AP BIOLOGY

Detailed explanation-1: -The first organisms to appear in areas of primary succession are often mosses or lichens. These organisms are known as pioneer species because they are the first species present; pioneer species must be hardy and strong, just like human pioneers.

Detailed explanation-2: -The first species to colonize bare rock are usually lichens. In primary succession, they are thus the pioneer organisms. Before they can colonize an environment, many organisms need soil. Acids that break down the rock and start the process of soil formation are secreted by lichens that colonize bare rock.

Detailed explanation-3: -Four seral stages are recognized: potential natural community, late seral, mid seral, and early seral (Hall et al. 1995).

Detailed explanation-4: -primary succession, type of ecological succession (the evolution of a biological community’s ecological structure) in which plants and animals first colonize a barren, lifeless habitat.