A Fall Walk in the Tallgrass Savanna

The slender footpath threads its way through an Illinois wilderness. In deep, rich colors, this growing season heads toward its end. We relish memories of the growing season – and think about what comes next.

Scarlet oaks stand out, and the bur oaks among them are nearly invisible. There's a reason for that.

In the foreground, a young bur oak's craggy limbs are already leafless. Bur oak foliage is the first to fall. Why? Perhaps because burs are the most fire-adapted of our trees. Fallen leaves are their weapons.
Thick-barked bur oaks live on the edge of woodland and savanna – nearest the fire-prone prairie. Burs can’t survive in the shade of any other tree. All other species can outcompete them in the shade - except for its weapon of fire. Through raging fire, bur oaks clear the young invading trees that would shade out and replace them. The sooner the leaves fall, the more chance their crisp, stored fire energy can burn the sap out of their competitors. 

Indian hemp grows among the oaks.
The Potawatomi didn't smoke it. They used the fibers to make string and rope. And they burned to keep such resources coming. This plant is a big supporter of now-rare pollinators at a crucial time. We who love the savanna are learning to re-inhabit and care for an ecosystem that has had people as a native part as long as it's been here. 

Not only trees, grasses, and wildflowers - shrubs characterize some savannas.
This one is arrow-wood viburnum. Deer eat shrubs. Arrows kill deer. People maintained the savanna in part because it was so rich in the food, medicine, and other materials that they needed. Our society today needs it for genes to benefit medicine and science, for ecosystem services, for generosity to the planet, and because its richness and beauty make our souls happy.

In prairies, New England aster is seen as kind of a weakling, typical of young restorations, 

dropping out as the community stabilizes. But savannas have trees that stir the ecosystem - growing larger and later dying. They never get as stable as a prairie. This aster fits well here.

Another non-stabilizer is this shrub - hazelnut. As with bur oak, its leaves fall early
and burn hot. But without bur's armored stem, the above-ground parts of the hazel burn off too. After every fire, its hearty roots send up new stems, and it starts over.
Plants adapted to disturbance, like New England aster (you can see its now green-red leaves below the hazel, above) find their niche for a year or two, until the shrub grows back. 

The fringed gentian is a much rarer and more conservative plant than New England aster.
But it too seems to appreciate disturbance.

Here the gentians are just a couple of blue dots in the background behind a partly-burned-off nannyberry shrub.

Probably the grasses, sedges, and flowers here have many adaptations to their dynamic fire-pruned shrub neighbors.   

Briars are beautiful, delicious, and under-appreciated members of the shrub club.
This one is black raspberry, identifiable by its powder-blue canes. 

Many species of roses also support shrubland wildlife. Tangles full of roses are especially appreciated by birds for sequestering their nests. This one, with most leaves in fives, is swamp rose. 

And here, most leaves in threes, is Illinois rose, one of the biggest, sometimes climbing ten or fifteen feet up through the shrubs and saplings. Its hips (fruits full of seed) are eagerly sought by Shrub Club restoration teams (for planting) and of course by animals (that eat them). 

But in the savanna, the oak dynamic is key. Here a lone bur oak (no leaves, center) - with its thick, corky bark - can be expected to outlast and replace the scarlet or Hill's oaks that surround it.
Scarlet oak, like hazel, has thin bark and under a natural fire regime it's mostly a shrubby "re-sprout tree."

In many areas of Somme Prairie Grove, most of the trees are the "upstart" scarlet oaks.
They invade former pastures quicker than burs because their small acorns are spread far and wide by blue jays. Most survive our relatively-mild controlled burns for many years, but bit by bit they seem to be replaced by burs. Squirrels rarely venture out here, so hard-working stewards play squirrel and spread the fat bur oak acorns. 

Gradually some savannas become bur oak groves, very resistant to fire.
But oaks may live three or four hundred years; some here predate the coming of the Europeans. They are our elders.

Vestal Grove's biggest oak is this giant, now with a fire-scarred hollow trunk.
We rake around it before fires, to keep it from burning up too soon, so its acorns with their ancient genes will continue to rain down, as this ecosystem recovers.  

This grand old wreck of a tree stands by itself, limbs resting on the ground. Fire would most likely have burned them off in the natural landscape.  

Nearby lichens, mosses, fungi, and animals are gradually turning the trunk of a fallen old giant back to soil and air. 

This old giant had been precious to us as a tree. Now it's precious as a life-filled log. It has many saplings nearby. These organisms are our friends. As we learn and understand more about these organisms, large and small, we enjoy being better neighbors. It's a good feeling to walk through all this thriving and changing natural richness, season after season.   

Sedge Heads

To know the sedges, you have to be serious. A fanatic? Perhaps not. But certainly you have to enjoy detail.

The sedges make up, by far, the region's most diverse genus. Swink and Wilhelm list 149 species of these grass-like plants (genus Carex) in the Chicago region. This contrasts with 16 species of buttercups (genus Ranunculus) and 6 blazing stars (genus Liatris).

Many of us have great affection for Somme forest preserve. Yet, our team doesn’t know the ecosystem until we can identify the plants. Facing this challenge squarely, six of us last Sunday braved heat and bugs to find and learn sedges. In the end, we found and identified 24 species. Pretty good for one morning.

The photo above wouldn't be complete without our teacher, fine citizen-scientist, John Balaban. 

Having a great teacher is an honor. John Balaban is a true "citizen scientist" - a volunteer expert. With his wife Jane, he has taught classes on subjects from trees to dragonflies to sedges - and they have the noble distinction of discovering the endangered "awnless graceful sedge" in Illinois. 

