The Unexpected Discovery of Somme Woods

A Treasure Trove of 1908 Data on the then “Virgin” Woods - a thrilling discovery

Have you ever wondered what it would be like to walk across your favorite landscapes – before the makeover by European civilization? Botanists certainly do. Was the prairie truly a kaleidoscopic masterpiece of rare wildflowers? Were the oak woods an Edenic paradise of birds, butterflies, flowers, and fruits?

We who work to restore health to nature have seen in bits of fragmented remnants how engaging and gorgeous pristine nature must have been. More and more we see, as they return to health, how inspiring the prairies are. But we have had a harder time understanding and re-imagining the oak woodlands. For a prairie, you cut all the woody vegetation; then health and richness can revive.

But the original woods remnants are more degraded than the prairie remnants. They have been replaced by “forests”[1] – which have superficial similarities, making the task harder. Stewards must tease apart the malignant invasives from the play-well-with-others species that will contribute to recovery.

Not long ago I published a photo of the recovering swamp-white-oak woods (see below). Some people wrote to challenge the species in flower. Are those really the species that grew with swamp white oaks?

An area along Middle Brook. Two years earlier, invasive trees had been thinned
and the area seeded with about 100 species of grasses and wildflowers.
Are the species in bloom the “right” species to be growing with swamp white oaks?
Cardinal flower, great blue lobelia, sweet black-eyed Susan, and spotted Joe-Pye-weed
are in flower. Swink and Wilhelm don’t list them as associates of this oak.

The Chicago region has probably the planet’s most advanced and comprehensive associates lists. These “parts manuals” are immortal contributions to conservation and restoration from the great minds of Floyd Swink and Gerould Wilhelm[2]. But these lists are not recipes. Associates lists don’t include all plant species of ecosystems, which are comprised of hundreds.

As a rule, when we endeavor to broadcast seed in the right places, we do not feel any great concern about exactly which species end up growing next to which. We do the best we can, so as not to waste rare seed, but we expect that ecosystem processes will work their magic over time. We just try to find the best places to use the various mixes: the mesic[3] prairie mix vs the wet woods mix vs the dry-mesic savanna mix, for examples.

On the other hand, we do eagerly seek to improve our understanding of fundamental principles of ecosystem health. Thus, for the forty years during which we have been seeking to nurse recovery of the Somme preserves, we've tried to weigh health indicators against our fragmentary knowledge of what a natural ecosystem here once was. Our vision is admittedly murky, depending on a few alluring tidbits[4] of historic data. Thus, the discovery of a detailed study – with Somme data on many animal and plant species – and even photos – from 1908 is like tantalizing dream come true.

At first, when this obscure study was mentioned to me[5], I have to admit I didn’t bother to dig it up. The title was “The Ecology of the Skokie Marsh Area, With Special Reference to the Mollusca.” It was written by Frank Baker, at that time unknown, later somewhat famous for his studies of the chambered nautilus. I would have been a bit more curious if I had seen his list of advisors. He first acknowledged Henry Chandler Cowles (University of Chicago), one of two scientists worldwide (the other was in Denmark) credited with the discovery of the ecological succession. Third on the list was Victor Shelford, Cowles' student, who became perhaps the most important scientific entrepreneur behind the emergence of ecosystem conservation.

But at first I didn't want to invest time studying the Skokie Marsh or its mollusks. The former marsh itself had been bulldozed, drained, and destroyed long ago. But then a second person, ecologist Debbie Antlitz, mentioned that this study seemed to include some nearby forest preserve land and included data on terrestrial plants and animals. I checked it out.

Frank Baker introduced his study[6] with these quiet words:

“The present paper is an attempt to place on record a minute study of a small area with special reference to its molluscan inhabitants. It is believed that this is one of the first attempts to apply the ecological method, so notably used by the botanists …”

Oh, Frank. That is way, way too modest. The paper is revolutionary. He cites as a forerunner a paper by Cowles that took an “ecological” approach. But that paper, while presenting plants in ecological communities, considered plants only. In contrast, Baker takes an early stab at documenting not just the communities of mollusks but also the associated plants, insects, birds, amphibians, and more. I wonder if anything like this had ever been done? And to think that we now have it – for the very area we are trying to learn to restore.

