Stand Development and Aboveground Biomass Carbon Accumulation with Cropland Afforestation in Taiwan

Afforestation in low-carbon-density areas has been proposed for mitigating climate change, because it leads to a reduction in the atmospheric carbon dioxide concentration. However, afforestation can be conducted for numerous purposes, and the complexity of tree species may render accurate estimation of the carbon (C) sequestration potential difficult. In this study, 22 cropland afforested plantations among 12 tree species and 4 study sites were investigated. We investigated stand development and aboveground biomass C accumulation of cropland afforestation in Taiwan, and examined how tree species and site conditions affected stand growth and yields. Results showed that average values of the mean diameter at breast height, tree height, stand density, and aboveground biomass C stocks for all studied plantation at 8~10 yr after planting were 12.1 cm, 8.5 m, 1272 trees ha^(-1), and 32.1 Mg C ha^(-1), respectively. The results also revealed that fast-growing tree species such as Swietenia macrophylla and Melia azedarach attained the highest growth rates and accumulated the most biomass C stocks, whereas slow-growing tree species such as Zelkova serrata exhibited the lowest growth rate and C accumulation potential. Trees grown at sites with deep soils outperformed those grown at sites with shallow and rocky soils. Overall, current cropland afforestation in Taiwan can enhance C sequestration, and also generate economic and ecological benefits.