Plant effects on soil N mineralization are mediated by the composition of multiple soil organic fractions

D. A. Fornara, R Bardgett, S Steinbeiss, D. R. Zak, G Gleixner, D Tilman

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    25 Citations (Scopus)


    Despite the topic of soil nitrogen (N) mineralization being well-studied, very few studies have addressed the relative contribution of different plant and soil variables in influencing soil N mineralization rates, and thus the supply of inorganic N to plants. Here, we used data from a well-studied N-limited grassland to address the relative effects of six plant and soil variables on net and on gross rates of soil N mineralization. We also addressed whether plant effects on soil N mineralization were mediated by changes in C and N concentrations of multiple soil organic matter (SOM) fractions. Regression analyses show that key plant traits (i.e., plant C:N ratios and total root mass) were more important than total C and N concentrations of bulk soil in influencing N mineralization. This was mainly because plant traits influenced the C and N concentration (and C:N ratios) of different SOM fractions, which in turn were significantly associated with changes in net and gross N mineralization. In particular, C:N ratios of a labile soil fraction were negatively related to net soil N mineralization rates, whereas total soil C and N concentrations of more recalcitrant fractions were positively related to gross N mineralization. Our study suggests that changes in belowground N-cycling can be better predicted by simultaneously addressing how plant C:N ratios and root mass affect the composition and distribution of different SOM pools in N-limited grassland systems.
    Original languageEnglish
    Pages (from-to)201-208
    JournalEcological Research
    Issue number1
    Early online date13 Nov 2010
    Publication statusPublished (in print/issue) - Jan 2011


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