HOMOLOGOUS ROWS OF VEGETATION COMMUNITIES - THEIR NATURE AND SIGNIFICANCE FOR SYNTAXONOMY

It was demonstrated that the homologous variation, known for,the objects of different level of organization, from that of atoms to that to organisms is also characteristic for the objects of the superorganismic level. It is supposed that the members of the same homologous row: 1) have the common pattern of organization; 2) are formed by monotypical elements; 3) differ in the number and arrangment of those elements. The principle of the homologous rows can be applied to the analysis of plant community variation. It was shown on marsh, forest, meadow and synanthropic vegetations of Scheuchzerio-Caricetea, Querco-Fagetea, Molino-Arrhenatheretea and Secalietea classes that closely related as well as distant types of plant communities have parallel rows' of variation in the floral composition. The method of graphic representation of syntaxon phytosociological structure was suggested. It allows to present a plant community diversity within an association as the system of radical-homologues with the mutual shaft (diagnostic species blocks of an association, union, order and class) and different sets of side-chains (diagnostic species of adjacent syntaxons of any rank). The application of the homologous rows principle to the plant classification increases the predictability of classification, offers some new criteria to estimate syntaxons' similarity, and the degree of classification's completeness. The mixed form of the syntaxon system is suggested: the hierarchical one for the major units (classes, orders, unions and associations) alla the combinative one for the units of the lower level.