We've been wrong about trees

Trees feel pain. They scream, even if we cannot hear them. Trees can learn. They have a sense of taste and a sense of hearing. They are social beings and can communicate messages to other trees. They sleep at night. Like human couples planning the best time to have a baby, trees plan their own procreation. Then they nurse their young.

So says German forester Peter Wohlleben in his remarkable book The Hidden Life of Trees, published in Germany in 2015 and translated into English in 2016. True, he may be guilty of a bit of anthropomorphism, but his essential points are supported by the work of researchers and by his own observations over decades spent in European forests.

Observing trees is difficult because everything they do they do slowly. They can live hundreds, even thousands of years, especially in dense forests where they are protected from the wind and have the company of others of the same species. So time moves slowly for trees, and they react slowly to change. When assaulted by insects, for example, they can sense the attack and send out toxins to their bark and leaves that taste so bad the insects will depart. In the case of oaks, their toxins can even kill the marauders. But this sending of messages and toxins through limbs and branches can take a long time moving at a rate of a third of an inch per minute.

Much of what people have long thought about trees is wrong, Wohlleben writes. We think they will do better alone, out in the sunshine and some distance away from other trees. Not so. We think healthy young trees grow quickly. Again, not so. Those trees that live the longest are those that grow very slowly during their earliest decades, mostly in the shade of older trees.

Wohlleben's book, relatively short, brims not just with amazing facts about trees but also with advice for humans with regard to growing trees, harvesting trees and enjoying trees. The blood pressure of forest visitors, he writes, "rises when they are under conifers, whereas it calms down and falls in stands of oaks. Why don't you take the test for yourself and see in what type of forest you feel most comfortable?"

And while there don't do anything to make a tree scream. This book convinces us that their comfort is important, too.