Late Holocene multiphasic use and occupation around a western Amazonian Lake

Competing hypotheses exist regarding the relative importance of flood events, droughts, and human activity in shaping northwest Amazonian vegetation within the last 2000 years. We hypothesize that drier conditions were more favorable for human occupation in these ever-wet forests, and we present a high-resolution multiproxy paleoecological record of the last two millennia from a currently uninhabited lake, Zancudococha, in northwestern Ecuador. Pollen, phytoliths, charcoal, XRF, and loss-on-ignition data were analyzed to reconstruct the relative roles of climatic changes and human activity in shaping local vegetation. Humans were probably already influencing this system at the onset of our study period. By modeling past forest cover changes using pollen percentages, we showed that land-use intensity was highest between c. 470 and 1360 CE. Overall, drier conditions were more likely to have supported maize cultivation over the last 2000 years than wet ones, and this was especially clear during the Medieval Climate Anomaly (c. 900–1250 CE). An abandonment phase occurred between 1360 and c. 1630 CE, when all signs of human activity disappeared from the record and forest cover increased. The lake was later reoccupied, and there were small-scale clearances during the Jesuit (1680–1890 CE) and Rubber Boom (1890–1925 CE) times, with near modern abandonment occurring c. 1925 CE.