Interannual consistency in canopy stomatal conductance control of leaf water potential across seven tree species
Interannual consistency in canopy stomatal conductance control of leaf water potential across seven tree species
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DOI：
10.1093/treephys/27.1.11
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发表时间：
2007-01-01
期刊：
影响因子：
4
通讯作者：
Samanta, S.
中科院分区：
文献类型：
--
作者：
Ewers, B. E.;Mackay, D. S.;Samanta, S.
研究了北方威斯康星州7个树种单位地面面积（E-C）和单位叶面积（E-L）冠层蒸腾量的年际变化。这些物种以前已被证明是足够的高档站水平蒸腾景观水平在一个生长季节。我们的目标是测试是否一个简单的植物水力模型可以捕捉蒸腾的年际变化。湿地香脂冷杉（Abies balsamea（L.）Mill）、椴木（Tilia Americana L.）和斑点桤木（Alnus rugosa（DuRoi）Spreng）的E-C和E-L在2000 - 2001年之间没有变化。从2000年到2001年，赤松（Pinus resinosa Air）的E-C和E-L分别增加了57%和19%，糖枫（Acer saccharum Marsh）的E-C和EL分别增加了83%和41%。从2000年到2001年，颤白杨（Populus tremuloides Michx）的E-C和E-L分别下降了50%和21%，这是由于森林帐篷毛虫（Malascoma district Huber）的完全落叶和随后较低的被覆盖树叶的总叶面积指数。白色雪松2001年，由于降水量减少和湿地流量管理，湿地地表水减少，导致E-C和E-L下降了20%。高地balsamea增加E-L和E-C分别为55%和53%，作为从光竞争的落叶，overstory P. tremuloides释放的结果。我们假设，无论不同的驱动程序的年际变化E-C和E-L，最低叶水势将被调节在相同的值。最低中午水势是一致的，在两年内的7个物种，尽管年与年之间的蒸腾量变化很大。这一调节独立地通过每日E-C和水汽压亏缺（D）之间的指数饱和以及参考冠层气孔导度（G（S））和G（S）对D的敏感性之间的权衡来验证，表明具有高G（S）的树木必须比具有低G（S）的树木更快地响应大气干旱而降低G（S）。研究结果表明，引入等水植物最小叶水势的G（S）规则可以简化森林冠层蒸腾模型。
We investigated interannual variability of canopy transpiration per unit ground area (E-C) and per unit leaf area (E-L) across seven tree species in northern Wisconsin over two years. These species have previously been shown to be sufficient to upscale stand-level transpiration to the landscape level during one growing season. Our objective was to test whether a simple plant hydraulic model could capture interannual variation in transpiration. Three species, wetland balsam fir (Abies balsamea (L.) Mill), basswood (Tilia Americana L.) and speckled alder (Alnus rugosa (DuRoi) Spreng), had no change in E-C or E-L between 2000 and 2001. Red pine (Pinus resinosa Air) had a 57 and 19% increase in E-C and E-L, respectively, and sugar maple (Acer saccharum Marsh) had an 83 and 41 % increase in E-C and EL, respectively, from 2000 to 2001. Quaking aspen (Populus tremuloides Michx) had a 50 and 21 % decrease in E-C and E-L, respectively, from 2000 to 2001 in response to complete defoliation by forest tent caterpillar (Malascoma district Huber) and subsequent lower total leaf area index of the reflushed foliage. White cedar (Thuja occidentalis L.) had a 20% decrease in both E-C and E-L caused by lowered surface water in wetlands in 2001 because of lower precipitation and wetland flow management. Upland A. balsamea increased E-L and E-C by 55 and 53 %, respectively, as a result of release from light competition of the defoliated, overstory P. tremuloides. We hypothesized that regardless of different drivers of interannual variability in E-C and E-L, minimum leaf water potential would be regulated at the same value. Minimum midday water potentials were consistent over the two years within each of the seven species despite large changes in transpiration between years. This regulation was independently verified by the exponential saturation between daily E-C and vapor pressure deficit (D) and the tradeoff between a reference canopy stomatal conductance (G(S)) and the sensitivity of G(S) to D, indicating that trees with high G(S) must decrease G(S) in response to atmospheric drought faster than trees with low G(S). Our results show that models of forest canopy transpiration can be simplified by incorporating G(S) regulation of minimum leaf water potential for isohydric species.