Maple Grove Forest Preserve is located 20 miles west of Chicago, in DuPage County, Illinois. It measures six-tenths of a mile from St. Joseph Creek at its northern end to Maple Avenue at its south, and a quarter mile between the backyards abutting its east and west boundaries. The forest is small enough that you could learn the calls of its common summer birds on a lunchtime walk. You could memorize its dominant trees and showier wildflowers in an afternoon.
Fast-forward through the last 10,000 years, and we would see a flickering mosaic of prairie, oaks, and maples, forests racing up and down glacial moraines.
But run a transect perpendicular to the main trail, and you’ll find that this forest is vast. In late January, after a fresh snow, trails of skunks, coyotes, and deer mice appear throughout the preserve, twining around carcasses of red and white oaks. Fallen ashes two feet in diameter, cracked open on impact, are perforated with ant galleries. Tangles of black fungal rhizomorphs creep 20 feet or higher under the skin of standing trees, exposed when the bark ruptures. Lichen-covered branches drop 60 feet to the forest floor, where they host orange mycena mushrooms and families of flat-backed millipedes. Entodon mosses colonize a fallen maple and keep it moist. They overtop mats of flat-brocade moss, then bump up against mounds of baby tooth moss. After a few years, the mosses share the log with bacteria-scavenging slime molds. Earthworms work the dead tree as it softens. Brilliant orange chicken-of-the-woods sprouts as the bark sloughs off, and the log is trampled back into the earth by human foragers cutting off the fungal fruiting body at its base to take it home and cook it in oil and wine. Within a few decades, the log will have given back to the woods everything it assimilated over two centuries of growth.
Maple Grove has been shaped by thousands of years of human settlement and of plant evolution, migration, and extirpation extending back through the Eocene. If we could rewind the tape and then fast-forward through 15 million years, we would see the landscape around Maple Grove undulate with forest, ice, and fire, populated by species we know well and those we may never know existed, ephemera that missed the fossil record. If we focused on the most recent 10,000 years, the same patch would appear as a flickering mosaic of prairie, oaks, and maple groves, streams writhing across the terrain, forests racing up and down moraines left by receding glaciers. Blink, and a Potawatomi trail between the sites we now call Chicago and Naperville would harden into a settlers’ plank road. Blink again, and the banks of St. Joseph Creek would steepen with erosion as the upstream stretch plunged beneath the streets of Downers Grove, channelized in concrete only to spill across the downstream floodplain in every storm. An infestation of emerald ash borer beetles would arrive, and ash trees would topple over. Then the movie would stop where we are now, with a stream of people on the Maple Grove trails, caught mid-step, enjoying a lazy afternoon in the midst of a pandemic.
On March 21, 2020, Illinois instituted its statewide shelter-in-place order. During that first month, I walked through Maple Grove every day or two. I have been watching these woods closely for several years and have been a naturalist in similar woodlands since I was in my 20s. I have seen the forest-understory species emerge, flower, fruit, and senesce; creep slowly into view some years and emerge like gangbusters in others. But it quickly became clear that walking here in COVID time would be different. I noticed details of the forest year that had escaped my attention despite decades of looking. Dutchman’s breeches bent like bobby pins as the seedlings pulled their yellow-green feathery leaves out of the ground, petioles thick and turgid as mung-bean sprouts, translucent as frosted glass. Toothwort seedlings were an alien purple. The brittle white rhizomes of white trout lily arched above the soil’s surface and plunged back in again, tipped with next year’s plants. My field notebook and camera roll were densely packed, and everything seemed new.
In the first months of the shutdown, public lands around Chicago swarmed with people who, like me, had their health and the freedom to work from home. In most years, an estimated four million people visit the DuPage County Forest Preserves; in 2020 they received closer to six million. 1 There has been so much mountain biking in Maple Grove that I have seen new trails appear in just a few weeks, swaths of bare dirt 20 feet long and three feet wide, where previously wild ginger, bloodroot, and white bear sedge grew. People working from home across the U.S. and Europe have taken up biking or birdwatching. 2 But this freedom to be outside is apportioned unevenly. In March, I corresponded with a colleague in Chicago who for a time hardly got out to local parks, not wanting to sit shoulder-to-shoulder on public transit to travel to her favorite places. Other friends were barred from almost any movement: a colleague in southern France, one of the best naturalists I know, completely missed the spring. A friend from Spain could not explain to his young son why their only outdoor forays were to the roof of their apartment building.
