A preliminary seasonal precipitation reconstruction from tree-ring stable carbon isotopes at Mt. Helan, China, since AD 1804

摘要

The relationship between the stable carbon isotope composition of tree rings from Mt. Helan, China, and precipitation was investigated for the period AD 1804-1997. The results reveal that in the Mt. Helan region, δ~(13)C of tree rings negatively correlates with the total precipitation from February to July. We calculated discrimination (Δ) to remove the effects of δ~(13)C of atmospheric CO_2 on the tree-ring δ~(13)C series, and reconstructed February to July precipitation back to 1804 using linear regression (R~2 = 0.415, R_(adj)~2= 0.394, F= 19.88, P<0.0001), with best chronology replication for AD 1845-1991. The reconstruction shows annual to decadal wetness/dryness fluctuations. The historically documented drought of 1926-1930, and the wet period in the 1940s were found in our reconstruction.