Seasonal pattern of solar-induced fluorescence as a proxy for canopy photosynthesis in a temperate deciduous forest

Wednesday, 17 December 2014
Xi Yang1, Jianwu Tang2, John F Mustard1, Jung-Eun Lee1, Micol Rossini3, Joanna Joiner4, J William Munger5 and Andrew D Richardson5, (1)Brown University, Providence, RI, United States, (2)The Ecosystems Center, MBL, Woods Hole, MA, United States, (3)Università degli Studi Milano-Bicocca, Remote Sensing of Environmental Dynamics Laboratory, DISAT, Milan, Italy, (4)NASA Goddard SFC, Greenbelt, MD, United States, (5)Harvard University, Cambridge, MA, United States
Photosynthesis in the terrestrial ecosystems contributes to the largest carbon flux in the global carbon cycle. The use of solar-induced fluorescence (SIF) as a proxy of photosynthesis at the ecosystem scale (Gross Primary Production, GPP) is a critical emerging technology. Satellite measurements of SIF were found to be significantly correlated with GPP, and several ground campaigns suggested that SIF could improve the GPP estimation. However, the robustness of using SIF as a proxy for GPP under different climate conditions, growth stages and vegetation types has not been explored. Here we presented the first-ever high-frequency (every 5 minutes) measurement of SIF in a temperate deciduous forest across the growing season of 2013. Concurrently, we estimated GPP with the eddy covariance method. We found a strong linear relationship between daily mean SIF and GPP (r2=0.725), and between SIF and absorbed photosynthetically active radiation (r2=0.705). The seasonal patterns of ground and satellite-derived SIF matched well. These results suggest strong evidence that SIF is a good proxy for direct measurements of canopy photosynthesis.