what is one difference between primary and secondary succession?
Primary succession develops a new community from scratch.
Secondary succession happens on a previously existing community that has been cleared.
One difference between primary and secondary succession is the starting point and the presence of soil.
Primary succession occurs in areas that have been completely devoid of life or where the soil has been completely wiped out, such as after a volcanic eruption or the retreat of glaciers. In primary succession, the first organisms to colonize the area are called pioneer species, which are generally lichens and mosses that can grow on bare rock surfaces. These pioneer species can break down the rock and create small amounts of organic matter, contributing to the development of rudimentary soil. Over time, as more plants and organisms colonize the area and die, the soil becomes richer and capable of supporting a wider range of species.
On the other hand, secondary succession happens in areas where the soil is already present, such as after a forest fire or the abandonment of agricultural land. Unlike primary succession, secondary succession begins with a larger variety of pioneer species. These may include grasses, shrubs, and small trees that are able to take advantage of the existing soil and nutrients. Over time, as the community develops and matures, more complex and diverse species gradually replace the earlier pioneer species.
So, the key difference lies in the starting conditions and the presence of soil. Primary succession starts from a barren landscape without any soil, while secondary succession occurs in an area with existing soil.