5
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9780226306490
$37.0
By Joel Greenberg
All right reserved.
ISBN: 9780226306490
1. The Great Forces
Sometime during July 1673, seven men exploring on behalf of New France and Catholicism left the Mississippi River and proceeded up the Illinois River. They reached the Des Plaines River, which they ascended to the portage that would lead them to the Chicago River and Lake Michigan. Commanded by Father Jacques Marquette and Louis Joliet, this party of Frenchmen became the first Europeans known to have entered the Chicago region. Marquette described his impressions: "We have seen nothing like this river that we enter, as regards its fertility of soil, its prairies and woods; its cattle, elk, deer, wildcats, bustards, swans, ducks, parroquets, and even beaver. There are many small lakes and rivers. That on which we sailedis wide, deep, and still, for 65 leagues. In the spring and during part of the summer there is only one portage of half a league."
Joliet echoed the sentiments of the priest in even more glowing terms: "The river which we named for Saint Louis [Illinois River] which rises near the lower end of lake of the Illinois [Lake Michigan], seemed to me the most beautiful, and most suitable for settlement.. . . The river is wide and deep, abounding in catfish and sturgeon. Game is abundant there; oxen, cows, stags, does, and turkeys are found there in greater numbers than elsewhere. For a distance of eighty leagues, I did not pass a quarter of an hour without seeing some."
The land they had reached lies within a great ecotone — a zone of ecological transition where hardwood forests meet tallgrass prairies. It is contested ground where trees compete with grass for dominance. Fires were frequent and tipped the balance in favor of prairie, which, along with the transitional shrubland and savanna, covered most of the region. Where ravines, water, or other barriers blocked the advancing flames, forests took hold.
As the great glacier that had covered the area for thousands of years melted and receded northward, vast quantities of water were left behind to create and nourish the lakes, rivers, and wetlands that adorned the landscape. These included Lake Michigan (the third largest of the Great Lakes) and some of the grandest marshes in inland North America. The force of the glacier also ordained that the Chicago region would straddle the eastern Continental Divide, separating the drainage area of the Atlantic Ocean from that of the Gulf of Mexico. The rivers Des Plaines, Fox, Kankakee, and their tributaries were in the Illinois and Mississippi watershed, while the Chicago, Calumet, Pike, Root, and St. Joseph fed the Great Lakes. (The Kishwaukee River, draining portions of McHenry, Kane, and Walworth counties, is in the Rock River watershed, and the Tippecanoe River, draining small parts of Starke and Jasper Counties, is in the Ohio River watershed.)
We will never know exactly how this region looked three hundred years ago. Attempts to decipher its original appearance have relied heavily on the data generated by the U.S. Public Land Surveys conducted in the region from 1821 (when Cook County's surveys began) to 1841 (when surveys in Kane and Lake Counties in Illinois were completed). These surveys created a national grid whereby property could be located with ease and precision. In the process, the surveyors noted tree species and size, prairies, location of water bodies, and other landscape features. Their work is the closest thing that scientists have to a systematic inventory of early nineteenth-century plant cover.
A number of ecologists have combined these data with soil distribution, travelers' descriptions, geologic features, and other information to create maps depicting vegetation at the time of the surveys. (For examples, see figs. 1–5.) As you can see, the maps are not uniform in the number and types of plant communities portrayed. This reflects differences not only among authors but also in the plant community classifications in vogue at the time of map preparation and the detail and accuracy of the surveyors' work. Despite their limitations, however, these maps are valuable as another source for illustrating the diversity that once defined this region.
That diversity brought to the land an almost unimaginable fertility and an abundance of life that in some manifestations was unrivaled by any other terrestrial environment on earth. To understand and appreciate this remarkable bounty, one must look at how it came to be.
Ice Sculptor: Glaciation
Part of a huge sheet of ice born in the Laurentide Mountains of Quebec, the Lake Michigan lobe of the Wisconsin Glacial Episode covered the Chicago region until about 13,800 years ago. The Wisconsin was the most recent of a series of glacial episodes over 2 million years, and it obliterated most of the topographic barriers left by its predecessors. The flowing ice, augmented by rocks that adhered to it, leveled the unconsolidated sediments in its path and filled vast areas with the crushed earth it had picked up along the way.
Because the underlying land was not uniform, neither was the glacial advance. The ice mass cut deeper and traveled farther in valleys where the substrate was softer. These advances, or lobes, gouged out tremendous amounts of earth, enough to create their masterpieces: the five Great Lakes holding more than 25 percent of the planet's unfrozen fresh water. The valley that was to hold Lake Michigan was deepened five hundred to nine hundred feet.
Just as a turn of the climatic cycle launched the glacier southward from its Canadian mooring, a warming trend halted its advance. As temperatures gradually increased, the ice began to melt, leaving water and pulverized earth in its wake. These remains formed the plains, uplands, rivers, and lakes that essentially make up the landscape of the Chicago Region. (Depositions by winds and tides, erosion, and beaver activity have wrought more recent changes.) Based on these glacial features, geographers have divided the Chicago region into seven natural divisions. (See fig. A1.)
Where the ice receded without interruption, the material left behind became ground moraines (also known as till plains), marked by flat or gently rolling surfaces. But the glacial retreat, like its advance, was uneven and halting. Where it stalled, the crushed earth and rock accumulated and became terminal moraines. A series of these moraines parallels and encircles the southern portion of Lake Michigan to form three concentric U-shaped uplands. The morainal system farthest from the lake is the Outer Uplands and includes Kane County, much of western McHenry County, and the southern portions of Jasper and Starke Counties but otherwise lies beyond the Chicago region.
Located in the middle, the Valparaiso Upland is the highest of the morainal systems, reaching 1,140 feet above sea level near Lake Geneva, Walworth County. Its northern sector, principally Walworth, McHenry, Kane, and Lake Counties in Illinois, exhibits some of the most picturesque scenery in the region: where earthen debris accumulated in cavities and channels of the thinning glacier, cone-shaped kames and the serpentiform ridges of eskers rise up from the flat countryside. The ebbing ice also endowed this portion of the upland with numerous lakes, including Lake Geneva, the Chain O' Lakes complex, Lake Elizabeth, Lake Zurich, and Lake Delevan.
Farther south, the Valparaiso Upland becomes less pronounced. Its relative flatness is seen to good advantage from a plane landing at Chicago's O'Hare Airport. As the moraine sweeps around the end of Lake Michigan into Indiana, it becomes three gently rolling ridges roughly coincident with U.S. Route 6 in Lake County and U.S. Route 30 in La Porte County. Cedar Lake is the only water body of any size.
The third morainal complex, and the youngest, is the Lake Border Upland. Its name is derived from the discontinuous bluff, in places reaching an elevation of 140 feet above the lake, that rims the Lake Michigan shoreline in northern Racine County and then from Waukegan southward to Winnetka. Numerous ravines, over thirty of them in the Illinois portion, cut the bluff perpendicular to the lake and provide a microclimate suitable for certain northern plants not otherwise found here. These picturesque landscapes also provide the location for many of the region's aristocracy, whose estates have often afforded protection to these rare natural communities. Two of the area's principal military installations are located here as well: Fort Sheridan, now deactivated, was established as Camp Highwood in 1887 to protect those same rich families should Chicago's social unrest threaten their baronial homesteads, and the Great Lakes Naval Training Center, in North Chicago, through which all of the nation's naval recruits must pass.
The Lake Border Upland was poorly drained by the shallow and slow-moving Des Plaines, Skokie, north branch of the Chicago, Root, and Pike rivers. As a result, extensive wetlands developed between the moraines. The largest was the Skokie Marsh, converted into the Skokie Lagoons by the Civilian Conservation Corps in the 1930s.
As the shrinking glacier retreated northward, the furrow enlarged by the Lake Michigan lobe filled with water. Hemmed in by the glacial edge and the Valparaiso Moraine, this meltwater ponded and formed Lake Chicago, an early stage of ancestral Lake Michigan. (Geologists consider Lake Chicago to have ended when its icy margin melted about eleven thousand years ago.) Expanding waters of the lake eventually cut through the morainal dike at two points near Willow Springs in southern Cook County and flowed southwest toward the Illinois River. The northern or Des Plaines channel provided the main outflow and the southern, known as the Sag, was a tributary that joined it about two miles downstream. Geologists refer to the stream formed by the convergence as the Chicago Outlet. The roughhewn piece of land turned into an island by the outlets became known as Mount Forest Island, now a part of the Palos Forest Preserve complex.
