How does secondary succession differ from primary, and what often starts secondary succession?

• A. Secondary succession occurs after a disturbance in an environment with existing soil and life, such as after a fire or flood.
• B. Secondary succession begins in lifeless rock with no soil.
• C. Secondary succession occurs only in aquatic ecosystems.
• D. Secondary succession proceeds more slowly than primary in all cases.

Answer: (A)

Secondary succession happens after a disturbance that damages an ecosystem but leaves the soil and some life in place. Because soil remains and nutrients are already there, seeds and roots from nearby areas or the remaining organisms can quickly recolonize, leading to faster recovery. Disturbances like fires, floods, storms, or human activities such as logging or farmland abandonment frequently trigger it. Early colonizers are typically fast-growing plants that establish quickly, then shrubs, and eventually trees as the community rebuilds.

This differs from primary succession, which begins on bare rock or barren ground with no soil, taking a much longer time to develop soil and the first communities. It’s not limited to aquatic systems, and it isn’t true that secondary succession is always slower than primary; it’s usually faster due to the already-present soil and life.