Question

Compare primary and secondary succession of an ecosystem. What is the distinction between them?

Primary succession is the sequence of plants that colonize a new area, while secondary succession is the sequence of animals that move once plant life is established.

Primary succession is the sequence of species that become established early in a newly colonized area, while secondary succession is the sequence of species that move in much later.

Primary succession is the establishment of a new community in an existing ecosystem that was disturbed, while secondary succession is the establishment of a community in an area that was altered due to fire.

Primary succession is the establishment of a community in an area with no soil, while secondary succession is the establishment of a new community in an existing ecosystem that was disturbed by some catastrophic event.

Answer 1

The correct choice is the fourth.

Primary succession occurs where no soil (or biological legacy) exists—e.g., newly cooled lava, bare rock left by a retreating glacier. Pioneer species (lichens, mosses, some bacteria) begin soil formation and a community develops slowly.

Secondary succession occurs where an existing ecosystem was disturbed but soil and many organisms (seeds, roots, microbes) remain—e.g., after a fire, clearcutting, or flood—so recovery is faster and proceeds from surviving life and seed banks.

(Other options are incorrect or imprecise: succession involves both plants and animals over time, and the key distinction is the presence or absence of soil/biological legacies, not simply timing or which type of organism appears.)