## 4 Discussion  
### How Is the Seasonal Dynamics of the Forest in the Southwest Portion of the Amazon?  
Seasonally, the phenological and physiological aspects show a diverse articulation in terms of survival strategy during the dry season, which, on average, reaches a total rainfall of \(\sim\)250 mm in the 5 (five) months duration. Stem growth is prioritized in the wet season, and leaf renewal (see litter and Gcc) in the dry season (Figure 8). Plant investment in different tissues, following climatic seasonality, was also observed in other Amazonian sites [25]. The seasonality of stem growth occurs in phase with the seasonality of precipitation (\(R^{2}\) = 0.44, \(p\)-value = 0.001) (Figure 8), this trend was observed in several biomes [3; 59; 68; 69]. In tropical forests, the relationship between stem growth and rainfall has been observed regardless of whether water or light availability acts as a limiting factor [3; 69], as low water availability inhibits cell expansion process [70]. [68] state that small rainfall events can accelerate radial growth, even without moistening the soil or fully rehydrating the tree. This indicates that more important than water stored in the soil is rainfall for stem growth, and a change in rainfall patterns over this region can lead to effects on stem growth.  
In the dry season, we also observed lower photosynthetic activity (represented by the EVI) and increased production of new leaves (represented by the Gcc and Litter) (Figure 8). This suggests that leaf renewal, in addition to weather conditions, is also related to the seasonality of wood growth, since the increase in the number of new leaves diverts energy from wood formation to the formation of leaf tissues [19]. The seasonality of stem growth following the seasonality of the EVI confirms this energy partition, as wood formation tends to occur in the season with greater availability of resources, e.g., water, nutrients and  
Figure 7: Relationship between DBH and HSM of species sampled in RJA. (**A**) Relationship of DBH and HSM of all measured trees; (**B**) Relationship of DBH and HSM excluding two outlier points.  
carbon. The reduction in stem growth at the RJA site during the drought corroborates global studies that have observed a decrease in net primary productivity driven by drought [1] and a decrease in stem growth in much of the Amazon [26; 71].  
Total litter increased in the dry season and decreased in the wet season (Figure 8), which corroborates the seasonality of the EVI, showing an increase in the wet season and decrease in the dry season with 3 months lag (\(R^{2}\) = 0.64, \(p\)-value \(<\) 0.001), when new leaves are expected to reach maturity 3-5 months after being produced [72; 73], thus increasing the photosynthetic activity of the canopy.  
Historical average of Gcc, is an important index to characterize leaf renewal in the study area, and to identify a bi-seasonal leaf flush aspect. However, its use to assess the seasonality of canopy phenology on a reduced time scale needs to be carefully analyzed due to the rapid response of this index to changes in the canopy in terms of leaf loss and renewal, which occurs throughout the entire year.