Leaf- and stand-level responses of a forested mesocosm to independent manipulations of temperature and vapor pressure deficit
Leaf- and stand-level responses of a forested mesocosm to independent manipulations of temperature and vapor pressure deficit
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DOI：
10.1111/j.1469-8137.2007.02035.x
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发表时间：
2007-01-01
期刊：
影响因子：
9.4
通讯作者：
Murthy, Ramesh
中科院分区：
文献类型：
--
作者：
Barron-Gafford, Greg A.;Grieve, Katherine A.;Murthy, Ramesh
在温度（T）和蒸汽压赤字（VPD）的变化强烈影响气体交换，但由于VPD是高度受T的影响，这两个因素的影响是难以分离的。在这里，T和VPD对CO2吸收，气孔导度，蒸腾作用在叶和冠层水平的影响进行了检查的一个立场的树木（美洲黑杨）封闭在大型的中生态系统。T和VPD被独立地改变，以产生低（24 ℃）或高（30 ℃）T和低（0.75）或高（1.75 kPa）VPD治疗的析因组合。传统的叶片水平的气体交换测量与整个冠层交换进行了比较，以验证典型的缩放方法。T升高导致中午的叶片水平和冠层水平的净CO2吸收，分别平均增加40%和14%。其他生理反应升高T和VPD在两个尺度上是相似的，但变化的幅度通常不太明显，在冠层level.Surprisingly，只有最小的T和VPD之间的相互作用被发现影响CO2吸收和气孔导度的响应在任何一个级别。
Alterations in temperature (T) and vapor pressure deficit (VPD) strongly influence gas exchange, but because VPD is highly influenced by T, the effects of these two factors are difficult to separate.Here, the concomitant effects of T and VPD on CO2 uptake, stomatal conductance, and transpiration at leaf- and canopy-levels were examined for a stand of trees (Populus deltoides) enclosed within large mesocosms. T and VPD were independently altered to yield a factorial combination of treatments of low (24 degrees C) or high (30 degrees C) T and low (0.75) or high (1.75 kPa) VPD. Traditional leaf-level gas exchange measurements were compared with whole-canopy exchange to verify typical scaling methods.Elevated T resulted in an average 40% and 14% increase in midday leaf-level and canopy-level net CO2 uptake, respectively. Other physiological responses to elevated T and VPD were similar at both scales, but the magnitude of change was usually less pronounced at the canopy-level.Surprisingly, only minimal interactions between T and VPD were found to influence responses of CO2 uptake and stomatal conductance at either level.