How can Populus euphratica cope with extremely dry growth conditions at 2,800 m a.s.l. on the northern Tibetan Plateau?

Euphrates poplar (Populus euphratica) is a key species of Tugai forests in the central Asian deserts and has been the topic of dendrochronological studies in west China since the 1980s. However, little is known about its growth performance at its highest occurrence in the southern Qaidam Basin of the northern Tibetan Plateau. Increment cores of the Euphrates poplar population there did well cross-date and thus showed a high dendrochronological potential. Its growth was persistently positively correlated with temperature from previous September to current August although not significant throughout. The annual precipitation of around 41 mm can not exert any significant effect on Euphrates poplar growth in view of the extremely high annual pan evaporation of 2,150 mm. Water in the nearby Tuolahai River is limited to the period from June–September. The positive correlation of tree growth with spring/early summer temperature indicates that the riparian Euphrates poplar trees may benefit from an increasing river runoff due to an advanced and accelerated snow and glacier melting under warmer conditions. An above-average autumn/early winter temperature in the preceding year may lead to an extended water flow in the river bed and hence to an increased tree growth in the next year. It is crucial to protect this invaluable natural forest from undue human activity.