| 摘 要： |
Precipitation decline in northern China since the mid-Holocene was probably driven by suppression of convective precipitation due to vegetation changes rather than by weakening of the East Asian summer monsoon, according to transient numerical experiments. Proxy-based reconstructed precipitation in northern China shows a peak in the mid-Holocene (7800-5300 years BP) followed by a declining trend until the present day. Most studies attributed this decline to the decrease in Northern Hemisphere summer insolation and weakening of the East Asian summer monsoon. However, the details of the drying mechanisms still remain elusive. Here we explore the drivers of this drying trend in northern China using two transient experiments, one that includes dynamic vegetation and one that does not. The experiment with dynamic vegetation successfully captured the slight increase in precipitation in the early mid-Holocene as well as the rapid decline of precipitation in the late mid-Holocene, whereas the experiment without dynamic vegetation predicted no change in precipitation. Specifically, in the dynamic-vegetation experiment, vegetation cover increased over time, which led to higher evapotranspiration and sensible heat and thus a reduction in convective precipitation from about 7800 years BP onwards. We suggest that the dynamics of vegetation played a key role in modulating the long-term trend of precipitation during the Holocene. |
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