Physiological and structural tradeoffs underlying the leaf economics spectrum.

Area of Science:

• Plant physiology
• Ecology
• Plant anatomy

Background:

• The leaf economics spectrum (LES) describes trade-offs in leaf traits like construction costs, nutrient concentration, and carbon fixation.
• Fundamental constraints underlying LES trade-offs remain incompletely understood.

Purpose of the Study:

• Investigate physiological and structural mechanisms driving LES trade-offs.
• Analyze the role of cell wall composition, nitrogen allocation, and CO2 diffusion in LES.

Main Methods:

• Compiled novel data on rarely considered leaf traits across hundreds of species.
• Included traits like dry mass fraction in cell walls, nitrogen allocation, and mesophyll CO2 diffusion.
• Analyzed anatomical traits and major growth forms.

Main Results:

• Cell wall constituents comprise a substantial leaf dry mass (18-70%), particularly in leaves with high leaf mass per unit area (LMA) and long lifespans.
• Increased cell wall mass correlates with reduced nitrogen investment in photosynthetic proteins.
• Higher cell wall thickness limits within-leaf CO2 diffusion rates.

Conclusions:

• Greater investment in cell walls underlies LES trade-offs.
• Long leaf lifespans are linked to higher LMA and cell wall mass, but at the cost of reduced photosynthetic efficiency.