Fig. 3

Assume that species A, A′ and A″ are functionally redundant in the sense that they all possess high protease activity (a functional trait). Thus, they can each exist in the same community characterized by low mineral N availability. Competitive exclusion does not occur because the species differ significantly in temperature preference (another functional trait). Species A may prefer the coolest temperatures and so is the most competitive species in the early spring or late fall. Species A′ may prefer intermediate temperatures and so is the most competitive in late spring or early fall. Species A″ may prefer the warmest temperatures and so is the most competitive in summer. Thus, as the seasons change (resulting in temporal heterogeneity of the habitat), first one species and then another will tend to become dominant, but none will permanently gain the upper hand