Abstract
A transition zone between two large vegetation cover types always presents a tantalizing aspect of vegetational characteristics, frequently suggesting instability. In such areas the microclimate of edaphic factors favors first one and then another group of species which are characteristic components of one of the other of the flanking formations, or smaller fluctuations in temperature and moisture find expression vegetational changes which will not be evident within the boundaries of the definitely expressed formations. This is emphasized boldly by disjunct distribution or intermingling of species of these flanking climaxes, where habitat exerts selective action far greater than is possible under optimum climax control; this may at times even dim the "real climax" status. As Dachnowski (3) points out, pollen profiles can here, perhaps, give the most reliable picture of the climatically flavored vegetation. It is, therefore, also logical to expect that small variations, or fluctuations, in climate ought to be recorded first in such tension areas by minor changes in vegetation, especially by variation in degree of importance of certain genera in the association complex.
