Volcanic activity in Hokkaido, Japan was studied to see if it changes the plants in bogs over time. Researchers looked at layers of volcanic ash in four bogs and analyzed plant remains in the soil. They found that even when ash fell on mossy areas, the plants didn't change much. The idea that ash would make bogs richer in nutrients was not seen in these bogs. The plants in the bogs didn't shift much even with ash falling on them.