Carbon Nitrogen Isotope Coupling of Soils and Seasonal Variation Characteristics in a Small Karst Watershed in Southern China

Carbon and nitrogen are among the most important biogenic elements in terrestrial ecosystems, carbon stable isotopes (δ13C δ15N) often used to indicate sources of turnover processes, study C N coupling can provide more precise indications. To this end, was conducted investigate effects different land use types on soil organic (SOC), (SON) relationship C-N isotopes, as well reveal seasonal variation characteristics N. The results showed that SOC SON contents forest were significantly higher than those agricultural grassland. C/N dry season rainy (p < 0.01), indicating decomposition rate matter (SOM) faster season, which not conducive accumulation C. Soil δ13C δ15N characteristics: did have a good linear but significant positive correlation (r2 = 0.75, p 0.05), there differences isotope fractionation under influence climatic factors. This provides reference for regional resource management cycle studies karst areas.