Photosynthetic Dynamics in Varying Light Environments: A Model and Its Application to Whole Leaf Carbon Gain

The light environment of a plant microsite can be highly dynamic with sunflecks lasting from seconds to minutes in length. Whole leaf photosynthetic response to such variations is complex and species—specific. A mathematical model based on a single enzyme pool is derived to mimic leaf response in varying light. The model is used to analyze carbon gain in Fragaria virginiana. I find that sunflecks can be responsible for an appreciable proportion of leaf carbon gain throughout a day, especially under light—limited conditions. Model results also indicate that the standard methods of estimating carbon gain in varying light using steady—state photosynthetic rates often give overestimates.