Is a very Fascinating place, a jelly of life that is neither solid nor liquid...
Permeable soil allows the life elements of water and air in to the sea of soil. This allows a million microscopic lives and deaths to condition and enrichen the soil biomass constantly.
Water carries dissolved nutrients to the roots to feed the tree, but will not just pass to the tree vessels through wood. So, a fleshy root tip is extended off of the woody root. But, this is still not fine enough system for the water to melt through the walls of the vessels and into th tree's circulatory system. so even finer root hairs grow off the tips. This task of absorbing the water is so specialized, the root hairs that absorb it all, are very delicate and live only about 10 days. They sprout right around a rain etc., so that they can perform this vital function, before they die.
As a root hair dies; it melts into the rich jelly of raw microscopic life coating the root tips called the RhizoSphere. This jelly is the final joining between the softest root hairs of the solid tree, and the thickest water of dissolved elements, so that they may join across the barrier as one, to connect and the tree can live. The Netherlands of the rhizosphere is neither liquid or solid, but a webbed gel that lies between them as the pipeline that joins the 2 worlds. This is the real raw sea of life in the soil that flows and coats the fleshy roots; this is what really feeds water and nutrients to the tree; the RhizoSphere.
Mychorhizae are so friendly feeding the tree during life, and when the mychorhizae filament dies, it becomes food for a certain nitrogen fixing bacteria, that then uses the burrow to hide in, specifically from amoebae that is a few microns bigger than the old Mycorhizae burrow. Eventually the bacteria too dies, and melts into feed the soup pot of life in the Rhyzosphere that actually feeds the tree. The empty burrow then becomes part of the soil permeability, Mychorhizae a friend to it's very end, and then some!!