## 3 Results
### Climate Factor Response Analysis  
#### 3.4.1 Comparison of the Climatic Factor Correlations Across Different Scales  
At annual, seasonal, and 16-day scales, the correlations were calculated using the full time series and arranged with elevation for a more intuitive comparison. Figure 8a illustrates the correlation of precipitation with GPP across the different scales with elevation. Firstly, overall, the annual scale exhibits the lowest correlation, the 16-day scale shows a relative increase, and the seasonal scale demonstrates the strongest correlation. This pattern is closely tied to the seasonal variations in precipitation and the seasonal heterogeneity of plant growth. At the annual scale, the GPP variations correlate with the interannual precipitation changes, but these changes are not pronounced year-to-year, resulting in lower correlation. At the 16-day scale, due to the proximity of the time steps, the precipitation differences between adjacent periods are minimal, and vegetation growth typically does not undergo abrupt changes, limiting the increase in correlation. At the seasonal scale, significant seasonal heterogeneity in both precipitation and plant growth leads to the highest correlation between GPP and precipitation. Secondly, analyzing the precipitation correlation changes with elevation reveals a similar overall trend across scales: an initial increase, followed by a decline, and a second peak near the highest elevations. At the annual scale, the precipitation correlation remains relatively stable after reaching the first peak, then rises to a second peak. At the 16-day scale, it drops to a first minimum around 1300 m after the first peak, rises again, reaches a second minimum around 2800 m, and then attains a second peak, reflecting the distribution of vegetation with elevation. At the seasonal scale, the precipitation correlation decreases steadily after peaking, which can be linked to changes in plant species and water demand with increasing elevation, before reaching a second peak at the highest elevation, which is closely related to the vegetation distribution in the Shennongjia region.  
Figure 8b illustrates the correlation of temperature with GPP across different scales with elevation. Firstly, overall, similar to precipitation, the annual scale shows the lowest correlation, the 16-day scale exhibits a relative increase, and the seasonal scale demonstrates the highest correlation. The underlying reasons are largely consistent with those for precipitation, i.e., closely tied to seasonal temperature variations and the seasonal heterogeneity of plant growth. Secondly, analyzing the temperature correlation changes with elevation reveals some differences in trends across scales. At the annual scale, the temperature correlation slightly decreases initially, then rises steadily with elevation, stabilizing around 0.2 with an overall upward trend. At the 16-day scale, it increases with elevation, drops to a first minimum around 1300 m, rises again, reaches a second minimum around 2800 m, and then attains a second peak, mirroring the precipitation correlation pattern at this scale, and is also related to the vegetation distribution with elevation. At the seasonal scale, the temperature correlation increases with elevation, then stabilizes with no significant variation with elevation, slightly decreases around 2800 m, and subsequently rises, which can be closely linked to the vegetation distribution in the Shennongjia region.