The swollen stream leaving Lake Chicago tore at its banks, creating a bluff-lined channel that was to become the lower Des Plaines River Valley. For twenty miles, from Willow Springs to Joliet, this segment of the Des Plaines provides locally unique habitat for such rare organisms as leafy prairie clover and Hine's emerald dragonfly. With the completion in 1848 of the Illinois and Michigan Canal, which linked the Illinois River and Lake Michigan, and in 1900 of the Chicago Sanitary and Ship Canal, the valley also became a major transportation route between the Mississippi and Great Lakes watersheds. In 1984, the National Park Service designated the Illinois and Michigan Canal as the country's first National Heritage Corridor. The corridor now draws over 1.3 million people a year.
The Chicago area's first tourist attraction, and one of its most notable geologic features, once stood near the edge of the Des Plaines River near Joliet, a creation of the same waters that raged out of Lake Chicago. Known as Mount Joliet, it was a gravel mound shaped in the figure of a cone except that it had a perfectly flat top. Unfortunately, people of the twentieth century know it only from the accounts of early travelers, for over 130 years have passed since the majority of it was hauled away to become city streets and ballast for railroad beds. But starting as early as the 1690s, visitors went out of their way to view it, and, curiously, estimates of its height increased over the years from sixty to one hundred feet. By the time James Paulding saw Mount Joliet in 1848, part of it had been removed during construction of the Illinois and Michigan Canal. Despite the marring, he could still write: "This mound is one of the most remarkable, as well as beautiful objects in nature.. . . It is as regular and perfect in construction, form, and outline as any work of art I ever saw.... It is, however, . . . a production of the cunning hand of Nature, who sometimes it would seem, amuses herself by showing how much she can excel her illegitimate sister, Art, even in her most successful attempts at imitation."
Over the thousands of years of its existence, Lake Chicago shrank in a series of successively lower lake phases. (See chap. 10.) When the ice eventually melted throughout the Great Lakes basin, changing elevation and drainage produced the modern configuration of Lake Michigan.
The receding of Lake Chicago's frigid waters exposed previously submerged land that became known as the Chicago Lake Plain. (In Indiana, some people now refer to it as the Calumet Lake Plain.) Millennia of inundation left this land extremely flat, leveled by waves and the still-water deposition of clays. Lake Michigan received the waters of the lake plain via the Root, Pike, Chicago, and Calumet Rivers, the latter two of which now flow toward the Mississippi because of canal construction and other engineering projects.
Most of the relief is provided by three elongated ridges, each of which corresponds to the shoreline of a particular stage of Lake Chicago. But the most massive lake relic of all is six-mile long Blue Island, Cook County, a detached extension of the Lake Border Upland that rises eighty feet above the plain. According to an old newspaper article quoted by historian Ferdinand Schapper, Blue Island, "when viewed from a distance, appears standing in an azure mist or vapor." As for the other part of its name, it was: actually an island, poking above the icy waters of Lake Chicago; practically an island, surrounded by marsh and streams; and metaphorically an island as its timbered slopes rose above the prairie.
Certainly, it would have been hard to imagine that such a landscape as the Chicago Lake Plain, with its marshes, timbered slopes, and prairies, would eventually become the setting for the people, commerce, and industry that have helped define the nation's heartland. The cities of Racine, Kenosha, Waukegan, Michigan City, and St. Joseph are here. So are the Bahai Temple (Wilmette, Cook County), Northwestern University (Evanston, Cook County), Oak Park's (Cook County) concentration of homes designed by Frank Lloyd Wright, and the steel mills of Gary. But the anchor for the region is, of course, Chicago. Home to 2.8 million people, the city draws millions each year as visitors to the Lincoln Park Zoo, Field Museum, Art Institute, McCormick Place, and Shedd Aquarium. Wrigley Field, Comiskey Park, Soldier Field, and the United Center provide examples of both the oldest and newest of professional sports venues. Rooted in the dolomite bedrock, the John Hancock Building, Sears Tower, and other architectural wonders that distinguish Chicago's skyline stand high above the ancient lakebed. Farther south, cultural features include Jackson Park, the University of Chicago, Museum of Science and Industry, and historic Pullman, America's first planned industrial city.
Not only was the Lake Plain attractive to the masses who settled there, it also held some of the region's most significant natural areas. Three are of such importance they warrant mention here. Although constantly augmented by wind and lake currents, the Indiana Dunes were originally the creation of wind-borne sand uncovered by the waning Lake Chicago. The pioneering ecologist Henry Cowles called these dunes "the grandest in the entire world," and most of what is left of them is now under state or federal protection. The Calumet region, on the Illinois-Indiana border, held marshes that were equally grand. Today, we can barely comprehend the abundance of wildlife that once inhabited them. Unfortunately, that area is where Chicago in effect decided to defecate, and most of the former wetlands are now buried under waste. Although perhaps lacking the historical or national significance of the other two sites, Illinois Beach State Park, Zion (Lake County, Ill.), encompasses more relatively undisturbed natural communities than any other place in Illinois.
Sandwiched between the Outer Upland and the Valparaiso Upland are two lowlands considered distinct physiographic provinces. The smaller is known as the Manteno Plain, a wedge-shaped region of ground moraines. The larger Morris-Kankakee Basin combines the Morris Basin, a former glacial lake, and the Kankakee Basin, a valley covered with sand by glacial meltwater and through which the Kankakee River flows. Within its borders are the "swamp and dunes" near Braidwood, Will County, which the botanist Willard Clute studied so carefully, and the once huge Kankakee marshes that rivaled Calumet in their marvelous richness.
Fertility Underfoot: Soils
In its slow and grinding march of expansion and contraction, the ice sheet left behind not only the conspicuous landforms just described but also the more evenly distributed deposits of granulated rock and earth. These deposits are categorized by the size of their particles. The most common of these in this area are clay (the finest grained), silt (less finely grained), sand (coarse), loam (a combination of the previous three and often organic material), and gravel (most coarse).
Although there are a few places where the underlying bedrock is exposed (particularly along the lower Des Plaines, Fox, and Kankakee River valleys), these deposits cover most of the region at depths of seventy-five feet or more. They are the precursors of soil, that layer of varying thickness and character that anchors terrestrial life and reflects the history of the land.
Soils develop from a base known as "soil parent materials." The manner of deposition determines the classification of these materials. In the Chicago region, the most frequently occurring soil parent materials are till (deposited by glacial ice), outwash (deposited by glacial meltwater), alluvium (deposited by rivers and streams), loess (silt deposited by wind), and eolian sand (deposited by wind).
The parent materials and the size of the particles determine the distribution of soils across the landscape. Gravel, for example, being large and heavy was moved by ice (till) and, for shorter distances, by meltwater (outwash); concentrations of it occur in morainal areas. Sand and silt took longer to settle out of water and are common in areas that were formerly submerged such as the Chicago Lake Plain and the Morris-Kankakee Basin. Clay, which took a very long time to settle, is thickest on lands once covered by sheltered ponds and bays. The silt exposed by receding rivers was often deposited as loess, most heavily on the east sides of valleys.
Parent materials became soils through the many agents of change to which they were subjected. Chemical and mechanical forces break down the particle sizes even further and facilitate the downward percolation of clay. Age, slope, and climate are other critical factors in the formation of the more than two hundred soil series that occur in the Chicago region. (Series are to soils as species are to plants and animals.)
Biotic factors are among the most important in determining soil character. Soils that developed under prairies (mollisols) have substantially more organic material than those that formed under forests (alfisols). The quantity of vegetative biomass produced in a prairie is similar to that of an oak woods, but the location of that material is different. Prairie grasses and forbs (herbaceous plants) send their roots deep into the earth to form dense tangles, the first three and a half feet of which can weigh more than 150 tons an acre. The same distance below the surface of an oak woods, however, yields only eighty tons of organic matter per acre; ninety tons are in trunks, limbs, and leaves.
The subterranean mats of woven roots further enrich the mollisols by providing habitat for numerous organisms, from moles to earthworms to bacteria. These inhabitants of the nether zones facilitate the decomposition of surface and subsurface plant matter, keep the soil loose and aerated, and replenish the nitrogen that is so critical to soil fertility. From an agricultural perspective, the deep and black mollisols are among the best soils in the world, a fact that goes a long way to explaining why the tallgrass prairie is virtually extinct.