Then I try to figure out streets and streams on the beautiful hand-drawn map of his study area:

That subdivision on the right is the newly expanding Village of Glencoe. The east-west street is Dundee Road, which then had no bridge across the North Branch. The smaller village of Northbrook (Shermerville at that time) is on the left, down Shermer Road. Much botany of those times was linked to train stations. Baker may have taken the train to Glencoe, walked to all those numbered plots, and returned to Chicago on the train from Shermerville. He took his data “once or twice a week from May 18 to September 5, 1908.”

The East Fork of the North Branch of the Chicago River – surrounded by the Great Skokie marsh – is on the right, now the Chicago Botanic Garden (north of Dundee Road) and “Skokie Lagoons” forest preserves to the south (which now consist mostly of drainage ditches, artificial ponds, mowed lawns, and excavated landfill covered with buckthorn).

The Middle Fork of the North Branch runs through the center of Baker’s map, now with Somme Woods and Chipilly Woods Forest Preserves along both banks and including substantial uplands, with Dundee Road bisecting Chipilly (south of Dundee) and Somme (north).

But one little piece of his study stopped me cold, once I figured out which roads were which. It's a little brook with three sampling plots or "stations" – shown below:

Stations 26, 27, and 28 are in what is now Somme Woods Forest Preserve. Thus, what to my wondering eyes should appear, but lists of plants, birds, insects, and other treasures, as they were in 1908 and equally thrilling: two photographs – all of which will provide clues about the “natural” and “healthy” “original” ecosystem here. (Station 34 is in Somme Woods South.)

Before we get to those photographs, that exciting data, and all the rest, we should understand that these “before” snapshots are not original nature. They show land already somewhat modified and “Europeanized.” Baker was wrong, when he enthusiastically described the woods surrounding his plots 26, 27, and 28 as “a rather large area (several acres) of virgin forest.” Europeans began colonizing this area after the “Blackhawk War” of 1832. The 1839 Public Land Survey shows few areas fenced or under cultivation at that time, but change was rapidly coming to all the good agricultural land. Probably in 1908, most prairie fires (and oak woods fires) were many decades in the past. The uplands were all parts of farms then, and the owners cut trees to make houses and barns, and for fuel. Horses and cows (and in some places sheep and pigs) grazed and trampled. The forest was not the way it had been for millennia.

Yet, a natural forest ecosystem – if the disturbances are not intense – changes slowly, even in the absence of fire and natural animal populations. A slow or gradual change may be especially characteristic of woodlands that are wet, like these plots that Baker studied. Landscapes good for agriculture change the fastest, perhaps in part because the invasive species the Europeans brought are best adapted to them, and in part because farmers often restricted their livestock from boggy areas where valuable animals might become mired. So, the older trees in Baker’s study certainly represent the ancient landscape; the conservative grasses and wildflowers are likely, in the less disturbed areas, to reflect what had long been there, as would many of the animals that are associated with plant species.

So – we’re excited by this glimpse into the past – but realize that we’re looking through a glass darkly.

Below is the most revealing of Baker’s Somme photographs.

The shapes of the trees are striking, but we’ll get to that later. To me, the most compelling element of this photo is the lush and diverse richness of the herb vegetation. That’s what we’d expect today in a high-quality woodland ecosystem. Although the image isn’t clear enough to identify species, it suggests a luxuriant, dense woodland turf. (Baker’s photos of other nearby woodlands show bare dirt, likely in response to grazing and darkening[7].)

A hypothesis shared today by some who work to restore oak woodlands is that the herb layer – the wildflowers, grasses, and sedges – may be a key. It is thought that the woodland trees and herbs are co-adapted. Oak canopies are relatively sparse and transmit plenty of dappled light. The woodland herbs (unlike the forest herbs) require plenty of light all summer long and pay back the oaks by excluding seedlings of the leafier, darker-shade-producing tree species that would prevent reproduction by the oaks. It’s a turf too dense to be easily penetrated by invasive trees. Seedling maple and basswood roots may get choked in such competition, because their seeds are too small. These forest tree seeds have the advantage that they can blow through the air for great distances, but they then need a weakened ecosystem to succeed. Trees of the woodland propagate with acorns, hickory nuts, hazel nuts, or plum pits. They have a lot more energy to fight the competition of the diverse, dense turf. They also are adapted to re-sprouting repeatedly after fires.

Let’s compare the photo above with a photo of the unrestored section of South Brook today.

