Woodland burn

February 22, 2017

I left the house a bit before five this morning. Drippy fog settled down on the region overnight. It was about 50 degrees, and a robin was singing. On a May morning two decades ago, I awoke at about 4:30 to the sound of an exotic thrush singing outside. I had just taken an ornithology class, and my head was brimming with bird songs. I dressed quickly and raced outside: that also was a robin. This morning’s robin caught me almost equally off guard. I know robins are early-morning singers, but it seems so early in the year for this sort of thing. We have winter-resident robins here and in fact well up into Wisconsin, and they are perhaps primed and ready to go when the temperatures rise early in the spring, as they have this year, even with the days still relatively short. The robin had sunrise beat by about an hour and a half. Can you measure backwards from sunrise to the first robin song of the morning? If so, does the length of the robin-ruler change with the temperature? Does stamina increase and singing start earlier as the spring wears on, or does it decrease?

Temperatures have been higher than average for most of January and February, and reading the high 50s and 60s for about a week now. In the past two weeks, bluebirds and mourning doves have been singing and moving around the neighborhoods. Chickadees have been singing their hearts out. Red-bellied woodpeckers have been especially noisy, even for red-bellied woodpeckers. Enormous flocks of cranes flew over on Sunday, impossibly high, as loud as if they were in a park on the other side of the street. Male redwing blackbirds showboated around the pond behind the visitor center yesterday. I think about our little prairie experiment on the west side and worry about about how early the weeds will emerge this spring.

We burned our rain garden over the weekend, and the Arboretum has been burning the East Woods. This morning I started at P10 and walked south and east through the blackened forest. The charred leaves and naked trees had a subduing effect in the fog. Aside from the sound of I-88 blaring away to the south, I was completely alone there. The burned woods stretched off as far as I could see. Heavy, isolated raindrops hit the charred leaves at intervals. The sound was shorter, less resonant, than it would have been on dead leaves. A fallen log was still burning steadily, flames darting out from beneath the edge of the burned-out base. The tree had fallen and the bark had decomposed. The burning base was no bigger than a campfire. How did it feel to come across spontaneous fire like this in the wild when it was still easier to carry fire from place to place than to start a fire from scratch​? Over and over, groups of people must have rediscovered this mystery and felt grateful, awed. Was it a living thing? Was it a gift? Even today, it’s hard to believe that such a thing as fire can exist here with us.

Further on, a spark rose from the darkness about 20 feet up and arced down toward the ground, going out before it had traveled more than 5 feet or so. I walked toward it and found a tree smoldering in a small section where the spark had emerged. The fire had apparently hit the tree on the downhill side and flamed all the way up, leaving one section burning. Fire is capricious: this looks to me to have been a particularly thorough, even fire, but even so there are strips and patches of unburned leaves in the middle of the woods, and some logs that might have burned well go untouched while others burn slowly for days.

Chorus frogs called from the lower parts of the woods toward the interstate. I crossed the road at P8 and walked the path separating the burned section to the west from unburned woods to the east. This is where I typically start sedge walks, but there was too much happening in the woods this morning for me to pay attention to sedges. Some bird had been calling in the woods since I started walking, and now that I’d gotten used to the burn I was puzzling over it. It was reminiscent of a spring peeper, though certainly not that, similarly incessant but less methodical, less insistent. I crossed the road and hit the edge of the spruce plot. A fire break had been raked along the length of it and I followed this to the road, walking through dry woods and spongy places with the burn off to the left and the spruces to the right.

I caught back up with the trail and crossed the road to the unburned section east of Big Rock. There was a sudden noise in the woods, like something hitting the ground abruptly. I sometimes think of myself as unflappable, but at times like this I’m not. I shined a light at the deer or coyote or potential assailant. A raptor—barred owl perhaps? I’m not sure what else it could have been—fumbled around on the ground and turned to fly up into a nearby tree. I followed with my light, but the fog was still too thick to see where the bird had gone. Barred owls don’t spend a lot of time on the ground, I don’t believe, and I suspect what I had heard was the moment of impact when the bird hit the mouse on the ground. If so, what a quiet descent! I hadn’t heard a thing before the impact. I’m not sure this is what happened. I’ve seen mice get taken, and they scrabble at least a little bit. I once heard what I believed to be a rabbit scream in the woods, taken by predator. So much happens in the dark that we see only a bit of, and we imagine the rest. I guess that’s why the dark is scary. We’d be fine out there at night without our overactive imaginations.

I walked back to my bike, retrieved my backpack, and rode toward the visitor center. To the west of the oak collection, I heard the unmistakable whistling of a woodcock flying low overhead. He landed and uttered a single peent in the field between the planted buckeyes and woods adjoining the Carex lacustris marsh. I waited a few minutes, but he had no more to say, not this time of day. I think evening is more a woodcock’s time. This is the second earliest in the year I have heard a woodcock call. The earliest was February 19, my mom’s birthday, up in Madison, Wisconsin, and I believe that was the record for our area at that time. Welcome back, woodcocks.

