Reciprocal Replacement and the Maintenance of Codominance in a Beech-Maple Forest

Regeneration of dominant species in an undisturbed beech-maple forest in Michigan, USA, was studied. Spatial distributions of saplings of beech and maple were related to influence by canopy trees of these species. Some factor effecting a differential mortality of young individuals of the two species was indicated and it is suggested that this factor is related to species of nearby canopy trees. This cause of mortality appeared to act on individuals between one and four meters in height. Assuming that replacement of fallen trees in such a forest is primarily by advance reproduction in the form of such seedlings and saplings as studied here, it appears that individuals of either dominant species will tend to be replaced by individuals of the other species in a pattern of reciprocal replacement. This, then, is a possible mechanism for indefinite maintenance of codominance in a climax forest.