Listening to the Thoughts of the Forest

The fate of a Tennessee forest was weighed in a boardroom by an assembly of businessmen, lawyers, and scientists. They never listened to the trees.

The offices of a Manhattan law firm seem like an unlikely place to try to read the mind of a forest. But after showing IDs at the skyscraper’s entrance, we walked our polished shoes across a marble-floored lobby into the elevators.

Doors closed. We ungrounded ourselves.

Standing in a forest, we are surrounded by billions of conversations. We need to listen to them.

The mellow ring of the elevator bell signaled our arrival. Leaders of environmental advocacy groups, senior managers of a timber corporation, and a small group of scientists strode into a wide-windowed room overlooking the city.

WHAT I LEFT OUT is a recurring feature in which book authors are invited to share anecdotes and narratives that, for whatever reason, did not make it into their final manuscripts. In this installment, author David George Haskell shares a story that didn’t make it into his latest book, “The Songs of Trees: Stories From Nature’s Great Connectors.”

At stake was the ecology and health of forests in Tennessee. Was the corporation damaging the ecological health of the forest? Should the company stop converting native oak-hickory forests into monoculture pine plantations? A forestry professor allied with the timber corporation trash talked a scientific report written by another forester and some biologists. The biologists sliced back, slamming graphs onto the screen. The environmentalists made clear, “We have satellite images of clear-cuts and data on biodiversity loss after logging. Work with us or we intensify a campaign aimed at your brand.” The satellite images directly contradicted the claim of a senior timber executive that no clear-cuts existed on the company’s land. PowerPoint, indeed. Afterward, the timber corporation’s CEO wouldn’t shake hands.

The boardroom was full of talk of the forest, yet the forest was barely there.

Of the people in the room, the most powerful had apparently spent little or no time in the Cumberland Plateau forests in question. They’d never wormed their fingers in the fungus-raveled leaf litter of the oak-hickory forest or smelled the litter’s tannic, nutty glow. The pine plantation’s bite, the brick-like smell of sun-burned mineral soil with no trace of duff, had not entered their nostrils. The varied weaves of bird song — impenetrably thick in the brush of 5-year-old plantation, gorgeously ornate in the oak-hickory, and thin as worn muslin in the older plantations — were nowhere in their memories.

Others in the room had visited forests and plantations, flying to Tennessee for short meetings, sometimes flitting in via private aircraft to touch ground for a few hours. Some scientists and land managers had spent more time in the woods, dozens or hundreds of hours, cruising timber, measuring trees, or supervising work crews. I was one of these scientists, at the meeting to report my statistical analysis of hundreds of bird surveys in forests and plantations. But I, like everyone else in the room, had experienced only a minuscule portion of the forest’s many natures. A divided human community further distanced us from the forest. We gave ourselves no opportunity to learn from the experience of others, from our supposed opponents. Conversation? Not in the playbook.

With so few listeners, the forest’s thoughts, its sylvan intelligence, went largely unheard.

To speak of intelligence in a forest is, on its face, an anthropomorphism, a violation of the creed of ecologists and science writers alike: Don’t treat other species like charming little humanoids! Trees are not leafy people and forests are not woody brains. But just as dangerous as projecting human fairytales onto forests is the overzealous rejection of all analogy between human minds and the networked flow of information within ecological communities. Mind emerges from relationships among living cells. We experience one manifestation of these relationships inside the bony plates of our skulls. Other minds may exist within other living networks. To speak of a forest’s mind and intelligence, then, is not to impose caricatures of humanity on other species. Rather, our human experience of mind allows us to imagine what might be possible in “the other.”

Consider this rich substrate for thought: In a gram of forest soil live between ten million and one trillion bacterial cells and dozens or hundreds of meters of fungal mycelia. Each one of these cells is in chemical conversation with those around it. Should a plant root poke its head into this network of microbes, chatter turns to clamor. Bacteria that halo the root tip send hormone signals promoting plant growth. Plant chemicals feed and house bacteria. Simultaneously, fungus and root converse and, if the talk goes well, press membrane-to-membrane, allowing faster, more open exchanges. When danger appears — pathogens or herbivores — the network carries this news through its multispecies strands. Above ground, every leaf is packed with bacteria and fungi that, through exchanges of material and information with plant cells, mediate the leaf’s life. Every square meter of forest contains = billions of connections and within these the forest gathers information, makes decisions, and carries memories.

Unlike the human brain, forest thought is diverse in its nature, but no less complex, agile, intelligent, or creative.

Animal networks stitch neurons into the forest’s mind. Insects live at the intersection of signals between plants, other animals, and microbes. Some signals are wide-ranging — the aromas that perfume the woods are conversations between trees, herbivores, and predators — and others act at the microscopic level of insect cells talking to their internal bacterial compatriots. As they carry seeds and prey on caterpillars, birds and other vertebrates connect their desires and memories to plants. Parasitic animals connect blood, soil, and saliva, mediating up to 75 percent of links in food webs. Every gut, breath, feather, or exoskeleton is a microbial community in relationship with the rest of the forest. Human understanding of the forest — whether carried in the oral traditions of hunter-gatherers, the experience of loggers or birders, or the zeroes and ones of electronic scientific journals — is also part of this mind.

