This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Thoreau went to the woods to suck out all the marrow of life. I also wanted to learn what the woods had to teach, but my teeth are weaker, so I worried at the gristle, gradually gnawing my way into the forest’s bones. For a year, I sat in silence, watching one square meter of forest on a mountain slope in south-eastern Tennessee.
I went to the forest seeking a new way to experience the natural world. Like most teachers and scientists, my everyday work is marked by an almost total lack of silence. I jaw at colleagues and profess to students. When I go to nature, I go with an agenda: a lesson plan to cover, a hypothesis to test, or a series of measurements to make. This way of loving nature has its place, but it is a garrulous love. I wanted to listen more closely.
So, I watched a small patch of leaves and jumbled rocks tucked in a notch on a wooded slope. I chose the square meter haphazardly, ambling through the forest until I found a rock that looked flat enough to sit on for a year without too much discomfort. I had never seen this little patch of forest before, so its promise was unknown. At dawn on the first of January, I settled in and started the watch. Every day or so for the rest of the year, I returned to the rock and observed the happenings in the forest. My visits had no set schedule, but that year I spent hundreds of hours sitting on my rock, observing without manipulating. I didn’t kill or remove any organisms. I kept soil disturbance to a minimum, simply peering down into small gaps in the leaf litter. Beyond the occasional use of binoculars and a hand lens, my senses were unimpeded by gadgetry.
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On almost every visit, the forest surprised me with interesting creatures (scuttling shrews, waddling salamanders, peculiar mushrooms) or ecological interactions (bees covered in pink pollen, writhing parasitic worms, ants wrestling with caterpillars). More often than not, I understood only a small part of what I had seen. To learn more, I ran to the library and sat in the company of my students, reading all I could for my self-assigned homework from the woods. The gristle, bone, and maybe a few pieces of marrow were slowly digested. Later, a book, The Forest Unseen, emerged from this watch and these readings. Every essay in the book grew from an unexpected observation. Throughout, the forest set the narrative; I followed the year and scribbled my thoughts.
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The forest, I soon discovered, is ruled by a proletariat of tiny and seemingly obscure creatures. By slowing down and paying attention, I found them everywhere.
Lying down, I pressed my nose to the litter: fat, warm, truffly smells. This is the scent of good soil, created by the exhalations of actinomycetes, an abundant group of bacteria. Who among us has heard of these, let alone appreciated their importance? Our nose understands what our mind does not. The pleasing smell of these bacteria indicates the human ecological niche. Their odor marks habitats where our food will grow, whereas unproductive soils smell acrid and unpleasant. Somehow, the aesthetics of aroma is tightly linked to our ecological needs. If our species’ habitat was wetlands instead of well-drained forests and field, we would feel an unconscious affinity for the odor of swamp gas.
Actinomycetes not only rule the ecology of the forest’s soil, they have given us many of our more useful antibiotics, streptomycin, erythromycin, neomycin, tetracycline, and more. Other species from the forest also yield helpful drugs. The fruit and stems of mayapple are loaded with anticancer chemicals, birth control pills came first from wild yams, and ginseng’s simulative and healing properties are so well known that the plant has been hunted nearly to extinction. Modern medicine is rooted here.
Above the leaf litter, tawny snails graze on lichens and mushrooms. These, too, are humble creatures. They are hard to see, even harder to identify, and ignored by even the most ardent naturalists. Yet, without the calcium that snails conveniently provide in snack-sized morsels, mother birds could not lay their eggs. The flaming exuberance of birds’ feathers and songs would be snuffed if the snails were to disappear. Indeed, where acid rain has soured the soil’s chemistry, snails have declined, and bird eggs are thin-shelled and inviable. On these esoteric ecological relationships, the whole wild world rests.
Even that most grand of ecological dramas, the ongoing destabilization of the world’s climate, is manifest here in lowly ways. Forests, along with the oceans, have absorbed half of the carbon that we’ve poured into the atmosphere from unearthed coal and oil. Forests have therefore shielded us from the full consequences of our profligacy.
The ledger of these carbon accounts is right before my eyes, etched onto every twig in the forest. The smooth bark of each twig is interrupted by rings left by the scales that protected last winter’s buds. These rings mark the places where the elongation of each twig stopped for the year. By reading back along the length of each twig, we can deduce the yearly growth pattern of every twig and thereby calculate the amount of biomass that the forest has added. This is our future, written in woody script. Worldwide, the twigs send a silent but sobering message: the forests’ ability to absorb carbon has a limit and the rate at which they sponge up our excess is slowing.
