Re-discovering the Composition of Oak Woodlands

Scientists don’t know the natural state of our woodlands.

A lot of great research has been done on the original character

of prairies and savannas.

But the problem with woods has been that most people

thought the answer was obvious.

They were wrong.

Yesterday I had a wild and unexpected time reading through an old manuscript. Higley and Raddin’s Flora of Cook County (1891) seems to have been mostly ignored, perhaps because some of their identifications have been questioned by later botanists. But what seemed so powerful about their catalog was the new perspective on the habitats of many easy-to-ID species.

Why is it exciting to discover how things were? New insights into the past suggest new possibilities for restoring ecosystem health. When we rise to that challenge, we need models of what we’re striving toward. They’re just one tool, but valuable. A model is a hypothesis to be tested. For each project, trying to restore health to our badly degraded natural communities, for all plants and animals dependent on this work at each site, we have to make choices. Thus we roll a lot of experimental dice, for example: a) selection of site; b) fire regime; c) selection of wildflower and grass species to restore by seed and plugs; d) what woody species to cut or restore; e) how open to make the canopy; f) management of animal communities; g) what kind and how much resource to put into which possibly malignant species; and h) what kinds of special care to give what selected plant species that may possibly be key – to name just a few decision that we have to make for each site.

Then we cut, plant, burn, watch for some years, and if the community seems to be moving in the direction suggested by the model, then (all else being equal) we continue what we’re doing. Or if some parts of the model are not being approached, and we can figure out why, then we change. Perhaps we do more or less of one of the measures above according to our understanding of the effects. Or perhaps some unexpected results lead us to re-evaluate our goals and expectations, and we change the model.

This is where Higley and Raddin (H&R) come it. I had assumed that the natural composition of woodlands was more or less what experts had identified in our “best” (least obviously degraded) remnants. But what if oak woodlands (the forest glory of the tallgrass region) had been very different for thousands of years. Could we have been misled in the last few decades, when most scientific sampling was done?

Dr. Robert Betz, our greatest prairie conservation entrepreneur, always reminded us that every prairie remnant today is profoundly changed and degraded. How about the woodlands?

The first surprise in H&R was the number of species that are now thought of as completely or mostly prairie species but which H&R identified as being more characteristic of woods at that time.

Consider H&R’s comments on the following five species that most experts today would say are clearly prairie species:

Astragalus canadensis. Milk Vetch. “Moist woods along streams and lakes”

Ceanothus americanus. New Jersey Tea. “Open woods”

Monarda fistulosa. Wild Bergamot. “Rather dry banks, open woods and fence-rows”

Pedicularis canadensis. Lousewort. “Open woods, banks, etc.”

Phlox glaberrima. Smooth phlox. “Prairies and open rich woods”

The second surprise was how many plants that rare are today were common then. H&R list the conservative prairie plant Yellow Star Grass as common in lawns, roadsides, and woods. Lawns and roadsides have fundamentally changed. From the examples below, woods have too.

The species below are listed in the order provided by H&R, as samples that seemed worth commenting on. The quotations following the common name are from H&R. The words following the quotes are my comments on the basis of four decades of conservation work in northeastern Illinois.

These samples don’t add up to a prescription or model in themselves; they just provide hints that should come to influence our models and goals. Many species of animals and plants may require that at least some of our “conserved” woods be much more open and sunny than the rarely and mildly burned state they’re maintained in today.

Viola sagittata. Arrow-leaved Violet. “Moist and rich open woods; infrequent.” This species today is found in prairies and savannas.

Silene nivea.  (Snowy Campion) Infrequent.  “Evanston. Niles. Riverside.” This species would probably do well in restored wet savanna. But we’ve never tried it because we’ve found it only twice in Cook County in recent decades. One time was just a couple of plants in a thicket edge on the Plank Road Prairies (Rich Township). The other time was just a single plant in Spring Lake Nature Preserve (Barrington Hills). In neither case did we manage to secure any seed.  

Silene virginica. Fire-pink. “Damp open woods; frequent.” Not frequent today. Too dark and too many deer? Only feeble results in restoration so far.  

Oxalis violacea. Violet Wood Sorrel. “Moist woods and banks; not common.” Not found in moist woods today. A characteristic plant of fine prairies.  

