Centre for Plants and the Environment, University of Western Sydney, Richmond, NSW 2753, Australia.
Tree Physiol. 2010 May;30(5):586-96. doi: 10.1093/treephys/tpq009. Epub 2010 Mar 23.
To identify environmental and biological drivers of nocturnal vapour exchange, we quantified intra-annual, intra- and inter-specific variation in nocturnal water transport among ecologically diverse Eucalyptus species. We measured sap flux (J(s)) and leaf physiology (leaf surface conductance (g(s)), transpiration (E) and water potential (Psi(l))) in three to five trees of eight species. Over 1 year, nocturnal J(s) (J(s,n)) contributed 5-7% of total J(s) in the eight species. The principal environmental driver of J(s,n) was the product of atmospheric vapour pressure deficit (D) and wind speed (U). Selected observations suggest that trees with higher proportions of young foliage may exhibit greater J(s,n) and nocturnal g(s) (g(s,n)). Compared with other tree taxa, nocturnal water use in Eucalyptus was relatively low and more variable within than between species, suggesting that (i) Eucalyptus as a group exerts strong nocturnal stomatal control over water loss and (ii) prediction of nocturnal flux in Eucalyptus may depend on simultaneous knowledge of intra-specific tree traits and nocturnal atmospheric conditions.
为了确定夜间水汽交换的环境和生物驱动因素，我们量化了生态多样的桉树物种之间和种内的夜间水分运输的年内、种内和种间变化。我们测量了 8 个树种的 3 到 5 棵树的 sap 通量 (J(s)) 和叶片生理特性（叶片表面导度 (g(s))、蒸腾 (E) 和水势 (Psi(l)))。在一年中，夜间 J(s)（J(s,n)）占 8 个物种中总 J(s)的 5-7%。J(s,n)的主要环境驱动因素是大气蒸气压亏缺 (D) 和风速 (U) 的乘积。一些观察结果表明，具有更高比例幼叶的树木可能表现出更大的 J(s,n) 和夜间 g(s)（g(s,n)）。与其他树木类群相比，桉树的夜间耗水量相对较低，且种内变化大于种间变化，这表明 (i) 桉树作为一个群体对水分损失具有强烈的夜间气孔控制，(ii) 预测桉树的夜间通量可能取决于对种内树木特性和夜间大气条件的同时了解。
