Evidence for Forest Clearance, Agriculture, and Human-Induced Erosion in Precolumbian El Salvador
It is now well established that Precolumbian farmers of Mexico and Central America were responsible for widespread environmental degradation before the arrival of Europeans. Relatively little is known, however, of the chronology, severity, and exact geographic distribution of these anthropogenic landscape impacts. This article addresses questions of Holocene land use and anthropogenic environmental change in the upper Rio Paz Valley, El Salvador, before and after the arrival of the Spanish in the sixteenth century. A lacustrine sediment sequence from Chalchuapa records the impacts of prehistoric agriculturalists on a mid-elevation tropical watershed during the past 3700 years. The 9.72 m sediment core from Laguna Cuzcachapa contains unequivocal evidence for human manipulation of the landscape: high levels of maize and agricultural weed pollen, charcoal, magnetic susceptibility, and sediment flux. The abundance of maize pollen (>6 percent) even in the basal sediments of the core indicates that an intensive system of maize cultivation was well established in Chalchuapa by 3700 cal yr BP. Proxy indicators of human disturbance continue to exhibit high values from 3700 cal yr BP to the present, interrupted only by two hiatuses: one centered on the ca. AD 430 Tierra Blanca Joven eruption of the Ilopango volcano, and another during a period of population decimation following the arrival of Europeans in the early sixteenth century AD. The periods of greatest anthropogenic disturbance include ca. 3700–1600 cal yr BP (Preclassic/“Protoclassic”) and ca. 1350–1000 cal yr BP (Late Classic and Early Postclassic Periods).