XVI International Botanical Congess
This study utilizes a physiologically-based model to estimate canopy C uptake at ambient and elevated [CO2] in the Duke Forest, where a Free-Air CO2 Enrichment experiment has been in progress since August 1996. The model estimates photosynthesis according to Farquhar model in 6 canopy layers and was validated against measured diurnal courses of leaf photosynthesis and net ecosystem C exchange. Application of the model to simulate canopy C fixation from August 1996 to December 1998 suggested that elevated [CO2] resulted in a substantial increase in C influx into the forest ecosystem. The CO2 effect on forest canopy C uptake was found to be sensitive to possible acclimation in leaf area index, canopy nitrogen distribution, and leaf photosynthetic capacity.