## 5 Conclusions  
This study simultaneously monitored SIF and Tr in three plantations in northern China, focusing on analyzing the species-specific responses of the SIF-Tr relationship to environmental changes and using SIF along with environmental factors to model Tr. The study found significant differences in the dynamic patterns of SIF and Tr among different tree species. As the season progressed, the deciduous species showed a decline in SIF and Tr in September due to leaf senescence, while the evergreen species did not exhibit the same trend. With the aggregation of temporal scales, the correlation between SIF and Tr strengthened. There is a threshold in the influence of environmental factors on SIF and Tr, which affects the SIF-Tr relationship. Incorporating environmental factors into the SIF model significantly improves the accuracy of Tr simulation. The extent of accuracy improvement and the selection of environmental factors are influenced by temporal scales and tree species. The influence of the environment on SIF, Tr, and the SIF-Tr relationship shows significant species specificity. Currently, the vegetation functional classification used in remote sensing may obscure the SIF-Tr relationship among different tree species. Therefore, future research should supplement observational datasets from various tree species and build a comprehensive understanding of how environmental factors influence SIF and Tr, to achieve reliable applications at the remote sensing scale.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/rs17091625/s1](https://www.mdpi.com/article/10.3390/rs17091625/s1)]([https://www.mdpi.com/article/10.3390/rs17091625/s1](https://www.mdpi.com/article/10.3390/rs17091625/s1)), Text S1: Calculation of fluorescence escape ratio (fesc); Text S2: Partial correlation analysis; Figure S1: The impact of PAR on SIF (left) and Tr (right) in Chinese cork oak (hollow triangle), poplar (hollow square), and arborviate (solid square) plantations; Figure S2: Diurnal dynamics of the fluorescence escape ratio (fesc) in Chinese cork oak (a), poplar (b), and arborviate (c) plantations under different weather conditions; Figure S3: The partial correlation coefficient of SIF and Tr with different environmental factors as controlled variables in plantations at half-hour (a) and daily (b) scales; Figure S4: The partial correlation coefficients of VPD with SIF and Tr after controlling for PAR (a) and Ta (b) in plantations at half-hour and daily scales.  
Conceptualization, J.Z. and S.S.; methodology, M.H. and X.C.; software, M.H. and X.W.; validation, Q.P. and C.G.; data curation, X.G. and Z.L.; writing--original draft preparation, M.H.; writing--review and editing, J.Z.; visualization, M.H.; supervision, J.Z. and S.S.; funding acquisition, S.S. All authors have read and agreed to the published version of the manuscript.  
This study was funded by grant number CAFYBB2023 PA001.  
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.  
We thank [PERSON] from Nanshan Forest Farm for the in situ observations. We are grateful to [PERSON], [PERSON], and [PERSON] for assistance with instrument maintenance.  
The authors declare no conflicts of interest.