Evolution of light use efficiency models: Improvement, uncertainties, and implications

• Demonstrate the trajectory of light use efficiency (LUE) GPP models. Track evolution parameters (PAR, FPAR, and LUE) in LUE Environmental stress factors experienced an evolutionary trend complexity. Review uncertainties caused by model structure, parameterization, input, validation data. Light models have been widely used to estimate terrestrial gross primary production (GPP) at local, regional, global scales, which is vital for understanding carbon flux dynamics under climate change. express as product incoming photosynthetically active radiation (PAR), fraction PAR absorbed plants (FPAR), maximum LUE, environmental (e.g., temperature, water, dioxide). Here, we investigate 21 reported literatures conclude their complicated evolutions aforementioned four components: 1) representation was improved from total direct diffuse PARs; 2) FPAR one-leaf two-leaf (i.e., sunlit shaded leaves) or chlorophyll based strategies; 3) parameterization a constant value 0.39 gC/MJ C3/C4- sunlit/shaded leaf-specific values; 4) both integration forms multiplication method law minimum method) proxy optimization specific factor. For example, water factor has evolved atmospheric vapor pressure deficit) soil moisture) indicators plant land surface index) indicators. We also identify structures, parameterizations, input data with various resolutions accuracies, scale mismatch issues between remote sensing tower observations. The newly emerged such photochemical reflectance index, solar-induced fluorescence, near-infrared vegetation simplify methods but fail disentangle influences different factors. These findings on are expected contribute future improvements.