MID- TO LATE-HOLOCENE ENVIRONMENTAL CHANGES OF THE TONLE SAP LAKE SYSTEM, CAMBODIA

Abstract

The Tonle Sap Lake, Cambodia is one of the most productive flood-pulse systems in the world and it is under significant threat. To estimate possible consequences of future environmental changes it is crucial to understand the system’s responses to past perturbations. This thesis reconstructs the Tonle Sap Lake system’s environmental history during the mid- and late-Holocene (6.800-600 cal yr BP) by analyzing different paleoecological proxies. Three periods of the system are identified: i) a transition from a calm lacustrine depositional environment to a shallower lake with higher productivity caused by a weakening of the Indian Summer Monsoon (6800-6000 cal yr BP), ii) a following period of high variability in the detrital input due to changes in the system’s basin; iii) the initiation of the present-day flood-pulse system as a consequence of severe dry conditions (4250-3900 cal yr BP). A shift to La Niña-like conditions around 2800 1700 cal yr BP is also identified.