Temperature signals complicate tree-ring precipitation reconstructions on the northeastern Tibetan Plateau

Abstract

Tree-ring width chronologies are a critically important material to reconstruct past precipitation variability on the northeastern Tibetan Plateau (NTP). However, temperature signals are often encoded in these chronologies, which complicate the precipitation reconstructions and should be carefully assessed. Here, a dataset of 487 Qilian juniper (Juniperus przewalskii Kom.) tree-ring width series from 16 sites on the NTP were collected to investigate the influence of different temperature signals on the precipitation reconstructions. Correlation analysis showed that all tree-ring series recorded similar precipitation information, but had positive (p ≤ 0.05, Group1), weak (p > 0.05, Group2), and negative (p ≤ 0.05, Group3) correlations with temperature, respectively. In view of this, all tree-ring series were divided into three groups to develop chronologies to reconstruct local precipitation. During the calibration period of 1957–2011 CE, the Group1 reconstruction had the fastest uptrend, which almost overlapped the observed precipitation; the Group2 reconstruction showed a slower uptrend, whereas the Group3 reconstruction lacked an uptrend. As a result, we get different results when the reconstructions were used to assess the current precipitation status over the past millennium. The Group1 (Group2) reconstructions showed that the recent 20 (10) years were the highest precipitation period over the past millennium, whereas the Group3 reconstruction did not capture this phenomenon. Therefore, we caution that the temperature effects should be evaluated carefully before tree-ring width chronologies being employed to study past precipitation variability.