Final answer:
Changing seasons do not typically trigger ecological succession because they are predictable, regular occurrences that ecosystems are adapted to handle, unlike the disturbances caused by river flooding, forest fires, or volcanic eruptions. So the correcct option is A.
Step-by-step explanation:
The question asks which of the following events would not trigger ecological succession in an area. Ecological succession is the process by which the structure of a biological community evolves over time. It can be triggered by both natural and anthropogenic events that significantly disturb or change an ecosystem.
Options B (River flooding), C (Forest fires), and D (A volcano erupting) are all examples of disturbances that can initiate ecological succession by altering the environment in such a way that it becomes suitable for colonization by new species. These events can lead to either primary or secondary succession.
However, option A (Changing seasons) does not typically initiate ecological succession because seasonal changes are a regular occurrence and ecosystems are generally adapted to them. Therefore, the correct answer is A. Changing seasons.