State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi, Xinjiang, 830011, People's Republic of China,
Environ Monit Assess. 2013 Dec;185(12):10027-38. doi: 10.1007/s10661-013-3310-4. Epub 2013 Jun 21.
The roots of Populus euphratica, a plant that grows in the lower reaches of the Tarim River, Northwest China, exhibit a significant level of hydraulic redistribution; however, quantitative assessments of the water-sharing process and its ecological effects are limited. This study was designed to obtain such data using an assessment model based on field observation parameters, including soil water content (soil water potential), root distribution, and stable isotope δ(18)O values of soil and plant samples during the entire growing season. The results showed that hydraulic redistribution in P. euphratica can be detected in 0-120 cm soil layers, with the amount of hydraulically redistributed water (HRW) in the soil found at different depths as follows: 60-80 > 40-60 > 20-40 > 0-20 > 80-100 > 100-120 cm. The variations in HRW in soil layers can be partly attributed to the vertical distribution of roots. The denser roots found at greater depths positively influenced the amount of redistributed water in lower soil layers. During the growing season, the amount of HRW reached a daily average of 0.27 mm, which allowed increased transpiration and provided an adequate water supply to herbs. Based on the stable isotope (δ(18)O) data, the amount of HRW provided by the roots of P. euphratica could meet 22-41% of its water demand.
胡杨的根系具有显著的水力再分配能力，其主要分布在 0—120cm 土层中，各土层水力再分配水量（HRW）大小依次为：60—80cm＞40—60cm＞20—40cm＞0—20cm＞80—100cm＞100—120cm。HRW 在土层中的变化部分归因于根系的垂直分布，较深土层中较密集的根系对较低土层中再分配水量的增加有积极影响。生长季内，HRW 的日平均值达到 0.27mm，增加了蒸腾作用，为草本植物提供了充足的水分供应。基于稳定同位素（δ(18)O）数据，胡杨根系提供的 HRW 量可以满足其 22%—41%的水分需求。
