## 7 Data Availability  
The NI-LUE GPP with 0.05\({}^{\circ}\) spatial resolution and at 8-day intervals from 2001 to 2018 and its uncertainty data can be accessed at [[https://zenodo.org/record/7057843](https://zenodo.org/record/7057843)]([https://zenodo.org/record/7057843](https://zenodo.org/record/7057843)). **Author Contributions:** [PERSON] developed the model, generated the product and wrote the original draft. [PERSON], [PERSON] and [PERSON] provided help for writing and coding. [PERSON] and [PERSON] assisted in completing the verification and comparison. [PERSON] provided help for improvement of the model and writing of the draft. All authors have read and agreed to the published version of the manuscript. **Funding:** This work was supported by the National Natural Science Foundation of China (42271330) and the National Key R&D Program of China (2017 YFA0603002). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Acknowledgments:** We thank NASA for providing the MODIS reflectance products (MCD43A4 & MYDXCGA) and all fluxnet communities of the eddy covariance data (FLUXNET2015, [[https://fluxnet.fluxdata.org/data/](https://fluxnet.fluxdata.org/data/)]([https://fluxnet.fluxdata.org/data/](https://fluxnet.fluxdata.org/data/)) (accessed on 11 October 2022)). We thank [PERSON] for providing FLUXCOM GPP products. We also thank [PERSON] and [PERSON] for providing LPI-GUESS GPP products. We are grateful to [PERSON], [PERSON], [PERSON], and [PERSON] for the canopy nitrogen concentrations data. We also thank the anonymous reviewers for their helpful suggestions on the manuscript. **Conflicts of Interest:** The authors declare no conflict of interest. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Site** & **Latitude** & **Longitude** & **Canopy N,** & **Vegetation Type** & **Date** & **References** \\  & **(\({}^{\circ}\))** & **(\({}^{\circ}\))** & **\% by Mass** & **Vegetation Type** & **Date** & **References** \\ \hline Bartlett Experimental & & & & & Mixed northern \\ Forest, NH & & & & & hardwood \\ Duke Forest & & & & & \\ Deciduous, NC & 35.97 & \(-\)78.90 & 1.85 & Oak-hickor & \\ Duke Forest Pine, NC & 35.97 & \(-\)78.92 & 1.47 & Loblolly pine & \\ Harvard Forest, MA & 42.53 & \(-\)71.83 & 1.95 & Mixed deciduous & Growing \\ Howland, ME & 45.20 & \(-\)67.27 & 1.16 & Boreal evergreen & season between & [PERSON] et al. [53] \\ Hubbard Brook, NH & 43.95 & \(-\)70.27 & 2.24 & Northern hardwoods & 2000 and 2006 \\ Morgan Monroe State & 39.32 & \(-\)85.60 & 2.06 & Mixed deciduous & \\ Forest, IN & 40.02 & \(-\)104.47 & 0.93 & Subalpine evergreen & \\ Nivot Ridge, CO & 40.02 & \(-\)104.47 & 0.93 & Subalpine evergreen & \\ Tremper Mount, NY & 42.08 & \(-\)73.73 & 2.35 & Mixed deciduous & \\ Willow Creek, WI & 45.80 & \(-\)89.93 & 1.79 & Temperate deciduous & \\ Wind River & & & & \\ Experimental Forest, WA & & & & \\ Hyytiala, Finland, HY & 61.85 & 24.30 & 1.2 & Coniferous & Spring 2003 & [PERSON] et al. [46] \\ Abisko, Sweden, AB & 68.35 & 18.78 & 1.79 & Deciduous & Jul., Aug. 2003 & [PERSON] et al. [46] \\ Sore, Denmark, SO & 55.48 & 11.63 & 2.3 & Mixed & Summer 2007 & [PERSON] et al. [46] \\ Teshio, Japan, TE & 45.05 & 142.10 & 1.63 & Mixed & Aug. 2001, Aug. 2003 & [PERSON] et al. [107] \\ Wind River, USA, WR & 45.82 & \(-\)120.05 & 1.11 & Coniferous & Sep. 2003 & [PERSON] et al. [46]; [PERSON] et al. [108] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._ \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **CRO** & **DBF** & **EBF** & **ENF** & **MF** & **GRA** & **WSA** & **SAV** & **CSH** & **OSH** & **WET** \\ \hline \(p\) & 0.31335 & 0.07883 & 0.29767 & 0.00002 & 0.00019 & 0.52879 & 0.18511 & 0.31125 & 0.32329 & 0.24062 & 0.78899 \\ \(q\) & 0.57816 & 1.26957 & 0.13659 & 1.73640 & 1.61985 & 0.00011 & 0.91392 & 1.03839 & 0.48866 & 0.33551 & 0.00002 \\ \(a\) & 0.00002 & 0.00092 & 0.00001 & 0.07253 & 0.00016 & 0.01613 & 0.01487 & 0.00814 & 0.00513 & 0.05444 & 0.92145 \\ \hline \hline \end{tabular}
\end{table}