What is a key feature of organisms in primary succession?

In primary succession, a key feature is the existence of microorganisms and small shrubs. This process begins in lifeless areas where soil has not yet formed, such as after a volcanic eruption or retreat of glaciers. The first organisms to colonize these bare environments are typically pioneer species, which include various microorganisms, lichens, and small plants like mosses and shrubs. These organisms play a crucial role in establishing an ecosystem by breaking down rock to form soil and creating conditions that enable more complex plants and animals to eventually inhabit the area.

Over time, as these initial species thrive and die, they contribute organic matter to the soil, enriching it and facilitating the growth of larger plants, including trees. As primary succession progresses, the community structure evolves, moving from simple life forms to a much more complex and diverse ecosystem. Thus, the presence of microorganisms and small shrubs represents the early stages in the development of a thriving ecosystem in primary succession.