The natural abundance of δ15N has been widely in research on terrestrial nitrogen cycling. The variations of material’s stable isotopes composition in natural abundance due to the enzymatic preferences for light N (14N), especially during enzymatic kinetic processes, therefore isotope fractionations can be used as integrators of different processed during nitrogen cycling (Robinson, 2002). Also spatial variations of N isotopes natural abundance in soils or plants generally decline with temperatures and increase with precipitation, which reflect the dominant pathways by nitrogen mass balance of a ecosystem in global or local scales. We use simple soil isotope model to simulate the global pattern of soil N stable isotope composition based on first principles, which presents the balance of N losses by runoff-dependent in hydrologic pathways and soil temperature-dependent in gaseous pathway.
Robinson, David. δ15N as an integrator of the nitrogen cycle. Trends in Ecology & Evolution 16.3 (2001): 153-162.