I was almost back to my office, trucking along, when suddenly a song sparrow began singing in the field to the east of the visitor center. Still foggy, sun still down, still February, and he was singing as though his life depended on it. Spring seems to have come.

Make it new

February 8, 2017


Do not move
Let the wind speak.
that is paradise.

Ezra Pound, Canto 120


This morning I locked up at Parking Lot 11, the northwestmost intersection of the main trail with the road. The temperature is hovering around freezing this morning. For a minute, the very faint sound of wind mixed with the the pattering of ice crystals in the branches above, and frozen mist drifted across my face and glasses. The air smelled smoky from a brush pile that had been burned earlier this month. The trail was gray in the glow from the clouds at two hours before sunrise.

I walked to the woodland trail that circles north and east from the Big Rock Visitor Station. I recall walking this with Larry Pinto, a neurobiologist from Northwestern University, when I first started working at the Arboretum. It was spring, and we walked the hilltop past a flock of Virginia bluebells. I don’t remember how I met Larry, and I am sure that’s the only time we went for a walk. Moreover, I think that was the only time I’d walked this particular trail before this morning. I am always seduced by the Big Rock, which leads me due north and then sometimes off to the west around the Heritage Trail. But the Woodland Trail was great, trailing out through the same forest I have been walking through but somehow altogether different. I think of Ezra Pound: “Make it new.” Any new trail changes your perspective and makes the familiar unfamiliar. The woodland trail turned to the northwest overlooking the prairie and wet meadows that run along the northeast edge of the Arboretum beneath the power lines, lined with red and white oaks upslope and bur oaks below. I looked down at the road I sometimes bike in on: I’d never seen it from above. I followed the shortcut trail to the Big Rock to keep walking along this overlook. There is a monstrous bur oak and many large ones. A cloud of scrubby little trees mushrooms up along the edge of the meadow – willows? If there are sugar maples in the woods, I’m not seeing them.

Looking at trees in the dark this past month has been a change in perspective. Tree silhouettes are largely unfamiliar to me. I’m a sedge systematist by training, and I spend much of my time with a hand lens, belly-down or pulling an inflorescence to my eye to study. I constantly tell students to bring the hand lens to their eye, bring the specimen up, maximize their field of view. You see more this way. I’ve approached oaks similarly: endbuds and acorn caps, trichomes, leaf characters. At night, these don’t serve quite as well. You get the tree against the cloudy sky, generally intermixed with others. You get the texture of the bark, the carpet of leaves beneath. You get the whole landscape: you get everything except the things you need a hand lens to see.

I spent yesterday plunging through a checklist of the world’s roughly 2000 sedges (Carex only, my friends… with the whole family it would have been closer to 6000), putting them into Tree of Life order. I have never had a great enthusiasm for sedge classification. I love sedges, the places they grow, the ways they divvy up the landscape and fill space, their shapes and textures and colors and shapes. But for whatever reason, I could not get enthused about infrageneric classification. That changed over the course of a one-week meeting late last month, when we had more than 20 sedge taxonomists in a room talking about the Tree of Life. The primary reason for our meeting was to take the work we’ve done on the phylogeny of sedges and try hammering it into a new classification. As the group talked, I took notes. My friend Eric has a brilliant way of keeping a conversation going, and with him leading, we walked through the Carex Tree of Life in a way none of us could alone. At each node we would stop and someone would say, in effect, “I know this place. This is where…” and the conversation would run off into why the sedges in that particular lineage might belong together despite the fact that they’ve been classified under disparate sections for so many years. We had the perspective of field work and herbarium study spanning numerous countries and all the continents where sedges grow. Like any walk in the woods with a group of excellent naturalists, I felt the place was completely new. I saw species I’ve known for 20 years in their correct context for the first time.

Yesterday I dove back in to reconstruct the structure of that conversation, align 2000 sedges according to their relations, hang them up under a mix of formal and casual names that seem to have been waiting in the wings for years. The Himalayan Clandestinae. The Bladder sedges. Everyone in the group is excited to start describing groupings. We’re seeing old friends by new paths and meeting new ones along the way. At every turn, there a surprise or something that is not expected, but satisfying in retrospect because of how it makes sense. It is a walk through evolutionary history, peppered with folks you know and folks you’d like to get to know.

I passed the Big Rock, and the geese were honking in the wetlands across the road to the north. We had a soaking rain the night before last, and water is still pooled at the base of the boulder. On the walk out, I heard a barred owl calling from the east end of the woods. I expect to hear great horned owls one of these mornings, then the screech owls will start up. I expect it will be two and a half months till the bluebells bloom. In the meantime, I have plenty of oaks and sedges to work on, and many to get to know.

