摘 要(英文)：Based on the determinations of soil organic matter (SOM) content ,SOMΔ 14C ,and SOMδ13C of the samples collected by thin2layered sampling method ,this paper studied the spatial and temporal differentiation of SOMδ13C in the soil profiles at different altitudes in Dinghushan Biosphere Reserve. The results showed that the vertical
differentiation of SOMδ13 C at different altitudes was controlled by the development of soil profile ,and closely
correlated with the composition of SOM and its turnover processes. The fractionation of carbon isotope was hap2
pened during both the transformation of vegetation debris into topsoil organic matter (OM) and its regeneration
after the topsoil buried ,which resulted in a significant increase of SOMδ13C. Relative to plant debrisδ13C ,theδ13
C increment of topsoil OM was more dependent on its turnover rate.Both theδ13C of plant debris and topsoil OM
increased with altitude ,indicating the regular variation of vegetations with altitude ,which was consensus to the
vertical distribution of vegetations in Dinghushan Biosphere Reserve. Soil profiles at different altitudes had similar
characteristics in vertical differentiation of SOMδ13C ,vertical distribution of SOM content ,and increasing appar2
ent age of SOM 14C with soil depth ,which were resulted from the successive turnover of SOM during the devel2
opment of soil profile. The maximum depth of SOMδ13 C in soil profile was different in origin and magnitude with the penetration depth of 14C produced by nuclear explosion in the atmosphere ,indicating the controlling effects of topography and vegetation on the distribution of SOM carbon isotope with soil depth.
鼎湖山土壤有机质δ13C 时空分异机制