Atmospheric Impacts: Climate and Weather
Solving the puzzle of the ecotonal landscape was an exercise that took over 150 years. By the end of the nineteenth century, at least ten different theories attempted to explain why some land supported prairie at the expense of forest. Among the factors thought to cause prairies were soil origin, soil composition, bison, a combination of fire and drought, and fire alone. While fire was the most often cited cause during that period, the scientists who worked at the beginning of the twentieth century largely rejected it in favor of climate. Botanists determined that the formation of prairie occurs where the ratio of precipitation to evaporation falls between 60 and 80 percent and is promoted by extreme droughts. In rebutting the fire camp, Henry Gleason noted that "in order to have a prairie fire, you first must have a prairie."
Biologists eventually reached the consensus that climate and fire are the keys to deciphering the complicated vegetation patterns that enrobed the land. Distilled to its essence, the accepted scenario says that the climate of eight thousand years ago was warm and dry enough for prairie species from the west and south to spread eastward through this region into eastern Indiana and Ohio. This projection became known as the prairie peninsula. Starting about five thousand years ago, however, the climate shifted in the other direction, producing wetter and cooler conditions that enabled the forests to regain some of the ground they had lost. Periods of drought hindered the arboreal advance, but it was fire that perpetuated the prairie dominance of the Chicago region. Climate allowed the prairie to develop; fire maintained prairie when the climate changed. In the words of plant ecologist Roger Anderson, "the vegetation of the prairie peninsula was most likely a shifting mosaic of grassland, forest, and savannah that was determined by fire frequency under a climatic regime capable of supporting any of these vegetation types."
Climate determines the vegetation of a region more than any other single factor. In this region three air masses most influence the climate. The dominant mass originates as humid air off the Pacific Coast but sheds its moisture as it rises to clear the Rocky Mountains. This dry rain shadow sweeps east on the same thousand-mile course that enabled it to create the prairie peninsula. Its effects on this region are tempered, however, by the other two air masses — humid air from the Gulf of Mexico meets dry cold air of the Canadian Arctic and produces most of the region's precipitation. The interplay of these air systems translates into the climatic changes that influence the evolving face of the landscape.
Climate manifests itself most noticeably in the day-to-day atmospheric events known as weather. In this region, the weather is marked by great variations in temperature, precipitation, and wind. Chicago has temperatures that average 75˚F in July and 26˚F in January. Highs and lows at O'Hare Airport have ranged from 104˚F on June 20, 1988, to -27˚F on January 20, 1985.
The region receives an average of about thirty-four inches of precipitation a year, most of it during the summer. Both prolonged droughts and deluges are uncommon. The wettest month on record, August 1987, produced 17.10 inches of rainfall, 9.35 inches of which fell within one twenty-four-hour period. August 1979 was the driest month ever, when a paltry .02 inches of precipitation fell.
Severe snowstorms occur from time to time, causing an array of serious consequences. Hard snows during the winter of 1842–43 are said to have killed thousands of prairie chickens (Tympanuchus cupido) and bobwhite (Colinus virginianus) throughout Lake County, Illinois. The storm of January 1979 was memorable in changing the political landscape: challenger Jane Byrne used the snow, and its clean-up, as an issue over which she defeated incumbent Michael Bilandic to become mayor of Chicago.
Winds in the area are predominantly from the west, although there is variation from month to month. They average 10.3 miles per hour, which would give Chicago the title of "eighty-first windiest city," at least among the 270 United States cities looked at as part of a major study of urban climate. Chicago's sobriquet "the windy city" actually came not from its climatic conditions but, rather, from the perceived boastfulness of its citizens during the planning and construction of the 1893 Columbian Exposition. But genuine gusts have exceeded eighty miles per hour, including the record one of eighty-seven miles per hour that came out of the northeast in February 1894.
The region's most spectacular weather arrives as storms, some of which lash the area with deadly fury. The most notorious was the Veteran's Day Storm of 1940. In the three-state area of Illinois, Michigan, and Minnesota, freezing temperatures and high winds killed sixty-six people, caused millions of dollars of property damage, and destroyed large tracts of forest. Fifty-nine more lives were claimed when the storm sank three ships off Pentwater, Michigan.
There are also the short-lived but potentially devastating tornados that occur more commonly on the central grasslands of the United States than anywhere else in the world. On August 28, 1990, a tornado ravaged parts of Will and Kendall Counties, killing twenty-nine, injuring 350, and destroying $115 million worth of property. It was the most destructive of any reported in the country that year.
Local weather conditions affect animal and plant populations in numerous ways. Moisture levels, wind speed, and wind direction at time of seed ripening help determine which plants will successfully colonize a new site. The absence of an insulating snow cover can increase winter plant mortality, especially for seedlings. Temperature and wind strongly influence phenological occurrences, defined by botanist John Curtis as "the seasonal march of observable biological events." Spring flowers bloom along the Des Plaines River two weeks earlier than at cooler sites near Lake Michigan. Major flights of migrating birds can be correlated to the passage of cold and warm fronts, and salamanders emerge in the spring to breed as higher temperatures thaw their winter quarters.
Aquatic ecosystems, particularly small lakes, are even more profoundly affected by weather conditions. Wind and the cycle of water warming and cooling ensure that essential nutrients disperse throughout the community. But during the winter a layer of ice covered by deep snow can prevent light from penetrating the water. Photosynthesis stops, along with the associated production of oxygen; meanwhile, decaying vegetation depletes the oxygen that is present. The devastating oxygen deficiency becomes apparent when the spring thaw reveals a lake surface littered with bloated fish.
Burned to Life: Fire
Perhaps because it was new to their experience, the early commentators were awestruck by the raging conflagrations they came to know on their travels through the Midwest. Many of those who witnessed these displays of heat and color found them exquisite, as glorious as the land itself:
The historical record demonstrates how common a phenomenon fire was on the open prairie. In the fall of 1837, a Chicago resident wrote to relatives in New England that "the prairie takes fire every day that we have, and in the evening burns beautifully and takes up the whole sky." A year later, a traveler entering Chicago by boat from Milwaukee noted "large clouds of smoke that could be seen in various directions," smoke that he was told originated from the prairie burns that occurred every spring and fall. One night in 1858, yet another visitor saw five different fires within a twenty- or thirty-mile stretch as she approached Chicago from Indiana.
There is disagreement among scientists as to whether prairie fires were primarily meteorological or cultural in origin. Those who take the former view argue that the Midwest is a region of unstable weather producing storms frequently punctuated by flashes of lightning. Ecologist Paul Sears points to this as "evidence that, however enthusiastic a pyromaniac man may be, lightning is a far more common and efficient igniter." Opponents counter that substantial quantities of rain accompany most lightning storms, a situation hardly conducive for sustained combustion. They attribute the fires to the human beings who arrived in the region roughly twelve thousand years ago. Burning was used for several purposes, most particularly as an aid to hunting. A fair conclusion is that both causes contributed to the fires, fires that through their power and frequency etched the shifting lines of grass, shrubs, and trees onto a background fixed by climate and topography.
With broad strokes, the relationship between topography, fire, and terrestrial vegetation can be easily outlined. On the level lake plains and ground moraines where the westerly winds could drive the flames unhindered, the prairies flourished. They are composed of perennial grasses and forbs that die back every year. The growing parts of these plants are beneath the soil and thus are unscathed by fire. (Although temperatures at the soil surface during burns can range from 175˚ to 1,300˚F, little increase in temperature has been noted at depths of as little as less than an inch below the surface.) And as fire consumes the thick litter that develops over time, prairie vitality is renewed: light reaches young plants and nutrients are made available for soil enrichment. For some species, scorching heat actually facilitates seed germination.
Lands that were sheltered from the full brunt of the conflagrations by watercourses or morainal ridges supported shrublands and savannas. One of the dominant trees of the open savanna is bur oak, a species endowed with a thick corky bark that enables it to survive repeated fire exposure. And where fires were most infrequent — such as the east side of rivers, north and east faces of morainic slopes, and in ravines — forests were able to develop.
A New Force
Over thousands of years, the great forces of glaciation, climate, and fire had created a seamless mosaic of waters, wetlands, prairies, shrublands, and woods. But the arrival of the Europeans set in motion a new force, one with the power and will to impose upon the landscape a uniformity that is now virtually complete. While this process has diminished our natural heritage to a sorrowful extent, it is a tribute to the resiliency of nature and the efforts of a few farsighted people that so many native plants and animals have managed to survive, albeit in ever shrinking refuges.
Continues...
