Tree-ring recorded hydroclimatic change in Tienshan mountains during the past 500 years

In Central Asia, tree rings provide one of the best sources of paleoclimatological information. However, dendroclimatology has not been widely applied in the coniferous forests of Central Asia. Tree cores of Picea Schrenkiana from four sites in the Hutubi River Basin were developed into a 606-year tree-ring width chronology. The analyses showed that the tree-ring width indices highly correlate with mean April–May PDSI in the Hutubi River Basin. Mean April–May PDSI of the Hutubi River was reconstructed using the tree-ring data with 41.5% of the variance explained. The reconstructed series contains both high- and low-frequency climate signals. Our new PDSI reconstruction agrees reasonably well with the dry and wet periods previously estimated from tree rings in western Tien Shan. The results reveal common climatic extremes over much of Central Asia. Spatial analysis shows that the PDSI reconstructions have strong common signals for the Tien Shan. The first principal component of PDSI reconstructions in Tien Shan is significantly correlated with sea surface temperature in the eastern equatorial Pacific Ocean and Atlantic Ocean. The linkages to the Atlantic and Pacific Oceans suggest the connection of regional moisture variations to the Asian monsoon and the Westerlies.