Assessment of MODIS imagery to track light-use efficiency in a water-limited Mediterranean pine forest

• Published in: Remote sensing of environment Vol. 123; pp. 359 - 367
• Main Authors: Moreno, A., Maselli, F., Gilabert, M.A., Chiesi, M., Martínez, B., Seufert, G.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.08.2012; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied geophysics; Biological and medical sciences; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Internal geophysics; Light-use efficiency; Mediterranean forest; MODIS; PRI; Teledetection and vegetation maps; Water stress; Light-use efficiency; Water stress; PRI; MODIS; Mediterranean forest; Pinus pinaster; Variable; time variations; Index; evaluation; Radiation use efficiency; Eddy covariance method; Daily; Gymnospermae; Informational content; imagery; Zenith distance; flux; Ability; Mediterranean vegetation; water; Sun; correlation; photochemistry; techniques; ecosystems; Coniferales; Spermatophyta; primary productivity; Mediterranean region; Reflectance; Coniferous forest
• ISSN: 0034-4257; 1879-0704
• DOI: 10.1016/j.rse.2012.04.003

Daily values of gross primary production (GPP) derived from an eddy-covariance flux tower have been used to analyze the information content of the MODIS Photochemical Reflectance Index (PRI) on the light-use efficiency (ε). The study has been conducted in a Mediterranean Pinus pinaster forest showing summer water stress. Advanced processing techniques have been used to analyze the effect of various external factors on ε and PRI temporal variations. The intra-annual correlation between these two variables has been found to be mostly attributable to concurrent variations in sun and view zenith angles. The PRI has been normalized from these angular effects (NPRI), and its ability to track ecosystem ε response to prolonged summer water limitations has been analyzed. The observed shift between ε and NPRI reveals that, for the study area and at MODIS spatial resolution, NPRI is informative on changes in pigments and canopy structure related to the vegetation response to prolonged water stress. ► GPP data from a flux tower are used to estimate the canopy light-use efficiency ε. ► Seasonal variations in ε and PRI are partly due to changes in sun and view angles. ► Statistical methods are used to normalize PRI (NPRI) from those angular effects. ► NPRI becomes informative on inter-annual ε variability due to water stress. ► A shift is observed between ε and NPRI signals.