I’ve been slowly working my way through Bill Mollison’s Permaculture Designer’s Manual and really, it is an amazing book. Lots to take in so I’m taking my time and really relishing it. From Chapter 6:
A tree is, broadly speaking, many biomass zones. These are the stem and crown (the visible tree), the detritus and humus (the tree at the soil surface boundary) and the roots and root associates (the underground tree).
Like all living things, a tree has shed its weight many times over to earth and air, and has built much of the soil it stands in. Not only the crown, but also the roots, die and shed their wastes to earth. The living tree stands in a zone of decomposition, much of it transferred, reborn, transported, or reincarnated into grasses, bacteria, fungus, insect life, birds, and mammals.
Many of these tree-lives “belong with” the tree, and still function as part of it. When a blue jay, currawong, or squirrel buries an acorn (and usually recovers only 80% as a result of divine forgetfulness), it acts as the agent of the oak. When the squirrel or wallaby digs up the columella of the fungal tree root associates, guided to these by a garlic-like smell, they swallow the spores, activate them enzymatically, and deposit them again to invest the roots of another tree or sapling with its energy translator.
The root fungi intercede with water, soil, and atmosphere to manufacture cell nutrients for the tree, while myriad insects carry out summer pruning, decompose the surplus leaves and activate essential soil bacteria for the tree to use for nutrient flow. The rain of insect faeces may be crucial to forest and prairie health.