The krakato eruption destroyed life and left behind volcanic ash. A large chemical spill can also destroy life. How would succession be very different following these two events?

Since chemical spills are very harmful to aquatic/land life for both plants and animals, plants probably wouldn't grow back and animals could be mutated or even killed, decreasing the population of that species. A volcano eruption, can be both good and bad, since a volcano can kill animals and plants, but ash from a volcano is extremely fertile, so plants can regrow, which in turn brings animals back so they can feed on those plants.