Coordination theory of leaf nitrogen distribution in a canopy

Area of Science:

• Plant physiology
• Ecology
• Photosynthesis research

Background:

• Leaf nitrogen concentration typically decreases with canopy depth.
• This decline is often linked to light availability and proposed to optimize canopy photosynthesis.

Purpose of the Study:

• To present an alternative to optimization theory for plant canopy nitrogen distribution: coordination theory.
• To propose that plants balance nitrogen to coordinate two key photosynthetic processes: Rubisco-limited carboxylation (Wc) and electron transport-limited carboxylation (Wj).

Main Methods:

• Developed coordination theory based on balancing Wc and Wj rates.
• Investigated the driving force for nitrogen allocation as the difference between required and current nitrogen content for balance.
• Modeled canopy carbon assimilation under this coordination strategy.

Main Results:

• Coordination theory suggests plants allocate nitrogen to balance Wc and Wj across canopy layers.
• Nitrogen allocation is driven by the discrepancy between current and balance-requiring leaf nitrogen content.
• Modeled canopy carbon assimilation using coordination theory closely matched results from optimization theory.

Conclusions:

• Coordination theory offers a new framework for understanding plant canopy nitrogen distribution.
• Balancing Wc and Wj is a key mechanism for efficient canopy carbon assimilation.
• This internal coordination mechanism results in carbon assimilation comparable to that predicted by optimization theory.