At least that's what its called in The Plants of the Chicago Region by Swink and Wilhelm. Most sources, if they give it any "common" name at all, call it "handsome sedge". Is there really a "common name" for such an obscure plant. Let's face it, no there is not. Its only real name is the scientific name, Carex formosa. "Formosa" does mean "handsome" or "beautiful." But someone who wants to learn sedges might as well learn the scientific name. At least then you can talk with botanists. 

To figure out the name of a sedge, you need a scientific "key" (a written series of choices), and the key requires you to study fine detail. Is the stem hairy? Are the seeds three sided?

One of the first sedges we found was Carex rosea. (In this case, the "common name" 

is actually helpful. It's called "curly-styled wood sedge." To tell most sedges apart you have to

look at their sexual organs. The "style" is the feathery sticking-out part of the female flower, 

the part that receives the pollen. In the case of Carex rosea, if you look close 

(through a ten-power lens), you can see that those styles make graceful curls. 

There's only one other sedge that you're likely to mistake for "curly-styled wood sedge." That's "straight-styled wood sedge" (Carex radiata). But in the field you can pretty much tell them apart by the fact that rosea stems stand up straight while radiata stems lay out flat to the sides. Perhaps they should have been called "stand-y up sedge" and "fall-y down sedge." But perhaps it's easier in the case of sedges to stick with the scientific names, that don't change from book to book. 

Some sedges are easy to recognize at a glance, like the one shown above, 

bur sedge (Carex grayi). There's nothing else that looks like it, 

at least once you get to know it a bit. 

Another one that's pretty easy is shown below. Somewhat similar, 

but the seedhead is cylindric rather than spherical.

It's called hop sedge (Carex lupulina). 

Hop sedge is named for its similarity to the hops (Humulus lupulus),
often shown on beer cans, because they're the main flavoring for beer. 

Many sedges have little clusters of little seed heads, like the one shown below, Carex tenera.

They often take a lot of study, but this one is distinctive 

because its stem takes a right-angled turn just below the seed head. 

Once we'd "learned" about twenty of these, some people's heads started to clog.

Others, those with orderly minds, seemed to thrive on the challenge.

Luckily, John Balaban, in common with God as shown on the ceiling of the Sistine Chapel, was capable of transmitting inspiration and knowledge through a single finger. 

The find of the day was the big endangered sedge shown below.

Carex tuckermanii. 

"Bent-seeded hop sedge" if you want the "common name" of this rare beauty.

The seed packets on this one are so fat that only a few can only fit around the stem.

What difference does it make if we know which sedge is which?

One answer (among many) is that, if we know where the rarities are, we can restore health 

to those habitats first. Many species are being lost in many preserves because of neglect. 

In the absence of fire, invasive species choke them out.

You could say that biodiversity is important because a long list of reasons. 

For example there are some species of butterflies that utterly depend on a few species of sedges. 

Of course, then some people will ask, who cares about butterflies?

This sort of question was raised at a contentious public hearing about whether some construction project would have to be moved - because wrecking the natural ecosystem on the site chosen would have wiped out a rare plant.

One angry citizen asked, "What good is this plant?!?"

Botany professor Hugh Iltis responded, "What good are you?"

His answer probably didn't convert many of the pro-developers. 

But he did imply a thoughtful question: What makes us think we're so important 

that we have the right to eliminate other species?

Fortunately in the North Branch Forest Preserves, there's no conflict with "progress."

The site was bought by the public decades ago 

"to protect and preserve, restore and restock the natural flora and fauna." 

The question now is, are we good stewards? 

Fortunately, learning to know, and appreciate, and take good care of the ecosystem 

is a great pleasure to many of us. It makes us happy to be generous to sedges.

A Note At The End

Below are the names of the species that we identified. 

(We still have more that we haven't keyed down yet.) 

SCIENTIFIC NAME                CC  W   COMMON NAME

Carex annectens xanthocarpa      7    0    small yellow fox sedge

Carex cephalophora                     3    3    short-headed bracted sedge

Carex crinita                               10  -5    fringed sedge

Carex crus-corvi                         10  -5    crowfoot fox sedge

Carex festucacea                         8    0    fescue oval sedge

Carex grayi                                  7   -4    common bur sedge

Carex grisea                                 2    1    wood gray sedge

Carex hirsutella                           4    5    hairy green sedge

Carex hirtifolia                            5     5    hairy wood sedge

Carex lupuliformis                    10   -5    knobbed hop sedge

Carex lupulina                             7   -5    common hop sedge

Carex muskingumensis              8   -5    swamp oval sedge

Carex pellita                                4   -5    broad-leaved woolly sedge

Carex pensylvanica                     5    5     common oak sedge

Carex radiata                               6    1     straight-styled wood sedge

Carex rosea                                  4    5     curly-styled wood sedge

Carex shortiana                          10    0     Short’s sedge

Carex sparganioides                    3    0     loose-headed bracted sedge

Carex sprengelii                          9    3     long-beaked sedge

Carex squarrosa                        10   -5     narrow-leaved cattail sedge

Carex stipata                               3   -5     common fox sedge

Carex tenera                                8    1     narrow-leaved oval sedge

Carex tuckermanii                    10   -5     bent-seeded hop sedge

Carex vulpinoidea                     2   -5    brown fox sedge 

In the list above, the "CC" is the Coefficient of Conservatism, a measure of how much a species indicates quality habitats. A "0" sedge might be found in any weed patch. But a "10" sedge would nearly always be found in a highly diverse, healthy ecosystem. 

The number under "W" indicates wetness, that is, how dependent the species is on dry habitats. A "5" species is most likely found in well-drained uplands. A "-5" species often grows in standing water. 

Acknowledgements

Thanks to John Balaban for great teaching and being a fine mentor to new stewards.

Thanks to Eriko Kojima for proofing and editing this post.

Thanks to the Cook County Forest Preserves for making a huge difference in the lives of plants, wild animals, and people.