## 3 Results
### Results of Correlation Analysis between eWUE and Hydrothermal Factors  
Temperature and precipitation are the main climatic parameters that impact vegetation growth. Figure 6 shows that the correlation coefficient between eWUE and precipitation in Inner Mongolia in spring was \(-\)0.876 to 0.623; 88.169% of regional WUE and precipitation was negatively connected, especially in the southwest and southeast of the research area, and 11.831% was positively correlated. It was positively associated, dispersed in the center of the research region (Figure 8a), and the significance test area accounted for 16.2% (\(p<0.05\)), mostly near the Wushen Banner in the southwest (Figure 9a). The correlation coefficients between eWUE and summer precipitation in Inner Mongolia varied from \(-\)0.915 to 0.771, with 89.104% of the region negatively linked with precipitation, mostly in the center and southwest, and 10.896% favorably connected, mostly in the northeast (Figure 8b). A total of 56.6% (\(p<0.05\)) of the research region passed the significance test, mostly in the center and southwest (Figure 9b). The correlation coefficient between eWUE and precipitation in autumn in Inner Mongolia ranged from \(-\)0.887 to 0.775, and 88.828% of the regional eWUE was negatively correlated with precipitation, mainly distributed around the Wushen Banner in the northeast and southwest of the study area; 11.172% of the regional eWUE was positively correlated with precipitation, distributed in the central part of the study and near the Hetao irrigation area (Figure 8c), and the area that passed the significance test accounted for 20.3% (\(p<0.05\)), mainly in the northeastern part of the study area (Figure 9c). In spring in Inner Mongolia, the correlation coefficient between eWUE and temperature ranged from \(-\)0.668 to 0.920. In 4.904% of the area, eWUE and temperature had a negative correlation, mostly in the central and western parts of the study area, especially in the Hetao Plain. In 95.096% of the area, eWUE and temperature had a positive correlation. A total of 52.7% (\(p<0.05\)) of the area that passed the significance test was in the agro-pastoral cross belt near Chifeng and the northeast of the study area (Figure 8d). Most of this area was in the northeast of the study area (Figure 9d). In summer in Inner Mongolia, the correlation between eWUE and temperature ranged from \(-\)0.834 to 0.724. A total of 64.105% of the area was negatively correlated with temperature, mostly around Chifeng and Tongliao; 35.895% of the area was positively correlated with temperature, mostly around Hulun Lake and Near Erenhot (Figure 8e). In total, 10.5% of the area passed the significance test (\(p<0.05\)), mostly around Tongliao and Chifeng (Figure 9e). eWUE correlated with Inner Mongolian autumn temperature from \(-\)0.793 to 0.842. Temperature was inversely linked with soil usage efficiency in 18.231% of the region, mostly in the southwest and northeast. eWUE was positively linked with temperature in 81.769% of the locations, dispersed in the central grassland region of Inner Mongolia (Figure 8f), and  
Figure 7: eWUE statistics for different vegetation types in spring, summer and autumn in Inner Mongolia. 22.6% passed the significance test (\(p<0.05\)), mostly at the intersection of the middle and east of the research area (Figure 9f). The correlation analysis results of the seasonal eWUE for different vegetation types and precipitation showed (Figure 10a) that, except for DBF and SA in summer, the eWUEs of vegetation types in other seasons were negatively correlated with precipitation. Except for grassland, the eWUE in summer was greater than that in spring and autumn among  
Figure 8: Correlation distribution map of eWUE with precipitation and temperature in different seasons. (**a–c**) Correlation between eWUE and precipitation for spring, summer and autumn; (**d–f**) correlation between eWUE and temperature for spring, summer and autumn. Figure 9: Significance distribution map of eWUE with rainfall and temperature in different seasons.