Differential hydro-climatic evolution of East Javanese ecosystems over the past 22,000 years.

The Maritime Continent, home to widespread tropical rainforest and millions of people, is the primary region of deep atmospheric convection on the Earth. However, debate exists whether the isotopologues of water reflect rainfall amount during the Last Glacial Maximum (LGM), resulting in different interpretations of the LGM climate of the Maritime Continent. Here we present paired leaf wax δ13C and δD records together with pollen data from a sediment core retrieved off East Java dating back to 22,000 years before present. We use three n- alkane homologues (n- C 29 , n- C 31 and n- C 33) in order to reconstruct past changes in vegetation types and seasonal rainfall. Our results suggest that in East Java, evergreen rainforest remained the dominant vegetation type in montane regions since the seasonality there remained relatively unaltered over the entire period. In contrast, the East Javanese lowlands were characterised by C 4 grass expansion and an extended dry season but a wetter rainy season, thus stronger seasonality, during the LGM. • Canopy structure of the montane rainforest of East Java remained relatively closed during the Last Glacial Maximum (LGM). • East Javanese lowlands were more seasonal with a shorter but wetter rainy season during the LGM compared to the Holocene. • Multiple-homologue leaf wax isotopes reflect rainfall regimes of distinct ecosystems. [ABSTRACT FROM AUTHOR]