One difference between primary and secondary successions is the presence of soil. In primary succession, there is no pre-existing soil present at the beginning of the process, as the area is typically barren, such as on bare rock or sand. In contrast, secondary succession occurs in areas where soil already exists, such as after a disturbance like a fire or logging. This difference in soil availability can impact the types of species that are able to colonize and establish in each type of succession.
