Does age matter? Unravelling the effects of replanted mangrove forests on the total ecosystem carbon stocks

Mangrove replanting is a fundamental approach for restoring the ecosystem services in the mangrove ecosystems. This study assesses and compares the total ecosystem carbon stock (TECS) in different stand ages of replanted mangrove forests (1, 2, 5, 9, 10 and 21 years old and an Intact/Undisturbed Forest as the control) in the west coast of Peninsular Malaysia. The preferred species for planting are Rhizophora mucronata, R. apiculata and Bruguiera parviflora, while the Intact Forest only has one species, Avicennia marina. Most sites recorded additional species recruits after a few years. The study determines the total ecosystem carbon stock (TEC) based on the above-ground standing trees, below-ground, dead wood and soil, uses the established allometric equations to calculate the biomass and carbon stock in vegetation, and determines the soil carbon using the LI method. In general, the results showed a linear relationship between the TECS and stand age (R=0.86, y=70.993x + 353.51). The ten-year-old stand had the highest TECS (875.79 Mg C ha −1), the one-year-old had the lowest (376.91 Mg C ha −1), and the Intact Forest was moderate at 530.57 Mg C ha −1. In all cases, soil contributed the highest percentage of 75%–98% to the TECS. The Principal Component Analysis (PCA) revealed that the primary determiners of the TECS are the stand age, followed by mangrove tree structure and soil carbon accumulation capacity.