Peter Wohlleben

One of the oldest trees on Earth, a spruce in Sweden, is more than 9,500 years old

But why are trees such social beings? Why do they share food with their own species and sometimes even go so far as to nourish their competitors? The reasons are the same as for human communities: there are advantages to working together. A tree is not a forest. On its own, a tree cannot establish a consistent local climate. It is at the mercy of wind and weather. 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.

would result in many large gaps in the tree canopy, which would make it easier for storms to get inside the forest and uproot more trees. The heat of summer would reach

but there are different levels of membership. For example, most stumps rot away into humus and disappear within a couple of hundred years (which is not very long for a tree). Only a few individuals are kept alive over the centuries, like the mossy “stones” I’ve just described. What’s the difference? Do tree societies have second-class citizens just like human societies? It seems they do, though the idea of “class” doesn’t quite fit. It is rather the degree of connection—or maybe even affection—that decides how helpful a tree’s colleagues will be

Trees can groW

HoW does WaTer ge

water

shoots up the trunk with such force that if you place a stethoscope against the

tree, you can actually hear it.