Vegetation and climate evolution during the Last Glaciation at Tengchong in Yunnan Province, Southwest China

Abstract

To better understand changes in vegetation and climate during the Last Glaciation in Southwest (SW) China, we studied microfossil assemblages in a peat/lake-sediment core collected in Tengchong Basin that spans the interval 66.6–11.8 ka (1 ka = 1000 cal yr BP), approximately equivalent to marine isotope stages (MIS) 4 to 2. The results show that patterns of climate change in Tengchong during the Last Glaciation were different from those in eastern China, and suggest that, compared with modern climates, SW China was cool and semi-humid during MIS 4, cold and semi-humid in the early and middle stages of MIS 3, and cool and humid in the late stage of MIS 3. During the Last Glacial Maximum (LGM), it was cool and dry, whereas after the LGM the climate remained dry but became warmer. Down-core changes in Abies and Picea pollen amongst the woody plants broadly match records of geochemical indices in parallel peat/lake-sediment cores and stalagmite oxygen isotope records from monsoonal Asia. Heinrich events 1–5 and volcanic eruption events are recognized in the Abies + Picea curve. As inferred from the microfossil assemblages in the Tengchong cores, the coldest interval in SW China during the Last Glaciation might not have been the LGM.