Review of remote Sensing indices for monitoring environmental grassland indicators in Europe

European grasslands provide biodiversity, carbon storage, and agricultural services, but face increasing pressure from intensification and climate change. We review remote sensing indices used to monitor conservation-relevant grassland environmental indicators in Europe, covering biochemical, structural, spatial, and temporal indices from satellite, airborne, uncrewed aerial vehicle (UAV) and ground-based sensors. We synthesize best-practice applications for landscape/habitat/species identification, biomass and LAI, biodiversity, management, fluxes, and temporal dynamics, and summarize key limitations (e.g., saturation and background effects, mixed pixels, and limited model transferability). Finally, we outline how data fusion and emerging hyperspectral/thermal missions can improve operational, policy-ready monitoring.