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

Trees produce growth rings inside their trunks when they expand in width each year. Wohlleben explains that by counting a tree’s growth rings you can determine its age.

Wohlleben defines lichen as a “symbiotic combination of fungi and algae” (168). He refers to lichen as an example of an organism which can benignly live on trees.

Lignin is a component of a tree’s cell walls. The author explains that some parasitic fungi may invade a tree to feed on its lignin, greatly weakening the tree’s structure.

Mycelium is the name of a fungi’s underground network, or root system, which may produce mushrooms above the ground. Wohlleben describes the important symbiotic relationship trees establish and maintain with many different types of mycelia.

The dictionary definition of a polymer is a “a chemical compound with molecules bonded together in long, repeating chains.” Wohlleben explains that fungi produce polymers to create borders around their “territory” when competing for access to the dead wood that they feed on.

Silviculture refers to the cultivation of trees. Wohlleben explains that, in his view, ethical silviculture methods allow forests to maintain trees of different ages and sizes and leave some trees to grow old and die naturally rather than being logged. He also argues that ethical silviculture would use natural methods of tree removal such as work horses, rather than heavy machinery.