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Are trees communicating? Research says yes.

Research shows trees communicate by sending underground electrical impulses and above-ground hormones or chemicals. File photo / Forum News Service

FARGO -- Did you know scientists are discovering that trees communicate with each other? They aren’t necessarily gossiping about you behind your back, and they probably aren’t sharing a joke about two trees walking into a bar, but researchers are finding fascinating ways that trees are talking among themselves.

This might sound as ridiculous as the round Earth theory sounded to those who believed the world was flat. But it doesn’t sound ridiculous to Smithsonian magazine, which in its March 2018 issue said, “A revolution has been taking place in scientific understanding of trees. The latest studies conducted at well-respected universities in Germany and around the world confirm that trees are far more alert, social and sophisticated — and even intelligent — than we thought.”

Since Darwin’s time, trees were believed to be loners, competing against each other for sunlight, moisture and nutrients, in a survival-of-the-fittest battle. New evidence shows the opposite, that trees actually help one another, communicating together in the process.

Examples of how trees communicate

Trees in a forest are connected through an underground network. Trees partner with beneficial fungi, which form an intricate network of tiny, thread-like strands between tree roots, and a teaspoon of soil contains miles of these filaments. The fungi consume about 30 percent of the tree’s manufactured food, and in turn the fungi scavenge soil for nutrients that are made available to the tree. This is called a mycorrhizal network.

Trees send chemical, hormonal and slow-pulsing electrical signals to each other by way of the underground mycorrhizal network. Swiss scientists have identified voltage-based signals that appear similar to the electrical impulses in an animal’s nervous system.

Messages sent from tree to tree are often distress signals that warn of drought, disease and insect attack. Other trees, upon receiving the messages, alter their behavior, adjusting their defenses to prepare for the upcoming battle.

University of British Columbia scientists have recorded electrical signals being transmitted from trees that are being cut down.Some trees communicate by sending scent signals or pheromones. Africa’s acacia trees emit ethylene gas when giraffes nibble their leaves. The ethylene gas is detected by neighboring trees, which in response begin pumping tannins into their leaves to make them unpalatable, should the giraffe head their way.

Elms and pines, when attacked by leaf-eating caterpillars, release pheromones, which attract parasitic wasps, which in turn attack the caterpillars.

An Israeli scientist, in a controlled experiment, found that when pea plants were subjected to drought conditions, the leaf stomate pores close, as expected, to conserve plant moisture. But other pea plants nearby that were being watered normally also unexpectedly closed their leaf stomates soon after the drought-stressed plants, as though warned. When these plants were signaled by others that a drought was coming, they took preparations.

Practical applications

If scientists can unlock the ways plants communicate with each other, foresters and agriculture producers can possibly trigger these responses to create plants and trees that are drought-, insect- and disease-resistant.

For example, if scientists can isolate how trees under attack signal other trees to produce insect-fighting compounds, they could use the information to develop trees with built-in resistance.

Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler’s Greenhouse in Fargo. Readers can reach him at forumgrowingtogether@hotmail.com.

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