Which term describes the process of gradual change in an ecosystem over time, starting with the colonization of barren land?

• A. Ecological succession
• B. Colonization of barren land
• C. An ecosystem
• D. A food chain

Answer: (A)

Ecological succession describes how an ecosystem gradually changes and develops over time as different species colonize, modify the environment, and create new conditions that allow other species to establish. When this process begins on bare, barren land, it’s called primary succession. It starts with pioneer organisms like lichens or mosses that can live on rock and help break it down to form soil. As soil builds up, grasses, shrubs, and then trees follow, creating successive communities until a stable end point, or climax community, is reached. The other terms don’t capture the whole process: an ecosystem is the living system itself, a food chain is a simple sequence of who eats whom, and “colonization of barren land” describes the initial step rather than the entire gradual change over time.