Trees often act in caring, borderline altruistic ways with one another. With their roots intermeshed, trees are able to share water and nutrients with those of the same species—and they often do, even when a fellow tree is only a stump in the woods with no hope of recovery. Wohlleben has experienced this in German forests, where he observed trees that continued to live after being cut down, supported underground by nearby tree friends.

Between healthy trees, common fungi connecting them balances the distribution of nutrients so no one plant gets too little, or too much, water and sugar. Isolated trees can often grow quicker without this balanced distribution, but trees that grow close and support each other this way end up living longer lives.