There is zero herb layer. The ground is bare dirt. (In early spring, some “ephemeral” “spring flora” species may emerge, complete their year, and die back before the dark forest canopy closes off the light.) The leaves right in your face, above, are buckthorn leaves, but higher up are the equally dense leaves of young and middle-aged basswoods and maples, and above them the high crowns of ancient bur, swamp white, and white oaks. Those oaks are clearly the original foundations of the ecosystem, but they have not reproduced in over one hundred years – because it was too dark.

Let’s look again at the 1908 photo.

I study this photo, again and again. It’s like looking at a myth. I stand there with Frank Baker (and Frank Woodruff, who took this photo and studied the birds while Baker was doing the mollusks). I see well-spaced trees with horizontal lower limbs. Clearly, they have spent their lives growing in the dappled light that blesses this photo.

Conservation ecologists have long used the terms “open grown” and “forest grown” to distinguish between two types of trees. The trees here are examples of a third type, more recently recognized, “woodland grown” trees. Open grown trees have wide-spreading lower branches, as seen in trees growing in yards and parks. Savanna trees are similar, except that the lowest branches tend to have burned off. Forest trees are typically tall, straight poles – with no surviving lower branches. The trees of oak woodlands are as those shown above. These trees somewhat reach up for sun, but the light is bright enough that they retain the lower branches they’ve invested in.

Most of the oldest trees in Somme Woods are none of the types listed above. They are huge; they show massive, broad-spreading lower branches; and in most cases those branches are dead, often just amputated stumps. They are victims of ecological degradation. If they are about 300 years old, as many of them seem to be, they spent the middle third of their lives growing in unburned grassland – pasture. Prior to that they grew in savanna.

But many of the big old trees along South Brook are huge old matriarchs with wide-spreading upper branches, as the larger (and possibly more distant) tree in the photo may be. In this photograph, we may be mostly looking at young, woodland-grown trees.

We have begun work to restore eco-health to South Brook. Three resulting photos are below:

Here the stream is nearly buried in somewhat diverse vegetation.

The sedge is the endangered Carex bromoides, which survived here all this time.

Most other species are from our seed mixes.

Another endangered species, forked aster, is the white flower here. 

It's now common along this stream.

Of course, over the decades of deep shade the trees have lost their leafy lower limbs. 

And there is no oak reproduction yet. 

But what a dramatic and positive change from the mostly bare ground here a few years earlier.

Tree and Herb Data

Actually, that part of Baker’s study has been a bit disappointing so far. Perhaps further analysis of more plots will yield insights. But so far Baker’s vegetation work gets an A for good intentions but a lower mark for results.

Baker’s brief lists of trees somewhat confirm what we would expect. Confirmation is valuable, if not thrilling. In his South Brook plots he recorded swamp white oak, American elm, hickory, hazelnut, basswood, and hawthorn. They are all there today, except for the hazelnut, which is the most quickly eliminated by shade of any on Baker’s list. I found hazel in Somme Woods when I first explored it, back when our energies were focused on the prairie and savanna. But it was gone before our woods revival efforts started.

Baker does not list bur oak or white oak, although the awe-inspiring specimens towering near the streams today were old trees even in Baker’s time. But he does explain that he’s focused on what’s closest to the stream, and certainly that’s the swamp white oak.

His herb data here is also meager – seven species. His spring species (red trillium, Jack-in-the-pulpit, and blue violet) are here today. The other four (water parsnip, green-headed coneflower, water hemlock, and tall bellflower) are missing – as species that need light all summer long. Water parsnip and tall bellflower are in our seed mixes and will be back soon. Green-headed coneflower and water hemlock seem to us too aggressive to include in early-stage seed mixes, but they’ll be back sooner or later.

Bird Data

Unexpectedly, the bird data is just short of breathtaking. There may well be no small study-site today with a similar richness of summering birds.

The list of "summer resident birds" for this area was compiled by Chicago Academy of Sciences ornithologist Frank Woodruff, a member of Baker's team. He lists 31 species, of which the following 17 stand out to me. What a glimpse into Somme’s past!

American Woodcock

Red-shouldered hawk

Screech owl

Yellow-billed cuckoo

Northern flicker

Crested flycatcher

Wood pewee

Song sparrow

Rose-breasted grosbeak

Indigo bird

Scarlet tanager

Cerulean warbler

Ovenbird

Yellow-breasted chat

American redstart

Brown thrasher

Wood thrush

Some of these are species that were absent from Somme Woods but have returned since the restoration work began. These include:

American Woodcock

Northern flicker

Crested flycatcher

Rose-breasted grosbeak

Indigo bird (today called indigo bunting)

Scarlet tanager

How gratifying to have documentation that these species summered at Somme Woods in Frank Baker’s day – and returned in response to restoration!

