Final answer:
Secondary succession cannot occur after a glacier melts and exposes rock because it only occurs in areas where soil is already present. This type of succession is characteristic of areas that had a disturbance but still contain nutrient-rich soil, such as after wildfires or abandonment of plowed farming land.
Step-by-step explanation:
Secondary succession cannot occur after a glacier melts and exposes rock, since it only occurs in areas where soil is already present. When a glacier recedes, the land exposed is devoid of soil, thus requiring primary succession for plants and a new ecosystem to become established. Secondary succession occurs in areas where an existing habitat with soil has been disturbed or destroyed by events such as wildfires, floods, or human activities like farming.
Wildfires are a prime example of a disturbance that can lead to secondary succession. After forest fires, whether caused by natural phenomena like lightning or human action such as arson, the nutrient-rich soil remains intact, allowing new plant life to sprout among the charred remnants of the previous vegetation.
Abandoning plowed farming land also leads to secondary succession because the soil contains the necessary nutrients for pioneer species to take root and rebuild the ecosystem over time. Lichens and other pioneer species are not necessary in these scenarios as a foundation of soil is already present, making the process of secondary succession faster compared to primary succession.