A Comparative Study On The Temporal And Spatial Distribution Of Carbon Density In Aerially-seeded Plantation And Natural Forest Of Pinus Massoniana

This paper investigated vertical distribution of carbon density between different age classes by dividing into two types(aerially-seeded plantation and natural forest), based on the standard investigation and sample determination of Pinus massoniana at different growth stages in the central and southern parts of Jiangxi Province, and proposed the corresponding management measures for the differences respectively. The main results were as follows:(1) The tree layer carbon density of same type between different age classes were increased with stand age and the differences were significant(P<0.05). At the age classⅡ, the trunks, branches and roots carbon density of aerially-seeded plantation were significantly lower than the natural forest(P<0.05), the differences were not significant at other age classes(P>0.05). The total carbon density of tree layer in aerially-seeded plantation were signficantly lower than natural forest at age classⅡ(P<0.05), no significant differences at age classⅢ-Ⅴ(P>0.05).(2) The understory vegetation and litter layer carbon density of the two types had no obvious variation with the increased of stand age, and had no significantly differences(P>0.05). At age classⅡ, the understory vegetation and litter layer carbon density of aerially-seeded plantation were signficantly lower than natural forest(P<0.05), but had no significantly differences with the stand age increased(P>0.05).(3) The soil organic carbon content and average carbon density of per 10 cm thickness of soil layer in the two types were decreased with the increased of the soil depth. The organic carbon density of 100 cm soil layerof the two types were being decreased in the order: age classⅤ>age classⅣ>age classⅢ>age classⅡ, and had significantly differences(P<0.05). The soil organic carbon density in aerially-seeded plantation were signficantly lower than natural forest at age classⅡ(P<0.05), but had no significantly differences with the stand age increased(P>0.05).(4) The ecosystem carbon density of the two types were increased with the stand age, the differences between the age classes were significant(P<0.05). The ecosystem carbon density of aerially-seeded plantation were signficantly lower than natural forest at age classⅡ(P<0.05), but the two types had no significantly differences with the stand age increased(P>0.05). The carbon density distribution ratio of each layer in the two types were: soil layer>tree layer>understory vegetation layer>litter layer. The carbon density between tree, soil layer and the ecosystem had a extremely significant positive correlation(P<0.01), the correlation coeffcient between soil layer and the ecosystem was the largest.(5) The carbon sequestration capacity of natural forest was better than the aerially-seeded plantation, therefore, forest conservation measures should be taken in the areas where have rich seed resource to protect the natural regeneration of vegetation. But aerially-seeded is also an effective means of rapid regeneration and achieving carbon sequestration fuction of forest in the areas where are lack of seed, large and inaccessible. Meanwhile, controlling rational stand density and replanting broad-leaved species can improve the ecosystem carbon density effectively.