Date of Award

5-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean Engineering and Marine Sciences

First Advisor

Mark B. Bush

Second Advisor

Crystal McMichael

Third Advisor

Robert van Woesik

Fourth Advisor

Brooke Wheeler

Abstract

The vegetation of the Amazonian rainforest is hypothesized to have been shaped by pre-Columbian activities, such as burning and palm management to various extents. Management of palms is hypothesized to have caused some of the most useful species to become hyperdominant in Amazonia. This study investigated the extent to which human activities over the past 5000 years affected palm abundances in mature lowland rainforests near Iquitos, Peru. I used phytoliths and charcoal from soil cores to determine the history of local floras, and modern palm surveys to compare modern phytolith occurrence with modern vegetation. Because pre-Columbian activity clustered along the rivers in the Amazon, the proximity of rivers was considered in the experimental design. I found 89 out of 180 samples contained charcoal. The particles large enough to date (n =19) provided an age range from c. 5160 to c. 1000 calibrated radiocarbon years before present, but no sample contained phytoliths of crops. The modern phytoliths reflected the local dominance of Oenocarpus bataua. The soil cores indicated an increase in the palm abundance over time. A rise in O. bataua most likely drives this increase. The distance to the nearest river was not correlated with this increase in O. bataua phytoliths. Similar studies from northwestern Amazonia also found an increase in palms evident in the last 4000 years. Although humans were present in the forest at Iquitos, as indicated by the charcoal, the primary influence on palm populations appears to be related to long-term climate change rather than human activity.

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