ON THE SYSTEM OF LEVELS OF THE CROWN STRUCTURE IN TEMPERATE ZONE TREES
The studies of temperate tree crowns were carried out in different species in various geographical and ecological conditions during several decades. The results made the base for the system of five hierarchic levels of the tree crown structure. The «biennial shoot system» is suggested as the key element for comprehension ofa tree architecture. Morphofunctional diversity of biennial shoot systems aids to reveal construction features of other levels. Discreteness and small amount of biennial shoot system types in each tree species give the opportunity of various comparative studies, unlike shoots known for their variability even within the same crown. A very specific level of the tree construction is the «epsion», by which is meant a dynamics unit. The epsion forms as a result of complete development of the biennial shoot system. The epsion explains a temporal aspect of tree crown characteristics. The «branch from the trunk» as a system unit gives information about the whole tree. Branch construction indicates tree age, condition and details of its interactions with environment. Each certain crown is a result of realization of the species genetic program which has been taking place in definite circumstances. Crown structure features vary at different ontogenetic stages. The article traces out several ways of space exploration by crowns of some tree species. The analysis of biennial shoot system diversity and construction features gives the opportunity to complement ecological and evolutional characteristics of taxonomically different trees species.