LAUSR

In this study, tree-ring width data of Schrenk spruce (Picea schrenkiana) from the upper timberline of the Tien Shan (Kyrgyzstan) were analyzed to investigate the effect of climate change. Growth–climate response analyses revealed that the tree rings of spruce at the upper timberline of the Tien Shan also can provide hydrometeorological (precipitation and streamflow) signals. Tree-ring records from both Kyrgyzstan and Xinjiang exhibited similar tree-growth variability at both annual and decadal time scales during the common period 1457–2009. In Xinjiang and Kyrgyzstan, tree growth was reduced during the Little Ice Age (LIA); however, the timing and magnitude of LIA differ between the two regions. During 1470–1660, the two chronologies diverged, and this phenomenon is considered to be caused by a different response to the harsh climate of the LIA. In this study, the tree-ring width series from the upper tree line of the Tien Shan is negatively associated with temperature. As opposed to previous studies, the tree-ring width series from the upper timberline of the Tien Shan appears to respond well to hydrometeorological factors. Therefore, we highlight the need for more detailed ecophysiological response studies for spruce trees at the upper timberline of the Tien Shan, in particular, with regard to the role of water availability and temperature during the growth season.