Both primary and secondary succession begin with pioneer species that:

• A. are typically large, slow-growing trees
• B. require well-developed soil to establish themselves
• C. are able to colonize and thrive in harsh or disturbed environments
• D. replace climax communities directly

Answer: (C)

Verified step by step guidance

1. Understand the concept of ecological succession: Primary succession occurs in areas where no previous life existed (e.g., bare rock after a volcanic eruption), while secondary succession occurs in areas where a disturbance has removed existing life but soil remains (e.g., after a forest fire).
2. Recognize the role of pioneer species: Pioneer species are the first organisms to colonize an area during succession. They are typically hardy and adapted to survive in harsh or disturbed environments, such as bare rock or nutrient-poor soil.
3. Identify the characteristics of pioneer species: These species are usually small, fast-growing, and capable of reproducing quickly. They often include organisms like lichens, mosses, and certain grasses that can tolerate extreme conditions and begin the process of soil formation.
4. Clarify why large, slow-growing trees or species requiring well-developed soil are not pioneer species: These organisms typically appear later in succession, once the environment has been stabilized and enriched by earlier colonizers.
5. Conclude that pioneer species are essential for initiating ecological succession by modifying the environment (e.g., breaking down rock into soil, adding organic matter) to make it suitable for subsequent species, eventually leading to the establishment of more complex communities.