What is ecological succession?

• A. A rapid change in population size caused by predation.
• B. The progressive change in species composition of an ecosystem over time after a disturbance.
• C. The immediate collapse of all species following a disturbance.
• D. The constant constancy of species composition regardless of disturbance.

Answer: (B)

Ecological succession is the gradual change in which the species composition of an ecosystem shifts over time, especially after a disturbance or when new habitat becomes available. It’s a stepwise process: pioneer species first inhabit exposed areas, they alter conditions (like soil formation or light availability), allowing other species to move in, and over time the community changes in which different species become dominant until the ecosystem reaches a more stable state. This explanation fits the idea of a progressive change in which the community composition evolves rather than an immediate crash or a constant, unchanging set of species. If the land is newly formed, like lava or bare rock, the process is primary succession; if soil remains after a disturbance, it’s secondary succession.