The tree ring is an important carrier of the evolution of climate in the study of global change.It enjoys advantages of accurate dating,strong continuity,high resolution ratio and high reconstruction precision.This paper tested the changes of Populus euphratica tree ring and the runoff in the upper and middle reaches of the Tarim River through the monotonic trend and analyzed the response of the tree ring in the lower reaches of the Tarim River to the water supply through the combined tree ring data and the historical literature,so as to confirm the accuracy of the response of Populus euphratica tree ring to river diversion.The results were included as follows.(1)From 1957 to 2010,the radial growth of Populus euphratica in the upper and middle reaches of the Tarim River decreased gradually in the time series,which was the same as the runoff.The downtrend was significant,and|Zc|was more than 0.96.(2)From1913 to 2000,the radial growth of Populus euphratica as a whole in the lower reaches of the Tarim River decreased.The downtrend was significant between 1973 and 2001,reaching the lowest level in the past 100years.The formation and diversion of the Layi River was as described in the historical literature.(3)The development of the ecological water delivery project has improved the ecological environment of the lower reaches,which has been verified from the Populus euphratica tree ring in the lower reaches.However,despite the ecological water delivery project in recent years,the growth of Populus euphratica tree ring has not reached to the level before 1920,indicating that the existing ecological water delivery is of limited value in recovering desert riparian forest.(4)In the analysis of the response of the Populus euphratica to the water resources,the wavelet analysis method and the historical literature review method have drawn the same conclusion.