So many people used Maple Grove last year that new trails appeared where wild ginger, bloodroot, and white bear sedge grew.
I’ve been acutely conscious of our good fortune. In Chicago, the enormous convention center just south of the Loop, McCormick Place, was transformed into a hospital and began accepting COVID patients in early April. But my neighbors and I witnessed this from a distance; hospitals in our county never filled. 3 I remained free to identify a millipede or mushroom, to make notes as fruits developed on the trilliums. Yet, on Memorial Day, as a fox trotted down our street with a squirrel in its jaws and monarch butterflies returned to our garden, George Floyd was killed by police on the streets of Minneapolis, and a White dog-walker called 911 on a Black birdwatcher in Central Park, for the offense of reminding her about the leash laws. 4 It has become more obvious than ever this past year that the woods where I feel at ease are not equally accessible to everyone.
Around the first of May, sugar maple leaves hung limp in the midstory. Within a week, they unfurled. Warblers filled the canopy, stopping over on their way north. Toads sang and wooed from the pond in the middle of the preserve. A month later, mosquitoes were drawing blood. Solomon’s seal flowers had almost opened. There were unexpected jewelweed cotyledons in ephemeral creek beds. Baby earthworms twitched beneath the leaves. I came across a few plants of green dragon. Its distant cousin, Jack-in-the-pulpit, is common in our region, and by this time its seedlings were ankle-high, but I had never seen green dragon in Maple Grove. Green dragon and Jack-in-the-pulpit are two of only three North American endemics among an estimated 170 species in the genus Arisaema. The genus arose in east Asia, and ancestors of the North American species migrated through Beringia 20 or 30 million years ago. 5 It’s easy to imagine them as émigrés from an alpine temperate forest on the other side of the world; they form exotic inflorescences, unlike anything else in our woodlands, and they are gender-changers, able to flip back and forth between seed- and pollen-production from year to year, as resources permit. They are packed with poisonous calcium oxalate crystals. But they wear their evolutionary heritage well, and we have come to think of them as natives.
The honeysuckles, which were by this time were in as magnificent a state of flower as I had ever seen, are more recognizable as exotics. There are several non-native species and hybrids in our area, most of which arrived from Eurasia in the 1940s, though some were known here as early as the 1870s. 6 Unlike the Arisaema, honeysuckles are invasive. They alter nutrient cycles and soil microbial communities; they supplant native shrubs and reduce the growth and diversity of native understory species. We’re watching them alter our forests in real time. When I see them flaunting their colors, I understand why people plant them. All the same, I’ll tear out a honeysuckle to make way for a native bloodroot or bugbane.
Honeysuckles, green dragon, and Jack-in-the-pulpit, along with everyone in this town and on this continent, are visitors who stayed.
Honeysuckles, green dragon, and Jack-in-the-pulpit, along with everyone in this town and on this continent, are visitors who stayed. The plant species of Maple Grove have been tracking changing climates and occupying new lands at others’ expense for tens of millions of years. Many of the species we favor today were upstarts at one time, moving in on the heels of residents who were pushed out by cold or drought or fire. We think of the honeysuckles as exotics because they arrived in the Americas “unnaturally,” by boat or airplane, and because we happen to be here while they are taking over the forest understory. Eventually, though, local insect herbivores and fungi will most likely take a liking to them and keep them in check, as parts of a novel forest community we can’t quite imagine.
Like any location carefully examined, Maple Grove records a history of unearned good fortune: one group’s dominance becomes another’s exclusion. What’s different this time around is that humans alive now bear responsibility for a great proportion of the ongoing extinctions and ecological transitions. We’re driving the process along at a phenomenal pace, and we understand very well what we are doing.
In one sense, Maple Grove is ancient. In the lower Eocene, about 56 million years ago, the tree genera here now — oak, maple, ironwood, elm, basswood — were congregated in the arctic. 7 An ocean cut through North America from south to north. The southeastern corner of the continent was dominated by tropical rainforest, while the east-central section (what is now the northeastern U.S. and upper Midwest) ranged from broad-leaved evergreen to deciduous forests of ginkgo, birch, elm, and viburnum. There were palms in what would become the Rocky Mountains, where we now find pines. 8 Then global temperatures began to cool, and eastern North America’s tropical species were pushed south. The Rocky Mountains rose, casting a rain shadow across the continent, and the great ocean drained from the Great Plains. Eastern deciduous forests sorted and assembled as species migrated from the north, interdigitated with the prairies that spread across the plains between eight and six million years ago. North American forests came to resemble what we would see on a walk today.
