Water‐use response to climate factors at whole tree and branch scale for a dominant desert species in central Asia: Haloxylon ammodendron
Water‐use response to climate factors at whole tree and branch scale for a dominant desert species in central Asia: Haloxylon ammodendron
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DOI：
10.1002/eco.1321
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发表时间：
2014-02
期刊：
影响因子：
2.6
通讯作者：
Chaolei Zheng;Quan Wang
中科院分区：
文献类型：
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作者：
Chaolei Zheng;Quan Wang
利用树干液流技术对生长在古尔班通古特沙漠南缘的优势荒漠树种梭梭的水分利用进行了研究。全树尺度的日液流与大气蒸发量呈良好的相关性（P < 0·001），而分支尺度的日液流与蒸腾速率呈良好的相关性（P < 0·01）。在两个尺度下，每小时的液流滞后被观察到作为微气象变量的函数，其中液流和蒸汽压赤字之间的滞后是顺时针旋转的，这表明H.梭梭不仅与气孔行为有关，还与植物对储存水分的利用有关。降水后树干液流与光合光子通量密度之间的滞后关系为逆时针方向，而在干旱条件下则为顺时针方向，且在整株尺度上更为明显。分支和整株树干液流对气候因子的响应不同，这强烈地表明H.梭梭具有一定的机制，在高蒸腾需求下减少整株树的水分利用，而在相对高的水分利用下维持部分冠层，这导致冠层尺度的斑块。版权所有© 2012约翰威利父子有限公司.
Water use of a dominant desert species, Haloxylon ammodendron, growing in the southern edge of Gurbantünggüt Desert in northwest China, was measured using sap flow technologies at both tree and branch scales. Daily sap flow at whole‐tree scale showed a good relationship with atmospheric evaporation demand (P < 0·001), whereas daily sap flow at branch scale showed good relationships with the variable of transpiration rate (P < 0·01). Hysteresis in hourly sap flow at both scales was observed as a function of micro‐meteorological variables, in which the hysteresis between sap flow and vapour pressure deficit was clockwise rotation, suggesting that the water use of H. ammodendron was related to not just the stomatal behaviour but also use of stored plant water. The hysteresis between sap flow and photosynthetic photon flux density was counter‐clockwise after precipitation, but turned to be clockwise under dry conditions, which was ever clearer at whole‐tree scale. Different responses of sap flows at branch and whole‐tree scale to climate factors were identified, which strongly indicated that H. ammodendron had some mechanisms to reduce whole‐tree water use at high transpiration demand, while maintaining part of canopy under relatively high water use, which resulted in canopy scale patchiness. Copyright © 2012 John Wiley & Sons, Ltd.