Another group stands out for an unexpected reason. These are forest birds:

Cerulean warbler

Ovenbird

Wood thrush

These three were certainly not species that I would have expected to return as a result of our work. It might even seem surprising that their populations did not increase as the formerly open woods darkened. Some people have speculated that a woodland like Somme was becoming more of a “forest habitat” after the fires stopped. But we now know that woody invasives do not turn a woodland into the kind of ecosystem that supports most forest biodiversity. Despite a vast increase in dense woody growth, the three birds above are now rare in northern Illinois. It is thought-provoking that they apparently found habitat in the Somme Woods of Frank Baker’s time. Could it be that there was so much quality remaining in that ecosystem that relatively small patches of appropriate habitat were able to support them? I had an inkling of that this summer, actually. I watched a pair of scarlet tanagers feed. These are birds we think of in the forest treetops. But in an area where the woodland grasses and wildflowers were coming back in abundance, there they were spending a lot of their time a foot or two off the ground, finding plentiful insect food where only bare dirt had been a few years before. Might some “forest birds” return to the Somme woodland someday, if our work restores enough quality?

Scarlet tanager. A bird of the sunny treetops? Perhaps not, if ecological health is restored to the woods.
Somme Woods photo by Lisa Culp Musgrave.

And yet, the final group of birds is the most striking to me. These birds (especially the chat and the thrasher) are known today from savannas and shrublands:

Red-shouldered hawk

Yellow-billed cuckoo

Yellow-breasted chat

American redstart

Brown thrasher

Many of us involved in woodland restoration like to quote the old accounts of the woods being so open that a person could gallop a horse through them – or shoot a deer at a great distance. Well, I can guarantee that no one could gallop a horse or see a long distance through yellow-breasted chat habitat. They choose the densest thickets. Somehow this woods in Baker’s day had niches for widely varied habitat specialists.

Summing Up

In recent years, as we attempt to rediscover and nurse health back into this precious ecosystem, the woodcock and woodhen have returned as breeding birds, following an absence of decades. A year ago, I first saw a woodhen fly up with her tail fanned and tucked under. She looked as if she could barely fly. It's a ruse she uses to entice me away from her cute downy chicks – now being raised in Somme Woods. Those first woodchicks represented a great little moment in our rediscovery. Yes, she told us, at least as far as she was concerned, we were on the right track.

We are discovering Somme Woods. It is a discovery of a very different type. To “discover” the North Pole was a physical feat. When Robert Peary and Matthew Henson got there (if they did; the ‘feat’ is much disputed), they saw nothing different from what they had seen for hundreds of square miles in every direction.

We are discovering South Brook today (and we’re not claiming to be the first; but perhaps there is some sort of claim to be made) partly in our minds and definitely over time, but the discovery changes the world. Our discoveries teach us how to heal a woods.

Lewis and Clark’s team have been called “The Corps of Discovery.” There is now a Somme corps of discovery. The pioneers include Travis Kaleo (his years of plant inventory work showed an expanding cast of green characters), Sai Ramakrishna (comparing soils data with existing vegetation), Karen Glennemeier and Jim Bland (inventorying the amphibians and some re-sampling of the mollusks and macro-invertebrates), and many others. Each is helping us all to discover through the lenses available to each.

On weekends, every steward and volunteer[8] contributes to the discovery. Like many, I find it a privilege.

Woodhen on nest at Somme. The return of the woodhen (and other declining species)
to the restored habitats is a crucial affirmation.

References

Baker, Frank Collins, “The Ecology of the Skokie Marsh Area, with Special Reference to the Mollusca.” Bulletin of the Illinois State Laboratory of Natural History, Urbana, Illinois, U.S.A. Vo. VIII. 1910
This treasure of a study is on line at: 

https://babel.hathitrust.org/cgi/pt?id=mdp.39015021561355&seq=14
This version doesn't seem to have a good copy of the map, but it can be read with map access in the post above. 

Swink, Floyd and Gerould Wilhelm, Plants of the Chicago Region, Morton Arboretum, 1994

Wilhelm, Gerould and Laura Rericha, Flora of the Chicago Region, Indiana Academy of Science, 2017

END NOTES

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[1] To many, a mature forest features maple, basswood, beech, and other trees that create (and can reproduce in) deep shade. Such forests are not dependent on frequent fire. But oak forests and woodlands feature oak, hickory, hazelnut, plum and other trees and shrubs that reproduce and thrive only in full or dappled sunlight. For that reason, they depend on frequent fire.

