Plant functional traits and canopy structure control the relationship between photosynthetic CO2 uptake and far-red sun-induced fluorescence in a Mediterranean grassland under different nutrient availability
Sun-induced fluorescence (SIF) in the far-red region provides a new noninvasive measurement
approach that has the potential to quantify dynamic changes in light-use efficiency and
gross primary production (GPP). However, the mechanistic link between GPP and SIF is not
We analyzed the structural and functional factors controlling the emission of SIF at 760 nm
(F760) in a Mediterranean grassland manipulated with nutrient addition of nitrogen (N), phosphorous
(P) or nitrogen–phosphorous (NP). Using the soil–canopy observation of photosynthesis
and energy (SCOPE) model, we investigated how nutrient-induced changes in canopy
structure (i.e. changes in plant forms abundance that influence leaf inclination distribution
function, LIDF) and functional traits (e.g. N content in dry mass of leaves, N%, Chlorophyll
a+b concentration (Cab) and maximum carboxylation capacity (Vcmax)) affected the observed
linear relationship between F760 and GPP.
We conclude that the addition of nutrients imposed a change in the abundance of different
plant forms and biochemistry of the canopy that controls F760. Changes in canopy structure
mainly control the GPP–F760 relationship, with a secondary effect of Cab and Vcmax.
In order to exploit F760 data to model GPP at the global/regional scale, canopy structural
variability, biodiversity and functional traits are important factors that have to be considered.
Migliavacca, M., Perez-Priego, O., Rossini, M., El-Madany, T. S., Moreno, G., van der Tol, C., Rascher, U., Berninger, A., Bessenbacher, V., Burkart, A., Carrara, A., Fava, F., Guan, J.-H., Hammer, T. W., Henkel, K., Juarez-Alcalde, E., Julitta, T., Kolle, O., Martín, M. P., Musavi, T., Pacheco-Labrador, J., Pérez-Burgueño, A., Wutzler, T., Zaehle, S. and Reichstein, M. 2017. Plant functional traits and canopy structure control the relationship between photosynthetic CO2 uptake and far-red sun-induced fluorescence in a Mediterranean grassland under different nutrient availability. New Phytologist 214: 1078–1091.