1. The Great Forces
Ice Sculptor: Glaciation,
Fertility Underfoot: Soil,
Atmospheric Impacts: Climate,
Burned to Life: Fire,
A New Force,
2. In Quality Unexcelled: Prairie Types and Composition
Of Breezes and Braided Roots: The Grasses,
Where Spring Begins: The Gravel Prairies,
The Richest of All: The Black-Soil Prairies,
On the Bones of Earth: The Dolomite Prairies,
Dr. Clute's Domain: The Sand Prairies of Braidwood,
3. In Quality Diminished: Prairie Settlement and Conservation
Under the Fleur-de-lis: The French Period,
The Prairie Resists: Treelessness, Fire, Disease, and Other Barriers to Settlement,
The Defenses Crumble but Some Prairie Survives,
The Turning Point for Prairie Conservation: Goose Lake Prairie,
Prairie Tales: A Few Prairies and the Battles to Save Them,
Protecting the Protected: Prairie Stewardship and Management,
4. The Nearly Vanished Transitions: Barrens and Savannas
Gone So Quickly: The Deep-Soil Shrublands and Savannas,
All Sorts of Floral Treasures: The Sand Savannas and Shrublands,
Like Nowhere Else on Earth: The Savanna of Langham Island,
5. Witnesses to History: Forests
Letting in the Light: Oak Forests,
Where Shadows Reign: Maple Forests,
Raised in Flood and Drought: Lowland Forests,
Mostly On or Under the Trees: Lichens and Mushrooms,
From Lumber to Ecosystems: Utilization and Conservation,
Knotty Questions: How Best to Treat Local Forests,
6. Of Two Worlds: Wetlands
The Pilgrims Progress to Section 404: Destruction and Conservation of Wetlands,
On a Cusp: Sedge Meadows and Marshes,
Wiggly Fields: Bogs and Fens,
7. The Last Wilderness: Lake Michigan
The Sullying of Lake Michigan: Pollution,
Floaters, Bottom Dwellers, and a Filter Feeder Run Amok: The Plankton and Benthos,
Agents of Change: Commercial Fishing and Alien Species,
Victims of Change: Native Fish,
8. Approaching the Way: Rivers and Small Lakes
Rivers in Flux,
Current Affairs: River Ecology,
River Atrophy: The Disappearing Mussels,
Like Crystals on the Landscape: The Small Glacial Lakes,
9. Casualties of a Modern World: The Marshes of the Kankakee and Calumet
Two Thousand Bends of a Silver Thread: The Kankakee's Great Marsh,
The Marsh That Will Not Die: The Calumet,
10. Lake Michigan's Rim: Beaches, Dunes, and Bluffs
Setting the Scene,
So Many Fine Examples of Rare and Beautiful Species: Natural Communities of the Indiana Dunes,
By Their Deeds, Ye Shall Know Them: Utilization and Conservation of the Indiana Dunes,
Steeper and More Mesic: The Dunes of Berrien County,
Not All Treasure Is at the Rainbow's End: The Western Dunesland,
Cool Shadowy Slopes: The Bluffs and Ravines,
11. Many More Than We Know: Insects
Beleaguered Beetles, Mystery Moths, and A Rediscovered Dragonfly: A Smattering of Endangered Insects,
Flitting on the Edge: The Mitchell's Satyr and the Karner Blue,
Mere Patches in Time and Space: The Corpse as Ecosystem and Forensic Entomology,
Conspicuous on a Large Scale: Insect Swarms,
The Musical Brood: Periodic Cicadas,
12. Survivors in Trouble: Reptiles and Amphibians
In the Soup and Pets of Plunder: Turtles,
Long and Suffering: Snakes (and Three Lizards),
Winding through History: Massasauga Rattlesnakes,
Under Cover or on the March: Salamanders,
Plight of the Choristers: Frogs and Toads,
13. Of Extinction and Resurrection: Passenger Pigeon, Prairie Chicken, Sandhill Crane, and Colonial Nesters
Remembering Martha and Her Kin: Passenger Pigeon,
A Chronicle of the Boom Times: Prairie Chicken,
Triumph of the Trumpeter: Sandhill Crane,
Changing Status of the Colonial Nesters: Cormorants, Herons, and Gulls,
14. For Everything There Is a Season: Birds through the Year
Nesting Season: Birds of Woodlands,
Nesting Season: Birds of Grasslands and Marsh,
In Passage: Migration and Vagrancy,
Thriving in the Cold: Wintering Birds,
15. Figures in Fur: Mammals
What a Time It Must Have Been: Extirpated Species,
They Fly by Night: Bats,
Burrowers, Tree Dwellers, and Engineers: Insectivores and Rodents,
Adaptable Song Dog of City and Suburb: The Coyote,
Meet the Neighbors: Raccoons, Opossums, and Skunks,
The Metamorphosis of Bambi: White-Tailed Deer,
Conclusion: Prospects for the Future
Do Go Gentle into That Good Fight: Ecological Restoration and Construction,
Sharing Space: Institutional Trends,
A Place for All: Midewin National Tallgrass Prairie and Prairie Parklands,
Notes
Bibliography
Index
In the sweeping A Natural History of the Chicago Region, Greenberg takes you on a journey that begins with European explorers and settlers and hasn't ended yet. Along the way he introduces you to the physical forces that have shaped the area from southeastern Wisconsin to northern Indiana and Berrien County in Michigan; the various habitat types present in the region and how European settlement has affected them; and the insects, reptiles and amphibians, birds, fish, and mammals found in them, then amidst the settlers and now amidst the skyscrapers. In all, Greenberg chronicles the development of 19 counties in Illinois, Michigan, and Wisconsin across centuries of ecological, technological, and social transformations.
This is a fascinating story told with humor and passion, offorests battling prairies for dominance; of storms battering towns and lakes; of prairies plowed, wetlands drained, and species driven extinct in the settlement of the Midwest; and of caring conservationists fighting to preserve and restore the native plants and animals. Drawing on historical sources as well as current scientific information, Greenberg places the natural history of the region in a human context, showing how it affects our everyday existence in even the most urbanized landscapes.
Encyclopedic, compelling, and compassionate, A Natural History of the Chicago Region is the definitive chronicle of the natural life of a major urban area and has much to offer historians as well as any fan of natural history, from birders, hikers, and paddlers to restorationists and ecologists. You will be captivated by everything from the spotted touch-me-not to the coyotes found in the city's most exclusive neighborhoods.
A Natural History of the Chicago Region / Edition 2 available in Paperback
A Natural History of the Chicago Region / Edition 2
by Joel Greenberg
Joel Greenberg
- ISBN-10:
- 0226306496
- ISBN-13:
- 9780226306490
- Pub. Date:
- 12/01/2004
- Publisher:
- University of Chicago Press
- ISBN-10:
- 0226306496
- ISBN-13:
- 9780226306490
- Pub. Date:
- 12/01/2004
- Publisher:
- University of Chicago Press
A Natural History of the Chicago Region / Edition 2
by Joel Greenberg
Joel Greenberg
Paperback
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Overview
In A Natural History of the Chicago Region, Joel Greenberg takes readers on a journey that begins in 1673 with Father Jacques Marquette and Louis Joliet—the first Europeans known to have visited the Chicago region—and that we're still on today. This is a fascinating story, told with humor and passion, of forests battling prairies for dominance; of grasslands plowed, wetlands drained, and species driven to extinction in the settlement of the Midwest; and of caring conservationists fighting to preserve and restore the native plants and animals. Intermingling historical anecdotes and episodes straight from the words of early settlers and naturalists with current scientific information, Greenberg places the natural history of the region in a human context, showing how it affects our everyday existence in even the most urbanized landscape of Chicago.
Product Details
| ISBN-13: | 9780226306490 |
|---|---|
| Publisher: | University of Chicago Press |
| Publication date: | 12/01/2004 |
| Series: | Center for American Places - Center Books on American Places |
| Edition description: | 1 |
| Pages: | 592 |
| Sales rank: | 796,593 |
| Product dimensions: | 7.00(w) x 10.00(h) x 1.50(d) |
About the Author
Joel Greenberg is a naturalist, writer, and environmental consultant. He is the author of A Natural History of the Chicago Region and coauthor of A Birder’s Guide to the Chicago Region.
Read an Excerpt
A Natural History of the Chicago Region
By Joel Greenberg
University of Chicago Press
Copyright © 2004 Joel GreenbergAll right reserved.
