Expansion of C4 plants in the tropical Leizhou Peninsula during the Last Glacial Maximum: Modulating effect of regional sea-level change.

Due to the lack of relatively long-term, high-resolution terrestrial records in tropical southern China, there is limited published research on terrestrial vegetation changes and their responses to regional and/or global climate forcings since the last glacial period. In this study, a 170-cm-long peat core (covering the interval from 44.1 to 9.3 cal kyr BP) recovered from the Xialu peatland in Leizhou Peninsula, South China, was analyzed for organic carbon isotope (δC), along with total organic carbon, total nitrogen, and bulk dry density, to investigate past vegetation and hydroclimatic changes. Our results showed that C4 plants dominated the study region during Marine Isotope Stage (MIS) 2 (29-14 cal kyr BP), indicating generally cooler and drier conditions during MIS 2 relative to late MIS 3 ( 44.1-29 cal kyr BP) and early MIS 1 (14-9.3 cal kyr BP). In particular, the driest conditions occurred during the Last Glacial Maximum (~ 25-19 cal kyr BP) when sea level was at its lowest. In addition, several millennial-scale climatic events associated with the expansion of C4 plants were clearly identified. Our record is sensitive to a variety of glacial-interglacial forcings, including regional processes and global forcing, among which the inundation history of Beibu Gulf due to sea-level change during the late Quaternary, which has been neglected in previous studies, may have played an important role in modulating paleo-hydroclimatic changes in tropical southern China.