The Competitive Factor and Root Competition

Abstract

The assumption is frequentiy made that the distribution of plants is determined directly by environmental conditions; this is, however, incorrect, for these are of importance only indirecily in that they affect the competitiveness of the plants. Only at the absolute limits of distribution, in arid and icy deserts, at the edge of the salt desert or where the forest shade is deepest—in other words, where competition is absent—do environmental factors (usually one extreme factor) have a direct effect on plant distribution. Apart from these exceptional cases and the pioneer plants on soil that is otherwise devoid of vegetation, all plants in natural conditions are in competition with each other. We must therefore move away from the purely physiologial to a more ecological approach.