ABSTRACT
Expected global changes of the natural environment are often attributed to man-caused increases of CO2 and other trace gases which might enhance the greenhouse effect in the atmosphere. Considering the fact that all living beings on earth ultimately depend on warmth, not much imagination is needed to suppose that vegetation has to respond to the warming trend in one way or the other. Change of species composition and horizontal and altitudinal shift of vegetation zones and belts might be expected. There are already impressive computed maps and other graphs showing the future position of vegetation zones and altitudinal belts, which indicate the space of potential change of ecological conditions (Kauppi and Posch, 1988; Environment Canada, 1989; Ozenda and Borel, 1991).
