Functional Isomorphism of Ecosystems and Its Significance for Ecological Prognoses

The general principle of the background landscape-ecological prognosis is expressed in the following assertion: the value of the climatic-caused transformation of one geo(eco-)system into another is the greater, the lesser the degree of intersection of its ecological niches in the initial state, that is, the greater are the contemporary contrast of its states and the range of the overlap of niches after the approach of geo(eco-)systems by the given geophysical attribute. In this case, it will be involve all set of transitions. Functional isomorphism of natural ecosystems is a significant correcting factor of climategenic transformations of soil-plant cover. The main structural reconstructions in every ecosystem must be preferable toward ecosystems, which are functionally isomorphic to the former system, i.e., they are most similar to it either in primary bioproductivity (an index of autotrophic biogenesis) or in the litter-abscission coefficient (a parameter showing the rate of organic passing through the detritus branch of metabolism). The degree of isomorphism is determined by taxonomic norm of the above functional parameters for the objects under consideration and by the structure of the ecological niches of these objects in the space of values of each parameter. Two fundamentally different types of functional isomorphism of phytocoenological and soil units, productive and destructive, have been established empirically. These types are territorially differentiated by their priority action on the behavior of transformed ecosystems. In forest systems of the boreal belt, including the zone of mixed forests, the leading role is played by destructive isomorphism, while in the sub-boreal belt (in broad-leaved forests, forest-steppe, and northern steppe) the leading role is played by productive isomorphism. As a whole, both branches of small biological turnover must be considered as indices of the function of regional biogeosystems.