Radial growth response of Populus xjrtyschensis to environmental factors and a century-long reconstruction of summer streamflow for the Tuoshigan River, northwestern China

Broad-leaved tree species have rarely been used in dendroclimatology and dendrohydrology in arid Central Asia. Core samples of Populus xjrtyschensis Ch. Y. Yang were collected along the Tuoshigan River in 2015. Correlation and response analyses indicate that the radial growth of P. xjrtyschensis shows a strong relationship to streamflow and a weak response to climate. We suggest that summer streamflow is a limiting factor for the radial growth of P. xjrtyschensis along the Tuoshigan River. Using tree-ring data from P. xjrtyschensis, we reconstructed the historical summer streamflow of the Tuoshigan River back to 1900. The reconstruction has an adjusted r2 of 0.407 (1957-2006). Statistical verification methods and historical documents indicate that the reconstructed series is stable and reliable. The results reveal that the beginning of the 20th century and the end of the 20th century to the present experienced above average streamflow, while the mid-20th century was characterized by a long dry period. The reconstructed streamflow data series revealed 6-yr (99%), 11-yr (95%) and 17-25-yr (99%) cycles. We suggest that variability in summer streamflow of the Tuoshigan River may be related to solar activity and large-scale oscillations in the climate system.