Growth and water use of Populus euphratica trees and stands with different water supply along the Tarim River, NW China
Growth and water use of Populus euphratica trees and stands with different water supply along the Tarim River, NW China
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DOI：
10.1016/j.foreco.2016.08.049
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发表时间：
2016-11-15
影响因子：
3.7
通讯作者：
Thomas, Frank M.
中科院分区：
文献类型：
--
作者：
Lang, Petra;Ahlborn, Julian;Thomas, Frank M.
地下植物树种胡杨 (Populus euphratica Oliv)。 （幼发拉底杨）在极度干旱的塔克拉玛干沙漠（中国西北部新疆省）北部和东部边缘的塔里木河沿岸形成河岸（tugai）森林。由于农业灌溉过度抽取水，这些森林受到地下水位下降的威胁。我们在塔里木河中游（英巴扎尔）和下游（阿尔干河）各三个样地，调查了不同供水量造成的长期影响。距地下水不同距离（2 至 12 m）或从水库补充水源，自 2000 年起将水输送至塔里木河下游，以保护和恢复杨树林。我们对 1946-2011 年期间的树木年轮进行了分析，并使用 Granier 方法量化了树木 (E-tree) 和林分水平 (E-stand) 的用水量。在过去四十年的调查中，供水量最大的地块的平均树木年轮宽度和断面积增量 (BAI)、累计 E-tree (5-8 月) 和 E-stand 显着高于距地下水距离最远的地块。然而，木质部液流密度的最大值和植被期平均的 E-tree 值在样地之间和地点之间没有显着差异。这些蒸腾值和即使在距地下水很远的地方也相对较大的 BAI 表明，与之前的研究相比，幼发拉底杨即使在地下水深度达 12 m 的情况下也能旺盛生长。额外供水导致 BAI 显着增加。供水量较低时的 E 值较低可以用稀疏的林分密度来解释。供水量的年际波动导致生长在距地下水位较近的树木或需要额外供水的树木的 BAI 发生明显变化。在该地区可用水资源有限的背景下，我们建议将额外的水集中输送到距离地下水较近的林分，以保持这些森林的充分功能并保持其再生能力。 (C) 2016 Elsevier B.V. 保留所有权利。
The phreatophytic tree species Populus euphratica Oliv. (Euphrates poplar) forms riparian (tugai) forests along the Tarim River at the northern and eastern fringe of the hyper-arid Taklamakan Desert (Xinjiang province, NW China). These forests are threatened by decreasing groundwater levels due to excessive withdrawal of water for agricultural irrigation. At three plots each at the middle (Yingbazar) and the lower reaches (Arghan) of the Tarim River, we investigated the long-term effects of different water supply due to. different distances to the groundwater (from 2 to 12 m) or to additional supply with water from reservoirs, which is being conveyed to the Tarim River's lower reaches since 2000 to conserve and restore the poplar forests. We conducted tree-ring analyses for the time period 1946-2011 and quantified the water use at the tree (E-tree) and the stand level (E-stand) using the Granier method.For the last four decades of investigation, the average tree-ring width and basal area increment (BAI), the cumulative E-tree (May-August) and E-stand were significantly higher on the plots with the largest water supply than on the plots with the largest distance to the groundwater. However, the maximum values of xylem sap flow density and E-tree values averaged for the vegetation period did not differ significantly among plots and between sites. These transpiration values and the relatively large BAI even at a large distance to the groundwater indicate that in contrast to previous studies Euphrates poplars can grow vigorously even at a groundwater depth of up to 12 m. Supply with additional water resulted in a marked increase in BAI. Lower E-stand at lower water supply can be explained with a sparser stand density. Interannual fluctuations in the water supply resulted in distinct alterations in BAI in trees that grow at a short distance to the water table or are supplied with additional water. Against the background of limited water availability in the region, we recommend concentrating the conveyance of additional water to forest stands with a short distance to groundwater to keep those forests fully functional and to maintain their ability to regenerate. (C) 2016 Elsevier B.V. All rights reserved.