Long-term evolution of vegetation and climate variability on the central Tibetan Plateau inferred from the palynological record of lake sediments recovered by the ICDP Nam Core drilling project

Nam Co (4,718 m a.s.l.), located in the ecotone of meadows and steppe on the central Tibetan Plateau, is an ideal site for studying past vegetation and climate changes due to its thick lacustrine sediments and climate-sensitive geographic location. In 2024, we successfully conducted an ICDP drilling campaign that recovered high-quality sediment cores, reaching a maximum drilling depth of 510 m. Using the pollen record, we will investigate vegetation and climate variability in central Tibet over glacial-interglacial timescales, and elucidate the associated dynamic mechanisms. We present preliminary pollen results from core catcher samples. The pollen content of the vast majority of samples satisfies the statistical requirements, even in sand layers. The pollen assemblages are dominated by Cyperaceae, Artemisia, Amaranthaceae, Poaceae, Thalictrum, Ranunculaceae, Hippophae, Ephedra, with other tree pollen types including Pinus, Picea, Abies, etc. The composition of the major pollen types shows several distinct changes throughout the entire sequence, indicating significant variations in vegetation and climate. Furthermore, the Pediastrum concentration, arboreal pollen, and Cyperaceae percentages show a periodicity with depth. Future work will focus on pollen-based quantitative reconstructions of paleovegetation and paleoclimate, which are expected to provide more robust evidence for regional paleoenvironmental evolution.