Ecological legacies and recent footprints of the Amazon’s Lost City

Once considered pristine forests, the mid-elevational forests of the eastern Andean flank are now known to have long histories of human occupation. Past habitations, such as the ‘Lost City of the Amazon’ in the Upano Valley of eastern Ecuador, were societally and temporally complex with sophisticated cultures emerging, flourishing, and disappearing. The cultures of the Upano Valley transformed local ecosystems, but whether lasting ecological changes from those activities persist in modern forests is not known. Here, using paleoecological reconstructions from Lake Cormorán, located immediately adjacent to the Upano Valley and within 10 km of an area of >300 km2 of abandoned mound complexes, we provide a timeline of human influence spanning the last 2770 years. We document the onset of maize cultivation c. 570 BCE, and changes in land use within the occupation phase that included slash-and-burn, slash-and-mulch, and silviculture. A gradual decline in forest exploitation presaged an apparent abandonment of the site c. 550 CE. A much later wave of land use that began about 1500 CE, coupled with abandonment and a succession influenced by a warmer and wetter climate, produced a distinctive forest composition unique to the last 120 years.