Growth, biomass, carbon stocks, and sequestration in an age series of Populus deltoides plantations in Tarai region of central Himalaya

Growth, biomass, carbon storage, and carbon sequestration potential along an age series in Populus deltoides plantations were assessed. The growth rate of diameter at breast height and height was higher in trees of 4 to 7 years and 2 to 5 years, respectively. The total aboveground biomass (AGB) increased with age and reached its maximum (180.2 Mg ha^–1) at 11 years of age. Mean carbon concentration in aboveground components varied from 39.7% to 51.7%. Allometric equations were developed to estimate biomass and biomass carbon in different tree components, which had adjusted R squares greater than 94%. Aboveground carbon stocks in P. deltoides increased from 0.5 Mg ha^–1 at 1 year to 90.1 Mg ha^–1 at 11 years. The carbon sequestration rate (i.e. carbon sequestrated in wood products and by the substitution of biomass for coal) in mature plantations (7–11 years) varied from 5.8 to 6.5 Mg C ha^–1 per year. Soil carbon stocks increased with age (1–11 years) from 61.2 to 66.8 Mg ha^–1 and decreased with soil depth. Soil carbon stock in different ages of plantations varied from 63.9 to 83.8 Mg ha^–1 at 0–30 cm depth, 57.5 to 60.1 Mg ha^–1 at 30–60 cm depth, and 55.5 to 59.7 Mg ha^–1 at 60–90 cm depth. The amount of total carbon stock (AGB and soil) increased from 64.4 Mg ha^–1 at 1 year to 173.9 Mg ha^–1 at 11 years. This study recommends P. deltoides planting as a viable option for sustainable production and carbon mitigation.