
%0 Journal Article
%A Liu, Q. M. 
%A Wang, S. J. 
%A Piao, H. C. 
%A Ouyang, Z. Y. 
%T The changes in soil organic matter in a forest-cultivation sequence traced by stable carbon isotopes
%J Soil Research
%D 2003/11/27
%V 41
%N 7
%P 1317-1327
%K dynamics, soil organic matter (SOM), &#948;13C values.
%R https://doi.org/10.1071/SR03004
%U https://www.publish.csiro.au/paper/SR03004 
%X There is an obvious difference in &#948;13C values between plants that assimilate carbon via the C3 photosynthetic pathway and those that do so by the C4 photosynthetic pathway. In terms of this characteristic, we analysed the organic carbon content and &#948;13C values of total soil and &#948;13C values in different size and density fractions of profile-soil samples either in farmland or in forestland near the Maolan Karst virgin forest, south-west China. This is an area where C3 plants grew previously, now replaced by C4 plants. Deforestation has accelerated the decomposition rate of soil organic matter and reduced the proportion of active components in soil organic matter and thus soil fertility. The &#948;13C values of different size fractions in forest soil are &#948;13Ccoarse sand &#60; &#948;13Cfine sand &#60; &#948;13Ccoarse silt &#60; &#948;13Cclay &#60; &#948;13Cfine silt, and the &#948;13C values of different size fractions in farmland soil are &#948;13Ccoarse sand &#62; &#948;13Cfine sand &#62; &#948;13Ccoarse silt &#62; &#948;13Cclay &#62; &#948;13Cfine silt, indicating that soil organic matter is fresh in coarse sand and oldest in fine silt. The &#948;13C values of different density fractions in forest soil are &#948;13Clight &#60; &#948;13Cheavy, and the &#948;13C values of different density fractions in farmland soil are &#948;13Clight &#62; &#948;13Cheavy, indicating that the soil organic matter is fresh in light fractions and old in heavy fractions. 
