Carbon and Nitrogen Stable Isotope Abundance and Soil Stoichiometry of Zanthoxylum planispinum var. dintanensis Plantations of Different Ages

Understanding the relationships between carbon; nitrogen, their stable isotopes delta C-13 and delta N-15, and soil stoichiometry may further our understanding of the regulatory mechanisms of the soil quality index on the equilibrium on isotopic fractionation. Four plantations of Zanthoxylum planispinum var. dintanensis (5-7, 10-12, 20-22 and 30-32 years) in the karst plateau gorge area, Guizhou Province, China, were selected to determine the variation characteristics and interactions between leaves, leaf litter, soil carbon (C), soil nitrogen (N) and their isotopes with plantation age, and to explore the relationship between soil stoichiometry and the isotopes delta C-13 and delta N-15. The results were as follows: (1) the delta C-13 in leaves, litter, and soil were -28.04 parts per thousand +/- 0.59 parts per thousand, -26.85 parts per thousand +/- 0.67 parts per thousand, and -19.39 parts per thousand +/- 1.37 parts per thousand, respectively. The contents of delta N-15 were 2.01 parts per thousand +/- 0.99 parts per thousand, 2.91 parts per thousand +/- 1.32 parts per thousand, and 3.29 parts per thousand +/- 0.69 parts per thousand, respectively. The contents of delta C-13 and delta N-15 were ranked in the order, soil > litter > leaf. (2) With increasing plantation age, the soil C-13 decreased; the leaf and the litter delta N-15 increased first then decreased, and the litter delta C-13 and the soil delta N-15 did not vary significantly. (3) The litter layer was positively correlated with soil delta C-13 and negatively correlated to delta N-15. (4) Redundancy analysis showed that the soil microbial biomass carbon (MBC) and the bacteria/fungi (BAC/FUN) were the dominant factors affecting the natural abundance of C and N isotopes

Automated summary

This study investigated the relationships between leaves, leaf litter, soil carbon, soil nitrogen and their isotopes in four different-aged Zanthoxylum planispinum var. dintanensis plantations in the karst plateau gorge area of Guizhou Province, China. The results showed that the delta C-13 and delta N-15 contents were highest in the soil, followed by litter and leaves. With increasing plantation age, soil C-13 decreased, while leaf and litter delta N-15 increased and then decreased. The litter layer was positively correlated with soil delta C-13 and negatively correlated with delta N-15.