## 3 Results  
### Annual Ecosystem Respiration  
Heterotrophic respiration was significantly different among the land cover types. It was lower in ES sites than in LPSF sites by 10 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\) and lower than in OP sites by 8 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\) (_p_ < 0.05) (Table 2 and Figure 3). Similarly, total soil respiration in ES (40.8 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) was significantly lower (_p_ < 0.05) than in PSF (48.5 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)), LPSF (50.2 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)), and OP (47.5 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)). All land cover types were similar in their autotrophic respiration, ranging from 9.3 to 10.8 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\). In addition, we found a very weak effect of environmental factors such as soil temperature and groundwater level (r\({}^{2}\) = 0.05) on respiration (heterotrophic and total soil). \begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Scheme**} & **Heterotrophic** & **Autotrophic** & **Total Soil** & **Water Table** & **Soil** \\  & **Respiration** & **Respiration** & **Depth** & **Temperature** \\ \cline{2-6}  & \multicolumn{4}{c}{**Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)**} & \multicolumn{2}{c}{**cm**} & \multicolumn{2}{c}{\({}^{\circ}\)**C**} \\ \hline Peat swamp forest 1 & 40.0 \(\pm\) 5.8 & 5.9 \(\pm\) 2.9 & 45.9 \(\pm\) 5.5 & 44.3 \(\pm\) 10.4 & 27.1 \(\pm\) 0.1 \\ Peat swamp forest 2 & 40.1 \(\pm\) 5.3 & 13.9 \(\pm\) 4.1 & 54.0 \(\pm\) 5.7 & 48.4 \(\pm\) 10.4 & 27.3 \(\pm\) 0.2 \\ Peat swamp forest 3 & 32.9 \(\pm\) 4.5 & 12.8 \(\pm\) 2.3 & 45.6 \(\pm\) 4.3 & 45.3 \(\pm\) 10.1 & 27.2 \(\pm\) 0.3 \\ Peat swamp forest mean (_n_ = 3) & 37.7 \(\pm\) 2.4 \({}^{\rm a}\) & 10.8 \(\pm\) 2.5 \({}^{\rm a}\) & 48.5 \(\pm\) 2.7 \({}^{\rm a}\) & 46 \(\pm\) 20.1 \({}^{\rm a}\) & 27.2 \(\pm\) 0.4 \({}^{\rm a}\) \\ \hline \end{tabular}
\end{table} 
Table 2: Heterotrophic, autotrophic, and total respiration, water table depth, and mean soil temperature in intact forest, logged peat forest, early serial, and oil palm estate are reported as mean \(\pm\) one standard error. Different lower-case letters represent the statistically significant difference (_p_ < 0.05) on a variable among land use types. Autotrophic respiration during wet months (4.7 and 3.2 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) was significantly lower (\(p\) < 0.05) than dry months (16.3 and 17.8 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) in LPSF and OP, respectively (Table 3). In contrast, heterotrophic respiration during wet months (45.7 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) was significantly higher than in dry months (28.8 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) in the oil palm estates (\(p\) = 0.001). During wet months, total soil respiration in oil palm estates was the highest among land cover types (48.9 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)). In this period, the heterotrophic respiration in PSF (36.7 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) was significantly lower than OP (45.7 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\); \(p\) < 0.01). The total and heterotrophic respiration of ES (38.8 and 29.7 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) were also significantly lower than OP (48.9 and 45.7 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\); \(p\) < 0.05). During dry months, total soil respiration in forests ranged from 53.4 to 54.7 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\) and was higher than in non-forest sites that ranged from 43.5 to 45.5 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\). In this period, heterotrophic respiration of OP (28.8 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\)) was lower than LPSF (38.4 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\); \(p\) = 0.006) and PSF (39.0 Mg CO\({}_{2}\) ha\({}^{-1}\) yr\({}^{-1}\); \(p\) = 0.09).