Fluxes of carbon and water along a vertical profile within a canopy, particularly the associations between canopy and ecosystem levels, are not well studied. In this study, gas exchange along the vertical profile in a maize canopy was examined. The relationships between leaf- and ecosystem-level carbon and water fluxes were compared. The results from research conducted over two growing seasons showed that during vegetative growth, the top and middle leaf layers in the canopy contribute most to the carbon and water fluxes of the entire canopy. During the grain-filling stage, gas exchange processes were performed mostly in the middle leaves with and near the ears. Significant relationships were observed between the net ecosystem CO₂ exchange rate (NEE) plus soil respiration and the assumed canopy levels (A_canopy) and between evapotranspiration rates at the ecosystem (ET) and assumed canopy levels (E_canopy). This highlights the close associations between these parameters by integrating the leaf gas exchange rates measured in a conventional leaf cuvette and those at the ecosystem level via the eddy covariance technique. These results improve our understanding of how carbon assimilation varies vertically within a canopy, highlighting the critical role of ear leaves.

冠层内沿垂直剖面的碳和水通量，特别是冠层与生态系统水平之间的关联，尚未得到很好的研究。在这项研究中，研究了沿玉米冠层垂直剖面的气体交换。比较了叶级和生态系统级碳和水通量之间的关系。两个生长季节的研究结果表明，在营养生长过程中，冠层的顶部和中部叶层对整个冠层的碳和水通量贡献最大。在籽粒灌浆阶段，气体交换过程主要在有穗和靠近穗的中间叶进行。观察到净生态系统 CO ₂交换率 (NEE) 加上土壤呼吸与假定的冠层水平之间存在显着关系（一_篷）和蒸散速度之间的生态系统（ET），并假定树冠水平（ē_篷）。这突出了这些参数之间的密切关联，通过整合传统叶试管中测量的叶气交换率和通过涡流协方差技术在生态系统水平上测量的叶气交换率。这些结果提高了我们对碳同化如何在冠层内垂直变化的理解，突出了耳叶的关键作用。