Many studies have increased our knowledge about the dynamics of C in mangrove forests. We still lack, however, a complete understanding of the dynamics of sedimentary organic carbon (SOC) in the mangrove forests. Sedimentary organic carbon (SOC) was quantified in two mangrove plantations and a nearby barren site based on measurements of C and C isotopes in sediment cores.we (1) quantified SOC accumulation in both plantations and in a reference barren flat located between the plantations; (2) separated SOC decomposition stages in both plantations based on vertical variations of ƒÔ13C values; and (3) estimated the contributions of new C to the total SOC in both plantations.
Results/Conclusions
Relative to the barren site, the native Kandelia candel plantation and the exotic Sonneratia apetala plantation greatly affected values for SOC content, ƒÔ13C, and 14C age from 0 to about 60 cm but not at greater depths. SOC densities to a 60-cm depth were 155 and 174 Mg ha-1 in the native and exotic plantation, respectively. Change of SOC ƒÔ13C with depth was similar in both plantations, and the new contributions to the total SOC in the upper 16 cm were also similar (45–47%). At 16–60 cm, however, the new C contributions were only 9% in the native plantation but as high as 31% in the exotic plantation, i.e., the exotic S. apetala stored more mangrove-derived new C in its anaerobic sub-surface than the native K. candel. From the perspective of SOC storage, S. apetala rather than K. candel is recommended for restoring the degraded coastal area in Southern China.