An enigma revisited: identification of palm phytoliths extracted from the 1983 Rapa Nui, Rano Kao2 core

Abstract

Collection of climatic, environmental and archaeological data from the remote southern oceanic island of Rapa Nui is a continuous process. There are many enigmas, such as the unique Moai statuary and sparsity of vegetation. Pollen studies concluded that the pre-human island Rapa Nui was dominated by a now extinct palm, Paschalococos disperta. The phytolith research reported here has identified the presence through time of other palm species. Plant biogenic silica phytolith microfossils were extracted from Rano Kau core sediments, a nearby ahu and pan-Pacific palm material for reference purposes. A palm phytolith classification was constructed from the many micrographs produced and all extracted sediment and palm phytoliths were classified and compared visually with each other. Six palm species were identified. Robust identification of these, now extinct on Rapa Nui, palms by phytolith analysis has shown them to belong to extant palm species occurring on Pacific islands in a north-west arc from Rapa Nui and on mainland South America. Data on the current habitats of these palms, when applied to Rapa Nui, has the potential to add to the vegetation and environmental history data base of the island.