# Evaluating Litter Yield and Decomposition for Re-Vegetated Mangroves in a Subtropical Mudflat
## 4 Discussion
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Location** & **Tree Age (year)** & **Tree Height (m)** & **Litter Yield (g m\({}^{-2}\))** & **Literature Source** \\ \hline Zhuhai, China (22\({}^{\circ}\)23\({}^{\prime}\) N; 113\({}^{\circ}\)36\({}^{\prime}\) E) & 9 & 5.5 & 745 & This study \\ Jiulong Estuary, Fujian, China (24\({}^{\circ}\)24\({}^{\prime}\)) & 30 & 6 & 863 & [29] \\ N; 117\({}^{\circ}\)55\({}^{\prime}\) E) & 30 & 2.0 & 2.0 & 2.0 \\ Nansha, Guangzhou, China (23\({}^{\circ}\)01\({}^{\prime}\) N; 113\({}^{\circ}\)41\({}^{\prime}\) E) & - & - & 460 & [30] \\ Shenzhen, China (22\({}^{\circ}\)31\({}^{\prime}\) N; 114\({}^{\circ}\)00\({}^{\prime}\) E) & 30 & 6.3 & 603 & [31] \\ Leizhou Peninsula, China (20\({}^{\circ}\)41\({}^{\prime}\) N; 110\({}^{\circ}\)12\({}^{\prime}\) E) & - & - & 848 & [32] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: A comparison of annual litter yield of _Heritiera littoralis_ at different locations along the South China coast. Figure 4: Relationship between the length of field incubation with the decomposition rate of the mangrove litter for (**a**) the branch of _Heritiera littoralis_; (**b**) the leaf of _Heritiera littoralis_; (**c**) the branch of _Thespesia populnea_; (**d**) the leaf of _Thespesia populnea_; (**e**) the branch of _Kandelia obovata_; and (**f**) the leaf of _Kandelia obovata_. decreased. This suggests that the carbon input, if any, into the soils from the decomposing mangrove litter was less than the carbon output from the soils due to decomposition of the soil-borne organic carbon. This might be due to the fact that the products of litter decomposition at the initial stage were mainly of highly soluble low-molecular-weight organic acids that were not retained by the soils [33; 34]. The increase in soil organic carbon content from the 90 th to the 180 th day may be attributed to the slowing mineralization of soil organic carbon due to reduced microbial activities under winter conditions. After winter, the mineralization of soil organic matter increased as a result of increasing temperature, leading to the exceedance of soil carbon loss over the soil carbon input. This may explain the decrease in soil organic carbon from the 180 th to the 270 th day. The marked increase in soil organic carbon from the 270 th to the 360 th day probably reflects the increased input of soil organic carbon from the decomposing mangrove litter because of the increasing production of high-molecular-weight organic acids, which tended to be recalcitrant to rapid decomposition. The formation of humic substances allowed for the retention of soil organic carbon. Under the field incubation conditions, an annual soil carbon increase from 2.37 to 4.64 g/kg in the top 5 cm of the soil was recorded for the investigated mangrove species. This transforms into an annual soil carbon capturing of 3.61 t C/ha for _Heritiera litteralis_, 2.41 t C/ha for _Kandelia obovata_, and 2.39 t C/ha for _Trespesia populnea_. There are approximately 22,260 ha of barren mudflats along the South China coast. Therefore, some 154,518 to 233,392 tons of carbon could potentially be sequestered through mangrove planting in the mudflats.