[H-QR04] Deep time perspective on the geological response to climate change

[HQR04-P09] Late Pleistocene vegetation dynamics and lagoon evolution in southeastern Taiwan

*LiangChi Wang¹, Neng-Ti Yu², Jiun-Yee Yen³, Jia-Hong Chen³ (1.National Chung Cheng University, Taiwan, 2.National Tsing Hua University, Taiwan, 3.National Dong Hwa University, Taiwan)

Keywords:Pollen, sea level, climate change, vegetation history

The coastal region is highly susceptible to the impacts of climate change. Insights from paleoenvironmental records obtained from lagoon sediments can significantly enhance our understanding and management strategies for these areas amidst contemporary global warming. While several lagoons are located along the western coast of Taiwan, comprehensive data detailing their developmental processes and historical environmental shifts still need to be made available. In this research, we report on the analyses of sediment cores extracted from Dapeng Bay, the largest lagoon in Taiwan. Our examination focused on radiocarbon dating, pollen analysis, grain size, and organic content within the 250-meter core samples. These records have revealed the existence of four distinct environmental phases: a backshore wetland (38-15 ka), a foreshore wetland (15-11 ka), a foreshore mangrove forest (11-5 ka), and freshwater wetlands (from 5 ka to the present). Eustatic sea-level fluctuations and climatic variations predominantly drive the sequential paleoenvironmental transitions outlined above. Notably, the transformation from a backshore wetland into a foreshore mangrove forest is linked to the onset of sea-level rise following the last deglaciation, culminating with the peak sea levels observed during the Holocene Thermal Maximum. A marked increase in cultivated pollen since 4 ka indicates the advent of local agricultural practices, offering insights into human influence on the lagoon ecosystem. These findings facilitate an assessment of human impacts on Dapeng Bay and enable us to project the short- to medium-term effects of current climate change trends on this sensitive coastal area.