Widespread reforestation before European influence on Amazonia

An estimated 90-95% of indigenous people in Amazonia died following European Contact. This population collapse is postulated to have caused decreases in atmospheric CO2 concentrations at c. 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery and warfare, whereby the attendant reversion to forest significantly increased terrestrial carbon sequestration. Based on 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric CO2 response following European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began c. 300 - 600 years before European arrival. Pre-European pandemics, social strife or environmental change may have contributed to these early site abandonments and ecological shifts