What is a feature of primary succession?

Primary succession is characterized by its beginning in lifeless areas, such as bare rock exposed by glacial retreat, volcanic eruptions, or other disturbances that leave behind a substrate devoid of soil and living organisms. This process starts with pioneer species, like lichens and mosses, that colonize the bare substrate. These organisms contribute to soil formation as they break down the rock and accumulate organic material, eventually allowing more complex plant communities to establish.

While primary succession can occur along with some natural disasters that create lifeless conditions, such as volcanic eruptions, the defining feature is that it initiates in environments without any pre-existing soil or biological life. This sets it apart from secondary succession, which occurs in areas where soil and organisms are already present, following disturbances that do not completely eliminate life.

The other options either relate to concepts of secondary succession or are not defining characteristics of primary succession. Thus, identifying the starting point of primary succession in lifeless areas is essential for understanding its ecological significance and dynamics.