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Field & Street



The phrase "presettlement conditions" has been bouncing around in the Sun-Times in recent days as the paper weighs in on the issue of what our forest preserves are and what they should be. It makes the claim that re-creating presettlement conditions would mean the destruction of forests. This is not what people involved in the work believe. The phrase has been commonly used by professionals in the ecology biz for many years. If you ask people who study or manage natural lands for a precise definition, you will get some variation in the answers, but the variations differ more in emphasis than in conception. However, the phrase seems to produce confusion among people who are not in the business, and that confusion adds heat to the controversy over how we should manage our preserves and gets in the way of reasonable discussion of the issues.

Full disclosure requires that I state at this point that I work for the Forest Preserve District of Cook County. However, I do not believe that my employment there has altered my point of view (other people may have biases; I have a point of view). Also everything that follows in this essay is my own opinion. I don't think my colleagues at the Forest Preserve District will have any major disagreements with it, but in no sense does it represent any sort of official Forest Preserve District opinion.

The problem with phrases such as "presettlement conditions" or "presettlement vegetation" starts with the words themselves. They are generally understood to refer to the period prior to the massive influx of people into northeastern Illinois that began about 1820. But people settled this region shortly after the glaciers left, so don't they count as settlers? Some writers try to get around this one by calling the recent immigration "European settlement," but that leads to the charge that they are overlooking the undeniable fact that not all the new settlers were Europeans or the descendants of Europeans.

I prefer using an expression like "large-scale settlement." The number of Native American populations had been drastically lowered by the plagues that swept across the continent in the wake of their first contact with European explorers, so populations in northeastern Illinois in 1820 were probably lower than they had been. However, there is no reason to think that native populations ever reached anything like the levels we have achieved in the past 175 years.

Of at least equal importance is the alteration in the relationship of the people to the land. Those who arrived after 1820 plowed thousands of square miles of prairie to support an agriculture based not on local needs but on the bottomless demand of a growing market. We removed bison and elk, the native grazing animals, and replaced them with cattle and horses, a change with major implications for native plant communities. We imported hundreds of new species of plants, some of which have gone wild, with devastating consequences to the native vegetation. We altered the hydrology of the region, turning former wetlands into uplands and upsetting the flood regime along the rivers. We removed such major ecological processes as fire from the landscape. And we remade a landscape where areas of human occupation had been islands in a sea of natural land into one in which the natural areas were isolated islands.

However, we also created forest preserve districts, first in Cook County and subsequently in the collar counties. We set aside state parks and created the nation's first system of nature preserves. Illinois nature preserves are granted the highest level of protection under state law. According to the Illinois Nature Preserves Commission, they are supposed to be places that retain "a high degree of their presettlement character." The enabling act that created Cook County's Forest Preserve District is quite specific in declaring that the purpose of the district is to save the "native flora and fauna." Many of the current difficulties arise from figuring out just what this obligation means in the context of a contemporary metropolis occupied by a people who have lost any historical memory of the native landscape.

The landscape of northeastern Illinois in 1820 was extraordinarily diverse. Several different kinds of forests grew here: sugar maple-basswood forests on glacial terraces along the rivers, American elm and silver maple forests on the floodplain, and oak-hickory forests--we now call them "woodlands"--on the slopes of the moraines. There were also savannas, grassland communities with some trees--more trees than could be found on the prairies but fewer than in the woods. Prairies covered great expanses. On the lake plain, where much of the city now stands, were wet prairies intergraded with marshes and sedge meadows--some of the most productive wetlands in North America.

Each of these natural communities had its characteristic species, and the juxtaposition of so many communities means that the Chicago region still has a very high level of biodiversity. According to Plants of the Chicago Region, by Floyd Swink and Gerould Wilhelm, 1,638 species of plants are native to this area, an amazing number for any location north of the tropics. We will never know how many native animals there were. In the past two years scientists from the Field Museum have found five species of beetles previously unknown to science in just one Cook County forest preserve.

Some of the biodiversity of 1820 is gone for good. Passenger pigeons are extinct. Black bears and bison are unlikely candidates for reintroduction to Cook County. Many species may have vanished before anyone had an opportunity to learn of their existence. But through a combination of foresight and dumb luck, we have managed to hold on to a very large number of species that have disappeared from much of their former range. You might say that rarities are commonplace here. Among the 102 counties in Illinois, Lake County has the most endangered and threatened species, and Cook County runs a close second.

We can be pleased that so many rare species survive here, but we also have to be worried that so many qualify as endangered or threatened. And our worries are compounded by the results of scientific investigations that clearly show species after species disappearing from preserves where they were once common. Woodland wildflowers go, taking with them the butterflies whose caterpillars once fed on their leaves. Mature oaks die by the thousands and leave no offspring to replace them. Prairies lose a plant species a year, and the accumulation of plant remains on the ground drives out the grasshopper sparrows that once nested there. Forests whose soils were held in place by a profusion of grasses and wildflowers have become wastelands where dense thickets of exotic shrubs shade bare, eroding earth.

Faced with clear evidence of ever steeper rates of decline, land management agencies throughout the midwest--for that matter, throughout North America--have turned to ecological management and restoration as a way to keep what we still have. Protecting rare and endangered species--or rare and endangered communities--is a complex business, but at the broadest level of generalization you could say that the best way to protect species is to protect communities and that the best way to protect communities is to return to the land the processes that created and sustained those communities in the past. The artificial flood the Interior Department sent crashing through the Grand Canyon two years ago is an example of ecological management. So are the prescribed burns now being conducted from the Florida Everglades to the prairies, woodlands, and wetlands of Cook County.

If you survey the wild lands that still survive in Illinois, most of what you look at conforms to a pattern. A modest number of species will be present, and those species will be common. Look at ten woodlands or ten wetlands and you are likely to find that a high proportion of the species you see are present in all ten. You will probably also see a significant number of exotic species; in some cases they dominate the landscape.

But every once in a while you will come across land that doesn't conform to this pattern. This land will have few exotic species, and those in small numbers. It will have a larger than usual number of native species, and--most significantly--many of those species will be rare. Check into the history of this unusual place and you are likely to find that some lucky combination of circumstances protected it from many of the upheavals that have been visited on our landscape in the past 175 years.

These are the places that retain "a high degree of their presettlement character." They are the kinds of places that are selected for inclusion in the Illinois Nature Preserve system. They are also our best single source of information about the native landscape of northeastern Illinois. Sixteen such preserves--woodlands, wetlands, savannas, and prairies--are located in the Cook County forest preserve system. You could reasonably define ecological management as an attempt to make the whole system as rich, diverse, and beautiful as these nature preserves.

When the surveyors from the Government Land Office were laying out section lines and township boundaries across northeastern Illinois 175 years ago, they were walking through a beautiful and endlessly varied landscape. Somehow through thousands of years all the animals and plants they saw had thriven in this place.

We could say that we will have achieved presettlement conditions when all the native species still with us are thriving. They can't all thrive in the same preserve, but somewhere there should be good sedge meadows for yellow rails, and somewhere there should be good woodlands for white oaks, and somewhere there should be good prairies for white fringed orchids and smooth green snakes.

Ecologists often talk of the health of natural communities. I think you can gauge the health of a community by asking three questions:

First, what species are present? Healthy communities support populations of a high proportion of the native animals and plants adapted to the conditions in that community.

Second, how are those species faring? Are they sustaining themselves or are they dying out?

Third, is the community as a whole perpetuating itself?

If the answer to these three questions is yes, then the community is healthy. Healthy, diverse natural communities were characteristic of presettlement times. They are the real goal of management now. i

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