Tree-ring delta O-18 inferred spring drought variability over the past 200 years in the Hengduan Mountains, Southwest China

摘要

In this study, we developed a tree-ring delta O-18 chronology of Abies delavayi from Diancangshan (25 degrees 41'N, 100 degrees 06'E), in the Hengduan Mountains of Southwest China, spanning 205 years (1810-2014 CE). Tree-ring delta O-18 from Abies delavayi showed the highest negative correlation with relative humidity in the spring (r = -0.59, P < 0.05). Therefore, we used our delta O-18 chronology to reconstruct spring relative humidity during the period 1810-2014, which accounted for 35.1% of the variance of actual relative humidity for the calibration period 1979-2014. The reconstruction revealed two significantly dry periods during 1815-1835 and 1923-1940 CE, and a continuous shift towards drier conditions during the past 30 years. The long-term variability of spring relative humidity was consistent with previous results from Northwest Yunnan and regions nearby. We further suggest that the spring relative humidity variability in our study region might be linked to the El Nino-Southern Oscillation (ENSO), which is stimulated by the variation of sea surface temperatures in the central and east Pacific Ocean.