Divergent tree radial growth patterns of Qinghai spruce (Picea crassifolia) at the alpine timberline along a moisture gradient in the Qilian mountains, Northwest China

•Radial growth increased with temperature in the eastern Qilian mountains.•Radial growth remained unchanged in the western Qilian mountains.•Moisture regulates the responses of radial growth climatic warming in mountains.•Future warming could lead to complex growth trends in the wetter and drier areas.