Which ecosystem would most likely require the most time for ecological succession?

The correct answer is "An island with a dense shrub population becomes submerged for over three (3) years. When the river water lowers, the island does not become submerged again for the net twenty (20) years."

Ecological Succession refers to the procedure of changes in the species structure of an ecological community over the years. The time scale may be decades or even millions of years after a mass extinction.