, but is a defining feature of restoration ecology in the United States.[27]

Restoration of the oak openings can not be achieved by stepping away from the land, expecting that nature preserved as wilderness will provide critical function and services. Instead, we must act in concert with “natural processes,” becoming active components of the ecosystem, not passive scientific observers. In his classic text Game Management, Aldo Leopold stressed that “effective conservation requires, in addition to public sentiment and laws, a deliberate and purposeful manipulation of the environment.”[28] He claimed that “game can be restored by the creative use of the same tools which have heretofore destroyed it – axe, plow, cow, fire, and gun…. Management is their purposeful and continuing alignment.”[29] Humans must step back onto the land, not as natureʼs master, but as its key facilitator. We must actively engage in the restoration of functioning ecosystems, not to preserve some form of wilderness devoid of humans, but to provide ourselves with high quality goods and services as the basis of our subsistence.

We no longer rely on functioning ecosystems for survival. Instead, we substitute with fossil fuels the generation of the goods and services such as food, fiber, fuel, clean water and fertile soil, those ecosystems once provided. As ecosystems collapse into dysfunctional states around the globe, this nearly complete substitution has left us helplessly reliant on fossil subsidies.[30] With peak oil, climate change, and wars in the Middle East, this reliance is becoming more and more unsustainable. We must act now to restore our ecosystems back to functional states. But this will require us to redefine our notions of nature and our role as organisms embedded within it. Fortunately, Wisconsin has the climate, soils, and genetic material available to once again support functioning oak opening ecosystems. Leopoldʼs vision has not yet been realized, but the words from his 1934 speech continue to ring true: “it is important to the future welfare of our state to know what it was like before we took it away from the Indians.”[31] His idea for the Arboretumʼs function as “a reconstructed sample of old Wisconsin, to serve as a benchmark, a starting point, in the long and laborious job of building a permanent and mutually beneficial relationship between civilized men and a civilized landscape,” is just as valid and important today.[32] By renewing their commitment to Leopoldʼs vision, not just in words but in deeds, the Arboretum could once again revolutionize the practice of restoration, creating landscapes with humans embedded as integral components and beneficiaries of functional ecosystems.[33] We can reopen the oak openings. They just need a little help from friends.


[1] Aldo Leopold, “An address at the dedication of the University of Wisconsin Arboretum June 17th, 1934,” in Our First 50 Years: The University of Wisconsin Arboretum 1934-1984, anonymous (Madison: University of Wisconsin Arboretum, 1984), 3.

[2] Robert S. Ellarson, “The Vegetation of Dane County Wisconsin In 1835,” Transactions of the Wisconsin Academy of Sciences, Arts, and Letters 39 (1949): 27

[3] David V. Mollenhoff, Madison, A History of the Formative Years, (Dubuque, Iowa: Kendall/Hunt Publishing Company, 1982; M. G. Winkler, A. M. Swain, and J. E. Kutzbach, “Middle Holocene Dry Period in the Northern Midwestern United States: Lake Levels and Pollen Stratigraphy,” Quaternary Research 25 (1986): 241-243.

[4] John T. Curtis, The Vegetation of Wisconsin: An Ordination of Plant Communities (Madison: University of Wisconsin Press, 1959), 326; Mark K. Leach and Laurel Ross, Midwest Oak Ecosystems Recovery Plan: A Call to Action (Springfield, Missouri: Midwest Oak Savanna and Woodland Ecosystems Conference, 1995), 44; Daniel Day, “Fire History and Post Settlement Disturbance,” in Oak Forest Ecosystems eds. William J. McShea and William M. Healy, (Baltimore: Johnʼs Hopkins Press, 2002), 53-56.

[5] Virginia M. Kline, “John Curtis and the University of Wisconsin Arboretum,” in John T. Curtis: Fifty Years of Wisconsin Plant Ecology, ed. James S. Fralish, et al. (Wisconsin Academy of Sciences, Arts & Letters, 1993), 51; Curtis, The Vegetation of Wisconsin.

[6] Nancy D. Sachse, A Thousand Ages (Madison: University of Wisconsin Arboretum, 1965), 49-50.

[7] William R. Jordan III, “A Perspective: The Arboretum at 50,” in Our First 50 Years: The University ofWisconsin Arboretum 1934-1984, anonymous (Madison: University of Wisconsin Arboretum, 1984), 23.

[8] Jordan, “A Perspective,” 21.

[9] Timothy F. H. Allen, Gregg Mitman, and T. W. Hoekstra, “Synthesis Mid-Century: J.T. Curtis and the Community Concept,” in John T. Curtis: Fifty Years of Wisconsin Plant Ecology, ed. James S. Fralish, et al. (Wisconsin Academy of Sciences, Arts & Letters, 1993)

[10] See William R. Jordan III, Michail E. Gilpin, and John D. Aber, Restoration Ecology: A Synthetic Approach to Ecological Restoration, (Cambridge: Cambridge University Press, 1990); Willam R. Jordan III, Sunflower Forest: Ecological Restoration and the New Communion with Nature, (Berkeley: University of California Press, 2003); Donald A. Falk, Margret Palmer, Joy Zedler, Richard J. Hobbs, eds. Foundations of Restoration Ecology, (Washington D.C.: Island Press, 2006); the quarterly, peer-reviewed journal “Ecological Restoration” was started by William R. Jordan in 1981 and is published by the University of Wisconsin Press.

