Stand structure and above ground biomass of Kandelia obovata Sheue, H.Y. Liu & J. Yong mangrove plantations in Northern, Viet Nam

Abstract Forest structure and biomass production of Kandelia obovata Sheue, H.Y.Liu & J.Yong mangrove plantations in Northern Viet Nam were investigated for 1- to 20-year-old stands. The measurements were implemented over the study plots which were set up in 1-, 5-, 6-, 7-, 8-, 9-, 10-, 18-, 19- and 20-year-old K. obovata plantations. Tree density, stem diameter at 30 cm height (D0.3) and tree height (H) were measured. These parameters increased with stand age from young to mature stage with the ranges from 3,700 ± 1,609 tree.ha−1 to 26,500 ± 1,153 tree.ha−1, 0.67 ± 0.18 cm to 8.73 ± 3.16 cm, and 0.46 ± 0.16 m to 4.12 ± 0.96 m for density, stem diameter at 30 cm height and stem height, respectively. Fifty trees were harvested to find an allometric relationship between tree size and dry mass. Allocation models were developed to estimate above ground biomass. The Akaike Information Criterion (AIC), the Bayesian Information Criterion (BIC), the root mean square error (RMSE), R2, and P-value of the models were calculated and compared to find the fitness models for biomass evaluation. The best correlation satisfied between D0.3*H and dry mass of tree components and total above ground biomass (AGB). Our results showed a rise in above ground biomass of 1- to 20-year-old K. obovata plantations, which ranges from 0.04 ± 0.02 Mg ha−1 to 115.39 ± 15.34 Mg ha−1. Of this, ~87% of the above ground biomass was represented by stems and branches. Above ground biomass and its components linearly increased with stand age. It was found that the biomass in the study area increased with an annual rate of 4.33 Mg ha−1 yr−1. These results provide a view of mangrove plantations in assessing the biomass of mangroves continuously from young to mature stages of reforestation.