Abstract
Plant photosynthesis mediates about 60Gt of the carbon uptake by vegetated ecosystems and is considered to be a critical component of the terrestrial carbon cycle. Photosynthesis is, however, a highly adaptive process and lack of knowledge on its dynamic causes uncertainties in current carbon budgets. New remote sensing approaches allow measuring the chlorophyll fluorescence signal (FS) and hold the potential to directly assess ecosystem photosynthesis and related carbon assimilation rates (i.e., gross primary production (GPP)).