The micro-effect among the factors listed is:
An invasive species of plant is introduced that outcompetes all local plants.
This is considered a micro-effect because it typically affects individual species and their interactions within a specific ecosystem, impacting local biodiversity on a smaller, more localized scale. The other examples, such as the stand of aspen trees dying and decaying, or a hurricane destroying a coral reef, generally have broader ecological impacts and are typically considered macro-effects. Similarly, the clearing of a forest for suburban development also has widespread consequences.