[2] The “associates” of a plant species are those species typically found growing nearby. Floyd Swink of the Morton Arboretum initially compiled lists in the field and published them in his “Plants of the Chicago Region” (1969). Swink enjoyed making lists and made many types of lists. But this one was monumental – over a thousand species of plants studied in varied habitats with multiple lists (by habitat) for many species. The lists have been expanded by Swink and Wilhelm (1994) and Wilhelm and Rericha (2017). As Swink and Wilhelm noted, “The lists of associates are not intended to be complete – nor could they ever be. … the reader should supply mentally some phrase such as “among others,” including,” or “such as,” where these phrases have been omitted from the text.” The lists are published only as scientific (Latin) names and made modest impact in their early years. But when “prairie restoration” captured the attention of many, the lists were recognized as invaluable contributions to “remnant recognition” and to “ecosystem assembly” planning. Conservationists without botany backgrounds had to start learning the Latin.  

[3] “Mesic” refers to “moderate wetness.” A mesic prairie is half way between a wet prairie and a dry prairie.

[4] This footnote lists our major sources of info on the “original” ecosystem of the Somme forest preserves. But I should point out that – contrary to what many seem to think – our goal is not to restore these landscapes “just as they were.” Ecosystems change. We expect them to continue to evolve – especially with changes in climate, air quality, naturalization of alien species, predator abundance, fragmentation, and many other changes.

Rather than to reproduce anything exactly, we want to restore the diversity of species that had been here. Many of these species had existed for hundreds of thousands to millions of years. It seems fundamentally wrong to just let them die out for no reason. To restore the high-quality habitats that many of these species require, we’d endeavor to understand the conditions under which those species lived.   

Data that is available throughout the Midwest is in the remarkable Public Land Survey (PLS) (initiated with great foresight by Thomas Jefferson). Those surveyors reached Somme in 1839 and recorded trees at a few nearby points. They recorded tree species, size, and distance from each other. Illinois PLS data is at http://isgs.illinois.edu/plss and an intro is at: https://clearinghouse.isgs.illinois.edu/data/landcover/illinois-landcover-early-1800s . (Can anyone suggest more or better references for people new to the PLS?)

We learned specifics of Somme by personally interviewing Louis Werhane – the last farmer in Northbrook, and who worked to keep these woods clear of brush, for grazing, before they were forest preserves.

We have also learned much from soils maps, the existing vegetation, and a variety of studies.

[5] I first heard of Baker’s study from Michael Swierz (a Habitat 2030 leader and co-compiler of the wonderful “Forgotten Flora” - a freely downloadable library of the earliest botanical accounts from our region - https://habitat2030.org/forgottenflora ). The second generous person to recommend the study was Debbie Antlitz, ecologist for the Forest Preserve District of Cook County. She went a little further than Michael. She told me, “I think some of his sampling points are in Somme or Chipilly Woods. And there’s a lot more there than just mollusks.” Okay, belatedly, I checked it out.

[6] Baker, Frank Collins, “The Ecology of the Skokie Marsh Area, with Special Reference to the Mollusca.” Bulletin of the Illinois State Laboratory of Natural History, Urbana, Illinois, U.S.A. Vo. VIII. 1910

[7] This post only skims the surface of helpful tidbits from in Baker’s study. I hope to present more. See, for example:  http://woodsandprairie.blogspot.com/2018/01/bird-bonanza-in-1908.html

Also - only after writing this post did I re-discover that H.S. Pepoon's "Plants of the Chicago Region" has the same Woodruff photo that Baker used. But the better reproduction in that book shows more detail. See below:

This photo confused me when I first saw it, because it's mis-labled. Not the Chicago River at all, it's South Brook, the small tributary Baker sampled. Unlike in this photo, the actual Chicago River in this area had no trees near it (as shown in Baker's map and photos in his paper). Excitingly to me, in this version, we see the vegetation better. Two species of wildflowers, for example, are blooming visibly to the left of the brook.  When I blow it up, I wonder if I can recognize wild geranium and some blue-eyed grass? I hope that the original negative of this photo will be found some day. There's much more to learn.

[8] For more about the Somme preserves – and for volunteering schedules, check out: https://sommepreserve.org or https://sommepreserve.org/calendar/