Ecological succession is best described as which of the following?

• A. A series of gradual changes that occur in a community following a disturbance
• B. A sudden, rapid change in a community
• C. A random fluctuation in population size
• D. A single-species replacement

Answer: (A)

Succession describes the gradual, directional change in which species dominate a community after a disturbance opens up habitat. Right after disturbance, pioneering species that tolerate harsh conditions establish and begin to modify the environment (soil formation, light filtering, moisture). This sets the stage for other species to arrive, and over time the community is replaced by species better suited to the evolving conditions. The process continues through multiple stages, leading to greater complexity and often greater stability. This stepwise progression is what makes it different from a single rapid shift, random fluctuations in population size, or the replacement by just one species.