Above-ground and soil carbon sequestration of white poplar (Populus alba L.) species in four different planting spaces in Chaharmahal and Bakhtiari province

Sequestration of atmospheric carbon in plant and the underlying soil is a mechanism to encounter the global warming. This study investigated carbon sequestration in biomass and soils of Chaharmahal and Bakhtiari’s poplar plantations. To this aim four one-ha regions were initially selected, in which Populus alba seedlings were planted. The 10-year individuals were planted at four different planting spaces (0.5×0.5, 1×1, 2×2 and 4×4 m). From each of the areas 10 trees (total number of 40 trees) were selected and felled. They were immediately weighted, and the wet weights for different tree parts were recorded separately. Biomass was derived after sampling carbon stocks, which revealed that the highest sequestration rates in tree organs is accumulated in trunk, branches, twigs and leaves, respectively. The sequestrated carbon in the biomass was derived by burning in electrical kiln. In addition, 10 soil samples were randomly drawn from two different depths (0 to 15 and 15 to 30 cm) across each region. The Walkley-Black method was applied to obtain the amount of carbon sequestration in the soil. The highest amount of sequestrated carbon (226.465 ton per ha) was recorded for 0.5×0.5 m planting space. The results indicated a 50% decrease in carbon sequestration along with increasing the planting space, with 79.6 and 76.3 tons per ha in 0.5 m and 1 m space, whereas 37.6 tons per ha was sequestrated in low-density plantation.