Quantification of Gross Primary Production of Dryland Conifer Forests by Remotely Sensed Chlorophyll Absorption Coefficient

Vegetation gross primary production (GPP) is mainly influenced by the amount of absorbed photosynthetically active radiation (PAR), making absorption by photosynthetic pigments a key determinant of photosynthetic capacity. This study explores the use of the chlorophyll absorption coefficient derived from Sentinel-2 and VENμS satellite data for GPP estimation across three dryland forests in Israel and California between 2017 and 2020. Results indicate high accuracy of GPP estimation using chlorophyll absorption coefficients within the PAR (400–700 nm) and the red-edge (690–740 nm) spectral regions. Sentinel-2-based estimations explained over 91% of GPP variation, while VENμS data accounted for more than 95%. Normalized RMSE values were below 22% for Sentinel-2 and 18% for VENμS without model recalibration across different sites.