Dolores Piperno

DOLORES PIPERNO, Smithsonian National Museum of Natural History, Washington, DC, was awarded funding in April 2018 to aid research on ‘Pre-Columbian Occupation and Modification of Forest in Western Amazonia: Terrestrial Soil Phytolith and Charcoal Records.’ This project carried out phytolith (plant biogenic silica) and charcoal analyses of ancient terrestrial soils underneath interfluvial forests of two previously unstudied, remote regions of the northeastern Peruvian Amazon. The regions were Medio Putumayo-Algod’n (MP-A) and Iquitos to Nauta. The goals were to address major questions concerning the impacts of prehistoric human populations on Amazonian forests by reconstructing vegetational and fire history, together with their modern legacies. Phytolith reference collections (used to identify ancient phytoliths) were significantly expanded through the analysis of 400 species of plants with a focus on previously understudied eudicotyledon representatives of the diverse Amazonian forest. Palms were also intensively investigated to test newer methods of identification and more closely study possible palm cultivation and management. Phytolith analysis of the 5000-yr-old sequence from MP-A showed little to no prehistoric impacts on the vegetation. Trees of mature forest did not decrease through time, major annual seed and root crops were absent, herbaceous indicators of human disturbance were rare to absent, and palm cultivation and management to the point of increases in economic palms in the flora were not indicated. Charcoal occurred infrequently in the soils, was dated to 2300-1800 years ago, and indicated that fire was not synchronous or recurrent across the landscape. The results from the Iquitos to Nauta records dating from about 3600 years ago to the present were the same as from MP-A. The results further indicate that human occupation and influences were heterogenous across the vast Amazonia interfluvial landscape, from intensive to sparse, depending in part on factors such as annual rainfall, soil type, and distance to watercourses. These results also showed that prehistoric Indigenous societies in the studied areas were stewards of their forests, highlighting their importance to modern conservation and sustainability efforts.