Describe the difference between primary and secondary succession.

Primary succession occurs in lifeless areas, while secondary succession happens in areas where a community previously existed but was removed.

Primary succession is the series of community changes that occur in an entirely new habitat that has never been colonised before. This could be a bare rock surface, newly formed sand dunes, or a place left bare after a volcanic eruption. The first species to colonise such an area are called pioneer species. These species are usually hardy, able to withstand harsh conditions, and can fix nitrogen or other essential nutrients. Over time, these species change the habitat in ways that make it more hospitable for other species. This process continues until a stable, mature community, known as a climax community, is established.

Secondary succession, on the other hand, occurs in areas where a community previously existed but was removed or destroyed by a disturbance such as fire, hurricane, human activity (like farming), or other natural disasters. The soil is already present, so the community's recovery is faster than primary succession. The first species to colonise these areas are usually grasses and other fast-growing plants. These species are replaced over time by larger, slower-growing species. Secondary succession also ends with a climax community, but the species composition may be different from the original community due to changes in the environment and species interactions.

In both types of succession, the species composition and community structure change over time. However, the rate of change and the specific pathways of succession can vary greatly depending on the specific conditions of the environment and the species present. In general, primary succession takes longer than secondary succession because it starts from a completely lifeless area, while secondary succession begins in an area that already has some form of life and nutrients present in the soil.