Most landscapes in Chiapas were recently subjected to a change in land use that has caused various environmental problems in a highland-lowland interactive system. In the Soconusco coastal plain, cash crops with long dry fallow periods caused a decline in precipitation, whereas in the lower escarpment of the Sierra Madre, coffee plantations with unshaded cultivation in rows and inputs of herbicides reinforced major hydrological fluctuations. While these impacts have been reduced during the last decade, demographic pressure in the upper part of the Sierra Madre and in the Altos de Chiapas, resulting in a growing need for land, is responsible for advancement of the frontier of settlement into steeper parts of the Sierra and toward Lacandonia. The resulting soil erosion and leaching cause further degradation, and, together with elevated runoff rates, also have a heavy impact on the forelands. This was evident in September 1998 in the form of disastrous floods and devastation in the Soconusco plain.