ISBN: 9780226306490
Scenery graces the American land in a way that seems haphazard. But that is not really true.... Each landscape is the result of the complex interplay of many forces throughout the long history of the continent. The true impact of landscape upon the beholder is not the present scene alone. Rather, understanding lies in knowledge of the many forces — climate, vegetation, soil, geologic change — that have molded the scene. —Peter Farb (1963)
Sometime during July 1673, seven men exploring on behalf of New France and Catholicism left the Mississippi River and proceeded up the Illinois River. They reached the Des Plaines River, which they ascended to the portage that would lead them to the Chicago River and Lake Michigan. Commanded by Father Jacques Marquette and Louis Joliet, this party of Frenchmen became the first Europeans known to have entered the Chicago region. Marquette described his impressions: "We have seen nothing like this river that we enter, as regards its fertility of soil, its prairies and woods; its cattle, elk, deer, wildcats, bustards, swans, ducks, parroquets, and even beaver. There are many small lakes and rivers. That on which we sailedis wide, deep, and still, for 65 leagues. In the spring and during part of the summer there is only one portage of half a league."
Joliet echoed the sentiments of the priest in even more glowing terms: "The river which we named for Saint Louis [Illinois River] which rises near the lower end of lake of the Illinois [Lake Michigan], seemed to me the most beautiful, and most suitable for settlement.. . . The river is wide and deep, abounding in catfish and sturgeon. Game is abundant there; oxen, cows, stags, does, and turkeys are found there in greater numbers than elsewhere. For a distance of eighty leagues, I did not pass a quarter of an hour without seeing some."
The land they had reached lies within a great ecotone — a zone of ecological transition where hardwood forests meet tallgrass prairies. It is contested ground where trees compete with grass for dominance. Fires were frequent and tipped the balance in favor of prairie, which, along with the transitional shrubland and savanna, covered most of the region. Where ravines, water, or other barriers blocked the advancing flames, forests took hold.
As the great glacier that had covered the area for thousands of years melted and receded northward, vast quantities of water were left behind to create and nourish the lakes, rivers, and wetlands that adorned the landscape. These included Lake Michigan (the third largest of the Great Lakes) and some of the grandest marshes in inland North America. The force of the glacier also ordained that the Chicago region would straddle the eastern Continental Divide, separating the drainage area of the Atlantic Ocean from that of the Gulf of Mexico. The rivers Des Plaines, Fox, Kankakee, and their tributaries were in the Illinois and Mississippi watershed, while the Chicago, Calumet, Pike, Root, and St. Joseph fed the Great Lakes. (The Kishwaukee River, draining portions of McHenry, Kane, and Walworth counties, is in the Rock River watershed, and the Tippecanoe River, draining small parts of Starke and Jasper Counties, is in the Ohio River watershed.)
We will never know exactly how this region looked three hundred years ago. Attempts to decipher its original appearance have relied heavily on the data generated by the U.S. Public Land Surveys conducted in the region from 1821 (when Cook County's surveys began) to 1841 (when surveys in Kane and Lake Counties in Illinois were completed). These surveys created a national grid whereby property could be located with ease and precision. In the process, the surveyors noted tree species and size, prairies, location of water bodies, and other landscape features. Their work is the closest thing that scientists have to a systematic inventory of early nineteenth-century plant cover.
A number of ecologists have combined these data with soil distribution, travelers' descriptions, geologic features, and other information to create maps depicting vegetation at the time of the surveys. (For examples, see figs. 1–5.) As you can see, the maps are not uniform in the number and types of plant communities portrayed. This reflects differences not only among authors but also in the plant community classifications in vogue at the time of map preparation and the detail and accuracy of the surveyors' work. Despite their limitations, however, these maps are valuable as another source for illustrating the diversity that once defined this region.
That diversity brought to the land an almost unimaginable fertility and an abundance of life that in some manifestations was unrivaled by any other terrestrial environment on earth. To understand and appreciate this remarkable bounty, one must look at how it came to be.
Ice Sculptor: Glaciation
Part of a huge sheet of ice born in the Laurentide Mountains of Quebec, the Lake Michigan lobe of the Wisconsin Glacial Episode covered the Chicago region until about 13,800 years ago. The Wisconsin was the most recent of a series of glacial episodes over 2 million years, and it obliterated most of the topographic barriers left by its predecessors. The flowing ice, augmented by rocks that adhered to it, leveled the unconsolidated sediments in its path and filled vast areas with the crushed earth it had picked up along the way.
Because the underlying land was not uniform, neither was the glacial advance. The ice mass cut deeper and traveled farther in valleys where the substrate was softer. These advances, or lobes, gouged out tremendous amounts of earth, enough to create their masterpieces: the five Great Lakes holding more than 25 percent of the planet's unfrozen fresh water. The valley that was to hold Lake Michigan was deepened five hundred to nine hundred feet.
Just as a turn of the climatic cycle launched the glacier southward from its Canadian mooring, a warming trend halted its advance. As temperatures gradually increased, the ice began to melt, leaving water and pulverized earth in its wake. These remains formed the plains, uplands, rivers, and lakes that essentially make up the landscape of the Chicago Region. (Depositions by winds and tides, erosion, and beaver activity have wrought more recent changes.) Based on these glacial features, geographers have divided the Chicago region into seven natural divisions. (See fig. A1.)
Where the ice receded without interruption, the material left behind became ground moraines (also known as till plains), marked by flat or gently rolling surfaces. But the glacial retreat, like its advance, was uneven and halting. Where it stalled, the crushed earth and rock accumulated and became terminal moraines. A series of these moraines parallels and encircles the southern portion of Lake Michigan to form three concentric U-shaped uplands. The morainal system farthest from the lake is the Outer Uplands and includes Kane County, much of western McHenry County, and the southern portions of Jasper and Starke Counties but otherwise lies beyond the Chicago region.
Located in the middle, the Valparaiso Upland is the highest of the morainal systems, reaching 1,140 feet above sea level near Lake Geneva, Walworth County. Its northern sector, principally Walworth, McHenry, Kane, and Lake Counties in Illinois, exhibits some of the most picturesque scenery in the region: where earthen debris accumulated in cavities and channels of the thinning glacier, cone-shaped kames and the serpentiform ridges of eskers rise up from the flat countryside. The ebbing ice also endowed this portion of the upland with numerous lakes, including Lake Geneva, the Chain O' Lakes complex, Lake Elizabeth, Lake Zurich, and Lake Delevan.
Farther south, the Valparaiso Upland becomes less pronounced. Its relative flatness is seen to good advantage from a plane landing at Chicago's O'Hare Airport. As the moraine sweeps around the end of Lake Michigan into Indiana, it becomes three gently rolling ridges roughly coincident with U.S. Route 6 in Lake County and U.S. Route 30 in La Porte County. Cedar Lake is the only water body of any size.
The third morainal complex, and the youngest, is the Lake Border Upland. Its name is derived from the discontinuous bluff, in places reaching an elevation of 140 feet above the lake, that rims the Lake Michigan shoreline in northern Racine County and then from Waukegan southward to Winnetka. Numerous ravines, over thirty of them in the Illinois portion, cut the bluff perpendicular to the lake and provide a microclimate suitable for certain northern plants not otherwise found here. These picturesque landscapes also provide the location for many of the region's aristocracy, whose estates have often afforded protection to these rare natural communities. Two of the area's principal military installations are located here as well: Fort Sheridan, now deactivated, was established as Camp Highwood in 1887 to protect those same rich families should Chicago's social unrest threaten their baronial homesteads, and the Great Lakes Naval Training Center, in North Chicago, through which all of the nation's naval recruits must pass.
The Lake Border Upland was poorly drained by the shallow and slow-moving Des Plaines, Skokie, north branch of the Chicago, Root, and Pike rivers. As a result, extensive wetlands developed between the moraines. The largest was the Skokie Marsh, converted into the Skokie Lagoons by the Civilian Conservation Corps in the 1930s.
As the shrinking glacier retreated northward, the furrow enlarged by the Lake Michigan lobe filled with water. Hemmed in by the glacial edge and the Valparaiso Moraine, this meltwater ponded and formed Lake Chicago, an early stage of ancestral Lake Michigan. (Geologists consider Lake Chicago to have ended when its icy margin melted about eleven thousand years ago.) Expanding waters of the lake eventually cut through the morainal dike at two points near Willow Springs in southern Cook County and flowed southwest toward the Illinois River. The northern or Des Plaines channel provided the main outflow and the southern, known as the Sag, was a tributary that joined it about two miles downstream. Geologists refer to the stream formed by the convergence as the Chicago Outlet. The roughhewn piece of land turned into an island by the outlets became known as Mount Forest Island, now a part of the Palos Forest Preserve complex.
