A late-Holocene palaeoecological record from Ambra Crater in the highlands of Papua New Guinea and implications for agricultural history

Abstract

A series of monoliths collected from Ambra Crater in the Upper Wahgi valley, Papua New Guinea have been subject to multiproxy (pollen, microcharcoal and diatom) palaeoecological investigation. The palaeoecological record enables a relatively high-resolution reconstruction from c. 4000—500 cal. BP. Throughout the sequence, the valley floor and crater area were continuously deforested and carpeted with a grassland-disturbance taxa mosaic. Vegetation communities in the valley were largely unaffected by successive tephra deposition events, although some muted effects occurred. Tephra deposition did have considerable local effects on soil water conditions and hydrology in the base of the crater. The Ambra Crater record is consistent with longer chronologies from wetlands in the Upper Wahgi valley, which document extensive disturbance to dryland forests and their replacement with grasses and other disturbance taxa from the mid Holocene. The Ambra Crater record, taken in conjunction with previously published multisite data, enables critique and discrimination of different interpretations of agricultural history in the highlands during the late Holocene.