Carbon-nitrogen isotope coupling of soil organic matter in a karst region under land use change, Southwest China

摘要

The soil stable carbon (C) and nitrogen (N) isotopes are widely used to indicate C-3/C-4 vegetation history, N sources and transformation processes, respectively. However, land use change, particularly converting forest into farm land, alters soil organic matter (SOM) sources and processes in soils, resulting in a hard understanding of soil C and N fate. In the present study, soil organic carbon (SOC) and soil organic nitrogen (SON) contents, and their stable isotope compositions (delta C-13 and delta N-15) were determined in the five soil profiles under land use change (i.e., conversion of native forest land into shrub land, grass land, maize field, and paddy land) in Lobo county, Guizhou province, Southwest China. A coupling of C-13 and N-15 isotope in SOM under land use change was verified whether it could provide more accurate indications of sources and transformation processes.