The swollen stream leaving Lake Chicago tore at its banks, creating a bluff-lined channel that was to become the lower Des Plaines River Valley. For twenty miles, from Willow Springs to Joliet, this segment of the Des Plaines provides locally unique habitat for such rare organisms as leafy prairie clover and Hine's emerald dragonfly. With the completion in 1848 of the Illinois and Michigan Canal, which linked the Illinois River and Lake Michigan, and in 1900 of the Chicago Sanitary and Ship Canal, the valley also became a major transportation route between the Mississippi and Great Lakes watersheds. In 1984, the National Park Service designated the Illinois and Michigan Canal as the country's first National Heritage Corridor. The corridor now draws over 1.3 million people a year.
The Chicago area's first tourist attraction, and one of its most notable geologic features, once stood near the edge of the Des Plaines River near Joliet, a creation of the same waters that raged out of Lake Chicago. Known as Mount Joliet, it was a gravel mound shaped in the figure of a cone except that it had a perfectly flat top. Unfortunately, people of the twentieth century know it only from the accounts of early travelers, for over 130 years have passed since the majority of it was hauled away to become city streets and ballast for railroad beds. But starting as early as the 1690s, visitors went out of their way to view it, and, curiously, estimates of its height increased over the years from sixty to one hundred feet. By the time James Paulding saw Mount Joliet in 1848, part of it had been removed during construction of the Illinois and Michigan Canal. Despite the marring, he could still write: "This mound is one of the most remarkable, as well as beautiful objects in nature.. . . It is as regular and perfect in construction, form, and outline as any work of art I ever saw.... It is, however, . . . a production of the cunning hand of Nature, who sometimes it would seem, amuses herself by showing how much she can excel her illegitimate sister, Art, even in her most successful attempts at imitation."
Over the thousands of years of its existence, Lake Chicago shrank in a series of successively lower lake phases. (See chap. 10.) When the ice eventually melted throughout the Great Lakes basin, changing elevation and drainage produced the modern configuration of Lake Michigan.
The receding of Lake Chicago's frigid waters exposed previously submerged land that became known as the Chicago Lake Plain. (In Indiana, some people now refer to it as the Calumet Lake Plain.) Millennia of inundation left this land extremely flat, leveled by waves and the still-water deposition of clays. Lake Michigan received the waters of the lake plain via the Root, Pike, Chicago, and Calumet Rivers, the latter two of which now flow toward the Mississippi because of canal construction and other engineering projects.
Most of the relief is provided by three elongated ridges, each of which corresponds to the shoreline of a particular stage of Lake Chicago. But the most massive lake relic of all is six-mile long Blue Island, Cook County, a detached extension of the Lake Border Upland that rises eighty feet above the plain. According to an old newspaper article quoted by historian Ferdinand Schapper, Blue Island, "when viewed from a distance, appears standing in an azure mist or vapor." As for the other part of its name, it was: actually an island, poking above the icy waters of Lake Chicago; practically an island, surrounded by marsh and streams; and metaphorically an island as its timbered slopes rose above the prairie.
Certainly, it would have been hard to imagine that such a landscape as the Chicago Lake Plain, with its marshes, timbered slopes, and prairies, would eventually become the setting for the people, commerce, and industry that have helped define the nation's heartland. The cities of Racine, Kenosha, Waukegan, Michigan City, and St. Joseph are here. So are the Bahai Temple (Wilmette, Cook County), Northwestern University (Evanston, Cook County), Oak Park's (Cook County) concentration of homes designed by Frank Lloyd Wright, and the steel mills of Gary. But the anchor for the region is, of course, Chicago. Home to 2.8 million people, the city draws millions each year as visitors to the Lincoln Park Zoo, Field Museum, Art Institute, McCormick Place, and Shedd Aquarium. Wrigley Field, Comiskey Park, Soldier Field, and the United Center provide examples of both the oldest and newest of professional sports venues. Rooted in the dolomite bedrock, the John Hancock Building, Sears Tower, and other architectural wonders that distinguish Chicago's skyline stand high above the ancient lakebed. Farther south, cultural features include Jackson Park, the University of Chicago, Museum of Science and Industry, and historic Pullman, America's first planned industrial city.
Not only was the Lake Plain attractive to the masses who settled there, it also held some of the region's most significant natural areas. Three are of such importance they warrant mention here. Although constantly augmented by wind and lake currents, the Indiana Dunes were originally the creation of wind-borne sand uncovered by the waning Lake Chicago. The pioneering ecologist Henry Cowles called these dunes "the grandest in the entire world," and most of what is left of them is now under state or federal protection. The Calumet region, on the Illinois-Indiana border, held marshes that were equally grand. Today, we can barely comprehend the abundance of wildlife that once inhabited them. Unfortunately, that area is where Chicago in effect decided to defecate, and most of the former wetlands are now buried under waste. Although perhaps lacking the historical or national significance of the other two sites, Illinois Beach State Park, Zion (Lake County, Ill.), encompasses more relatively undisturbed natural communities than any other place in Illinois.
Sandwiched between the Outer Upland and the Valparaiso Upland are two lowlands considered distinct physiographic provinces. The smaller is known as the Manteno Plain, a wedge-shaped region of ground moraines. The larger Morris-Kankakee Basin combines the Morris Basin, a former glacial lake, and the Kankakee Basin, a valley covered with sand by glacial meltwater and through which the Kankakee River flows. Within its borders are the "swamp and dunes" near Braidwood, Will County, which the botanist Willard Clute studied so carefully, and the once huge Kankakee marshes that rivaled Calumet in their marvelous richness.
Fertility Underfoot: Soils
In its slow and grinding march of expansion and contraction, the ice sheet left behind not only the conspicuous landforms just described but also the more evenly distributed deposits of granulated rock and earth. These deposits are categorized by the size of their particles. The most common of these in this area are clay (the finest grained), silt (less finely grained), sand (coarse), loam (a combination of the previous three and often organic material), and gravel (most coarse).
Although there are a few places where the underlying bedrock is exposed (particularly along the lower Des Plaines, Fox, and Kankakee River valleys), these deposits cover most of the region at depths of seventy-five feet or more. They are the precursors of soil, that layer of varying thickness and character that anchors terrestrial life and reflects the history of the land.
Soils develop from a base known as "soil parent materials." The manner of deposition determines the classification of these materials. In the Chicago region, the most frequently occurring soil parent materials are till (deposited by glacial ice), outwash (deposited by glacial meltwater), alluvium (deposited by rivers and streams), loess (silt deposited by wind), and eolian sand (deposited by wind).
The parent materials and the size of the particles determine the distribution of soils across the landscape. Gravel, for example, being large and heavy was moved by ice (till) and, for shorter distances, by meltwater (outwash); concentrations of it occur in morainal areas. Sand and silt took longer to settle out of water and are common in areas that were formerly submerged such as the Chicago Lake Plain and the Morris-Kankakee Basin. Clay, which took a very long time to settle, is thickest on lands once covered by sheltered ponds and bays. The silt exposed by receding rivers was often deposited as loess, most heavily on the east sides of valleys.
Parent materials became soils through the many agents of change to which they were subjected. Chemical and mechanical forces break down the particle sizes even further and facilitate the downward percolation of clay. Age, slope, and climate are other critical factors in the formation of the more than two hundred soil series that occur in the Chicago region. (Series are to soils as species are to plants and animals.)
Biotic factors are among the most important in determining soil character. Soils that developed under prairies (mollisols) have substantially more organic material than those that formed under forests (alfisols). The quantity of vegetative biomass produced in a prairie is similar to that of an oak woods, but the location of that material is different. Prairie grasses and forbs (herbaceous plants) send their roots deep into the earth to form dense tangles, the first three and a half feet of which can weigh more than 150 tons an acre. The same distance below the surface of an oak woods, however, yields only eighty tons of organic matter per acre; ninety tons are in trunks, limbs, and leaves.
The subterranean mats of woven roots further enrich the mollisols by providing habitat for numerous organisms, from moles to earthworms to bacteria. These inhabitants of the nether zones facilitate the decomposition of surface and subsurface plant matter, keep the soil loose and aerated, and replenish the nitrogen that is so critical to soil fertility. From an agricultural perspective, the deep and black mollisols are among the best soils in the world, a fact that goes a long way to explaining why the tallgrass prairie is virtually extinct.
