Amazonian Dark Earths, Polyculture Agroforestry Systems, and their Modern Legacy

Dr. José Iriarte, Professor of Archeology, University of Exeter, UK

The human-made soils of Amazonia, Amazonian Dark Earths (ADEs), are arguably one of the most compelling pieces of evidence of the human transformation of tropical environments in the Americas.  Much progress has been made on the genesis and archaeology of these anthrosols. However, until recently, we knew very little about the type of land-use practiced on ADEs. In this presentation, I summarize the results of the PAST project along the Amazon, showing that polyculture agroforestry involving soil fertilization, closed-canopy forest enrichment, limited clearing for crop cultivation and low-severity fire management was practiced on ADEs. These millennial-scale agro-ecosystems had an enduring legacy on persisting patches of highly fertile soil and the modern composition of the forest, including legacy plots of fruit trees. We argue that ADE agro-ecosystems provide evidence of successful, sustainable subsistence strategies while also highlight a millennial rich indigenous cultural-ecological heritage.