Practice question

Ecological succession is directional change in community composition and structure through time, often following formation of new habitat or disturbance. Colonization, local extinction, environmental modification, and species interactions cause one assemblage to replace another; ordinary seasonal fluctuations do not constitute this long-term sequence. Classical succession terminology divides community development into site exposure, arrival, establishment, interaction, environmental reaction, and relative stabilization. Modern ecology treats these as useful descriptions rather than a rigid deterministic program. Local resource conditions, dispersal limitation, life-history trade-offs, herbivory, pathogens, and stochastic events jointly determine which species replace others. Early species often grow rapidly under open conditions, whereas later species commonly persist under lower resources, but the precise pattern varies among ecosystems and disturbance regimes. In this context, the keyed term, Sequential change in species composition over time, 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.