Atmospheric Impacts: Climate and Weather
Solving the puzzle of the ecotonal landscape was an exercise that took over 150 years. By the end of the nineteenth century, at least ten different theories attempted to explain why some land supported prairie at the expense of forest. Among the factors thought to cause prairies were soil origin, soil composition, bison, a combination of fire and drought, and fire alone. While fire was the most often cited cause during that period, the scientists who worked at the beginning of the twentieth century largely rejected it in favor of climate. Botanists determined that the formation of prairie occurs where the ratio of precipitation to evaporation falls between 60 and 80 percent and is promoted by extreme droughts. In rebutting the fire camp, Henry Gleason noted that "in order to have a prairie fire, you first must have a prairie."
Biologists eventually reached the consensus that climate and fire are the keys to deciphering the complicated vegetation patterns that enrobed the land. Distilled to its essence, the accepted scenario says that the climate of eight thousand years ago was warm and dry enough for prairie species from the west and south to spread eastward through this region into eastern Indiana and Ohio. This projection became known as the prairie peninsula. Starting about five thousand years ago, however, the climate shifted in the other direction, producing wetter and cooler conditions that enabled the forests to regain some of the ground they had lost. Periods of drought hindered the arboreal advance, but it was fire that perpetuated the prairie dominance of the Chicago region. Climate allowed the prairie to develop; fire maintained prairie when the climate changed. In the words of plant ecologist Roger Anderson, "the vegetation of the prairie peninsula was most likely a shifting mosaic of grassland, forest, and savannah that was determined by fire frequency under a climatic regime capable of supporting any of these vegetation types."
Climate determines the vegetation of a region more than any other single factor. In this region three air masses most influence the climate. The dominant mass originates as humid air off the Pacific Coast but sheds its moisture as it rises to clear the Rocky Mountains. This dry rain shadow sweeps east on the same thousand-mile course that enabled it to create the prairie peninsula. Its effects on this region are tempered, however, by the other two air masses — humid air from the Gulf of Mexico meets dry cold air of the Canadian Arctic and produces most of the region's precipitation. The interplay of these air systems translates into the climatic changes that influence the evolving face of the landscape.
Climate manifests itself most noticeably in the day-to-day atmospheric events known as weather. In this region, the weather is marked by great variations in temperature, precipitation, and wind. Chicago has temperatures that average 75˚F in July and 26˚F in January. Highs and lows at O'Hare Airport have ranged from 104˚F on June 20, 1988, to -27˚F on January 20, 1985.
The region receives an average of about thirty-four inches of precipitation a year, most of it during the summer. Both prolonged droughts and deluges are uncommon. The wettest month on record, August 1987, produced 17.10 inches of rainfall, 9.35 inches of which fell within one twenty-four-hour period. August 1979 was the driest month ever, when a paltry .02 inches of precipitation fell.
Severe snowstorms occur from time to time, causing an array of serious consequences. Hard snows during the winter of 1842–43 are said to have killed thousands of prairie chickens (Tympanuchus cupido) and bobwhite (Colinus virginianus) throughout Lake County, Illinois. The storm of January 1979 was memorable in changing the political landscape: challenger Jane Byrne used the snow, and its clean-up, as an issue over which she defeated incumbent Michael Bilandic to become mayor of Chicago.
Winds in the area are predominantly from the west, although there is variation from month to month. They average 10.3 miles per hour, which would give Chicago the title of "eighty-first windiest city," at least among the 270 United States cities looked at as part of a major study of urban climate. Chicago's sobriquet "the windy city" actually came not from its climatic conditions but, rather, from the perceived boastfulness of its citizens during the planning and construction of the 1893 Columbian Exposition. But genuine gusts have exceeded eighty miles per hour, including the record one of eighty-seven miles per hour that came out of the northeast in February 1894.
The region's most spectacular weather arrives as storms, some of which lash the area with deadly fury. The most notorious was the Veteran's Day Storm of 1940. In the three-state area of Illinois, Michigan, and Minnesota, freezing temperatures and high winds killed sixty-six people, caused millions of dollars of property damage, and destroyed large tracts of forest. Fifty-nine more lives were claimed when the storm sank three ships off Pentwater, Michigan.
There are also the short-lived but potentially devastating tornados that occur more commonly on the central grasslands of the United States than anywhere else in the world. On August 28, 1990, a tornado ravaged parts of Will and Kendall Counties, killing twenty-nine, injuring 350, and destroying $115 million worth of property. It was the most destructive of any reported in the country that year.
Local weather conditions affect animal and plant populations in numerous ways. Moisture levels, wind speed, and wind direction at time of seed ripening help determine which plants will successfully colonize a new site. The absence of an insulating snow cover can increase winter plant mortality, especially for seedlings. Temperature and wind strongly influence phenological occurrences, defined by botanist John Curtis as "the seasonal march of observable biological events." Spring flowers bloom along the Des Plaines River two weeks earlier than at cooler sites near Lake Michigan. Major flights of migrating birds can be correlated to the passage of cold and warm fronts, and salamanders emerge in the spring to breed as higher temperatures thaw their winter quarters.
Aquatic ecosystems, particularly small lakes, are even more profoundly affected by weather conditions. Wind and the cycle of water warming and cooling ensure that essential nutrients disperse throughout the community. But during the winter a layer of ice covered by deep snow can prevent light from penetrating the water. Photosynthesis stops, along with the associated production of oxygen; meanwhile, decaying vegetation depletes the oxygen that is present. The devastating oxygen deficiency becomes apparent when the spring thaw reveals a lake surface littered with bloated fish.
Burned to Life: Fire
Perhaps because it was new to their experience, the early commentators were awestruck by the raging conflagrations they came to know on their travels through the Midwest. Many of those who witnessed these displays of heat and color found them exquisite, as glorious as the land itself:
For a mile and more before you reached the edge of the fire you were in its bright orange light, which made everything as visible as if it were noon day, and the sun was shining fiercely through a blood colored haze.... At last you gain a little rise and look beyond into such a scene as nothing but a prairie fire can show. It spreads out a sea of red smoldering ashes, glowing for miles in all directions, while the deep white ridge of flames ahead mount the slopes with awful rapidity, and flap their heavy tongues up into the air with a hoarse roaring noise that fills you with astonishment and almost terror. Hour after hour you may stand, fascinated with the terrible beauties of the scene, as the mass of red sultry ruins grows and grows each minute, till your eyes are pained and heated with its angry glare, and you almost dread the grand, fierce sheet of fire, which has swept all trace of vegetation from the surface of the prairie.... On Monday night ... the wind changed ... and turned the flames nearly back upon the ground they had already devastated.... On the next day, however, they sprang up fresh and raged faster and faster than before.... And on the last night the glare was tremendous — as if the world itself was burning. (Near Dwight, Illinois, 1861)
The historical record demonstrates how common a phenomenon fire was on the open prairie. In the fall of 1837, a Chicago resident wrote to relatives in New England that "the prairie takes fire every day that we have, and in the evening burns beautifully and takes up the whole sky." A year later, a traveler entering Chicago by boat from Milwaukee noted "large clouds of smoke that could be seen in various directions," smoke that he was told originated from the prairie burns that occurred every spring and fall. One night in 1858, yet another visitor saw five different fires within a twenty- or thirty-mile stretch as she approached Chicago from Indiana.
There is disagreement among scientists as to whether prairie fires were primarily meteorological or cultural in origin. Those who take the former view argue that the Midwest is a region of unstable weather producing storms frequently punctuated by flashes of lightning. Ecologist Paul Sears points to this as "evidence that, however enthusiastic a pyromaniac man may be, lightning is a far more common and efficient igniter." Opponents counter that substantial quantities of rain accompany most lightning storms, a situation hardly conducive for sustained combustion. They attribute the fires to the human beings who arrived in the region roughly twelve thousand years ago. Burning was used for several purposes, most particularly as an aid to hunting. A fair conclusion is that both causes contributed to the fires, fires that through their power and frequency etched the shifting lines of grass, shrubs, and trees onto a background fixed by climate and topography.
With broad strokes, the relationship between topography, fire, and terrestrial vegetation can be easily outlined. On the level lake plains and ground moraines where the westerly winds could drive the flames unhindered, the prairies flourished. They are composed of perennial grasses and forbs that die back every year. The growing parts of these plants are beneath the soil and thus are unscathed by fire. (Although temperatures at the soil surface during burns can range from 175˚ to 1,300˚F, little increase in temperature has been noted at depths of as little as less than an inch below the surface.) And as fire consumes the thick litter that develops over time, prairie vitality is renewed: light reaches young plants and nutrients are made available for soil enrichment. For some species, scorching heat actually facilitates seed germination.
