You can just buy some land and build a forest. We can do it. Chicago can do anything. –Richard M. Daley, December 4, 1991

We could offer as a dissenting opinion Joyce Kilmer’s famous line about how only God can make a tree, but of course Kilmer didn’t live in Chicago, so what did he know? Maybe we could amend his line to read “Only God can make a tree, but Mayor Daley can make a forest.”

The mayor’s comments on how easy it would be to build a forest came in response to questions about the proposed conversion of Cook County Forest Preserve land into an airport. The new, improved, scaled-down version of the city’s Lake Calumet airport would gobble up 195 acres of Burnham Woods, 140 acres of Eggers Woods, and 172 acres of the Burnham Woods Golf Course.

The loss of the golf course is not a problem. Satan is in charge of golf courses, and he can be safely relied on to provide a replacement for the one at Burnham Woods. But state law does put serious restrictions on forest preserve lands, and thus far the city has not made any official overtures to the County Board for permission to grab this land.

What would we lose if they did bulldoze these lands out of existence? Twenty years ago, when I first got seriously interested in birding, I used to go to Eggers Woods pretty regularly. Part of it is a low, wet woods, and part of it is an open marsh. Birders have been visiting it for generations, particularly in early May, when the songbird migration hits its peak. I saw my first Kentucky warbler– an uncommon bird in the Chicago area–at Eggers. I saw my first Wilson’s phalarope at Burnham Woods. The marsh gave me my first and only least bittern and my first yellow-headed blackbird and black tern, all three of which are on the endangered list in Illinois.

But the value of this site goes far beyond its importance as a migratory stopover or a nesting ground for rare birds. Part of the preserve is an artificial body of water called Powder Horn Lake that was originally excavated to provide fill for the Calumet Skyway. The Forest Preserve District stocks the lake with fish. The banks are manicured and mowed, and picnic tables are scattered about. The lake provides recreation; it has little natural value. But adjoining the lake is Powder Horn Prairie, one of the finest prairie remnants in the state. In the late 70s, the Illinois Natural Areas Inventory surveyed every bit of our state’s remaining natural landscape. Out of all the land examined, only about seven-hundredths of 1 percent of Illinois’ 55,000 square miles were determined to be high quality natural areas, places where healthy native ecosystems still survived. Powder Horn Prairie was one of those sites.

For some reason, the prairie was never dedicated as an Illinois Nature Preserve, as other inventory sites on public land have been. If it had been it would have gained the highest level of protection possible under Illinois law. In the nearly 30 years since the Illinois Nature Preserves system was created, no dedicated preserves have been destroyed by development. Some nondedicated inventory sites–which enjoy the slightly more limited protection accorded all forest preserve lands –have been lost, but as far as I can discover none of these were on public land. The mayor, if he succeeds, would have the dubious distinction of heading the first public body to destroy an inventory site.

At the north end of Burnham Woods is a small natural lake, apparently a remnant of Wolf Lake. The area between this body of water and present-day Wolf Lake was filled in to provide land for housing and other purposes. The prairie itself lies on a series of beach ridges that record ancient shorelines of Lake Michigan. This kind of landscape, which features oak savanna or sand prairie on the ridges and wet prairie or marsh in the swales between them, used to be common around the southern end of Lake Michigan, but almost none of it now remains. If we destroy Powder Horn, we will have even less.

Joe Nowak has been the volunteer steward of Powder Horn Prairie for eight years. With his wife Marlene, he has done extensive surveys of the site’s plant life. The Nowaks have discovered more than 250 kinds of native plants in the natural area, ranging from the prickly-pear cactus that grows on the sand ridges to an assortment of sedges–15 identified so far–that live in the strips of wet prairie and marsh that lie between the ridges.

It’s easy to understand the value of the area’s flora if you consider Plants of the Chicago Region, a book by Floyd Swink and Gerould Wilhelm of the Morton Arboretum in which the authors provide a scale for classifying native plants. The scale runs from zero for species that are “nearly or quite ubiquitous under a broad set of synecological conditions” to ten for plants that “typify stable or near-climax conditions” and grow only in certain well-defined communities. Using this scale, two of the species so far discovered at Powder Horn are so extremely rare that they’d probably rate a 15.

