[Geographical pattern of plant affinity to different communities and its causes (by the example of North-European...

The same vascular plant species occur in communities of different types in different parts of their ranges. This phenomenon can be traced in both the latitudinal and the longitudinal directions. Changes in plant affinity to communities of different types are viewed by the example of the North-European forest studied in 1993-2001. Species occurring near their range limits, prefer habitats with smoothed amplitudes of minimum factors ("the law of preference for non-varying environments"). That's why Oxalis acetosella and other boreal-nemoral species demonstrate affinity to riparian forests of the middle-boreal subzone. Another cases of latitudinal change in ecological behavior may be caused by decrease in competitive ability (in Milium effusum), respective changes in the regeneration niche (in Cystopteris fragilis), or behavior of birds dispersing seeds (in Lonicera xylosteum). The longitudinal variation in plant behavior, as viewed by the example of the European-Siberian riparian-subalpine tall-herb synusia, is connected with the post-glacial plant migration in the European North. There is a lot of evidence for the individualistic character of the process, but it looks coherent in the historical retrospective. The possible role of refugia and long-distance dispersal in the process of formation of the present-day ranges of species is briefly reviewed. Conditions for plant dispersal in the past seemingly differ from those nowadays observed. The principal factor, which governs the dispersal rate, is that of interspecific competition level. Plant dispersal could be rather fast in the course of the corresponding primary succession following the glacier retreat or the marine retrogression (the "impulse" hypothesis). Since the climax pattern is established running waters and disturbed lands serve as "migration channels" for plants.