## 5 Conclusions  
This study explores the influences of land cover change and multisource products' differences on GPP estimation by NIRv. It is reported that the land cover of the YRB has undergone drastic dynamic changes in recent decades due to the ecological projects. Therefore, this study took the YRB as the study area and used MCD12C1 and ESACCI land cover data during 2001-2018 to explore the impacts of land cover on NIRv-based estimated GPP. Our results showed: (1) The dominant land cover types in the YRB were grassland, followed by cropland and forest. The main land cover transfer was characterized by the conversion from other types of land to grassland in the northwest of the YRB and from grassland and shrubland to cropland in the southeast of the YRB during the study period. (2) The temporal and spatial pattern of GPP was highly consistent with that of NIRv, and the average increase in GPP was 2.14 gCm\({}^{-2}\)yr\({}^{-1}\) across the study area. (3) Both LCC and DMP had significant influences on GPP estimated by NIRv. Specifically, the areas with obvious differences in NIRv-based GPP closely corresponded to those where land cover types dramatically changed. Our study thus demonstrates that the influences of land cover on the relationship between NIRv and GPP are non-negligible, and considering the land cover change and differences of multisource products would be beneficial to improve the accuracy of carbon flux estimation.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/rs15194693/s1](https://www.mdpi.com/article/10.3390/rs15194693/s1)]([https://www.mdpi.com/article/10.3390/rs15194693/s1](https://www.mdpi.com/article/10.3390/rs15194693/s1)). Text S1: Comparison between the site EC data and the experimental results; Table S1: Details of the three EC flux towers (CN-HaM, CF-HBG_S01, and CN-Ha2) in the Yellow River basin employed in this study. Note that GRA refers to grassland, and SHR refers to shrubland; Figure S1: Geographical location of the three EC flux towers (CN-HaM, CF-HBG_S01, and CN-Ha2) in the Yellow River basin employed in this study; Figure S2: Scatter plots between the observed EC GPP against MODIS monthly static and dynamic schemes. The blue, orange, and green points represent the CN-Ha2, CN-Ham, and CF-HBG_S01 sites, respectively. References [55; 56; 57; 58] are cited in the supplementary materials.  
Conceptualization, J.J. and L.W.; methodology, software, validation, and formal analysis, [PERSON] and [PERSON]; resources, [PERSON] and [PERSON]; writing--original draft preparation, [PERSON], [PERSON] and L.W.; writing--review and editing, [PERSON], [PERSON], [PERSON], Q.Z., X.F. and L.R.; visualization, [PERSON] and L.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (U2243203, 41971374 and 41807173) and the Carbon Peak and Carbon Neutralization Key Science and Technology Program of Suzhou (ST202228).  
No applicable.  
The authors would like to thank the following institutions or projects for generously providing the data used in this study: the United States Geological Survey (USGS), the European Space Agency (ESA), Google Earth Engine (GEE), FLUXNET, ChinaFLUX, and the North American Carbon Program (NACP) Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP).  
The authors declare no conflict of interest.