What could be more insignificant than a twig? Yet, like bacteria, wildflowers, and snails, these unobtrusive members of the biological community can tell us things worth hearing, if we’re willing to listen.
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Aspiring naturalists must learn to be quiet. The noise that we humans make, chattering and laughing as we move through the forest, drives away many animals and, more subtly, changes the patterns of communication among the animals that remain. Loudness is our inheritance as primates; chimpanzees and monkeys are the same way. But we’re also so boisterous because we’ve lost the need to move with stealth. Re-entering the forest requires that we unlearn some habits.
By sitting for hours, resisting the urge to fidget, rustle, or wander, I tried to sink into the forest’s network. Raccoons and deer came close; birds perched briefly on the sleeve of my jacket. I listened and heard the animals listening to each other. When a deer nearly walked into me as I sat, it leapt away, snorting. Chipmunks, squirrels, and thrushes picked up the alarm, sending sharp chik notes out across the mountainside in concentric circles. The waves took more than an hour to quiet down. As I got better at listening, I learned that hikers coming down forest trails were preceded by bow waves of animal calls; I could detect approaching people many minutes before arrival of the sound of their voices. The movement of forest animals creates more subtle ripples. A crow flying overhead creates a momentary pulse of irritation from squirrels; a passing hawk is tracked with soft whistles from songbirds.
It is not just animals that are connected in this way. Plants are joined by underground networks of fungi. Tiny fungal strands penetrate plants’ roots and carry molecules from one plant to another. The sturdy individuality of trees is therefore an illusion; sugars from one tree can travel into the trunk of another. Plants also communicate with each other with messages that drift through the air. By sniffing the air, plants can sense whether their neighbors are being attacked by insects. The “alarm chemicals” from damaged plants allow other plants to prepare defensive chemicals in their leaves, before marauding insects arrive.
We, too, are part of the forest’s chemical network. When we walk in the woods, the airborne plant chemicals enter our lungs and our blood stream, binding to our nerves and giving us a sense of well-being. This chemical interpenetration might partly explain part of our affinity for nature. Deep in our bodies, our nerves are rewarded for participation in the forest’s community. Botanical highs are not just for stoners.
Every individual in the forest is connected to others in an invisible web of communication, a “social network” of many dimensions.
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What is the relationship between contemplation and action? Are silent observation and active engagement in opposition? At one level, they are. I entered the forest alone, without students and without scientific paraphernalia. The forest set the pace of my watch. I let go of the talk and control that dominate classrooms and scientific research. But this contrast exists at the surface only. After a year in the woods, I learned that the discipline of silence can lead to more vivid speech. Further, the best observers are those who want to share what they have learned. My sit in the woods has enriched my work as a teacher more than any other experience. Paradoxically, action and contemplation feed each other.
I came away from my watch in the forest with a better grasp of how the ecosystem works and with hundreds of stories to tell my students. Perhaps more important, I appreciated in a new way the limitations of these stories. As teachers, our interpretations capture only a portion of the richness of our subjects, whether those subjects are animals, scientific processes, literary texts, or works of art. This knowledge, that there are insights, challenges, and wonders still unknown, is a great motivator for professors and students alike. At a deeper level, facing the vastness of our ignorance, seeing the unknown turn into the unknowable, is a teacher of epistemological humility. After a year of study, I still could not name all the species visible in the one square meter, let alone the invisible hordes of microscopic creatures. Understanding the origins of these organisms or the relationships among them was even further out of reach. Nature is a vast and ancient manuscript; we’ve recovered and read only scraps of these pages.
These are soaring conclusions to have drawn from a year-long study of a square meter of forest. On the face of it, such flights through the canopy of academe can hardly be warranted by the modest scope of my observations. But my hope is that the circle of forest has served as a window into something larger. If not, then I am content down here with the snails and can tell you some interesting tales about their mating habits…
I’ll close, as professors so often do, with an exhortation: please try this at home. Pick a tree in an urban park, a patch of land behind your house, a stream running behind some condominiums, or a view of the sky. Then, return to it often and watch how the narrative of the place gets richer and deeper with time. My experience suggests that as you give one small place your attention, life’s marrow will become just a little easier to find.