塔里木河下游阿拉干断面胡杨枝下高对应急输水的响应

Under crown height of Populus Euphratica along the Arghan section in the lower reaches of Tarim River in response to the emergency water transportation

根据近5a来对塔里木河下游阿拉干断面胡杨林(Populus euphratica Oliv.)的监测数据和不同离河距离的地下水位监测信息,结合"面"上宏观调查与"点"上典型研究,集中对100hm2长期监测样方内的4499棵胡杨树进行了详细的调查,将胡杨个体实测数据和卫星影像信息进行对比,分析了塔里木河下游胡杨枝下高对应急生态输水的响应。结果显示,塔里木河下游的胡杨具有伴河生长的特性,不同等级枝下高的胡杨都主要分布在距离河道200m的范围,且其分布都与离河道距离呈显著负相关关系;应急输水后,不同离河距离的胡杨枝下高都有不同程度的下降,河道附近100m的范围内下降幅度最大,达到了0.36m,枝下高的下降主要是由于胡杨茎部和基部萌生新枝所引起的,说明应急输水对于胡杨的自然更新产生了积极的影响。

The Tarim River is about 1 320 km long and thus one of the longest continental inland waterways worldwide. In an undisturbed state, it is accompanied on both sides by floodplain forests of Euphrat poplars （Populus euphratica Oliv.）. The rising water consumption in the upper and middle reaches and, in the past decades, massive hydrotechnical interventions during the development of uncultivated land use （cotton growing）, led to the widespread destruction of the natural ecosystems, particularly in the lower reaches of the river where on 320 km the floodplain forests are either highly degraded or dead. Since 2000 the Chinese government has made efforts to restore these ecosystems and conducted ecological water transportation. According to the monitoring data of Populus euphratica and groundwater levels along the Arghan section in the lower reaches of Tarim River, comparison and analysis of the data was made seeking to determine the response of the under crown height of P. euphratica to emergent water transportation. This was combined with the method of macro observation at the ＂surface＂ level and classical research at ＂spot＂ level. The study sample included a total of 4 499 individual trees of P. euphratica in an area of 100 hectares. The study results showed the following： Populus euphratica in the lower reaches, which always grow along the river, mainly distribute within 200 m from the river. There is an obvious negative correlation between the distribution of Populus euphratica of different under crown heights and the distance from the river. Under crown height of Populus euphratica declines variously with the different distance from the river after water transport, the maximum reached 0.36 m within 100 m from the river bank. The decrease is mainly caused by new sprouting branches from stem and base. It is concluded that emergent water transportation played an important role in regeneration of Populus euphratica.