What does ecological succession refer to?

Ecological succession refers specifically to the gradual process in which the species composition of an ecological community changes over time. This process can occur in stages, typically starting with pioneer species that are well adapted to colonize disturbed or barren environments. As these species thrive and alter the environment, they create conditions that allow other species to establish themselves, leading to a more complex and diverse community. There are two main types of succession: primary succession, which occurs in lifeless areas where soil has yet to form, and secondary succession, which takes place in areas where a disturbance has cleared out a community but left the soil intact.

The other options address concepts that do not capture the essence of ecological succession. Seasonal migration refers to the movement of species driven by climate and resource availability, while the introduction of new species pertains more to biotic interactions and human impacts rather than the natural progression of community development over time. Lastly, extinction of a species leads to a change in community dynamics but does not encompass the entire process of succession, which involves a succession of species replacing one another rather than a singular loss.