# Phenology and Seasonal Ecosystem Productivity in an Amazonian Floodplain Forest
## Results  
Seasonal Meteorological, Gross Primary Productivity (GPP) and Enhanced Vegetation Index (EVI) Patterns  
The seasonal variation of GPP and its interaction with environmental drivers (rainfall, evapotranspiration, cumulative water deficit, vapour pressure deficit, soil moisture, net radiation \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameter** & **Acquisitions** & **Start Year** & **End Year** & **Usage** \\ \hline LE & Tower & 2004 & 2014 & ET computation \\ PAR & Tower & 2011 & 2013 & NEE computation \\ Press & Tower & 2004 & 2014 & Relative humidity (RH) computation \\ q & Tower & 2004 & 2016 & RH and VPD computation \\ Rn & Tower & 2004 & 2014 & Correlation variable \\ GPP & Tower & 2011 & 2013 & Productivity estimate/Correlation variable \\ ET & Tower & 2004 & 2014 & Correlation variable \\ VPD & Tower/Satellite & 2004 & 2016 & Correlation variable \\ Ta & Tower/Satellite & 2004 & 2016 & VPD and ET computation/Correlation variable \\ Rainfall/TRMM & Tower/Satellite & 2004 & 2014 & Correlation variable \\ CWD & Tower/Satellite & 2004 & 2016 & Correlation variable \\ EVI & Satellite & 2004 & 2016 & Phenology and productivity proxy/Correlation variable \\ Soil moisture & Field & 2014 & 2016 & Correlation variable \\ Litterfall & Field & 2004 & 2005 & Phenology proxy/Correlation variable \\ Flood height & Tower & 2004 & 2016 & Define seasonal flooding \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Availability and usage description of tower, satellite and field data. and temperature) and phenology (described through EVI), showed different patterns among periods of the year. We observed an extended dry season from May to September, when rainfall was below 100 mm\(\cdot\)month\({}^{-1}\), while ET remained high through all seasons (mean of 110 mm\(\cdot\)month\({}^{-1}\)), especially during the flooding (Figure 2a). This high ET values indicated that soil moisture was sufficient to attend the atmospheric demands, which were described by the increased VPD (Figure 2c) and decreased CVD from April to August (Figure 2b). Although ET at this site exhibited a flat pattern, slight maximum values coincided with maximum GPP (Figure 2f), but the first and more pronounced peak occurred in March (123 mm), mid-flooding, in response to an increase of Rn at this month (Figure 2e). The second peak occurred in June/July (116 mm), mid-dry season, and a third in December, mid rainy season (122 mm), before the period of flooding. Net radiation did not seem to be the main productivity driver on this site, since during the months of highest GPP values (June and December), Rn varied between 276 and 282 W\(\cdot\)m\({}^{2}\), respectively, and not close to the maximum value of 314 W\(\cdot\)m\({}^{2}\) in August (Figure 2e). Soil moisture seems to be the main productivity driver at this forest (Figure 2d). Soil water content remained relatively constant from March to June, especially for layers at 20 cm, 40 cm, 80 cm, and 200 cm depth, indicating that the soil was 100% saturated. Layers at both 150 cm and 293 cm depth remained saturated for a longer time, extending until July and August, respectively. During the months of maximum GPP (June and December), the mean soil moisture of layers at 20 cm, 40 cm, 80 cm, and  
Figure 2: Average annual cycle of ET (2004 to 2014; black line) and rainfall from TRMM (2004 to 2016; dark grey bar) (**a**), cumulative water deficit (2004 to 2016; CWD) (**b**), vapour pressure deficit (2004 to 2014; VPD) (**c**), soil moisture (2004 to 2016; SM) and flood height (2004 to 2016; dark blue line) (**d**), net radiation (2004 to 2016; dashed black line) and air temperature (2004 to 2014; brown solid line) (**e**), GPP (2011 to 2013; black solid line) (**f**), and EVI (2004 to 2016; long dashed black line) (**g**). The shaded blue area corresponds to the flooded period. 200 cm were 0.541 and 0.501 m\({}^{3}\) m\({}^{-3}\). Conversely, in April and August (months of minimum GPP), the average volumetric soil moisture content was 0.585 and 0.344 m\({}^{3}\) m\({}^{-3}\), respectively.