Therefore, we have classified the development of a stand or group of trees into four “phases of development” according to their height and diameter: Regeneration (I), Young (II), Medium (III), and Adult (IV). The phases are not mutually exclusive in space or over time because, under certain conditions, they may occur together in the same stand, e.g., in the complex stand structures characteristic of “close-tonature” forestry. However, defining these phases is a means of arranging silvicultural operations and decisions along management cycles (Table 1).