Which of the following is NOT an example of secondary succession?

Secondary succession refers to the process of ecological recovery that occurs in an area where a disturbance has destroyed an existing ecosystem but where soil and some organisms still remain. This process typically follows events such as fires, floods, or human activities like agriculture, and involves the gradual re-establishment of plant and animal communities.

The correct answer is that a volcanic island forming is not an example of secondary succession. This scenario represents primary succession, where life begins to develop on bare rock or newly formed substrates that have not been previously inhabited. In primary succession, the process starts from scratch, requiring pioneer species to colonize the area, build soil, and facilitate the establishment of more complex communities over time.

In contrast, the other listed scenarios all involve prior ecosystems that were disturbed but still retained some soil or organisms, allowing for a more rapid re-establishment of ecological communities. For instance, when a forest regrows after a fire, the underlying soil and seed bank are intact, supporting regrowth. Similarly, weeds can quickly take root in a recently plowed field due to the presence of existing soil nutrients. Finally, fields recovering after crops are harvested also indicate the previous presence of an ecosystem that can rehabilitate through secondary succession processes.