Plant and soil evidence can provide clues to what happened in the past. You may want to examine this pollen slide, which comes from a sample taken from the bottom of a bog in a farming area outside of Copán.
Mahogany pollen
This slide is of mahogany pollen, dating to around A.D. 1200-1250. It shows that the Copán Valley had largely returned to forest by that time. Before A.D. 1200-1250, there is little evidence of mahogany pollen in the sample. Mahogany pollen would be present in areas of tall forest, but not in areas of heavy farming.