Final answer:
Primary succession begins in lifeless areas such as bare rocks left by retreating glaciers or newly formed volcanic islands, requiring soil formation to commence. Pioneer species like lichens initiate this process, gradually leading to a diverse and stable ecosystem.
Step-by-step explanation:
Primary succession begins on bare rock after glaciers have passed, or on newly formed volcanic islands. This type of ecological succession occurs in areas where there was no pre-existing life, often following significant geological events such as the retreat of a glacier or a volcanic eruption. In these settings, soil must first be produced before a stable ecosystem can be established.
The process begins when forces like weathering break down the substrate, providing a foothold for pioneer species, such as lichens and certain hardy plants with few soil requirements. These organisms start the breakdown of the mineral-rich substrate into soil. As pioneer species die, they contribute organic material, promoting soil formation. Eventually, this soil supports the growth of other plants and, over time, leads to a community quite different from the original colonizers, reaching an equilibrium state of biodiversity.