Holocene Human Influence in the Ecuadorean Amazon

Abstract

The extent to which the spectacular biodiversity of Amazonia has been shaped by Pre-Columbian humans is actively debated. Forests that today appear to be pristine wildernesses may have supported complex human societies as recently as 300 years ago. Understanding human history and the potential successional trajectories that result from site abandonment are important to conservation and policy-making. The Yasuni, is famed for its human and biological diversity and yet its pre-history is poorly known. Lake Añangucocha, a small blackwater lake in northwestern Ecuador, is unusual in that it is not a riverine lake, and has the potential to provide the first detailed history of human occupation within the Yasuni. In 2019, a 2.65m sediment core was raised from Lake Añangucocha. The core was dated using 14C, establishing a chronology that extended about 4000 years. Due to shipping limitations and the Covid-19 Pandemic, only the last 2100 years were used in this analysis. This study aimed to determine whether the disturbances around this area were anthropogenic, or climate caused. Hydrological change altered both the limnology and the pollen representation Añangucocha as the organic dam isolated the river from the Napo at c. AD 430. Añangucocha has been continuously used by humans for the last 2000 years, mostly sporadically until AD 1300, after which a sharp increase in fire suggested some forest clearance and ecosystem alteration. Despite this signal, the disturbances were probably highly localized as there was very little impact on either the proportion of forest pollen or on indicators of open ground. Fossil pollen and phytoliths of maize occurred before and after the major transition in burning practices at c. AD 1300, and a full archaeological investigation of the site is recommended.