[11] Grant Cottam, “Progress Report: The Plant Communities,” in Our First 50 Years: The University of Wisconsin Arboretum 1934-1984, anonymous (Madison: University of Wisconsin Arboretum, 1984), 13;

[12] Wingra Woods, “History Points” www.uwarboretum.com/map (15 November, 2010)

[13] For Wingra Woodʼs current status see: Wingra Woods, “History Points” www.uwarboretum.com/map (15 November, 2010). For its description in 1984, see Cottam, “Progress Report,” 13.

[14] Wingra Woods, “History Points”

[15] Cottam, “Progress Report,” 15-16. 12

[16] Professor Timothy F. H. Allen, a friend and colleague of the late Cottam, spoke of his attempted western pine community during a field trip for the course, “The Vegetation of Wisconsin,” on June 16 2009.

[17] Nancy D. Sachse, A Thousand Ages, 17. The quote from Thoreau she cites as Henry Thoreau, “On Walking,” Writings, Walden Edition, Vol. 5, Cambridge, 1906. 224-29.

[18] Arboretum Manual, June, 1949, Part 1, Arboretum office file, Birge Hall, University of Wisconsin.

[19] Marc D. Abrams, “The Postglacial History of Oak Forests,” in Oak Forest Ecosystems, 40.

[20] Curtis, The Vegetation of Wisconsin, 334-37.

[21] Gerald W. Williams, References on the American Indian Use of Fire in Ecosystems. http://www.blm.gov/ heritage/docum/Fire/Bibliography%20-%20Indian%20Use%20of%20Fire.pdf (20 November, 2010) 2-3.

[22] Henry T. Lewis, “Why Indians Burned: Specific Versus General Reasons.” in James E. Lotan, et al. (technical coordinators) Proceedings–Symposium and Workshop on Wilderness Fire: Missoula, Montana, November, 15-18, 1983. GTR-INT-182. Ogden, UT: USDA Forest Service, Intermountain Forest and Range Experiment Station. 75-80, cited in Gerald W. Williams, References, 3.

[23] Probably the earliest and most comprehensive account of American Indian ethnobotany in the Midwest can be found in: Melvin R. Gilmore, Uses of Plants by the Indians of the Missouri River Region, (Lincoln, Nebraska: University of Nebraska Press, 1977). Additional information can be found in: Kelly Kindscher, Edible Wild Plants of the Prairie: An Ethnobotanical Guide, (Lawrence, Kansas: University Press of Kansas, 1987; Kelly Kindsher, Medicinal Wild Plants of the Prairie: An Ethnobotanical Guide, (Lawrence, Kansas: University Press of Kansas, 1992. For an account of the use of medicinal and edible plants by the Ho-Chunk tribe in southern Wisconsin, see: Cindy Bloom, Pathologies, Plants, and Healers: Medicinal Ethnobotany of the Winnebago and Other Eastern North American Tribes, (Wisconsin?, 1994).

[24] For an entertaining fictional account of bees in the oak openings, see: James Fenimore Cooper, The Oak Openings or The Bee-Hunter, (London: G. Routledge, 1856), 9-24.

[25] Nancy D. Sachse, A Thousand Ages, 24-25.

[26] Robert A. Birmingham, Sprits of Earth: The Effigy Mound Landscape of Madison and the Four Lakes, (Madison: The University of Wisconsin Press, 2010), 25

[27] The International Society for Restoration Ecology (see: http://www.ser.org/content/ ecological_restoration_primer.asp; November 20, 2010) recognizes that the actions of traditional cultures often served to enhance ecosystem health and sustainability. They argue that these activities can be utilized in restoration, especially in developing countries, or in Europe, but even this international organization is tainted by the American pristine myth when they argue that “the North American focus on restoring pristine landscapes makes little or no sense in places like Europe where cultural landscapes are the norm, or in large parts of Africa, and Latin America, where ecological restoration is untenable unless it manifestly bolsters the ecological base for human survival.” I argue that the focus on restoring pristine landscapes in North America, where cultural landscapes have been the norm for thousands of years makes equally little sense! Stressing that oak ecosystems are the most degraded and that their functioning is critical for the regionʼs ecosystem heath, a large group of concerned ecologists collaborated in 1995 to produce the Midwest Oak Ecosystem Recovery Plan Unfortunately, their vision for “Oak ecosystem recovery throughout its range” stated that the main goal was “the restoration of all natural ecosystem functions and processes, including a natural range of biotic community types…and conditions in which natural selection can operate.” (Mark K. Leach and Laurel Ross, Midwest Oak Ecosystems Recovery Plan, 17). There is no room in the plan for beneficial human use of these oak ecosystems.

[28] Aldo Leopold, Game Management, (New York: Charles Scribnerʼs Sons, 1936), 21. 13

[29] Leopold, Game Management, xii

[30] For a comprehensive look at the current state of ecosystems around the globe, see: Millennium Ecosystem Assessment, Ecosystems and Human Well-Being: Current State and Trends: Findings of the Condition and Trends Working Group, (Washington: Island Press, 2005). The entire book is also available free online at www.maweb.org/en/Condition.aspx (November 21, 2005).

[31] Leopold, “An address,” 3.

[32] Leopold, “An address,” 5.

[33] Aldo Leopold is commonly referenced in Arboretum publications. The Arboretumʼs current mission statement even includes a commitment to “foster the land ethic.” See: Mark Wegener and Joy Zedler, “Taking Stock: Status Report on our 75th Anniversary,” Arboretum Leaflets, www.uwarboretum.org/ research and www.botany.wisc.edu/zedler/leaflets.html (November 20, 2010).

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