Vegetation-hydrology coupling in subtropical China during the Younger Dryas: A quantitative reconstruction from high-resolution pollen records at Luoxiao Mountains

The Younger Dryas (YD; 12.9–11.7 cal. ka BP) represents one of the most abrupt and intense climatic disruptions during the last deglaciation. It is a vital benchmark for investigating ice sheet dynamics and Earth system responses to rapid climate shifts. In this study, we present a quantitative reconstruction of YD climate, floristic richness, and rates of vegetation change based on high-resolution pollen data from the Zhaogongting (ZGT) peat in southern China during the entire study period (13.1–8.6 cal. ka BP). Prior to the YD event, MAP was approximately 1595.8 mm. During the YD, reconstructed MAP values were lower (1375.4–1671.4 mm; mean: 1562.3 mm). MAP increased substantially in the early Holocene, peaking at ∼1771.3 mm around 10.0–9.6 cal. ka BP, while seasonal precipitation patterns diverged. Mean Summer Precipitation (MSP) decreased during the YD but became more variable afterward, whereas Mean Winter Precipitation (MWP) and Mean Annual Relative Humidity (MAH) remained comparatively elevated throughout the YD. The pollen data suggest a tightly coupled vegetation-hydrology response during the YD. The early YD (12.9–12.3 cal. ka BP) was marked by progressively reduced MAP and MSP, concurrent with declines in the rate of vegetation change and plant diversity. In the late YD (12.3–11.7 cal. ka BP), increasing MAP and MAH coincided with accelerated vegetation turnover and greater diversity. These shifts are interpreted as a regional response to weakened Atlantic Meridional Overturning Circulation, which triggered divergent seasonal precipitation anomalies over subtropical China via an eastward-propagating atmospheric wave linked to North Atlantic forcing.