Contrasting strategies of hydraulic control in two codominant temperate tree species
Contrasting strategies of hydraulic control in two codominant temperate tree species
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DOI：
10.1002/eco.1815
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发表时间：
2017-04
期刊：
影响因子：
2.6
通讯作者：
A. Matheny;R. Fiorella;G. Bohrer;C. Poulsen;T. Morin;A. Wunderlich;C. Vogel;P. Curtis
中科院分区：
文献类型：
--
作者：
A. Matheny;R. Fiorella;G. Bohrer;C. Poulsen;T. Morin;A. Wunderlich;C. Vogel;P. Curtis
对植物水分状况的生物物理控制存在于叶、茎和根水平。因此，我们认为水力策略是这三个层面上控制用水的特征的组合。我们研究了红橡树 (Quercus rubra) 和红枫树 (Acer rubrum) 的树液通量、茎储水、气孔导度、光合作用和生长。这些物种的气孔水力策略和木质部结构不同，并且可能在不同的深度扎根。木质部水的稳定同位素分析用于确定根部吸水深度。研究表明，橡树比枫树能获得更深的水源。在非限制性土壤湿度条件下，枫树的蒸腾作用大于橡树。然而，在土壤干燥期间，枫树的蒸腾作用和茎储水量分别减少了 80% 和 28% 以上，而橡树仅减少了 31% 和 1%。我们建议红橡树优先使用深水，使该物种能够在土壤水限制期间继续蒸腾和生长。在这种情况下，更深的根可能可以缓冲干旱引起的死亡。使用 14 年的生长数据，我们发现枫树生长与 30 厘米处的年平均土壤湿度相关，但橡树生长则不然。观察到的橡树和枫树对干旱的反应不能仅用叶子和木质部生理学来解释。我们采用有限差分生态系统规模树冠流体动力学模型版本 2 植物流体动力学模型来演示根、茎和叶控制对树级蒸腾的影响。我们的结论是，定义水力策略需要所有三个级别的水力特征。
Biophysical controls on plant water status exist at the leaf, stem, and root levels. Therefore, we pose that hydraulic strategy is a combination of traits governing water use at each of these three levels. We studied sap flux, stem water storage, stomatal conductance, photosynthesis, and growth of red oaks (Quercus rubra) and red maples (Acer rubrum). These species differ in stomatal hydraulic strategy and xylem architecture and may root at different depths. Stable isotope analysis of xylem water was used to identify root water uptake depth. Oaks were shown to access a deeper water source than maples. During non‐limiting soil moisture conditions, transpiration was greater in maples than in oaks. However, during a soil dry down, transpiration and stem water storage decreased by more than 80% and 28% in maples but only by 31% and 1% in oaks. We suggest that the preferential use of deep water by red oaks allows the species to continue transpiration and growth during soil water limitations. In this case, deeper roots may provide a buffer against drought‐induced mortality. Using 14 years of growth data, we show that maple growth correlates with mean annual soil moisture at 30 cm but oak growth does not. The observed responses of oak and maple to drought were not able to be explained by leaf and xylem physiology alone. We employed the Finite‐difference Ecosystem‐scale Tree Crown Hydrodynamics model version 2 plant hydrodynamics model to demonstrate the influence of root, stem, and leaf controls on tree‐level transpiration. We conclude that all three levels of hydraulic traits are required to define hydraulic strategy.