Stratigraphic and Paleobotanical Evidence for Prehistoric Human-Induced Environmental Disturbance on Mo'orea, French Polynesia

Abstract

Humans played an important role in modifying the prehistoric environments of most Pacific Islands. In this paper we reconstruct the role of Polynesians in transforming the late Holocene landscape of the 'Opunohu Valley, Mo'orea, Society Islands (French Polynesia). Stratigraphic, sedimentary, chronometric, and paleobotanical evidence are used to reconstruct a sequence of geomorphological and vegetation changes during the past 1500 yr. Our results indicate substantial human inputs to landscape changes in the 'Opunohu Valley during the late Holocene. Vegetation burning in the upper 'Opunohu Valley, possibly for agricultural purposes, led to conversion of primary forests into early successional forests and degraded fernlands. Erosion of slopes in the upper valley led to massive deposition of sediments onto the valley floor, thus transforming the valley bottom swamp into a relatively dry alluvial flat. These results contribute substantially to an appreciation of the role played by the indigenous Polynesian people in modifying the Society Islands ecosystems and landscapes.