Which of the following best describes the difference between primary and secondary succession in an ecosystem?

• A. Secondary succession always leads to a less diverse community than primary succession.
• B. Primary succession requires the presence of pioneer species in an already established ecosystem, while secondary succession does not.
• C. Primary succession begins on bare rock or soil with no previous life, while secondary succession occurs in areas where a disturbance has destroyed a community but left the soil intact.
• D. Primary succession occurs after a forest fire, while secondary succession starts on newly formed volcanic islands.

Answer: (C)

Verified step by step guidance

1. Understand the concept of ecological succession: Ecological succession is the process by which ecosystems change and develop over time. It can be categorized into primary and secondary succession.
2. Define primary succession: Primary succession occurs in areas where there is no pre-existing soil or life, such as newly formed volcanic islands or bare rock exposed by a retreating glacier. Pioneer species, like lichens and mosses, are crucial in establishing the initial stages of life.
3. Define secondary succession: Secondary succession happens in areas where a disturbance (e.g., forest fire, flood, or human activity) has destroyed an existing community but left the soil intact. This allows faster recovery since the soil already contains nutrients and seeds.
4. Compare the two types of succession: Primary succession starts from scratch, requiring pioneer species to create soil and establish life, while secondary succession builds on the remnants of a previous ecosystem, making recovery quicker and often leading to similar biodiversity levels as before the disturbance.
5. Clarify misconceptions: Primary succession does not occur after a forest fire (this is secondary succession), and secondary succession does not always lead to less diversity than primary succession. The key difference lies in the starting conditions—bare rock versus intact soil.