Human impact on the environment in Western Flores, Indonesia during the late Holocene: identifying agricultural transitions

• Main Authors: St Pierre, E, Zhao, JX, Aplin, K, Drysdale, R, Golding, S, Griffiths, ML, Hua, Q
• Format: Conference Object
• Language: English
• Published: 18th INQUA Congress 2011
• Subjects: Quaternary period; Environment; Carbon; Oxygen; Isotopes; Deposition; Rattus rattus
• Online Access: http://apo.ansto.gov.au/dspace/handle/10238/4255

Limestone caves can act as excellent repositories of palaeoenvironmental information and past human activities. This paper presents a multi-proxy record of late Holocene palaeoclimate and palaeoenvironmental change derived from environmental archives in Liang Luar (Steam Cave), western Flores, Indonesia. Liang Luar, located ~1 km from Liang Bua (the discovery site of the hominid species Homo floresiensis), is a ~1.6km long passage with several large chambers and numerous speleothems (stalagmites and stalactites). A palaeoclimate record was compiled using stable carbon and oxygen isotope ratios from a stalagmite precisely dated to 0-1800 yr BP using U/Th dating. The stalagmite isotope record preserves an episode of rapid vegetation change c. 800 yr BP marked by a large shift in carbon and decoupling of the carbon from the oxygen isotopes, and thus thought to be unrelated to climate. Excavated owl pellet deposits in the entrance of Liang Luar dated by 14C AMS on charcoal, reveal continuous sediment deposition from at least 2400 yr BP to the present. The 14C chronology demonstrates a sudden increase in depositional rates at the cave entrance as well as an increase in the abundance of charcoal fragments, at the time of the vegetation change inferred from the stalagmite record. Faunal remains indicate the commensal species Rattus exulans, arrives early in the sequence, while Rattus rattus appears much later. A surprisingly late appearance of two rodents associated with irrigated rice fields, together with a surge in frog remains, indicates wet rice farming was only recently introduced to the area. These paleoenvironmental records act as a basis from which to understand the timing and intensity of human impacts on late Holocene environments in western Flores, and the relationship of this incursion to changing land use patterns. Copyright (c) 2011 INQUA 18