A stomatal optimization approach improves the estimation of carbon assimilation from sap flow measurements
A stomatal optimization approach improves the estimation of carbon assimilation from sap flow measurements
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DOI：
10.1016/j.agrformet.2019.107735
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发表时间：
2019-12
影响因子：
6.2
通讯作者：
Yanting Hu;T. Duman;D. Vanderklein;P. Zhao;K. Schafer
中科院分区：
文献类型：
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作者：
Yanting Hu;T. Duman;D. Vanderklein;P. Zhao;K. Schafer
模拟植物的碳吸收过程为全球植被模型提供了基础。基于气孔优化理论，对冠层传导率约束的碳同化（4C-A）模型进行了改进。一种新的方法来计算最佳气孔导度和碳同化（Anet），它考虑了Rubisco活性和RuBP再生的共同限制，现已被纳入修改后的4C-A模型。结果表明，修正后的4C-A模型计算的日平均Anet值低于原4C-A模型和大叶模型，但与实测值吻合较好。当边际水分利用效率（λ）较高时，计算出的日平均Anet值低于较低时的值。当冠层气孔导度较高或VPD较低时，修正模型与原模型的Anet差异较大。因此，更准确的Anet估计的修改后的模型在黎明和黄昏或在潮湿的日子，当低VPD发生。此外，改进后的4C-A模型在估算Anet和气孔导度的昼夜时间尺度上优于原模型。这个改进的4C-A模型提供了一个更现实的估计Aneton半小时到每日的时间尺度，因此，可以应用于阐明碳和水循环之间的耦合和测试碳同化对环境变化的响应。
Modeling the carbon uptake process by plants provides the foundation for global vegetation models. We modified the Canopy Conductance Constrained Carbon Assimilation (4C-A) model, a multi-level assimilation model that utilizes sap-flux measurements, based on the stomatal optimization theory. A novel method of calculating optimal stomatal conductance and carbon assimilation (Anet), which considers the co-limitation of Rubisco activity and RuBP regeneration, has now been incorporated into the modified 4C-A model. Results show that the calculated daily averageAnetby the modified 4C-A model was lower than that from the original 4C-A and a big-leaf model but agreed well with that from leaf gas exchange measurement. When the marginal water use efficiency (λ) was high, the calculated daily averageAnetbecame lower than that derived from lowerλ. Differences inAnetbetween the modified and original model were larger when the canopy exhibited higher stomatal conductance orVPDwas lower. Hence, a more accurateAnetwas estimated by the modified model at dawn and dusk or during humid days when lowVPDoccurred. In addition, the modified 4C-A model performed better on a diurnal timescale forAnetand stomatal conductance estimation compared to the original one. This modified 4C-A model provides a more realistic estimation ofAneton half hourly to daily timescales, and, thus, can be applied to elucidate the coupling between carbon and water cycles and test the responses of carbon assimilation to environmental change.