## 4 Discussion
### Limitations and Perspective  
Although this study enhances our understanding of the impact of extreme CHD events of varying intensities on GPP, several limitations remain and should be addressed in future research. First, due to the limited availability of data, this study only analyzed three extreme CHD events in the YRB, which may constrain the representativeness and generalizability of the findings. Second, the lack of continuous observational data prevented us from incorporating site-level measurements for validation. Third, further model validation and a more precise quantification of the contributions of different influencing factors are crucial aspects that need to be refined in future studies.  
These limitations also highlight key directions for future research. First, the study of tipping points in GPP responses to extreme CHD events remains an area in urgent need of further exploration. Existing studies have shown that GPP responses to extreme CHD events exhibit significant regional differences on a global scale. For example, in mid-latitude regions such as Europe and North America, CHD events (e.g., the 2003 European heatwave) have led to substantial GPP reductions [12], while the responses of high-latitude boreal  
Figure 10: The scatterplot of the relationship between anomalies in GPPGOSIF (X-axis) and GPPFluxSat (Y-axis) for the three CHD years. Panels correspond grid points dominated by (**a**) evergreen forests (EF), (**b**) deciduous forests (DF), (**c**) mixed forests (MF), (**d**) shrubs, and (**e**) crops, respectively. The numbers represent the correlation coefficients between the two GPP products, and the two asterisks indicate a significant correlation (\(p\) < 0.01).  
forests are more complex--warming may extend the growing season but can also exacerbate water stress [47]. Therefore, future research should incorporate a broader selection of extreme CHD events of varying intensities across different regions worldwide. A systematic investigation of the diverse GPP response characteristics, particularly the identification and mechanistic understanding of GPP tipping points, will be a crucial direction for future studies. Second, establishing a long-term, continuous site observation system on a global scale is essential. This would not only enhance our understanding of key processes and factors influencing terrestrial ecosystem carbon cycling but also provide reliable data support for model validation. Future efforts should focus on expanding global terrestrial ecosystem observation networks, particularly in data-scarce regions such as the tropics and high-latitude areas [17, 48]. Third, developing terrestrial ecosystem models that accurately capture the responses of the land carbon cycle to extreme CHD events is another crucial research priority. This requires integrating multi-source observational data and improving model parameterization schemes, particularly by enhancing the representation of key processes such as plant physiological responses, soil moisture dynamics, and ecosystem resilience [49, 50]. Furthermore, incorporating emerging technologies such as machine learning into model development should be considered to improve both prediction accuracy and interpretability [51].