An international team of archaeologists and paleoecologists analyzing records of pollen, charcoal and other plant remains like phytoliths spanning more than 2,000 years has created the first detailed picture of land use in the Amazonian savannas in French Guiana.
The study, published in the journal Proceedings of the National Academy of Sciences, shows that indigenous people, living in the savannas around the Amazonian forest, farmed without using fire and practiced ‘raised-field’ farming, which involved constructing small agricultural mounds with wooden tools.
These raised fields provided better drainage, soil aeration and moisture retention: ideal for an environment that experiences both drought and flooding. The fields also benefited from increased fertility from the muck continually scraped from the flooded basin and deposited on the mounds. The raised-field farmers limited fires, and this helped them conserve soil nutrients and organic matter and preserve soil structure.
“We used radiocarbon dating to establish the age of the raised beds,” said study co-author Dr. Mitchell Power, a curator of the Garrett Herbarium at the Natural History Museum of Utah and an assistant professor at the University of Utah. “We came to the conclusion that corn pollen we found dated to 800 years ago by dating charcoal deposits from above and below the sediment where the pollen was found.”
It has long been assumed that indigenous people used fire as a way of clearing the savannas and managing their land. However, the new study shows that this was not the case here.
“Our results force reconsideration of the long-held view that fires were a pervasive feature of Amazonian savannas,” Dr. Power explained.
This study could provide insights into the sustainable use and conservation of these globally-important ecosystems, which are being rapidly destroyed.
“This ancient, time-tested, fire-free land use could pave the way for the modern implementation of raised-field agriculture in rural areas of Amazonia,” said lead study author Dr. José Iriarte of the University of Exeter. “Intensive raised-field agriculture can become an alternative to burning down tropical forest for slash and burn agriculture by reclaiming otherwise abandoned and new savannah ecosystems created by deforestation. It has the capability of helping curb carbon emissions and at the same time provide food security for the more vulnerable and poorest rural populations.”