Swink and Wilhelm also use their ratings of individual plants to produce a combined Natural Area Rating Index, which provides a numerical evaluation of the botanical value of any piece of land. If you apply the index and get a number of 40 or more, you know you are dealing with land of “sufficient native character to be of rather profound environmental importance.” The index for Powder Horn Prairie is 85.

The diverse plant life supports an equally rich assortment of animals. Four species of turtles live at Powder Horn, and the reptile fauna also includes the smooth green snake, a small harmless species found only in high quality prairies. Franklin’s ground squirrels live on Powder Horn Prairie too. The 13-lined ground squirrel, a species that likes manicured lawns, is the common one at the Burnham Woods Golf Course across the road; the Franklin’s lives only in the tall-grass prairie.

Nesting birds include the endangered least bittern and pied- billed grebe and the threatened common moorhen, as well as a number of other wetland species– green-backed heron, yellow-crowned night heron, blue-winged teal, Virginia rail, American coot, spotted sandpiper, willow flycatcher, marsh wren, and swamp sparrow. Such rich avifauna is another indication of the high quality of this natural area.

The mayor is saying that we won’t really lose anything if we bulldoze Burnham and Eggers woods; we will just build new preserves even better than the old ones. Ecological restoration is an advancing science. Old strip-mine sites have been made to support native vegetation. Tall-grass prairies are reclaiming old cornfields; why can’t we have a new Eggers Woods or a new Powder Horn Prairie? My own experience with restorations makes me suspect that the creation of a new forest may possibly be beyond the abilities of even a Daley. Even the best restorations have a Frankenstein’s-monster quality about them. Natural systems are vigorous and brilliant, like Michael Jordan and Albert Einstein rolled into one; restorations communicate in grunts and lurch along with electrodes protruding from their necks. They are infinitely better than weed patches, and in a state like Illinois, where practically the entire natural landscape has been destroyed, they may be the only hope for the continued survival of many native species. But they are not a substitute for the real thing.

Looking for a professional opinion on the subject, I called Gerould Wilhelm at the Morton Arboretum. In addition to being coauthor of Plants of the Chicago Region, Wilhelm has carried out studies of the plant communities of the Indiana Dunes National Lakeshore and has been involved in restoration work on wetlands and prairies. I asked him if the mayor could build a new forest to replace the preserves destroyed by the airport.

“That depends on how you define a forest,” he told me. “If all it takes is a bunch of trees forming a closed canopy, then he can do it. But the kinds of forests we have in the forest preserves are another matter. Those are life systems analogous to an organism. You have 200 to 250 species of plants, each with its own pollinators and its own mycorrhizal fungi, and you have all the things that feed on those plants and all the things that feed on those things. It is a whole network of life capable of reproducing itself over thousands of years. No one has ever built one of those.”

But what about the restored prairies? Aren’t they examples of natural systems put together by people? “Only a few of the restorations come close to the complexity of natural prairies, even if we just look at the plant life. We are still missing much of the insect fauna and most of the other animals. And the soil and root development are not the same as natural prairies. It remains to be seen how long these will endure.”

Living ecosystems exist in the present, but they also carry within them a legacy from the past. Their collective genetic memory is the structural underpinning for the complex interrelationships that make the system work. If you want to create a functioning replica of an ecosystem from the southern end of Lake Michigan, says Wilhelm, the last thing you do is destroy the originals, which contain all the information on how to keep the system going. If we really wanted to create a new Powder Horn Prairie or Eggers Woods to replace the old, we would start working on the problem now, and in a century or two, when enough time had gone by to allow us to conclude that we had succeeded, we could safely destroy the originals.

Of course the crackpot realists will scorn such an impractical idea. We need the airport now, just as we need an oil field in the Arctic National Wildlife Range and more cattle ranches in the rain forest and more timber from the old-growth forests of the Pacific northwest. Everybody is all for nature in the abstract, but when we get down to specific cases there’s usually a good reason for burying it in the concrete. Which is why we will probably destroy the planet while piously declaring our intention to preserve it.