Skunks and Martin Luther

February 6, 2017

Grant Avenue smelled of skunk this morning from Lee almost all the way to Finley. I wonder whether Aldo Leopold would have thought differently about skunks if he’d lived in Downers Grove in the 21st century. He opens A Sand County Almanac with “January Thaw:”

Each year, after the midwinter blizzards, there comes a night of thaw when the tinkle of dripping water is heard in the land. It brings strange stirrings, not only to creatures abed for the night, but to some who have been asleep for the winter. The hibernating skunk, curled up in his deep den, uncurls himself and ventures forth to prowl the wet world, dragging his belly in the snow. His track marks one of the earliest datable events in that cycle of beginnings and ceasings which we call a year.

Downers Grove is an exceptionally skunky town, and while there has been an uptick of skunk activity as it warmed up the past few weeks, I am not sure the skunks ever did lie down to sleep for the winter this year. Hibernation for a skunk in the Chicago region in 2017 may not be the hibernation of a skunk in central Wisconsin in the 1940s. We know that the wildflowers Leopold tracked at his shack on the Wisconsin River bloom earlier now then they did when he was making notes. It’s probably reasonable to expect the skunks to behave differently as well, and all the more so 100 miles south of the shack and 60 miles closer to Lake Michigan.

It was about 25 degrees when I got to the gate, partly cloudy, ten minutes past five. I had thought I’d do a short walk today so I could get into work earlier, but I was struck by a desire to park my bike at the Big Rock Visitor Station and walk the long way around to work, come in by foot. I recalled Martin Luther, who is said to have made the statement that he had so much to do, he had to start his day with three hours of prayer. I have so much less to do than Luther did. He set about reforming the church: today I had meetings and some oak research to conduct. I could surely spare as much time for meditation as Luther could.

I walked what may be my favorite section of the east woods, the rolling moraine to the east of the Big Rock station, with the depressional woods off to the north and topography reminiscent of the driftless area. I stumbled off the trail and meandered down along the edge of the standing water. The soil is frozen solid, crunchy and ragged from heaving with every freeze and relaxing with each thaw. The leaves are frosted in place, and a massive dead log emerges from the water. There’s no sound: I think I hear a bird, but I realize it’s my nose whistling. Warblers will be back in a couple of months.

I followed the road back to the trail, crossed over to the hilltop at the eastmost turn in the trail and down through the bur oaks above Parking Lot 10. One oak struck me this morning: it’s a bur oak near the bottom of a slope, bristling with adventitious shoots clustered around the scars left by fallen lateral branches. There wasn’t another tree like it in sight, and I didn’t see another one on my walk today. I doubt this is a response to some mistreatment visited on this tree in particular. It is perhaps a heritable predilection to resprout in response to injury. Is it adaptive here? Perhaps not, but we should know in a few generations. Oaks carry a lot of variation in each population. They are so highly heterozygous that the progeny of even a first-generation cross between populations of a single species may carry a great proportion of the range of variation of the parent populations. This works if the variation you care about is governed by a lot of genes and the parent populations are heterozygous for a good number of them. This may not be the only way it works, but it’s sufficient, and oaks certainly are configured this way.

Further on in the oak collection, I found a marcescent oak I hadn’t noticed last month. It is a small Hill’s oak (Quercus ellipsoidalis E.J.Hill) planted from seed 25 years ago, accession 204-92. This tree, like one of our marcescent black oaks, is collected from northern climates, this one from Winneshiek County, Iowa. Like the bristly shoots of the bur oak that passed earlier in the morning, these marcescent leaves may reflect past adaption, or they may a juvenile attribute that is neither adaptive nor particularly maladaptive. I begin to doubt, however, that the variation within species has much if anything to do with climate of origin. We’ll see.

Much of the trail to the west of the oak collection was dominated by bur oaks, with some red oaks and ironwood (Ostrya virginiana). One oak confused me: it had the appearance above of being a bur oak, but the bark was much more shallowly ridged. I was guessing in fact that it was a black walnut, but I couldn’t find any leaves beneath to support that. I think the East Woods would be as good a place as any to study hybridization between bur and white oaks. The problem would be sampling: how to get to the canopy and sample those leaves? I’ve always made do with sampling shoots ca. 15 feet up at the most… this may be the year to get serious about canopy leaves.

I passed the Carex lacustris marsh, Marlin Bowles’s dry prairie, Meadow Lake, the Children’s Garden and the groundcover garden and got to my desk 20 minutes earlier than I had thought I would. It’s 8:15 now, just 3 hours into my morning, and, Martin Luther and the skunks, I’d better get back to work.