A palynological and palaeoclimatological record from the southern Philippines since the Last Glacial Maximum

A palynological analysis of a marine sediment core in the southern Philippines, provides a detailed regional vegetation and climate history for the West Pacific Warm Pool (WPWP) since the Last Glacial Maximum (LGM). Chronology was determined by a detailed oxygen isotope record. A higher representation of pollen from tropical upper montane rainforest during the LGM indicate that this forest type moved down along elevation, probabaly due to the lowered temperature. During the last deglaciation and the early Holocene, mangroves were more expanded and tropical mid and upper montane rainforests were restricted, suggesting a rising sea-level and temperature increase. Herbaceous pollen and pteridophyte spore records indicate a much drier condition during the LGM than the Holocene. Mangrove development is controlled by conditions at the river mouth influenced by river discharge. Pteridophyte spores are abundant in wet conditions and are mainly transported by rivers. During the mid-Holocene, the reduction in mangrove pollen and pteridophyte spore appears to be a result of climate change: mainly decrease in river discharge. This may have been affected by the decreasing intensity of the Southeast Asian Monsoon, and the increasing frequency and intensity of warm ENSO events, El Niño, in this region.