Many regions are projected to experience an increase in the probability of compound events with higher global warming (high confidence). In particular, concurrent heatwaves and droughts are likely to become more frequent.
—Valérie Masson-Delmotte and Panmao Zhai, “Regional trends in extreme events in the IPCC 2021 report”
The Celts believed a tree’s presence could be felt more keenly at night or after a heavy rain, and that certain people were more attuned to trees and better able to perceive them. There is a special word for this recognition of sentience, mothaitheacht. It was described as a feeling in the upper chest of some kind of energy or sound passing through you. It’s possible that mothaitheacht is an ancient expression of a concept that is relatively new to science: infrasound or “silent” sound. These are sounds pitched below the range of human hearing, which travel great distances by means of long, loping waves. They are produced by large animals, such as elephants, and by volcanoes. And these waves have been measured as they emanate from large trees.
—Diana Beresford-Kroeger, To Speak for the Trees
It is the balance between the rational and imaginative that will ultimately solve the most serious problems that threaten us.
—David Dunn
There’s a tree I see in my mind when I need to find shelter. This Douglas fir tree lives on an island in the northwest, and simultaneously this tree lives inside me. It’s one of the few remaining old-growth trees on the island. I’ve sat inside the burned-out cave at its base where lightning struck. I’ve watched light glitter across strands of spider silk spanning its entrance, breathing cool air and smelling damp earth, bark, and wood. Inside the tree, I am young and old and animal and human. I am held inside the slow language of xylem, phloem, cambium, sap, and centuries of survival. When I approach the tree as I walk on the duff trail around the border of the lake, I feel the tree’s voice move like water through my chest. The voice of the tree is a hush, a swell, a silent rolling wave like the slow rising of a whale.
What is called silence is usually the absence of human sounds.
There’s another kind of silence in my chest when I walk through the beetle-killed forests of northern New Mexico and Colorado. This silence is brittle. It spreads from too much sky, cracks along barkless gray branches, unsheltered, unsheltering. I’ve watched forest after forest that I love succumb to the mountain pine beetles. Where my mom has a cabin in the high Fraser Valley in Colorado, I’ve watched whole mountainsides of lodgepole pines erupt with sap balls along the trunk as they try to expunge the beetles. And then I’ve watched as rusty red clusters of dead needles spread like dull fire, until all the needles are rust. It’s almost the color of fall. It’s almost beautiful. Eventually the needles drop and leave skeletons of gray.
What is called silence is usually the absence of human sounds. Inside the cave in my tree on the island, surrounded by Douglas fir, western red cedar, and hemlock forests, I hear the upward spiral of a russet-backed thrush, a loon calling from nearby on the lake, and the high tinkling glassy sounds of a Pacific wren. The thick layers of moss and duff and bark cushion each voice, as my body is held inside the body of the tree.
Inside what used to be a living forest in the Rocky Mountains, inside what is now a tangle of fallen and standing dead lodgepole pine, I hear the far-off hammering of a woodpecker. Other than the woodpecker, all I hear is wind. I hear the way dead branches creak and carve the wind.
What are the sounds of drought and climate unravelling in a forest? If you insert a homemade microphone inside the phloem and cambium of a drought-stressed piñon tree, as artist, composer, and acoustic ecologist David Dunn did, you’ll hear a symphony of sounds. I called David during the pandemic from across our hometown of Santa Fe, New Mexico, to learn more about his acoustic work with beetles and trees. If you listen to his recordings from inside the tree, you’ll hear the whines and cracks and pops of a tree stressed by drought, otherworldly screeches and sirens like the keening of whales.
Inside a tree, sound can be a celebration or an invitation or a weapon.
These songs of stress light up listeners who have adapted for millennia to hear the tree’s voice. These listeners are hungry beetles the size of a grain of rice, with specialized organs to hear these trees, to swarm the sounds of stress, and to create their own music of clicks and chirps and creaks. With these tiny violins—scrapers on their bellies that they rub against a striated surface under their wings—mountain pine beetles stridulate from inside their tunnels in the tree, announcing their new home and singing for others to join. Once they find a new world inside the tree, the beetles burrow chambers and galleries to grow their food and feed their young.
Ambrosia: food of the gods, or something extremely pleasing to taste or smell.
Ambrosia: nectar.
To a mountain pine beetle, ambrosia is a fungus. Like us, pine beetles are farmers. They carry a blue-stained fungus in special chamberlike organs called mycangia and release the spores into the tree where the fungus can grow and be harvested for food. It is the combination of this fungus and the feeding by their larvae that girdles the trunk, cutting off the circulation of water and nutrients and eventually killing the tree.
Mountain pine beetles have a long-tuned relationship to trees. They have coevolved with them, killing some to open light and opportunity for others. But the climate crisis is not moving at the pace of these long adaptations. With warm winters and drought-stressed trees, beetles are overwhelming whole forests.
Inside a tree, sound can be a celebration or an invitation or a weapon. When predators like lions hunt, they often make a low-frequency infrasonic sound that causes a freeze reaction in their prey. Inside their host tree, beetles make chaotic, wild sounds to freeze and attack their competition, to announce territory and deter others. After recording the beetles’ sonic world, David used a chaotic oscillator system to scramble the sounds and play them back in a way that confused and exhausted the beetles. Their own sounds became a weapon. Though this sonic technology cannot yet be used at scale to protect forests, David and collaborators found it effective to protect individual trees. Sound can be an invitation. Sound can be a weapon.
A few years back, I covered the ceiling of my bedroom with blue-stained pine. The swirls and streaks of blue that wash through the grain of the wood are beautiful. As I lie in bed, I stare at the blue painted patterns of fungi and listen to David’s recording The Sound of Light in Trees, the watery, clicky, squeaky, groaning landscape inside a beetle-infested piñon pine. This is the sound of climate change inside the world of one tree. This is the blue beauty and death of unraveling.
Everything has a voice. Beneath or above our human hearing, everything is singing. When I am overwhelmed with the wreckage of the climate crisis and the dying of precious shade and shelter in Rocky Mountain forests, I close my eyes and return to the cave of the Douglas fir tree on the island. I take my body inside the body of an old tree. I listen not with my ears but with my whole body, letting an older language hold me
