What are the effects of deforestation?

Deforestation, in the Amazon for example, dramatically decreases the amount of water intercepted by the forest canopy (type of storage), leading to increased surface run-off and thus river discharge (an output from the system) as well as soil erosion due to instability following root removal. The latter may cause silt deposition in nearby rivers, altering major transport routes and impacting on water security. Furthermore, evapotranspiration may cease to exist as there are no plants to take water up from the soil and subsequently release it as water vapour through their stomata.
If the deforestation is severe, a carbon source may form, where more CO2 is released than absorbed. Most of the carbon stored in above-ground biomass is released into the atmosphere, exacerbating the human-induced greenhouse effect, having impacts on a global scale, such as increased flooding, crop failure and a higher prevalence of tropical diseases.