Ceanothus americanus. New Jersey Tea. “Open woods; frequent.” Very rare in woods today; most frequently cited as a prairie plant.  

Staphylea trifolia. American Bladder-nut. “Wet and rather dark woods; not rare.” The comment “rather dark woods” is interesting. H&R seem attuned to the varied amounts of shade in various woodlands.

Astragalus canadensis. Milk Vetch. “Moist woods along streams and lakes; frequent.” Not a woodland plant today. To be healthy, do some types of woodland need enough thinning to support milk vetch, violet wood sorrel, New Jersey tea, etc. etc.?   

Desmodium dillenii. (Smooth Tick Trefoil) “Open woods; frequent.” (Perhaps this is the species that Swink and Wilhelm call D. glabellum.) I know of no woods where this and the next two tick-tre-foils are frequent. Sadly, this and the next species don’t survive in prairie either, so we’re likely to lose these important legumes if woodland habitats can’t once again be made hospitable to them.

Desmodium paniculatum. (Panicled Tick Trefoil) “In open woods; frequent.”

Desmodium canadense.  (Showy Tick Trefoil) “Rich woods; frequent or common.”

Lespedeza violacea. (Violet Bush Clover) “Dry open woods and copses.” This species is almost gone. It survived in a mowed, wooded campground near Barrington. It came back after decades when mowing stopped in a lawn at Barbara Turner’s house adjacent to Reed-Turner Woodland Nature Preserve. In the darkness of the nature preserve, it was entirely gone. This species was restored and is now spreading by the thousands in Somme Prairie Grove.

Vicia caroliniana. (Carolina Vetch) “Banks of streams and shaded places; common.” Really? Common? I’ve only seen it twice in my life. The first was one plant on a ridge in Black Partridge Woods Nature Preserve. The other was a plant or two in Moraine Hills State Park in McHenry County. We should find some populations of this species, harvest seed, propagate it, and restore substantial populations before we lose it.

Vicia Americana. American vetch. “Moist banks, woods and copses; frequent.” Swink and Wilhelm characterize its habitat today as “grassy places, prairies, and woodland borders.” It’s still rather common but, perhaps a temporary refugee from its real woodland home.

Lathyrus ochroleucus. (Pale Vetchling) “Railroad banks and shaded bluffs; frequent.” Far from frequent, today it’s a threatened species in Illinois. In the case of one oak woods, it appeared and flourished once we’d started burning. There’s no reason it couldn’t be frequent again. In one Lake County site it seems to be thriving in a burned woods, but only inside a deer-exclusion cage.  

Lathyrus venosus. (Veiny Pea) “Open woods, copses and shaded banks; not common but widely distributed.” Swink and Wilhelm report that “In our area this is a plant of dry prairies and savannas.” Yes, it is, today. But it has vanished from many of them.  In one Cook county site with a heavy deer populations, it wasn’t found for decades, but a few leaves were spotted after a deer reduction program was established. The plants remained as just a few leaves until caged, after which they grew into great rambling vines, flowered, and set seed.

Prunus americana. (Wild Plum) “Moist open woods and banks of streams; frequent.” Still a common plant along some roadsides but almost completely gone from the interiors of woods.

Prunus serotiina. Wild Black Cherry. “Woods; infrequent.” Today the most invasive canopy tree in the oak woodlands according to the Chicago Wilderness Woods Audit. Its numbers need to be controlled if oaks are to reproduce.

Epilobium angustifolium. Fireweed. “Usually in copses and low grounds; frequent.” It is said to thrive after fires. I’ve never seen it in our region.

Daucus carota. Carrot. “Occasionally spontaneous in waste places and old gardens, but usually dies out in three or four years.” An interesting statement on how our flora has changed since 1891. Today “carrot” or “Queen Ann’s Lace” is a common plant in most disturbed situations.  

Galium circaezans. Wild Licorice. “Dry woods and copses; common.” Our woods would have to be very much ore open for this plant to be common.  

Vernonia fasciculata. Iron-weed. “Prairies, open woods and banks; common.” Still common in prairies but no longer found in woods.  

