Climatic implications of a 3585-year tree-ring width chronology from the northeastern Qinghai-Tibetan Plateau

In this study we develop a tree-ring width chronology of Qilian juniper (Sabina przewalskii Kom.) in the northeastern Qaidam Basin (northeastern Qinghai-Tibetan Plateau), China, which extends from 1580 BC to AD 2005 lasting 3585 years. This is by far the longest ring-width chronology in China. It is composed of archaeological wood samples from 13 sites, samples of living trees growing at a site with relatively good moisture condition and other long living trees from multiple sites approximately 100 m below the local upper treeline. Our results suggest that the archaeological wood and long living tree-ring width series belong to the same statistical population, which allows the construction of a single, regional composite chronology. We find that ring-width variations of the archaeological wood have statistical characteristics that are more similar to those trees from the lower part of the forest belt, where the moisture regime during the months at the onset of the growing season is the primary control on tree growth. Only after these analyses it becomes certain that the ring-width variations of the archaeological wood represent the variation of moisture conditions in the past. Therefore, the entire composite chronology is moisture-sensitive and suitable for reconstruction of the drought history and the related climate forcing over the past three millennia in the study region. The composite chronology shows considerable variations at inter-decadal to centennial timescales, with ten major multi-decadal low-growth periods corresponding to severe drought events in the past 2850 years, especially for two prominent events centered on AD 1480s and AD 1710s. On the other hand, significant high-growth periods were found centered on AD 590s and AD 1570s, and also in the past 30 years. (C) 2010 Elsevier Ltd. All rights reserved