What happens when trees die? Dying doesn’t always look the same—animals and plants do it differently, just as differently as they live.
If you’ve ever wondered if Tolkien’s Fangorn Forest or Mirkwood from The Hobbit actually exists somewhere on this planet, look no further than Canada’s Vancouver Island. It’s rather not a forest than a construction site; an architectural skeleton of trees so huge they can hardly fit our imagination. They’re a combination of living and dead trees that stoically hum to the tune of photosynthetic cycles, and others that have completely died—tree corpses. A genuine thousand-year-old forest is obviously alive, consuming billions of trillions of photons, pumping sticky juices and salty water there and back again. It breathes. The trees throb with biochemistry, they talk to each other, get jealous of one another. It is hard to believe that all the might and rigor of the forest—tree trunks that sometimes even lean on human backs, hard boughs soaring, fractal-like, towards the sky—all of it is a part of the forest because its parts died at the right moment. It killed itself, purposely mummifying fragments of its incorporated tree-body, sacrificing them to utilitarianism.
The Cambium’s Chorus
Let’s start with the wood. Without it, the tree could not survive in the two worlds it occupies—the wet darkness of the forest floor, and the sunny, windy emergent layer, several-dozen feet above. The tree has some business in both of these spaces. Underground, it bores microtunnels in search of water and nutritious minerals, it spreads its communication networks, murmuring in its rooty whisper to other trees, fungi, and microorganisms. It is an important area, this is where the bargaining for the spoils of soil takes place. But the realm of light where green leaves undulate—a realm that, when filmed by a drone flying above the tree crowns, looks like a rough celadon sea—is also very important. The sun’s photons penetrate the leaves and their energy is converted into sugar particles that feed all the machinery, from the tip of each leaf to the end of every root hair.
The tree stretches a column of pipes and wires out between these two domains, stiff microscopic water conduits push the sugary solution high into leafy food factories. The best way to keep these tubes in good shape is to kill them, leaving little canals encrusted with a hard substance left over from sticky living cells. Thus the tree keeps producing new layers of these pipelines, new slices made up of new little canals. A paper thin layer of cells is responsible for production, which forms a gummy ring around the tree, close to the trunk’s surface. This wood-forming machinery is called cambium.
The painstaking labor of the pulp, quietly constructing new wood conduits, is performed to the rhythm of the days and the seasons. This is perfectly visible on the cross section of a felled trunk—the rings of wood, the so-called growth rings, are testament to this cadenced, wood- forming chorus of cambium. Similar processes take place in the bark. If you look at the bark of some tree—preferably one that has already been cut, such as a piece pulled from a woodshed—you’ll see a multi-layered waffle, wafer-like structures of hard cells, stuck together and filled with air. Bark is formed similarly to wood; here too there is a cambium-like tissue that pushes past the new generations of cells it produces. Once the cells reach the surface, they commit mass suicide, killing themselves and emptying their insides of life’s stickiness. Only a hard, cork skeleton is left. This is all the bark needs to be the tree’s corset, its insulation wrapping. In these cells, life would only be an unnecessary extravagance.
Trees and other woody plants can afford to die bit-by-bit because the dying of certain areas and parts has been carefully planned. All this because a plant—although made up of well-connected cells and interwoven tissues—is still, to a certain degree, a conglomerate of independent parts. Perhaps this is due to the slowness of a plant’s existence, a lifestyle which enforces an attachment to a particular place. Therefore, particular parts of the plant can die, while the rest will peacefully continue to consume the saltiness of the soil and the sweetness of the sun, as if nothing happened. If you cut off the branch of a willow tree and plant it in wet ground, the tree will not groan at the act of violence and the cut branch will eventually come back to life, take root, and reorient its physiology to become—suddenly, just like that—a new, complete tree. It is the modular structure of plants, a certain independence they constitute, that makes them resilient to local deaths and annihilations.
Naturally, plants can also die in their entirety. Some do it strictly according to plan: annual plants have death programmed into them the moment they germinate. Everything they do, each twitch of the meristem and every twist of the leaf’s petiole, is headed for an inevitable end. They die without regret as individual death means very little. The plant in question dies having produced hundreds, or even thousands of seeds. Genetically, it is still alive.
A much slower death, stretched through several dozens of years can happen to giants, like those from the Canadian Fangorn Forest. It is difficult to pinpoint the precise moment of death. It could be the collapse of the water pumping-wood. When a tree dies, its hydraulic powers diminish. The streamlets locked in microscopic pipes slow down, and eventually stop climbing, once the flow in the little canals is broken by air that filters through the wood. This second “dying” can be heard as the disintegrating streams of water shooting up with a quiet popping sound. The modularity of the plant stretches out the process of dying. A nearly dead tree can have a clump of still-green leaves somewhere on its top, fed by the last working water supply, unaware they are on death row.
The Cost of Living Fast
Compared to plants, animals are in a real race to death. The more complex an animal is, the more sophisticated systems and mechanisms it uses to move and function on an everyday basis, the quicker it is devoured by its eventual demise. An animal’s body—except for the remote and rather uncomplicated cases of invertebrates—has very little by way of plant modularity. It is true that human cells also commit collective harakiri; millions of them lay their lives on the altar of the organism’s future, in order to make space for new, fresh copies. Vertebrates, however, cannot afford the extravagance of plant death. Their bodies are usually powered by a metabolism so fast that any minor hiccup in the life-giving energy system usually ends in death, or very severe damage. Something what a plant would never notice, whether a momentary slowing down of water and sap flow, or cutting off a small piece of flesh—would severely upset the balance of an animal. In an instant, the injured animal is in danger of dying and performs a whole series of biochemical actions that are equivalent to a panicked scream, aiming to alert every part of the body. Hormones and transmitters released into its blood and lymph fluid anesthetize its pain receptors, constricting the vessels to minimize possible fluid loss, and mobilize all energy reserves. Simultaneously, the nervous system activates entire programs of reflexes and instinctive behaviors causing the animal to run away, hide, or attack, depending on the situation. As if this weren’t enough, the racing metabolism of many parts of the body doesn’t stop moving in a mad rush to produce life-giving energy, thus poisoning the already endangered body with toxins and the products of a frantic oxidation of various chemical substances.
Recovering from such a physiological catastrophe is not easy, so it is no wonder that animal death comes so fast, instead of taking its time like that of plants. Evolution, of course, hasn’t failed to come up with a response to the deadly pressure—animals are equipped with a host of reactions that help them flee the place of danger, escaping the clutches of death before they manage to sustain real wounds. One should add that a fast death also means the possibility of a fast life, and what more does a human need than a life so fast it can accommodate one’s ambitions, plans, and dreams?
Should you ever wonder why an apple tree can enjoy a century of slow living, while people must sprint through theirs, feeling death’s breath and barely being able to hit age eighty, think about the lifestyle plants need to adopt to pay for their leisurely pace. It may be that, if humans were to live hundreds of years, they would also have to accept a death, so sluggishly slow that it would be almost unbearable.
Translated from the Polish by Adam Zdrodowski
This translation was re-edited for context and accuracy on January 12, 2023.
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