An eco-evolutionary optimality model explains the acclimated temperature response of photosynthesis

Area of Science:

• Plant physiology
• Ecology
• Climate change science

Background:

• Optimal temperature for photosynthesis (Topt) generally rises with plant growth temperature.
• Changes in Topt correlate with maximum carboxylation capacity (Vcmax25) and electron transport rate (Jmax25) at 25°C.
• The ratio of Jmax25 to Vcmax25 decreases as temperatures rise, impacting photosynthetic efficiency.

Purpose of the Study:

• To investigate how Topt changes with plant growth temperature using an eco-evolutionary optimality (EEO) model.
• To assess the capability of the subdaily P model in simulating photosynthetic thermal acclimation.
• To provide a more accurate representation of leaf-level photosynthetic responses for climate change projections.

Main Methods:

• Utilized the subdaily P model, an EEO-based photosynthesis model.
• Separated instantaneous and acclimated photosynthetic parameter responses to temperature.
• Validated model simulations against controlled experiments and eddy covariance flux tower data.

Main Results:

• Simulated Topt increases with growth temperature, consistent with empirical observations.
• Model accurately predicts changes in assimilation rate at Topt.
• Changes in Topt are directly linked to alterations in carboxylation and electron transport capacities as hypothesized by the EEO model.

Conclusions:

• The subdaily P model, based on EEO, effectively simulates the thermal acclimation of photosynthesis.
• This modeling approach offers a simpler alternative to empirical methods and plant functional types (PFTs) in land surface models.
• Accurate modeling of photosynthetic thermal responses is crucial for predicting terrestrial carbon cycle dynamics under climate change.