The Hidden Life of Trees: What They Feel, How They Communicate — Discoveries from a Secret World

by Peter Wohlleben

One reason that many of us fail to understand trees is that they live on a different time scale than us. One of the oldest trees on Earth, a spruce in Sweden, is more than 9,500 years old. That’s 115 times longer than the average human lifetime. Creatures with such a luxury of time on their hands can afford to take things at a leisurely pace.

The electrical impulses that pass through the roots of trees, for example, move at the slow rate of one third of an inch per second.

The wolves turned out to be better stewards of the land than people, creating conditions that allowed the trees to grow and exert their influence on the landscape.

When you know that trees experience pain and have memories and that tree parents live together with their children, then you can no longer just chop them down and disrupt their lives with large machines.

forests are superorganisms with interconnections much like ant colonies.

But together, many trees create an ecosystem that moderates extremes of heat and cold, stores a great deal of water, and generates a great deal of humidity. And in this protected environment, trees can live to be very old.

Every tree, therefore, is valuable to the community and worth keeping around for as long as possible. And that is why even sick individuals are supported and nourished until they recover.

Trees, it turns out, have a completely different way of communicating: they use scent.

The saliva of each species is different, and trees can match the saliva to the insect. Indeed, the match can be so precise that trees can release pheromones that summon specific beneficial predators.

For if they can identify saliva, they must also have a sense of taste.

Thanks to selective breeding, our cultivated plants have, for the most part, lost their ability to communicate above or below ground—you could say they are deaf and dumb—and therefore they are easy prey for insect pests.

This is because a tree can be only as strong as the forest that surrounds it.

After extreme droughts bring many trees to the brink of death, they all bloom together the following year, which goes to show that large quantities of beechnuts and acorns don’t indicate that the next winter will be particularly harsh. As blossoms are set the summer before, the abundance of fruit reflects what happened the previous year and has nothing to do with what will happen in the future.

Back to the odds. Every five years, a beech tree produces at least thirty thousand beechnuts (thanks to climate change, it now does this as often as every two or three years, but we’ll put that aside for the moment). It is sexually mature at about 80 to 150 years of age, depending on how much light it gets where it’s growing. Assuming it grows to be 400 years old, it can fruit at least sixty times and produce a total of about 1.8 million beechnuts. From these, exactly one will develop into a full-grown tree—and in forest terms, that is a high rate of success, similar to winning the lottery.

Scientists have determined that slow growth when the tree is young is a prerequisite if a tree is to live to a ripe old age.

As people, we easily lose sight of what is truly old for a tree, because modern forestry targets a maximum age of 80 to 120 years before plantation trees are cut down and turned into cash.

Their mothers are in contact with them through their root systems, and they pass along sugar and other nutrients. You might even say they are nursing their babies.

The thick outer layer of the oak’s bark is also much more robust than the smooth, thin skin of the beech, and it can take a great deal of punishment. This has given rise to a saying in German, “Was schert es eine alte Eiche, wenn sich ein Wildschwein in ihr scheuert?” which roughly translates as: “It’s no skin off an old oak’s back if a wild boar wants to use its bark as a scratching post.”

“Und wenn ich geh, dann geht nur ein Teil von mir.” “And when I go, only a part of me is gone.” This phrase from a hit by German pop singer Peter Maffay could have been written by a tree. For the dead trunk is as indispensable for the cycle of life in the forest as the live tree.

In total, a fifth of all animal and plant species—that’s about six thousand of the species we know about—depend on dead wood.

When trees are planted in these restricted spaces, conflicts are inevitable. In such places, plane trees, maples, and lindens like to feel out underground wastewater pipes. We notice the damage when the next storm comes and the streets fill with water. Then specialists armed with root probes investigate to see which tree has caused the blockage. The culprit is sentenced to death for its excursion under the sidewalk and into what it thought was paradise. The offending tree is cut down, and its successor is planted in a built-in root cage to discourage such behavior in the future.

Are you surprised that summer storms topple a particularly large number of street trees? Their puny underground anchoring systems—which in Nature could cover more than 700 square yards and are now restricted to an area shrunk to a tiny percentage of that—are not capable of supporting trunks that weigh many tons.

In Fishlake National Forest, Utah, there is a quaking aspen that has taken thousands of years to cover more than 100 acres and grow more than forty thousand trunks. This organism, which looks like a large forest, has been given the name “Pando” (from the Latin “pandere,” which means to spread).61 You can see something similar in forests and fields in Europe, albeit not on such a grand scale.

large construction site near Zurich shows just how abrupt. Workers here came across relatively fresh tree stumps, which, at first, they set aside without paying them any attention. A researcher found them, took samples, and investigated their age. The result: the stumps came from pines that were growing there almost fourteen thousand years ago. Even more amazing, though, were the fluctuations in temperature at that time. In less than thirty years, the temperature dropped as much as 42 degrees Fahrenheit, only to finally rise again by about the same amount.

I made a calculation for the old beech stands in the forest I manage using available scientific data. Even if we were to have a Spanish-style climate here in Hümmel sometime in the future, an overwhelming number of the trees would cope. The only proviso is that the social structure of the forest is not disturbed by lumber operations so that the forest can continue to regulate its own microclimate for itself.

An old German saying about storms in the forest, “Eichen sollst du weichen, Buchen sollst du suchen,” translates as “Avoid oaks, seek beeches.” The saying originates in the fact that on some gnarly old oaks you can see a channel a few inches wide extending down the trunk where a lightning strike has split the bark open and penetrated deep into the wood. I’ve never seen a scar like this on the trunk of a beech. But the conclusion that lightning never strikes beech trees is as false as it is dangerous. Large old beeches offer no protection from lightning because they are struck just as often. The main reason there is next to no damage on beech trees is because their bark is so smooth.

Pay attention to the cause the next time you hear a news report about a forest fire: most are attributed to human activity.

However, the character of forest fires in North America has been changed by naturally increasing drought conditions and the human practice of fire suppression, and forests that would once have survived, or even thrived, in the face of fire are now threatened by its destructive force.

Korean scientists have been tracking older women as they walk through forests and urban areas. The result? When the women were walking in the forest, their blood pressure, their lung capacity, and the elasticity of their arteries improved, whereas an excursion into town showed none of these changes.

Walkers who visit one of the ancient deciduous preserves in the forest I manage always report that their heart feels lighter and they feel right at home. If they walk instead through coniferous forests, which in Central Europe are mostly planted and are, therefore, more fragile, artificial places, they don’t experience such feelings. Possibly it’s because in ancient beech forests, fewer “alarm calls” go out, and therefore, most messages exchanged between trees are contented ones, and these messages reach our brains as well, via our noses. I am convinced that we intuitively register the forest’s health. Why don’t you give it a try?