Beginning two-and-a-half million years ago, temperatures dropped abruptly, and northern portions of the continent were repeatedly glaciated. The glaciers ground away the forests and prairies, scrubbed the soil into a dusty loess, then receded from the Chicago region approximately 17,000 years ago, making way for a succession of plant communities. The first forests that formed along the glaciers’ south edge mixed spruce, aspen, and hardwoods such as elms and oaks, assemblages of species without an exact contemporary analogue. Surveys of pollen grains in lake-sediment cores show ash trees at their highest level of dominance in our region around 14,000 years ago, while maple pollen was barely discernible. At around 10,000 years ago, local spruces disappeared, and maples increased in number. Prairies spread, reaching their maximum extent about 8,000 years ago, filling the Great Plains and extending eastward to form a broad, irregular delta whose terminus falls in what is now Indiana. This “Prairie Peninsula” at the far end of the Rockies’ rain shadow tapered into oak savanna at its northern edge, near where Maple Grove stands now. Where fires were frequent, prairie and fire-tolerant oak trees thrived, particularly the thick-barked bur oak; fire-sensitive trees such as basswood and sugar maple flourished only where they were protected. Maple Grove, cradled by St. Joseph Creek and secluded among glacial moraines, was one of these islands of forest. 9
It’s plausible that Maple Grove as we recognize it today has existed for 10,000 years, though we can’t say for sure. We do know that when the Public Land Survey came through in the 1840s, surveyors walking the section line that ran through the grove’s east lobe encountered trees still here today. 10 A 1948 study of forest-stand structure in southern Wisconsin and northeastern Illinois estimated that Maple Grove was a closed forest — with dense, mature canopy — by the first half of the 17th century. Quantitative work on forest structure in the region, using tree cores to estimate ages and rates of growth, found that, as of the early 21st century, the area’s oldest living tree was a white ash that arose in 1818, and that by the time this ash was born, the grove was already densely shaded. 11
It’s plausible that Maple Grove as we recognize it today has existed for 10,000 years. Yet this tiny forest is still changing, sometimes rapidly.
Yet this tiny forest is still changing, sometimes rapidly. In the 1990s, the emerald ash borer beetle arrived in southern Michigan as a colony of stowaways burrowed into shipping pallets. 12 Like the avian H1N1 virus that caused the global pandemic of 1918–1919, or the mammalian SARS-CoV-2 virus causing the pandemic now, these insects switched hosts — from east Asian ash species to North American ashes species in the case of the ash borers, and from bats or other mammals to humans for SARS-CoV-2. These pathogens spread around the world only because they hitched a ride with us. Emerald ash borers proliferated undetected in the U.S. until the early 2000s, by which time their populations were too widespread to contain. They arrived in Maple Grove sometime around 2007, when they started feeding on the crowns of American ashes. As the upper leaves wilted, the ash borers ate their way downward, inscribing passageways under the bark of 200-year-old trees, devouring the phloem that carries the sugars of photosynthesis down from the leaves and scratching the outer layers of xylem that carries water up from the roots. The ashes wasted slowly, though when the trees finally gave up, it seemed abrupt. Today, hulking boles two feet in diameter lie shattered on the forest floor or stand with broken crowns. Ash seedlings continue to sprout — but for now, in Maple Grove as in almost every eastern North American forest, mature ashes are a memory.
On the land that now includes Maple Grove, we can track human uses dating back to the recession of the glaciers. Archaic flint points 13,000 to 9,500 years old have been recovered from the DuPage River a few miles west of Maple Grove; this would have been around the time that sugar maple migrated to fill most of its contemporary range. The people living here then passed part of their year in villages, where they cultivated native plants. 13 They foraged for tree nuts, and by 4,000 years ago they were trading for copper. 14 By 1,000 years ago, in the Woodland Indian period, there were established seasonal sugaring camps farther north in the Midwest, and the high caloric value of the syrup would have encouraged the establishment of camps in our immediate area as well. 15
Archaic flint points 13,000 to 9,500 years old have been recovered from the DuPage River a few miles west of Maple Grove.
