## 3 Results and Discussion
#### 3.2.4 Combined Effect of Temperature and Precipitation Extremes on Daily CO\({}_{2}\) Fluxes  
In the second step, we examined the combined effect of temperature and precipitation on CO\({}_{2}\) fluxes (Figure 7). The most significant impact on daily CO\({}_{2}\) fluxes had the aggregated effect of cold/wet (CW) conditions, i.e., extremely high precipitation and extreme low temperatures (Figure 7b). In all considered stations, the CW conditions were mostly associated with positive CO\({}_{2}\) flux anomalies: 20-100% of the days with CW conditions corresponded to CO\({}_{2}\) flux anomalies exceeding 1 STD. Maximum simultaneous occurrences of CW and positive CO\({}_{2}\) flux anomalies were observed in evergreen forests, whereas they were rare in the tropical rain forests and tropical seasonal deciduous forests. The increase in the release of CO\({}_{2}\) into the atmosphere under CW conditions likely resulted from the combined effect of GPP and ER changes: cold, wet, and cloudy weather promoted reduced plant photosynthesis and GPP; cold weather led to a decrease in ER; and increased soil water content, SWC (at SWC < field capacity), may have, in turn, resulted in ER increase. The surface water logging under abundant precipitation may have resulted in reduced GPP because of hypoxia and increased heterotrophic soil respiration [55; 56]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Types of Tropical**} & \multirow{2}{*}{**Stations**} & \multicolumn{4}{c}{**Correlation Coefficients between Daily**} \\
**Ecosystems** & & \multicolumn{4}{c}{**Temperature, Precipitation, and CO\({}_{2}\) Fluxes**} \\ \hline \hline \multirow{8}{*}{Savannas} & \multicolumn{2}{c}{**T STD**} & \multicolumn{1}{c}{**T Q90**} & \multicolumn{1}{c}{**T Q95**} & \multicolumn{1}{c}{**P Q90**} & \multicolumn{1}{c}{**P Q95**} \\ \cline{2-7}  & AU-Ade & \(-\)0.17 & \(-\)0.08 & 0.11 & 0.14 & **0.27** \\ \cline{2-7}  & AU-Dry & 0.12 & 0.04 & 0.11 & 0.14 & 0.17 \\ \cline{2-7}  & AU-RDF & **0.33** & \(\mathbf{-0.40}\) & \(\mathbf{-0.32}\) & 0.16 & 0.17 \\ \cline{2-7}  & CG-Tch & \(-\)0.07 & 0.02 & 0.05 & 0.14 & **0.20** \\ \cline{2-7}  & SD-Dem & \(-\)0.07 & 0.25 & \(\mathbf{0.34}\) & 0.06 & \(-\)0.03 \\ \cline{2-7}  & SN-Dhr & \(-\)0.18 & \(-\)0.23 & \(\mathbf{-0.30}\) & 0.18 & 0.14 \\ \hline \multirow{8}{*}{Evergreen broadleaf forests} & \multicolumn{2}{c}{BR-Sa1} & \(-\)0.14 & 0.04 & 0.04 & 0.16 & 0.23 \\ \cline{2-7}  & AU-Rob & **0.34** & **0.39** & 0.01 & **0.71** & **0.81** \\ \cline{2-7}  & GH-Ank & \(-\)0.10 & 0.29 & 0.25 & \(-\)0.14 & \(-\)0.21 \\ \cline{2-7}  & MY-PSO & \(\mathbf{-0.30}\) & \(-\)0.11 & \(-\)0.14 & **0.33** & **0.37** \\ \hline Grasslands & AU-Stp & 0.04 & \(-\)0.04 & 0.06 & \(-\)0.09 & \(-\)0.11 \\ \hline \multirow{2}{*}{Permanent wetlands} & AU-Fog & \(-\)0.13 & \(\mathbf{-0.41}\) & \(\mathbf{-0.32}\) & 0.09 & 0.11 \\ \cline{2-7}  & PE-QFR & \(\mathbf{-0.33}\) & 0.07 & \(-\)0.17 & 0.17 & 0.23 \\ \hline Deciduous needleleaf forest & BR-CST & \(\mathbf{-0.51}\) & \(-\)0.17 & \(-\)0.17 & 0.16 & **0.31** \\ \hline Tropical rain forest & BNS & 0.12 & \(-\)0.05 & 0.07 & 0.07 & \(-\)0.03 \\ \hline \multirow{2}{*}{Tropical season deciduous forest} & MKL & \(-\)0.04 & \(-\)0.04 & 0.09 & \(-\)0.07 & \(-\)0.17 \\ \cline{2-7}  & Zm-Mon & \(-\)0.13 & \(-\)0.06 & \(-\)0.16 & 0.12 & **0.23** \\ \hline \hline \end{tabular} Statistically significant correlation coefficients (\(p\) < 0.05) are shown in bold.  
\end{table} 
Table 1: Correlation coefficients between daily temperature anomalies, daily precipitation amounts above thresholds and daily net CO\({}_{2}\) flux anomalies. Figure 7: The percentage of the days with daily net CO\({}_{2}\) flux (NEE) anomalies, exceeding STD, observed during the periods of extremely hot/wet (**a**), cold/wet (**b**), hot/dry (**c**), and cold/dry (**d**) conditions. The effect of hot/wet (HW) anomalies on daily CO\({}_{2}\) fluxes was manifested only in savannas and woody savannas, and they could lead to both positive and negative CO\({}_{2}\) flux anomalies.