Net primary productivity

Rate of net carbon fixation by primary producers — gross primary productivity minus autotrophic respiration. In-situ measurement via eddy-covariance flux towers (FLUXNET, ICOS, AmeriFlux, NEON, OzFlux); satellite proxies via MODIS, Sentinel-2/3, and the new EE flux-tower constellations. Anchors carbon-market MRV and EU LULUCF reporting.