塔里木河下游生态输水后胡杨径向生长量的时空变化

Spatiotemporal variation of Populus euphratica's radial increment at lower reaches of Tarim River after ecological water transfer

以塔里木河下游胡杨为对象,基于树木年轮水文学的方法,分析了生态输水后胡杨枝条径向生长量的时空变化.结果表明:生态输水前后胡杨平均径向生长量差异极显著,输水后,胡杨径向生长量明显增加,增幅达125%;生态输水期间,随着输水量的增加,胡杨径向生长量逐渐增加,二者呈正相关关系(R2=0.394),可以将胡杨径向生长量作为输水效益的一个重要量化指标;生态输水后,离河道不同距离处的胡杨径向生长量差异极显著(P=0.007),且随着与河道距离的增加,胡杨径向生长量逐渐减小;不同河段的胡杨径向生长量差异显著(P=0.017),离水源地大西海子水库越近的河段,胡杨径向生长量变化越大.目前输水的影响范围有限,不足以从根本上遏止本区生态环境的持续恶化.

Taking the Populus euphratica at lower reaches of Tarim River as test object,and by the methods of tree dendrohydrology,this paper studied the spatiotemporal variation of P. euphratic＇s branch radial increment after ecological water transfer. There was a significant difference in the mean radial increment before and after ecological water transfer. The radial increment after the eco-water transfer was increased by 125%,compared with that before the water transfer. During the period of ecological water transfer,the radial increment was increased with increasing water transfer quantity,and there was a positive correlation between the annual radial increment and the total water transfer quantity （R2=0.394）,suggesting that the radial increment of P. euphratica could be taken as the performance indicator of ecological water transfer. After the ecological water transfer,the radial increment changed greatly with the distance to the River,i.e.,decreased significantly along with the increasing distance to the River （P=0.007）. The P. euphratic＇s branch radial increment also differed with stream segment （P=0.017）,i.e.,the closer to the head-water point （Daxihaizi Reservoir）,the greater the branch radial increment. It was considered that the limited effect of the current ecological water transfer could scarcely change the continually deteriorating situation of the lower reaches of Tarim River.