## 5 Conclusions  
In this study, we developed an advanced observation system capable of simultaneously measuring gas exchange, actively induced chlorophyll fluorescence, and passively induced chlorophyll fluorescence. Using this system, we conducted comprehensive measurements of light response curves, \(\text{CO}_{2}\) response curves, and temperature response curves across 52 species representing seven PFTs. Our findings reveal that \(f_{\text{PSII}\_760}\) exhibited limited sensitivity to environmental variations. Moreover, \(\text{ChIF}_{\text{PSII}}\) derived from \(f_{\text{PSII}\_760}\) showed a strong correlation with that calculated based on PAM parameters (\(R^{2}=0.85\), \(\text{RMSE}=3.44\) umol m\({}^{-2}\) s\({}^{-1}\), and \(\text{rRMSE}=12.09\%\)). Additionally, we extended the semi-empirical model for \(q_{\text{L}}\) estimation proposed by [PERSON] et al. [22]. Our results demonstrate that the modeled \(q_{\text{L}\_{\text{MOD}}}\) could explain 90% of the observed \(q_{\text{L}\_{\text{PAM}}}\) variability (\(\text{RMSE}=0.09\) and \(\text{rRMSE}=10.01\%\)). With the increasing availability of satellite-based SIF observations, our findings provide a promising pathway for large-scale estimation of \(\text{ChIF}_{\text{PSII}}\) and \(q_{\text{L}}\). This advancement contributes to improving the ability to estimate GPP using SIF in a mechanistic framework, while also deepening our understanding of photosynthetic processes. **Supplementary Materials:** The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/s25061700/s1](https://www.mdpi.com/article/10.3390/s25061700/s1)]([https://www.mdpi.com/article/10.3390/s25061700/s1](https://www.mdpi.com/article/10.3390/s25061700/s1)): Text SI: Estimation of \(f_{\text{PSII},760}\); Figure S1: Elementary fluorescence emission spectrum of Photosystem II (\(S_{\text{PSII}}\), unitless) obtained from the SCOPE model, Version 1.73; Figure S2. The light response curve of the contribution of PSII to total chlorophyll fluorescence at 760 nm (\(f_{\text{PSII},760}\)) and 740 nm (\(f_{\text{PSII},740}\)): Figure S3: CO\({}_{2}\) response curve of (a) upward chlorophyll fluorescence (ChlF\({}_{\text{UP}}\), mW m\({}^{-2}\) nm\({}^{-1}\) sr\({}^{-1}\)) and (b) downward chlorophyll fluorescence (ChlF\({}_{\text{DOWN}}\), mW m\({}^{-2}\) nm\({}^{-1}\) sr\({}^{-1}\)). Temperature response curve of (c) upward chlorophyll fluorescence (ChlF\({}_{\text{UP}}\), mW m\({}^{-2}\) nm\({}^{-1}\) sr\({}^{-1}\)) and (b) downward chlorophyll fluorescence (ChlF\({}_{\text{POWN}}\), mW m\({}^{-2}\) nm\({}^{-1}\) sr\({}^{-1}\)); Table S1: The fitted parameters (\(m_{\text{opt}}\), \(H_{\text{d}}\), \(H_{\text{a}}\), and \(T_{\text{opt}}\)) of the ChlF\({}_{\text{PSII}}\)-\(q_{\text{L}}\) relationship for different species. References [43; 44; 45; 46] are cited in the supplementary materials. **Author Contributions:** Conceptualization, C.G. ; data curation, C.G. and Z.L. ; formal analysis, C.G. and X.L. ; funding acquisition, Z.L. and X.L. ; investigation, C.G. ; methodology, C.G. and Z.L. ; project administration, X.L. ; software, C.G. and Z.L. ; supervision, X.L. ; validation, C.G. ; writing--original draft, C.G. ; writing--review and editing, Z.L. and X.L. All authors have read and agreed to the published version of the manuscript. **Funding:** This work was supported by the National Natural Science Foundation of China (Grant No. 42071328 to X.L., and No. 41901293 to Z.L.) and the Chinese Universities Scientific Fund (24520212452021125 to X.L.). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data used for the analyses are available at [[https://github.com/luxiaoliangnwafu/Dataset-multiSpecies](https://github.com/luxiaoliangnwafu/Dataset-multiSpecies)]([https://github.com/luxiaoliangnwafu/Dataset-multiSpecies](https://github.com/luxiaoliangnwafu/Dataset-multiSpecies)) (accessed on 8 March 2025).