Water contained in cellulose cavities that run within the cellulose fibers of a tree in a vegetative state. With the knocking down of a tree, the imbibition water is freed until it reaches a point of saturation, and there is a consequential weight loss. Then, the wood begins to loose impregnated water (water contained within the cellular walls): and in this phase, the wood begins to loose, not only weight, but volume. See aging.