Practice question

Species richness often rises during succession as soil development, structural complexity, and habitat heterogeneity create additional niches and more species reach the site. The trend is a broad expectation rather than an inviolable rule, because strong dominance or late disturbance can produce plateaus or declines. Successional trajectories emerge from dispersal, establishment, species interactions, and organism-driven environmental change. Priority effects can make arrival order important, while retained soil and propagules strongly accelerate recovery after disturbance. Facilitation, tolerance, and inhibition are alternative mechanisms rather than mandatory universal stages; more than one may operate at the same site or at different times. The eventual assemblage also depends on climate, substrate, disturbance frequency, and the regional species pool, so a climax is better viewed as dynamic persistence than permanent equilibrium. In this context, the keyed term, Species richness, identifies the relevant mechanism or quantitative relationship and links the observed pattern to its underlying ecological cause.