ObjectiveTo analyze the carbon density of natural Pinus massoniana in southern Jiangxi Province of eastern China was to provide references for accurate estimation of forest carbon stocks in regional scale, and to develop scientific management of carbon sequestration forest.

MethodBased on the investigation of standard plots and the determination of carbon content, the distribution characteristics of carbon density of different stand ages, layers and components were analyzed by one-way ANOVA and LSD multiple comparison methods.

Result(1) the total carbon density of stand was 129.00 t/ha. The carbon density of different age groups ranked as mature forest (185.41 t/ha)>near-mature forest (140.54 t/ha)>middle-aged forest (114.21 t/ha)>young forest (75.83 t/ha). The carbon density of different layers followed a sequence of soil layer (80.02 t/ha)>arbor layer (43.81 t/ha)>understory vegetation layer (4.60 t/ha)>litter layer (0.57 t/ha), accounted for 62.03%, 33.96%, 3.57% and 0.44% of total carbon density, respectively. The distribution law of carbon density in different layers performed as follows: the arbor layer was trunk>branch>tree root>tree leaf, the understory vegetation layer was herb layer>shrub layer, the litter layer was half-decomposed layer>undecomposed layer, the carbon density of unit thickness at each soil layer decreased with the increase of soil depth. (2) The variation law of carbon density in different layers differed with the increase of stand age. The carbon density of arbor and soil layer increased along forest development, and in mature forest was the largest. The carbon density of different components of arbor layer in mature forest was significantly higher than in other age groups (P < 0.05), but there were significant differences in the carbon density of soil layer among different age groups (P < 0.05). The carbon density of understory vegetation layer decreased firstly and then increased with the increase of stand age, but in young forest was the largest. There were significant differences in the carbon density of shrub layer, herb layer and their components among different age groups (P < 0.05), the largest carbon density of shrub and herb layers was respectively in near-mature forest and mature forest. The carbon density of litter layer increased firstly and then decreased with the increase of stand age, the carbon density of undecomposed layer in near-mature forest was significantly higher than in other age groups (P < 0.05), and there were no significant differences in the carbon density of half-decomposed layer among different age groups (P>0.05).

ConclusionThe majority of carbon density of the natural Pinus massoniana ecosystem was stored in the arbor layer and soil layer. The carbon density of arbor layer and its components, and soil layer increased along forest development, but the changes in carbon density of understory vegetation layer, litter layer and their components did not display such a pattern.