## 3 Results and Discussion
### Soil Respiration  
Soil respiration accounted for 11% in fringing forests, 6.5% in fringing forests and 14% of GPP in P fertilized scrub forests (Table 2). Using values of root respiration and annual root production rates from [15], we estimated the proportion of soil respiration that may be due to root metabolism (Table 3). Approximately 100% of soil respiration could be due to root respiration in the seaward fringing forest and P fertilized scrub forests, while only 20% of soil respiration can be accounted for by root respiration in the scrub habitat, the balance (80%) is then attributed to respiration of the microbial community.  
That respiration of roots could completely account for soil respiration in both the seaward fringing forests and P fertilized scrub forest suggests low activity of the heterotrophic microbial community, consistent with high level of accumulation of organic matter in mangrove ecosystems [1, 2, 3, 4, 5]. Our estimates of the amount of live roots are probably underestimated because under control conditions (not fertilized) root mortality was not observed during the experiments of [PERSON] _et al._[15]. In Florida, fine to small roots had longevities of 1.7 to 4.4 years [64], indicating that the abundance of live roots may be much larger than annual production and thus root respiration could be \(\sim\)2 to 4 times higher than our conservatively estimated value. Studies in terrestrial forests have also found that root respiration can be a major component of soil respiration [65]. However, respiration of the microbial community contributed 80% of the CO\({}_{2}\) flux in the scrub habitats. The C sources and nutrients supporting microbial respiration in the scrub forests are derived from litter and the microbial mats [37,38] but may also be from the mangrove peat. High rates of CO\({}_{2}\) emissions were observed following clearing of mangroves at Twin Cays [18] suggesting that the peat may be decomposed under some conditions [66] and also that living tree roots may suppress decomposition of soil organic matter [67]. Although anoxia due to tidal flooding contributes to slow rates of decomposition of soil C in mangroves, other factors, potentially associated with productivity of trees, e.g., competition for limiting P, may also play important roles in suppressing microbial metabolism and thus decomposition of soil organic matter [67].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Budget Components**} & \multicolumn{3}{c}{**Forest Type**} \\ \cline{2-4}  & **Fringe** & **Scrub** & **P fertilized Scrub** \\ \hline Soil Respiration & 61.2 & 34.7 & 92.7 \\ \hline Root respiration & 64.2 & 6.9 & 102.4 \\ (stock \(\times\) respiration rate) & & & \\ \hline Microbial respiration (by difference) & \multirow{2}{*}{\(-\)3.0 (\(-\)5\%)} & \multirow{2}{*}{27.8 (80\%)} & \multirow{2}{*}{\(-\)9.7 (\(-\)10\%)} \\ (\% of soil respiration) & & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Rates of soil respiration in mol C m\({}^{-2}\)-year\({}^{-1}\) from mangrove forests of Twin Cays, Belize and estimates of the components of soil respiration due to root respiration and respiration of the microbial community.