Preliminary dendrochronological studies on Populus euphratica in the lower reaches of the Heihe River basin in northwest China

To date, preliminary dendrochronological studies of Euphrates poplar trees have not been reported, even though some dendrohydrological studies have been performed. Based on 11 sites in the Ejin Oasis, located in the lower reaches of the Heihe River basin in northwest China, our studies of Euphrates poplar trees concentrates on the characteristics of the tree-ring structure and the stem radial growth, which is the foundation of accurate crossdating and detrending. The results indicate that the Euphrates poplar trees studied have identifiable ring boundaries; the narrow rings and the same ring width variation pattern make the crossdating achievable. The local habitat, the stem radial growth trend of the poplar trees and the completeness of cores should be valued when selecting a detrending method. The complex ring width variation pattern of the poplar trees in the area suggest that comprehensive sampling and preliminary dendrochronological studies are required to gain insights into the spatiotemporal growth patterns of the poplar trees and their relationship with the changing water environment.