# Exploring the Spatiotemporal Alterations in China's GPP Based on the DTEC Model
## 3 Results
### Drivers of China's GPP Change and Their Relative Contributions  
The regions where climate change contributed (C\({}_{\text{CC}}\)) to GPP were equal to an area of approximately 50.2% (Figure 7a). The regions where it contributed moderately and significantly were equal to an area of approximately 23.3%, mainly in the junction regions of NWC, NC, SWC, CC, IM, and NEC. The area where climate change suppressed GPP was approximately 8.6%. The area where GPP moderately and significantly decreased was approximately 4.7%, mainly in the central region of CC, the eastern coastal region of NC, the southern region of NEC, and the northeastern region of SEC. The areas where human activity contributed (C\({}_{\text{HA}}\)) to GPP accounted for approximately 61.1% of the total area (Figure 7b). The area of moderate and significant contribution of human activities to GPP was larger than that of climate change (approximately 43.3%). The regions where human activities suppressed GPP accounted for approximately 6.1%, and these regions were mainly in the northern part of the NC and the northeastern part of the SEC.  
Figure 8a shows that approximately 66.4% of the regional C\({}_{\text{CC}}\) had a positive effect on GPP. The area with a contribution between 0% and 60% was larger, accounting for 59.4% of the total area, and the area with a contribution greater than 80% accounted for approximately 2.7% of the total area, which was mainly concentrated in the central part of the TP and the eastern coast of the SEC. The regions with negative C\({}_{\text{CC}}\) to GPP accounted for approximately 8.1% of the total area, which was mainly distributed in the southern part of the NEC, the eastern part of the NC, the northern part of the SEC, the TP, and the central part of the CC. Figure 8b shows that approximately 72.6% of the regional C\({}_{\text{HA}}\) had a positive effect on GPP. Within this range, the areas with contributions in the range of 40% to 80% and greater than 80% are larger, and these areas account for approximately 67.4% of the total area. The areas with a contribution rate of more than 80% are mainly concentrated in NEC, NC, the TP, and NWC, with an area share of 23.3%. The regions with negative C\({}_{\text{HA}}\) to GPP accounted for approximately 1.8% of the total area and were mainly concentrated in the central part of the TP and the northeastern coastal area of the SEC. In comparison, the contribution of HA was greater than that of CC in most regions. The contributions  
Figure 6: Spatial distribution of partial correlation coefficients between GPP and aerosol optical depth (**a**), solar radiation (**b**), precipitation (**c**), and temperature (**d**) in China from 2001 to 2020 and partial correlations of nine ecological regions to four climate factor coefficients (**e**); only pixels that passed the significance test are shown in the figure.  
of climate change and human activities to changes in the gross primary productivity of vegetation in China were approximately 28% and 72%, respectively.  
At the regional scale, the C\({}_{\text{CC}}\) ranged from 18% to 37%, as shown in Figure 9. Among them, the C\({}_{\text{CC}}\) in the SWC, TP, IM, and SC regions were greater than 30%; the highest contribution was in the IM and SWC regions, both with 37%, and the lowest was in the NC region, with 18%. The C\({}_{\text{HA}}\) ranged from 63% to 82%; statistically, the C\({}_{\text{HA}}\) exceeded 60% in all nine ecoregions; the highest was 82% in NC, and the lowest was 63% in IM.  
Figure 8: Spatial distribution of the contribution rates of climate change (**a**) and human activities (**b**) to the GPP in China from 2001 to 2020 and the area percentage of each contribution rate (**c**).  
Figure 7: Spatial distribution of the impacts of climate change (**a**) and human activities (**b**) on GPP in China from 2001 to 2020 and the percentage of area affected by each impact level (**c**).