Objective To compare the differences of biomass and its distribution pattern among plantations of 4 tree species in south subtropical area, provide data for evaluating the production capacity and carbon sink potential of plantation, and provide support for the selection of tree species for improving quality and efficiency of regional plantation and building high-efficiency carbon sink forest.

Method The biomass and its distribution pattern of 33-years-old Schima superba, Mytilaria laosensis, Nyssa sinensis and Cunninghamia lanceolata plantations planted in the same period on Pinus massoniana clear-cutting site in Liuzhou City, Guangxi, were studied by the method of standard plot investigation combined with biomass measurement.

Result Under the same site conditions, management measures and forest age, there were significant differences in tree layer and stand biomass among different tree species plantations, the order of stand biomass was S. superba plantation (376.37 t·hm⁻²) > M. laosensis plantation (284.51 t·hm⁻²) > C. lanceolata plantation (200.02 t·hm⁻²) > N. sinensis plantation (175.56 t·hm⁻²). The biomass of tree layer accounted for 93.0%-98.3% of the stand biomass, which was in an absolute dominant position. The biomass of shrub and herb layers accounted for a relatively low proportion (0.9% in average) and had a large spatial heterogeneity but no significant difference among different plantations. The biomass proportion of humus layer (2.3% in average) was higher than that of shrub and herb layers, and the humus pool of S. superba plantation was significantly higher than that of the other three plantations. The distribution pattern of biomass in tree layer was the largest in trunk, followed by root or branch, and the lowest in leaf. The distribution pattern of biomass in shrub and herb layers was different among different plantations.

Conclusion In south subtropical plantation management and stand transformation, the selection of fast-growing broad-leaved tree species for afforestation can obtain higher stand productivity and carbon sequestration benefits than coniferous forest. It is suggested to take appropriate control measures to increase understory vegetation and to increase the system stability and sustainable development potential.