Analysis on the Respond of the Tree-rings of Populus euphratica to the Change of Moisture Conditions in the Lower Reaches of the Tarim River

After the Daxihaizi Reservoir was built in 1972,the stream of the mainstream in the lower reaches of the Tarim River was cut off.In order to regenerate the vegetations along the watercourse of the lower reaches of the Tarim River,a project of urgently transfusing stream water to the lower reaches of the Tarim River has been started since 2000.Since then many scientists begin to investigate and analyze the ecological response including the physiological response and ecological response of the vegetations in the lower reaches of the Tarim River.In this paper,the tree-rings of Populus euphratica in the lower reaches of the Tarim River after implementing the project of urgently transfusing stream water are sampled and analyzed.The results reveal that the zone width of the physiological and ecological response of Populus euphratica along the Karday section,perpendicular to the watercourse of the Tarim River,was up to 1 000 m in the lower reaches of the Tarim River after implementing the third time of urgently transfusing stream water;the growth of Populus euphratica is reduced and the groundwater depth is increased with the increase of distance away from the watercourse of the Tarim River and the Daxihaizi Reservoir after urgently transfusing stream water;the growth of Populus euphratica is increased and the groundwater depth is decreased with the increase of transfused water volume and of the time;under the same transfused water volume and of the time,growth of Populus euphratica is higher in spring than that in summer.