Department of Biology, Franklin and Marshall College, PO Box 3003, Lancaster, PA, 17603, USA.
Plant Cell Environ. 2014 Jan;37(1):261-72. doi: 10.1111/pce.12151. Epub 2013 Jul 14.
The ecophysiology of tropical montane cloud forest (TMCF) trees is influenced by crown-level microclimate factors including regular mist/fog water inputs, and large variations in evaporative demand, which in turn can significantly impact water balance. We investigated the effect of such microclimatic factors on canopy ecophysiology and branch-level water balance in the dry season of a seasonal TMCF in Veracruz, Mexico, by quantifying both water inputs (via foliar uptake, FU) and outputs (day- and night-time transpiration, NT). Measurements of sap flow, stomatal conductance, leaf water potential and pressure-volume relations were obtained in Quercus lanceifolia, a canopy-dominant tree species. Our results indicate that FU occurred 34% of the time and led to the recovery of 9% (24 ± 9.1 L) of all the dry-season water transpired from individual branches. Capacity for FU was independently verified for seven additional common tree species. NT accounted for approximately 17% (46 L) of dry-season water loss. There was a strong correlation between FU and the duration of leaf wetness events (fog and/or rain), as well as between NT and the night-time vapour pressure deficit. Our results show the clear importance of fog and NT for the canopy water relations of Q. lanceifolia.
热带山地云雾林（TMCF）树木的生态生理学受到树冠层微气候因素的影响，包括定期的雾/雾水输入和蒸发需求的巨大变化，这反过来又会显著影响水分平衡。我们通过量化水分输入（通过叶片吸收，FU）和输出（白天和夜间蒸腾，NT），研究了这些微气候因素对季节性 TMCF 树冠生态生理学和树枝水平水分平衡的影响，该 TMCF 位于墨西哥韦拉克鲁斯州。我们在树冠优势树种 Quercus lanceifolia 中获得了 sap 流、气孔导度、叶片水势和压力-体积关系的测量结果。我们的结果表明，FU 发生的时间占 34%，导致从单个树枝蒸腾的整个旱季水分中有 9%（24 ± 9.1 L）得到了恢复。对另外七种常见树种的 FU 能力进行了独立验证。NT 占旱季水分损失的约 17%（46 L）。FU 与叶片湿润时间（雾和/或雨）之间以及 NT 与夜间蒸气压亏缺之间存在很强的相关性。我们的研究结果表明，雾和 NT 对 Q. lanceifolia 的树冠水分关系具有明显的重要性。