Lands that were sheltered from the full brunt of the conflagrations by watercourses or morainal ridges supported shrublands and savannas. One of the dominant trees of the open savanna is bur oak, a species endowed with a thick corky bark that enables it to survive repeated fire exposure. And where fires were most infrequent — such as the east side of rivers, north and east faces of morainic slopes, and in ravines — forests were able to develop.
A New Force
Over thousands of years, the great forces of glaciation, climate, and fire had created a seamless mosaic of waters, wetlands, prairies, shrublands, and woods. But the arrival of the Europeans set in motion a new force, one with the power and will to impose upon the landscape a uniformity that is now virtually complete. While this process has diminished our natural heritage to a sorrowful extent, it is a tribute to the resiliency of nature and the efforts of a few farsighted people that so many native plants and animals have managed to survive, albeit in ever shrinking refuges.
Continues...
Excerpted from A Natural History of the Chicago Region by Joel Greenberg Copyright © 2004 by Joel Greenberg. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
Preface and Acknowledgments1. The Great Forces
Ice Sculptor: Glaciation,
Fertility Underfoot: Soil,
Atmospheric Impacts: Climate,
Burned to Life: Fire,
A New Force,
2. In Quality Unexcelled: Prairie Types and Composition
Of Breezes and Braided Roots: The Grasses,
Where Spring Begins: The Gravel Prairies,
The Richest of All: The Black-Soil Prairies,
On the Bones of Earth: The Dolomite Prairies,
Dr. Clute's Domain: The Sand Prairies of Braidwood,
3. In Quality Diminished: Prairie Settlement and Conservation
Under the Fleur-de-lis: The French Period,
The Prairie Resists: Treelessness, Fire, Disease, and Other Barriers to Settlement,
The Defenses Crumble but Some Prairie Survives,
The Turning Point for Prairie Conservation: Goose Lake Prairie,
Prairie Tales: A Few Prairies and the Battles to Save Them,
Protecting the Protected: Prairie Stewardship and Management,
4. The Nearly Vanished Transitions: Barrens and Savannas
Gone So Quickly: The Deep-Soil Shrublands and Savannas,
All Sorts of Floral Treasures: The Sand Savannas and Shrublands,
Like Nowhere Else on Earth: The Savanna of Langham Island,
5. Witnesses to History: Forests
Letting in the Light: Oak Forests,
Where Shadows Reign: Maple Forests,
Raised in Flood and Drought: Lowland Forests,
Mostly On or Under the Trees: Lichens and Mushrooms,
From Lumber to Ecosystems: Utilization and Conservation,
Knotty Questions: How Best to Treat Local Forests,
6. Of Two Worlds: Wetlands
The Pilgrims Progress to Section 404: Destruction and Conservation of Wetlands,
On a Cusp: Sedge Meadows and Marshes,
Wiggly Fields: Bogs and Fens,
7. The Last Wilderness: Lake Michigan
The Sullying of Lake Michigan: Pollution,
Floaters, Bottom Dwellers, and a Filter Feeder Run Amok: The Plankton and Benthos,
Agents of Change: Commercial Fishing and Alien Species,
Victims of Change: Native Fish,
8. Approaching the Way: Rivers and Small Lakes
Rivers in Flux,
Current Affairs: River Ecology,
River Atrophy: The Disappearing Mussels,
Like Crystals on the Landscape: The Small Glacial Lakes,
9. Casualties of a Modern World: The Marshes of the Kankakee and Calumet
Two Thousand Bends of a Silver Thread: The Kankakee's Great Marsh,
The Marsh That Will Not Die: The Calumet,
10. Lake Michigan's Rim: Beaches, Dunes, and Bluffs
Setting the Scene,
So Many Fine Examples of Rare and Beautiful Species: Natural Communities of the Indiana Dunes,
By Their Deeds, Ye Shall Know Them: Utilization and Conservation of the Indiana Dunes,
Steeper and More Mesic: The Dunes of Berrien County,
Not All Treasure Is at the Rainbow's End: The Western Dunesland,
Cool Shadowy Slopes: The Bluffs and Ravines,
11. Many More Than We Know: Insects
Beleaguered Beetles, Mystery Moths, and A Rediscovered Dragonfly: A Smattering of Endangered Insects,
Flitting on the Edge: The Mitchell's Satyr and the Karner Blue,
Mere Patches in Time and Space: The Corpse as Ecosystem and Forensic Entomology,
Conspicuous on a Large Scale: Insect Swarms,
The Musical Brood: Periodic Cicadas,
12. Survivors in Trouble: Reptiles and Amphibians
In the Soup and Pets of Plunder: Turtles,
Long and Suffering: Snakes (and Three Lizards),
Winding through History: Massasauga Rattlesnakes,
Under Cover or on the March: Salamanders,
Plight of the Choristers: Frogs and Toads,
13. Of Extinction and Resurrection: Passenger Pigeon, Prairie Chicken, Sandhill Crane, and Colonial Nesters
Remembering Martha and Her Kin: Passenger Pigeon,
A Chronicle of the Boom Times: Prairie Chicken,
Triumph of the Trumpeter: Sandhill Crane,
Changing Status of the Colonial Nesters: Cormorants, Herons, and Gulls,
14. For Everything There Is a Season: Birds through the Year
Nesting Season: Birds of Woodlands,
Nesting Season: Birds of Grasslands and Marsh,
In Passage: Migration and Vagrancy,
Thriving in the Cold: Wintering Birds,
15. Figures in Fur: Mammals
What a Time It Must Have Been: Extirpated Species,
They Fly by Night: Bats,
Burrowers, Tree Dwellers, and Engineers: Insectivores and Rodents,
Adaptable Song Dog of City and Suburb: The Coyote,
Meet the Neighbors: Raccoons, Opossums, and Skunks,
The Metamorphosis of Bambi: White-Tailed Deer,
Conclusion: Prospects for the Future
Do Go Gentle into That Good Fight: Ecological Restoration and Construction,
Sharing Space: Institutional Trends,
A Place for All: Midewin National Tallgrass Prairie and Prairie Parklands,
Notes
Bibliography
Index
Recipe
If you had canoed in July of 1673 with Father Jacques Marquette and Louis Joliet-the first Europeans known to have visited the Chicago region-you would have passed through a landscape harboring a biological richness in some ways unsurpassed anywhere else on the planet. Poised on the fertile borderlands where hardwood forests met tallgrass prairies, and rivers and streams meandered through expansive wetlands and into vast lakes, the area teemed with wildlife. And if you were a nineteenth-century visitor in what is now-and was then-the heart of downtown Chicago, you might have been overtaken by a group of men with guns and knives hunting an errant bear who had wandered into the city from the prairie to the west. While Chicago may be known today as a city of "wild life," from Al Capone to the Playboy headquarters, Joel Greenberg dazzles readers with the story of Chicago's true and enduring wildlife.In the sweeping A Natural History of the Chicago Region, Greenberg takes you on a journey that begins with European explorers and settlers and hasn't ended yet. Along the way he introduces you to the physical forces that have shaped the area from southeastern Wisconsin to northern Indiana and Berrien County in Michigan; the various habitat types present in the region and how European settlement has affected them; and the insects, reptiles and amphibians, birds, fish, and mammals found in them, then amidst the settlers and now amidst the skyscrapers. In all, Greenberg chronicles the development of 19 counties in Illinois, Michigan, and Wisconsin across centuries of ecological, technological, and social transformations.
This is a fascinating story told with humor and passion, offorests battling prairies for dominance; of storms battering towns and lakes; of prairies plowed, wetlands drained, and species driven extinct in the settlement of the Midwest; and of caring conservationists fighting to preserve and restore the native plants and animals. Drawing on historical sources as well as current scientific information, Greenberg places the natural history of the region in a human context, showing how it affects our everyday existence in even the most urbanized landscapes.
Encyclopedic, compelling, and compassionate, A Natural History of the Chicago Region is the definitive chronicle of the natural life of a major urban area and has much to offer historians as well as any fan of natural history, from birders, hikers, and paddlers to restorationists and ecologists. You will be captivated by everything from the spotted touch-me-not to the coyotes found in the city's most exclusive neighborhoods.
From the B&N Reads Blog
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