Solidago speciosa. (Showy goldenrod) “Woods and shaded banks, frequent.” Today thought of as a species of sand savannas and prairies. But we found this species surviving on the edge of a forest preserve on Devon Avenue in Chicago, where a road cut allowed in extra light.   

Solidago juncea. (Early Goldenrod) “Banks of streams, open woods and moist fields; frequent.” Like the next three, no longer found in most woods.

Solidago serotina (gigantea). (Late goldenrod) “Woods; common.”

Solidago rigida. (Rigid Goldenrod) “Prairie, open woods, fence-rows; frequent or common.”

Cirsium altissimus. Tall Thistle. “Fields and newly-cleared lands and in open woods; frequent.” Today this fine plant is rare. It was restored and now thrives in the bur oak woodland at Vestal Grove.  

Gentiana alba. Whitish Gentian. “Low grounds and open woods, glades, etc.” Many people have thought of this one as a prairie species, but it fades out there over time.  

Phlox glaberrima. (Smooth Phlox)“Prairies and open rich woods; frequent.” Many experienced people will find it easier to believe that “prairie” species were also in dry woods. But this is a species of mesic and wet-mesic prairies (and woods?). Such a “rich open woods” is a community I’d dearly like to see.

Phlox pilosa. Hairy Phlox. “Prairies and open woods; common or abundant.”

Lithospermum canescens. Hoary Puccoon. “Prairies and open woods; abundant.”

Veronica virginica.  Culver’s Physic (Culver’s Root). “Rich woods, moist banks and prairies; frequent.”

Pedicularis canadensis. Lousewort. “Open woods, banks, etc.; common.”

Pedicularis lanceolata.  (Swamp) Lousewort. Wet open woods and swamps; frequent south, infrequent elsewhere.

Monarda fistulosa. Wild Bergamot. Rather dry banks, open woods and fence-rows; common.

Cypripedium pubescens. Yellow Lady’s Slipper. “Moist rich woods and bogs; frequent.” This fine plant deserves to be common again. Often I’ve seen it common in Wisconsin under occasionally mowed power lines (and uncommon in adjacent woods). Like so many, it needs more light.  

Hypoxis erecta. Star-grass. “Meadows, lawns, roadsides, woods, etc.: common or abundant.” Another almost unbelievable comment on how plant associations have changed. Common in lawns? Woods? This is a dominant spring plant in many fine prairies, but that’s about it.  

Tradescantia virginica. Common Spiderwort. “Moist open woods, prairies and fields; common or abundant.” (probably T. ohiensis).

From:

THE FLORA OF COOK COUNTY, ILLINOIS, AND PART OF LAKE COUNTY, INDIANA 

by William K. Higley and Charles S. Raddin. 1891.

Bulletin of the Chicago Academy of Sciences.

Available electronically at: http://babel.hathitrust.org/cgi/pt?id=hvd.32044106354335;view=1up;seq=183

Caution: Higley and Raddin used different scientific names than the most recent ones. Yet, between the scientific name (given first, in italics) and the common name, it’s usually easy to figure out which species they probably meant. Common names given within parentheses were omitted by H&R and supplied by me. Note: if you happen to be an expert and can correct any misleading species identifications, by all means let us know, and we’ll make corrections.

Comment on the scientific significance of such a list:

Some people think that conservationists, as scientists, ought to do our management experiments by controlling one variable and one species at a time – extensively replicated. At this stage of our understanding of ecosystem management, this is a fool’s errand for trusting graduate students. No one can try 10 different 100-acre patches each for 10 different soil/hydrology/topographic conditions, planting 10 different seed mixes, with 10 different burn regimes, watching each for 20 years. For that you need 10,000 similar ten-acre patches, for this one experiment.

We’re in a somewhat comparable position to medical doctors trying to restore health to human patients. In some ways we’re worse off, because human medicine has so much longer a history. In other ways we’re better off, because in all likelihood, ecosystems are so much more complicated that feedback loops may do a lot of our work for us, if given original conditions and diversity.  Also, in the very degraded systems we so often work with, we can be satisfied by a wide variety of outcomes. If the choices turn out to be good for half the species we’re concerned about on a given site, then we can celebrate a victory, as 50% of our goal is so much better than the 0% that we’d get if we didn’t try.