I wrote this summary in Latin class based on an article about deforestation and the lasting effects of it in Rome
Erosion and situation were extensive in classical Greece and Rome because of deforestation. The Greeks and Romans used to destroy all forests since they used a huge quality of wood for furniture and tools as well. Trees protect the soil from heavy rain with their roots, preventing erosion. Without trees, torrential floods increased making dangerous sediments leak into rivers. Malaria and other swamp-bred diseases were also a reason for the population decrease as household materials and sediments from the cities filled the rivers.
Malaria and other so called swamp bred illnesses are a secondary result of deforestation and erosion. Which also contributed to population decrease. The sediments that clogged the rivers were deposited in low lying valleys and along the Mediterranean shores where some tides exist that carry the material away.