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Discussed are the possibilities of using syntaxa from floristic classification for the analysis of secondary restorative successions after forest cutting in South Ural Region. Peculiarities of secondary forest communities classification that may be viewed as subjects of indigenous vegetation syntaxa forming, sub-associations or could be systematized according to 'deductive' classification introduced by K. Kopecky and S. Heiny are considered. An example is presented of an analysis of communities succession system formed after cutting down hemiboreal pine and birch-pine herbaceous forests of Bupleuro-Pinetum association. Within this system the processes of divergence and convergence of succession series take place. Divergence occur as a result of lifting of the influence caused by dominants edificating role and manifestation of differences in soil humidification, also as a consequence of soil enrichment by mineral elements after burning down the felling debris. The reason behind convergence is grading influence of renewed forest stand. Trends in species richness changes during restorative successions may differ depending on ecotope features. In course of a succession, models of tolerance and inhibition become apparent.

This study was carried out during the period 1989-2011. The following areas were included: Vietnam, Laos, Cambodia, Indonesia, and Malaysia. Climax tropical forest and anthropogenically transformed ecosystems, including those damaged by the chemical warfare program of the United States in Vietnam, were investigated. Some regularities in the structure dynamics and functioning of forests ecosystems under a tropical monsoon climate have been revealed. The principles of classification of tropical forests have been elaborated. The major results of investigation of the tropical monsoon forests in Vietnam are given.

Evolutionary prerequisites of dicots current ecological diversity are studied. Structural and functional differences of the taxa generations replacing one another under the influence of the planet climate changes are described. The results of comparison of plant groups belonging to different subclasses confirm the adaptive parallelism in the structural and functional evolution, as well as the relationship between adaptogenesis and climate changes in Cenozoic. The supposition is made that the system of structural and functional traits of a taxon forms in compliance with climate specificity at the time and place of its establishment. Stability of plant species characters and their environmental requirements is corroborated by shift of species ranges in full accordance with habitat drift under climate changes influence. The similarity of evolutional and zonal series of dicots is shown. The present structural and functional diversity of taxa and ecosystems is considered to be a consequence of dissimilarity in their phylogenetic age. The conclusion is made that the current biological diversity is founded on historical diversity of habitats and plant species being phylogenetically adapted to them.

The dependence of trans factor of radionuclides on the soil to the vegetation (wood etc.) caused by natural-climatic conditions determine a duration period of the rehabilitation of ecological and social-economic functions of forests landscapes polluted by radionuclides. It firstly allows to classify forest ecosystems by groups of their radioecological stability with division into three appropriate radioecological districts. The forest ecosystems characterized by a rather short-term duration of the rehabilitation period of ecological and social-economic functions after the radiation contamination (till 30 years) are relatively stable in the radioecological reference. They are typical to steppe and forest-steppe zones and appropriate radiological district (related to natural zone). The forests ecosystems with the intermediate-term rehabilitation period after the radiation impact (30-60 years) are weakly stable in the radioecological reference and typical to broadleaved and coniferous-broadleaved forest zones and appropriate radiological district. The forest ecosystems with a long-term rehabilitation period after the radiation contamination (more than 60 years) are characterized as radioecologically unstable. The appropriate radiological district is include north-taiga forests and pre-tundra open woodlands.

To estimate the role of history in variation of tree species richness in the forests of the Western Caucasus we analyzed correlation between their local richness (S--the mean number of species per 300 m2) and size of actual species pool (N--the number of species per 1 ha). If compared communities are differently distant from the point of evolutionary equilibrium one should expect a significant variation in correlation between S and N (determined with the greater sensitivity of N than S in respect of historical factors). The lower value of N/S corresponds to less saturated level of historically determined species richness. A mean N/S ratio in Japana temperate broadleaved forests (Masaki et al., 1999) provided the basis for analysis. The present tree species richness of the forest communities in the 1 ha plots seem essentially determined by the historical processes. The mountain forest communities of Western Caucasus are characterized on the average with lower saturation level of the actual tree species pool in comparison with the Japan temperate broad-leaved forest communities. On the Western Caucasus the middle mountain beech and coniferous-broadleaved communities (400-1600 m a.s.l.) are characterized with the higher saturation level of the actual species pool in comparison with communities located lower and higher. These results confirm published historical reconstructions, according to which the middle mountain forest communities in the Western Caucasus are older than forests located higher or lower. Present low mountain forests of the southern (to Black Sea) and the northern macroslopes of the Western Caucasus are characterized with similar saturation level of the actual species pool. These data agree with the assumption of Dolukhanov (1980) that low mountain zone of the southern macroslope was not a refuge for tree species in Pleistocene.