Erratum to: Temporal and spatial variation of NPP and its response to climatic factors in main river valleys grasslands on the southern slope of Qilian Mountains. - Xu, Z.B.; Chen, D.Q.; Liu, J.Y.; Yang, Rong-rong; Cao, Guang-chao; Cao, Sheng-kui; Lan, Yao; Zhang, Zhuo; Chen, Zhi-rong; Chen, Zhen (E3S Web of Conferences, 2019)