A Late Holocene palaeoenvironmental reconstruction of Ulong Island, Palau, from starch grain, charcoal, and geochemistry analyses

This study represents the first starch grain analysis undertaken in Palau, performed on a sediment core extracted from a sinkhole on Ulong Island. Radiocarbon dating indicates the core spans the likely period of human occupation on Ulong (ca. 3000 years) as established by prior archaeological evidence. Samples were analysed for macrocharcoal, starch content, and geochemical composition. The results of the analyses indicate an initial period of intensive clearance and gardening from ca. 3000–2000 BP, during which banana (Musa spp.), yams (Dioscorea spp.), Polynesian arrowroot (Tacca leontopetaloides), Tahitian chestnut (Inocarpus fagifer), and breadfruit (Artocarpus sp.) were being utilised and/or cultivated. This initial phase was then followed by a period of reduced and stabilized gardening activity until ca. 1000 BP, during which banana (Musa spp.) disappears from the starch record. The period after 1000 BP represents the transition between the first permanent settlements on Ulong, abandoned between 500 and 300 BP, and the arrival of Europeans in 1783. This period is marked by a dearth of charcoal indicating the absence of significant burning, as well as a decrease in the variety of starch grains from cultigens.