Eucalyptus plantations are a significant carbon sink as a first growing species in Bangladesh, but little is known in terms of biomass, carbon output, and dynamics with stand age. We, therefore, assessed the stand structure, biomass accumulation, carbon storage, and their changing patterns with age in Eucalyptus camaldulensis plantations in the northern part of Bangladesh in early 2021. We used the data from 45 sample plots (100 sq. m each) covering different age classes such as 2, 5, 7, 8, 11, 13, and 21 years. The aboveground, belowground, and total biomass and carbon significantly varied between stand age (p<0.05). The highest aboveground (302.6 ± 10.9 Mg C ha−1), belowground (49.4 ± 1.6 Mg C ha−1) and total carbon (352 ± 12.5 Mg C ha−1) stocks were observed at the age of 21 years. In contrast, the lowest aboveground (0.8 ± 0.2 Mg C ha−1), belowground (0.3 ± 0.1 Mg C ha−1) and total carbon (1.1 ± 0.3 Mg C ha−1) stocks were at the juvenile stage (i.e., 2 years). We observed a positive and strong relationship between total carbon and stand variables such as stand height, diameter at breast height, basal area, density, crown width, crown length, and bole height. The mean annual increment of both biomass and carbon increased sharply up to seven years, and then started to decrease. Despite having some ecological constraints, eucalyptus spp. accumulate a large amount of carbon from the atmosphere, perhaps aiding in climate change mitigation
