Practice question

Autogenic succession is generated by the organisms already occupying a site. Their growth and metabolism modify resource levels and physical conditions—for example, by shading, litter accumulation, nitrogen fixation, or soil development—creating feedbacks that favor some later species and disadvantage others. 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, Resident organisms, identifies the relevant mechanism or quantitative relationship and links the observed pattern to its underlying ecological cause. The distinction is testable by measuring changes in organisms, resources, or process rates through time rather than relying on the label alone.