Ecological engineers ahead of their time: The functioning of pre-Columbian raised-field agriculture and its potential contributions to sustainability today

Getting at the Maya Collapse has both temporal and geographic dimensions, because it occurred over centuries and great distances. This requires a wide range of research sites and proxy records, ranging from lake cores to geomorphic evidence, such as stratigraphy and speleothems. This article synthesizes these lines of evidence, together with previously undescribed findings on Maya wetland formation and use in a key region near the heart of the central Maya Lowlands. Growing lines of evidence point to dryer periods in Maya history, which correlate to major periods of transition. The main line of evidence in this paper comes from wetland use and formation studies, which show evidence for both largescale environmental change and human adaptation or response. Based on multiproxy studies, Maya wetland fields had a long and varied history, but most evidence indicates the start of disuse during or shortly after the Maya Terminal Classic. Hence, the pervasiveness of collapse extended into a range of wetlands, including perennial wetlands, which should have been less responsive to drought as a driver of disuse. A synthesis of the lines of evidence for canal infilling shows no attempts to reclaim them after the Classic Period.Mesoamerica | proxies | wetland agriculture S cholars have explored many proxy lines of evidence to understand the environmental change and timing of societal transitions in the Maya Lowlands of Mesoamerica. These proxies include lake and ocean cores; speleothems; geomorphic evidence; architecture; modeling; and, recently for Mesoamerica, tree rings. One repository of evidence we examine here comes from ancient Maya wetland field systems and their canals. Over the past decade, we have studied more than 50 of these systems, which can provide unique insights into site abandonment because their canals started to fill with sediment and proxy evidence after the Maya ceased maintaining them. We can thus date the infill of sediment and use multiple proxies to study ecological change from near the time of abandonment forward. These canals also provide

Section: Resultsmentioning

confidence: 99%

Wetland fields as mirrors of drought and the Maya abandonment

Luzzadder–Beach

Beach

Dunning

2012

“…Fires result in the loss of nutrients, such as nitrogen and phosphorus, through formation of gases and aerosols (31,32). Fallows would probably have been most effective at restoring plant biomass, soil organic matter, and soil structure for the next cycle of raised-field agriculture in the absence of fire (33)(34)(35). Furthermore, tight control of burning would have also avoided the labor cost of weeding fire-adapted plants (33).…”

Section: Resultsmentioning

confidence: 99%

Fire-free land use in pre-1492 Amazonian savannas

Iriarte

Power

Rostain

et al. 2012

104

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...

“…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.…”

Section: Study Areamentioning

confidence: 99%

Environmental impact of geometric earthwork construction in pre-Columbian Amazonia

Carson

Whitney

Mayle

et al. 2014

108

175

There is considerable controversy over whether pre-Columbian (pre-A.D. 1492) Amazonia was largely "pristine" and sparsely populated by slash-and-burn agriculturists, or instead a densely populated, domesticated landscape, heavily altered by extensive deforestation and anthropogenic burning. The discovery of hundreds of large geometric earthworks beneath intact rainforest across southern Amazonia challenges its status as a pristine landscape, and has been assumed to indicate extensive pre-Columbian deforestation by large populations. We tested these assumptions using coupled local-and regional-scale paleoecological records to reconstruct land use on an earthwork site in northeast Bolivia within the context of regional, climate-driven biome changes. This approach revealed evidence for an alternative scenario of Amazonian land use, which did not necessitate labor-intensive rainforest clearance for earthwork construction. Instead, we show that the inhabitants exploited a naturally open savanna landscape that they maintained around their settlement despite the climatically driven rainforest expansion that began ∼2,000 y ago across the region. Earthwork construction and agriculture on terra firme landscapes currently occupied by the seasonal rainforests of southern Amazonia may therefore not have necessitated large-scale deforestation using stone tools. This finding implies far less labor-and potentially lower population densitythan previously supposed. Our findings demonstrate that current debates over the magnitude and nature of pre-Columbian Amazonian land use, and its impact on global biogeochemical cycling, are potentially flawed because they do not consider this land use in the context of climate-driven forest-savanna biome shifts through the mid-to-late Holocene.paleoecology | Amazonian archaeology | human-environment interactions | Anthropocene | Amazon rainforest