## 3 Results
### Response of Corn NPP to Climatic Factors
#### 3.3.2 Response of Corn NPP to Climatic Parameters  
Geographical correlation coefficients were computed by analyzing the relationship between corn NPP and climatic parameters, including temperature, precipitation, and solar radiation. This analysis was conducted for each month from May to October 2020 within the Fen River Basin. The resulting correlation coefficients were categorized into six distinct classes and their spatial distributions are shown in Figure 8. Table 2 provides detailed information on the pixel counts and the corresponding proportions within each correlation class. The geographical correlation coefficients between corn NPP and air temperature ranged from 0.1264 to 0.9344. The response of corn NPP to air temperature within the Fen River Basin demonstrated a predominantly positive correlation, with mild correlations comprising 92.07% of the overall relationship. These mild correlations were primarily observed in the western upper region, northeastern, central, and southern areas of the middle section and in the eastern and southwestern portions of the lower section. Moderate positive correlations accounted for 7.78% and were concentrated in the central area of the middle section, with scattered occurrences in the southern region of the middle section, as well as in the eastern and southwestern regions of the lower section. The category of significant positive correlation was the least prevalent, constituting only 0.15% of the  
Figure 6: Trends in temperature and precipitation timing from May to October in Fen River Basin. Figure 7: Temporal trend of solar radiation from May to October in the Fen River Basin. total, with only a few isolated pixels displaying significant positive associations. These significant positive associations were limited to specific locations within the middle and southern areas of the middle section and the southern part of the lower section of the Fen River Basin. The geographical correlation coefficients between corn NPP and precipitation ranged from \(-0.2344\) to \(0.9942\). In general, the spatial relationship between corn NPP and precipitation within the Fen River Basin was predominantly positive, accounting for \(99.92\%\) of the total. Furthermore, the upper region displayed higher positive correlations than the downstream region, with the midstream region registering higher values than the upper region. Specifically, there were only 16 instances of mild negative correlation, constituting a mere \(0.08\%\). The largest proportion (\(38.22\%\)) was characterized by significant positive correlations, primarily found in the western and northern areas of the upper section and the central and northeastern regions of the middle section, with relatively sparse occurrences in the lower section of the Fen River Basin, particularly in the southwestern region. Moderate positive correlations constituted the next highest proportion at \(37.88\%\), with prevalent distribution in the western region of the upper section, the northeastern, central, and southern regions of the middle section and the southwest and eastern regions of the lower section. Mild positive correlations accounted for \(23.82\%\) and were mainly distributed