Highly specialized and minute ecosystems that can exist on trees. Wohlleben cites a study which found over 2,000 insects from 241 species living on one old-growth tree alone. Additionally, trees with tiny pools or cavities of water begin to function as wetland ecosystems for animals that require these conditions such as small flies, beetles, and the bumblebee hoverfly.

Wohlleben explains that when trees die all of the nutrients they have taken from the soil is slowly released back into the ground, where it is extremely useful to the younger trees. The author writes that fungi, bacteria, and insects that specialize in decomposition quickly colonize the tree in a “culinary relay race” that biodegrades the tree into humus (132).

He continues his chapter by debunking the myth that allowing dead wood to remain in a forest puts living trees under threat of being colonized by decomposers. He explains that this belief is completely unfounded; the types of fungi, bacteria, and insects that break down dead trees could never harm a living one since their characteristics are too different. Further, he argues that removing dead wood from forests for this purpose is detrimental to those ecosystems since creatures require these habitats and their work adds nutrients to the forest soil.