Forest contraction in north equatorial Southeast Asia (Malaysia, Sarawak, Palawan, Borneo and the Philippines) during the Last Glacial Period from stable carbon isotope data

Brief description

Using stable carbon isotope compositions of ancient cave guano profiles, we show that there was a substantial forest contraction during the Last Glacial Period on both peninsular Malaysia and Palawan, while rainforest was maintained in northern Borneo.

Full description

Insular Southeast Asia is rich in Karst terranes that house large populations of insectivorous bats and swiftlets. Although some cave sites are roosts to relatively large populations of fruit bats, we limited our selection to those with insectivorous colonies. Extraction of insect cuticles from the guano sediment, pH, and C:N ratios confirmed that insectivorous populations remained dominant throughout each record. We located four sites with LGM sediment deposition within ~10° north of the equator. Along a transect from west to east are deposits in Batu cave (3°13'N, 101°42'E) near Kuala Lumpur in peninsular Malaysia; Niah cave (3°49'N, 113°46'E) in Sarawak, northern Borneo, and two sites in Palawan, Philippines, Gangub cave (8°31'N, 117°33'E) in the south and Makangit cave (10°28'N, 119°27'E) in the north. Age control is provided by radiocarbon dates on insect cuticles (1)taken from discrete intervals through each guano sequence, one charcoal sample from the Batu deposit, and three solvent-extracted bulk guano samples. Radiocarbon dates were calibrated to calendar years using the IntCal09 calibration curve (2) implemented using OXCAL 4.1 (3) (Tables 1, 2). References: (1) Wurster CM, Bird MI, Bull ID, Bryant C, Ascough P (2009) A protocol for radiocarbon dating tropical subfossil cave guano. Radiocarbon 51:977–986. (2) Reimer PJ, et al. (2009) IntCal09 and Marine09 radiocarbon age calibration curves 0–50,000 years cal BP. Radiocarbon 51:1111–1150. (3) Ramsey CB (2009) Bayesian analysis of radiocarbon dates. Radiocarbon 51:337–360.

Notes

Dataset consists of 2 tables in open document format and csv.

Coinvestigators: Charlotte Bryant. Natural Environment Research Council, Radiocarbon Laboratory, East Kilbride G75 OQF, United Kingdom. Jennifer A. J. Dungait. Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom. Victor Paz. Archaeological Studies Program, University of the Philippines, Diliman, Quezon City 1101, Philippines. Related JCU Research Themes: Tropical Ecosystems, Conservation and Climate Change Peoples and Societies in the Tropics