| In this study,a laboratory incubation experiment was carried out to study the distributon of fresh carbon in soil carbon fractions by δ13 C method.Soil collected from natural forest of(Altingia gracilipes),secondary forests(Castanopsis carlesii),plantation(Cunninghamia lanceolata)and orchard(citrus orchard)in Jian’ou city,Fujian province,China.And to trace dynamics of fresh carbon in soil carbon fractions 13 C-labelled Cunninghamia lanceolata residual was applied to the soils,which were incubated at 20℃ for long time.And the soil samples were screened out free light fraction organic matter(free LF),coarse particulate organic carbon(cPOM),fine particulate organic carbon(fPOM),mineral-associated organic carbon(mSOC),then their quality percentage,the soil organic carbon(SOC),δ13C values were estimated.The study will provide scientific insights on distribution of soil organic carbon applied plant materials and the stability of soil organic carbon.1.With the increase of the residual quantity,the quality percentage of free LF increased.Particulate organic carbon(POM)and mineral-associated organic carbon(mSOC)decreased.After inputting in different quality residual,the quality percentage of free LF and POM showed leaf>root,and the mSOC in contrast.The effects of different land use types on the free LF showed Altingia gracilipes>Castanopsis carlesii>Cunninghamia lanceolata>citrus orchard,and the mSOC in contrast,the POM showed Castanopsis carlesii、Cunninghamia lanceolata>Altingia gracilipes>citrus orchard After inputting in orangic matter under different land use types,the quality percentage of different carbon fractions showed mSOC>cPOM>fPOM>free LF.2.With the increase of the residual quantity,the content of SOC was increasing in different land use types;After inputting in different quality residual,the content of SOC showed 1.2%root>1.2%leaf>CK.Although the quantity and quality of exogenous carbon were different,the content of SOC in different land use types showed Altingia gracilipes>Castanopsis carlesii>Cunninghamia lanceolata>citrus orchard.And different carbon fractions showed mSOC>POM>free LF.3.With the increase of the residual quantity,the content of fresh carbon was increasing;After inputting in different quality residual,the content of fresh carbon showed root>leaf.Although the quantity and quality of exogenous carbon were different,the proportion of the fresh carbon in mSOC is highest.And in heavy fractions showed mSOC>fPOM>cPOM.Land use types also affect the proportion of the fresh carbon in different carbon fractions.Under normal circumstances,with the increase of native soil organic carbon content,the proportion of the fresh carbon decreased. |