Standing in a forest, we are surrounded by billions of conversations. The connections that make up the forest come in many forms. So, unlike the human brain, forest thought is diverse in its nature, but no less complex, agile, intelligent, or creative. Indeed our own 86 billion brain neurons — being structurally and functionally quite uniform, all serving the same organism — produce thoughts that are surely monotone and narrowly focused when compared to those leaping from decentralized connections among cell types drawn from the entire tree of life.

The forest comprehends. Com prehendere: “together” “catch hold of.” The forest grasps and knits many strands of understanding: biochemical, genetic, physiological, and cultural.


“Biodiversity” is the conventional metric by which we assess the conservation value of different habitats. In Tennessee, conversion of oak-hickory forests to pine plantations about halves the number of bird species living in the forest, surely an indication that plantations come with an ecological cost in this region. But measures of forest biodiversity are like counts of neurons in a brain: They sketch a general pattern, telling us little about how losses of species or brain cells affect the intelligence of the whole.

Let us become sommeliers of forest soils, tree-listeners, and interlocutors of root tips, bird memories, and human experience.

At present, our quantifications of biodiversity are entirely inadequate to the task of representing these forest relationships, communities where information is shared, lessons learned, and new ideas developed. Science is still in an exploratory phase, uncovering the existence and nature of signals and connections. No one has yet cataloged and enumerated all the creatures in any forest (although DNA sequencing combined with new methods for growing bacteria in the lab can give a glimpse), let alone described the dynamics of the network of connections among them. How creative, retentive, and supple are the thoughts of an oak-hickory forest? Is a plantation single-minded, focused on one thought to the exclusion of all others? As a species whose culture is partly built with paper and wood, how should we converse with the forest? Can we encourage creativity, new patterns of thought, in the forest network? Science will eventually allow us to ask these questions — like neuroscientists building brain models, ecologists are mapping portions of forest communities — but, for now, forest networks mostly live beyond scientific description.

Scientific measurement, though, is not the only way into the forest’s mind. A complementary way to access intelligence is through sustained bodily and mental relationship. An fMRI can glimpse the nature of creativity in musicians. But stepping onto the stage to join the players in making music gives us a direct experience of creativity, with less technological precision but no less truth. In the Manhattan boardroom, each side brought their calculations to the table, using scientific measurements to illustrate their points. These graphs were enough to show that the ecological community is diminished when a forest is converted into a plantation. But the question, “How do we belong and participate in the music of this forest?” went unasked. We could not ask such a question about belonging, because the answer can only come from within, from people in conversation with each other and the forest.

The meeting yielded a memorandum of understanding and a press release. The corporation agreed to stop converting native forests to plantations. In print, all parties congratulated one another. The governor added a supportive statement. By the standards of a technocratic world, this was a success, albeit one whose effects were mitigated over the following decade by fluctuations in newsprint pulp prices, mill closings, corporate mergers, and divestment of land. Now, a dozen years after this 2005 agreement, pressure to convert forests to plantations continues in the southeastern U.S. The chasm between the people in the room persists, as does our collective deafness to the forest.

It is perhaps absurd to suggest that lawyers, scientists, lobbyists, and MBAs spend more of their time listening to trees, smelling the leaf litter, visiting paper mills, and talking to one another in the woods and the logging yards. In a data-driven world, one governed by quantifiable financial and scientific information, a practice of open-ended listening and bodily engagement seems out of place, a diversion or an irrelevance. But financial and scientific data are abstractions. The forest is not made of abstractions. It is not even made of separate, interacting objects. The forest is instead made of relationship. To enter this gargantuan conversation is to connect our bodies and brains to creatures and processes beyond ourselves. This is ecological “big data” wired directly into human cellular and cultural networks.

It is time, then, for some unconventional in-service training: immersion in the forest’s mind. No polished shoes under tables, no soil-covering marble slabs, no slides of graphs delivered like slap shots at a goal. Instead, let us become sommeliers of forest soils (smell the varied overtones of ascomycete), tree-listeners (what crackle of drought do we hear in twigs, what rustle of unmade paper in the pine?), and interlocutors of root tips, bird memories, and human experience. We do so not to unearth ourselves into mysticism or to run away from disagreements in boardrooms. Rather, listening in the woods is a radical — radix, from the root — form of empiricism.


David George Haskell is the author of “The Songs of Trees.” His previous book, “The Forest Unseen,” was a finalist for the 2013 Pulitzer Prize in nonfiction and won numerous awards including the 2013 National Academies’ Best Book Award. He is Professor of Biology and Environmental Studies at the University of the South in Sewanee, Tennessee.

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    White Fir is the predominate tree species at this altitude in the Northern Sierras. I noticed yesterday that they ’emit’ a certain frequency or spectral transmission of light. Briefly I saw such a tree release light in red, white and gold. Doug Firs trees also in the vicinity seemed to be releases blue and green.
    I will investigate further;

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