Journal Article

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

Sönke Zaehle, Tiana W. Hammer, Thomas Wutzler, Talie Musavi, Oscar Perez-Priego, Anna Berninger, Andreas Burkart, Enrique Juarez-Alcalde, Francesco Fava, Javier Pacheco-Labrador, Uwe Rascher, Tommaso Julitta, Arnaud Carrara, Kathrin Henkel, M. Pilar Martín, Mirco Migliavacca, Christiaan van der Tol, Olaf Kolle, Andrea Pérez-Burgueño, Micol Rossini, Gerardo Moreno, Tarek S. El-Madany, Markus Reichstein, Jin-Hong Guan, Verena Bessenbacher

2017

Overview

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 completely understood. 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 (V cmax)) 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 V cmax. 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.

• Publisher: New Phytologist Trust,Wiley Subscription Services, Inc
• Subject: Abundance / Biodiversity / Canopies / Canopy / canopy structure / Capacity / Carbon dioxide / Carboxylation / Chlorophyll / Chlorophyll a / Distribution functions / Emission analysis / Emissions control / energy / far‐red sun‐induced fluorescence / Fluorescence / functional traits / Grasslands / gross primary productivity (GPP) / Inclination / leaf inclination distribution function / Leaves / Mineral nutrients / Nitrogen / nitrogen content / Nutrient availability / nutrient manipulation / Nutrients / phosphorus / Photosynthesis / Primary production / primary productivity / Soil / Soil investigations / soil–canopy observation of photosynthesis and energy (SCOPE) model / Structure-function relationships / Uptake