## 3 Results  
### SIF\({}_{757}\) Phenological Diversity across ER and Climate Zones  
The SIF\({}_{757}\) across ERs showed different spatial (Figure 2A) and temporal (Figure 2B) dynamics over the period from September 2014 to December 2018. We find subtle differences in SIF\({}_{757}\) phenology across different forest regions. MBF-ER (green values in Figure 2A) showed the highest SIF\({}_{757}\) values, but we also found that the SIF\({}_{757}\) from the DBF and GSS biomes was equal to or higher than that of the MBF-ER on reiterated occasions. We acknowledge that this SIF\({}_{757}\) variability, particularly that from GSS and DBF ER, may arise from natural or disturbed grasslands type vegetation, which we could not differentiate in the scope of our study. Moreover, we found a relatively higher temporal variability in the ERs close to the Andes (ERs 13 and 30), in those in the south and south-west (ER 9 and 18), and in those neighboring the non-MBF ERs, where forest cover is uncommon (Figure S2).  
Figure 2: (**A**) The distribution of monthly SIF\({}_{757}\) means for the period of 52 months across the 32 ecoregions (ERs) within the Amazon river basin displayed in the boxplot and grouped according to  
decreasing SIF\({}_{757}\) values in a gradient from top to bottom. In the boxplots, the boxes show the interquartile ranges, the solid lines indicate the median, the whiskers show values 1.5 times higher (upper whisker) and lower (lower whisker) than the interquartile range, and the black dots indicate outliers. The numbers on the right side of each boxplot are the number of months reported per ER. (**B**) The time-series of the monthly SIF\({}_{757}\) means and their standard errors for the observation period from September 2014 to December 2018. The colors in (**A**) and (**B**) indicate the biome type to which each ER belongs. The ERs belonging to the moist broadleaf forest (MBF) biome are stratified using three different levels of green based on their monthly means medians, with the thresholds \(<\)0.95; [0.95, 1.05]; and \(>\)1.05 W/m\({}^{2}\)/sr/\(\upmu\)m. (**C**) Orbiting Carbon Observatory-2 (OCO-2) solar-induced chlorophyll fluorescence (SIF) and MODIS Aqua absorbed fraction of the photosynthetically active radiation (fPAR) 15 day-resolution time-series for the period of September 2014 to December 2018. The signals are aggregated in Af, Am, and Aw Koppen-Geiger climate zones within the Amazon river basin.  
Although we did not determine the dry or the wet season for each ER, we observed a yearly phenological variation that resembles that of the climate zones in most ERs (Figure 2B), except for those with \(<\)0.95 W/m\({}^{2}\)/sr/\(\upmu\)m. These MBF-ER-SIFs remain relatively stable throughout the year compared to all other ER-SIFs from the MBF biome.  
The MBF-ERs cover approximately 5.2 million km\({}^{2}\) (\(\sim\) 87% of the Amazon basin) and five of these ERs are some of the most productive regions, with a monthly median SIF\({}_{757}\) of more than 1.05 W/m\({}^{2}\)/sr/\(\upmu\)m (ER 1, 2, 4, 5, and 6; \(\sim\)1.3 million km\({}^{2}\)). The gradient of the SIF\({}_{757}\) medians across the ERs (Figure 2A) indicates that the first five ERs, with a monthly median \(>\)1.05 W/m\({}^{2}\)/sr/\(\upmu\)m, may have a relatively higher contribution to SIF\({}_{757}\) within the basin. Among the 32 ERs under analysis, only 13 ERs reached or exceeded a monthly median of 1.25 W/m\({}^{2}\)/sr/\(\upmu\)m (ER 2, 3, 4, 5, 6, 7, 9, 12, 13, 14, 18, 20, and 28; \(\sim\)2.6 million km\({}^{2}\)). Five presented a notably wider interquartile range (\(\geq\)0.24 W/m\({}^{2}\)/sr/\(\upmu\)m), indicating a stronger seasonality (ER 1, 4, 7, 15, 26; \(\sim\)1.7 million km\({}^{2}\)).