At around 700 years ago, a people referred to by archeologists as the Oneota appear to have displaced the Woodland Indians, developing an increasingly local culture and living in smaller villages. They were succeeded in turn by the Illinois, a diverse nation composed of at least twelve tribes or subtribes. The historic territory of the Illinois was massive. Their population numbered 13,000 or more. 16 But in the mid 1600s, European fur traders decimated beaver populations in what is now upstate New York, home of the Iroquois. The Iroquois consequently fought with tribes to the west to take over their portion of the fur trade, employing guns they had obtained through trade with the Dutch. They pushed the Illinois west to the Mississippi, and by 1750, seven of the Illinois tribes had been destroyed or absorbed into the remaining five, with their total population reduced to about 2,000. By 1818, there were two Illinois tribes left, and a single village of approximately 80 people remained east of the Mississippi. 17
As the Illinois were driven out ahead of settler-colonialists moving westward, the Potawatomi moved in from the north. In March 1831, one of the first White families to settle in the county, the Hobsons, observed hundreds of Potawatomi making sugar near what is now Naperville; their chief, Aptakisic, is said to have used Maple Grove as his sugar bush. 18 The next year, Pierce Downer made a three-day, 20-mile journey from the sparse settlement of Chicago, along the “High Prairie Trail,” the Potawatomi track heading west out of what is now Chicago, to what would become Downers Grove. Downer stopped at a roughly section-sized woodland in a sea of tallgrass prairie. He claimed a quarter section, 160 acres, and purchased it at $1.25 per acre from the U.S. Government under the Land Act of 1820. He was followed closely by other settlers, and his purchase consequently marked the end of an estimated 10,000 years of land use here by native people.
Part of the mythology of Downers Grove is that Pierce Downer had a close friendship with the Potawatomi, despite the fact that the land he settled is said to have been a seasonal residence for Chief Waubonsee. 19 School kids in our town are taught that Downer learned from the Potawatomi to tap sugar maples. They learn that Chiefs Aptakisic, Waubonsee, and Shabbona were regular visitors to the home of the Blodgetts, one of the village’s founding families. They are told that Aptakisic saved the inhabitants of Naper Settlement by warning them when Chief Blackhawk of the Sauk was planning a raid. I don’t doubt that this is true. But it’s also true that, as local lands were claimed by settlers, Aptakisic’s people were forced west to the DuPage River. Henry Blodgett reported that, though their exclusion was a source of “grievance,” Aptakisic “submitted to the inevitable and remained the friend of the settlers.” 20 There was, of course, nothing inevitable about it: Blodgett, Downer, and ultimately my own family were able to form a community around what would become Maple Grove only by expelling the people already living here.
However close it may have been, Pierce Downer’s friendship with local Potawatomi was probably not enduring. Under the 1833 Treaty of Chicago, the Potawatomi lost their remaining land in the region to the U.S. Government, as did the Chippewa and Ottawa to the north, in exchange for a tract beyond the Mississippi. The treaty was ratified in 1835, and by 1837, the last Indians had been banished from the area, removed to the Great Plains — a very different landscape from the mosaic of forest, savanna, and tallgrass prairie they had known. Chief Aptakisic came to see the Blodgetts before his people were removed to Kansas. Henry Blodgett wrote years later that he could “well remember the sad face of the old chief as he came to bid our family goodbye … We all shed tears of genuine sorrow … his generous kindness to my parents has given me a higher idea of the red man’s genuine worth.” 21 But by fifteen years later, as settlers planked over the heavily-used Potawatomi trail from Chicago, children playing in Maple Grove would not have been thinking of Chief Aptakisic’s “genuine worth.” 22 It must have seemed to them, as it always seems to children, as though they were the first to discover the forest.
Downers Grove grew rapidly. In 1850 the first township meeting was held. The first passenger train came through in 1864, connecting to Chicago. In 1872, a group of investors led by insurance executive Arthur Charles Ducat purchased 800 acres of largely wooded land from earlier homesteaders, intending to subdivide and develop it; their purchase included what would become Maple Grove. 23 The next year, Downers Grove incorporated as a village of 350 inhabitants. Ducat laid out roads in the tract he had purchased, but in the end did not develop homes. Instead, in 1892 he sold 700 acres to the department-store magnate Marshall Field at $300 per acre. 24 This was the same year that Field engaged Daniel Burnham to design his flagship store in downtown Chicago, in anticipation of the 1893 World’s Columbian Exposition. Field endowed the city’s Field Museum of Natural History and contributed substantially to establishing the University of Chicago. He built a golf course at the edge of Downers Grove, but left much of the land he had purchased in DuPage County undeveloped. When he died in 1906, the estate passed to his grandsons, Henry Field and Marshall Field III.
