Diffuse solar radiation can increase light use efficiency in plant canopies compared to direct sunlight. This can impact terrestrial gross primary production (GPP). Yan et al.  have developed a novel diffuse-fraction-based two leaf model of GPP that better explains seasonal variations, particularly at a test site in the Amazon forest. The model also directly accounts for the effects of soil water variations and the difference between C3 and C4 photosynthetic pathways for biomass production that exist in different types of plants. Explained variance in observed monthly GPP increased from about 50 per cent in an existing “big leaf” GPP algorithm to more than 70 per cent in the new scheme, with potential to improve biomass modeling and predictions.
Citation: Yan, H., Wang, S.-Q., Yu, K.-L., Wang, B., Yu, Q., Bohrer, G., … Shugart, H. H. . A novel diffuse fraction-based two-leaf light use efficiency model: An application quantifying photosynthetic seasonality across 20 AmeriFlux flux tower sites. Journal of Advances in Modeling Earth Systems, 9. https://doi.org/10.1002/2016MS000886
—Paul A. Dirmeyer, Editor, Journal of Advances in Modeling Earth Systems