Figure 19.12 Tests of succession mechanisms in an intertidal community. (a) When rocks were scraped bare of all organisms, the first species to dominate was the little brown barnacle. Over time, the acorn barnacle became more abundant, followed by an increase in several species of macroalgae. (b) To determine which mechanisms were responsible for these successional changes, the presence of each barnacle species was manipulated. The acorn barnacle was critical to facilitate the macroalgae, whereas the little brown barnacle was not.

Data from T. M. Farrell, Models and mechanisms of succession: An example from a rocky intertidal community, Ecological Monographs 61 (1991): 95–113.