Chicago magnate Marshall Field bought the land in 1892 — the same year that Daniel Burnham designed Field’s flagship store downtown.
As Chicago grew, Downers Grove sold itself as a haven from the city. Ordinances enforced quiet on Sundays. The village described itself as a place where citizens could “sit under the wide-spreading branches of … stately forest trees and refresh themselves with pure air, free from the odors of Bridgeport, the Chicago River, and the cold and chilly fogs of the lakefront.” 25 In 1915, DuPage County formed its Forest Preserve District, and a front-page story in the local paper pleaded with residents to vote for preservation of the village’s remaining undeveloped forest, arguing that, “For years we have gloried in the possession of a beautiful woodland surpassing in natural attractions all the glories of the artificial parks of the great cities. At any moment our freedom to wander through the sylvan shades, to pluck the fragrant flowers and to delight in the wonders of nature can be taken from us.” 26 Eighty years had passed since ratification of the Treaty of Chicago, just one human lifetime. But the appeal expressed only urgency, no irony.
The country was at war, and efforts to preserve a section of forest were delayed. Henry Field had died, leaving his brother Marshall Field III, who was soon to be serving overseas, heir to an estimated 200-million-dollar fortune, including most of the land that would become Maple Grove. 27 Establishment of the preserve may also have been hindered by the 1918-1919 pandemic, which killed 373 out of every 100,000 Chicago residents, about two-and-half times the 2020 per capita mortality from COVID-19 in the city. 28
Maple Grove is a palimpsest of forest species, glacial recessions, colonial expansions, department-store fortunes, and kids in a pandemic, building forts.
The war ended and the pandemic subsided, the latter to all but disappear for decades from the history books. 29 In November 1919, ten days after the first anniversary of the Armistice, the village of Downers Grove treated the County Board of Supervisors to a dinner at the Masonic Hall. Afterwards, presumably in high spirits, the group proceeded at Field’s invitation to inspect his estate, seeking to identify anywhere from seven to 160 acres as a site for future public rambles through “the sylvan shades.” Field had offered the land to DuPage County at $200 per acre, a third less than his grandfather had paid nearly 50 years earlier, and the board of supervisors purchased 80 acres. The population of Downers Grove thus preserved for themselves an island of forest whose roots stretched back to the recession of the glaciers. The Downers Grove Reporter described it at the time as “a playground for present and future needs.” 30 In many ways, that is how it is viewed still.
As an administrative entity, Maple Grove Forest Preserve is sharply bounded. But the forest itself radiates through nearby neighborhoods, as bur oaks shed acorns onto car roofs and colonies of bloodroot and green dragon grow in ditches along the roads. Great horned owls hunt in the fields and yards that back up to the preserve. Coyotes chase white-footed mice across the boundary between the woods and the adjacent schoolyard. Detritus from the neighborhoods flows in via St. Joseph creek, which begins as a trickle in the formerly prairie-clad moraines to the east, runs through ditches between commercial buildings and the train line, then vanishes beneath downtown Downers Grove before it reappears just east of the preserve. 31 On its way through the forest, the creek exchanges trash from the streets and seeds from upstream for insect frass, fungal spores, silt and clay sliding downhill between the oaks and maples. It all flows west, past the sewage treatment plant and under high-tension lines at the ComEd substation, under the Burlington Northern Santa Fe railroad tracks, through the Village of Lisle to the East Branch of the DuPage, thence to the Des Plaines River, the Illinois River, the Mississippi, and finally the Gulf of Mexico.
Maple Grove is a palimpsest, written and overwritten with diverse histories: the origin and extinction of forest tree species, department-store fortunes, civic pride and self-interest, glacial recessions, colonial expansion, international shipping routes, viruses, and kids in a pandemic summer, dirt-biking and building forts from the bark of downed ash trees. Maple Grove is an evolving response to the questions, What species will control the canopy one hundred years from now? How do human choices form Maple Grove? I turn my hand lens on this neighborhood-sized forest in order to move beyond thinking of it as a portrait of the past, a place to walk, or a naturalist’s playground. Maple Grove, like any landscape, replays the same indeterminate processes year after year, but every year is remarkable, a novel variation on old themes. Each individual plant or square foot of land in this forest is a point of entry into paths braided through the Anthropocene.