Tree replacement in small canopy gaps of a Tsuga canadensis forest in the Southern Appalachians, Tennessee

The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community. This may not happen if gradual changes in climate favor different species. If equilibrium is reached, a lesser degree of diversity may be sustained by niche diversification or by a compensatory mortality that favors inferior competitors. However, tropical forests and reefs are subject to severe disturbances often enough that equilibrium may never be attained.

In a central New Hampshire forest, three co-occurring tree species were found to occupy different positions on a reproductive strategy gradient. These reproductive strategy differences, in part, described separate niches for the species. The three-species complex is hypothesized to form a dynamic climax overstory characterized by cyclical replacement of one dominant species by another.