Fire-free land use in pre-1492 Amazonian savannas

Abstract

The nature and scale of pre-Columbian land use and the consequences of the 1492 "Columbian Encounter" (CE) on Amazonia are among the more debated topics in New World archaeology and paleoecology. However, pre-Columbian human impact in Amazonian savannas remains poorly understood. Most paleoecological studies have been conducted in neotropical forest contexts. Of studies done in Amazonian savannas, none has the temporal resolution needed to detect changes induced by either climate or humans before and after A.D. 1492, and only a few closely integrate paleoecological and archaeological data. We report a highresolution 2,150-y paleoecological record from a French Guianan coastal savanna that forces reconsideration of how pre-Columbian savanna peoples practiced raised-field agriculture and how the CE impacted these societies and environments. Our combined pollen, phytolith, and charcoal analyses reveal unexpectedly low levels of biomass burning associated with pre-A.D. 1492 savanna raised-field agriculture and a sharp increase in fires following the arrival of Europeans. We show that pre-Columbian raised-field farmers limited burning to improve agricultural production, contrasting with extensive use of fire in pre-Columbian tropical forest and Central American savanna environments, as well as in present-day savannas. The charcoal record indicates that extensive fires in the seasonally flooded savannas of French Guiana are a post-Columbian phenomenon, postdating the collapse of indigenous populations. The discovery that pre-Columbian farmers practiced fire-free savanna management calls into question the widely held assumption that pre-Columbian Amazonian farmers pervasively used fire to manage and alter ecosystems and offers fresh perspectives on an emerging alternative approach to savanna land use and conservation that can help reduce carbon emissions.pre-Columbian agriculture | anthropogenic fire | indigenous fire practices | savanna ecology | tropical seasonal wetlands M ounting archaeological and paleoecological evidence indicates that societies of considerable size and complexity emerged in some regions of Amazonia and began to transform landscapes at an unprecedented scale during the late Holocene (1-4). Anthropogenic dark-earth soils associated with intensive agriculture developed along the bluffs of major rivers in forested areas of Amazonia and its periphery, and large expanses of previously uncultivated seasonally flooded savannas were reclaimed for intensive raised-field agricultural systems (5, 6).Many seasonally flooded tropical savannas of South and Central America, such as the coastal belt of the Guianas (7), the Mompos depression in Colombia (8), and the Beni in the Bolivian Amazon (9), were reclaimed into vast agricultural landscapes through the construction of raised fields by pre-Columbian farmers during the Late Holocene. Early European chronicles illustrate the practice of raised-field agriculture by the Otomac in Venezuela (10) and by the Tainos in Hispaniola (11), who constructed small mounds u...

Climate variability and human impact in South America during the last 2000 years: synthesis and perspectives from pollen records

“…savanna gallery forest) rather than regional climate. Many of these records from small basins were specifically selected in the original study to investigate local-scale human impacts around known occupation sites (Iriarte et al, 2012;Whitney et al, 2014;Carson et al, 2014Carson et al, , 2015. Examples of continuous anthropogenic signals during the last 2 kyr are Laguna El Cerrito, Laguna Frontera, and Laguna San José (Fig.…”

Environmental impact of geometric earthwork construction in pre-Columbian Amazonia

“…Gaining a sound understanding of the historical role of humans in shaping Amazonian landscapes, and the extent to which Amazonian forests were resilient to historical disturbance, is critical to informing policy makers on sustainable Amazonian futures (8,12,16,19,45). However, the debate so far has considered only the extent of past human impact and land use in what is assumed to have been a forested landscape, based upon the modern distribution of forest.…”

Phytoliths as a tool for archaeobotanical, palaeobotanical and palaeoecological studies in Amazonian palms

“…As such, they can persist in a variety of soil types for thousands or even millions of years, making them useful for archaeology, palaeobotany and palaeoecology (reviewed by Piperno, ). Applications for research include reconstructing ancient floras, landscapes and palaeoenvironments (Zucol et al ., ; Iriarte et al ., ), interpreting events in plant evolution (Strömberg, ) and documenting plant use by ancient peoples (Piperno & Pearsall, ; Pearsall, ; Iriarte & Paz, ; Dickau et al ., ).…”