Plant litter decomposition is a central process in the carbon (C) cycle and sensitive to ongoing anthropogenic nitrogen (N) fertilisation. Previous syntheses evaluating the effect of N fertilisation on litter decomposition relied largely on models that define a constant rate of mass loss throughout decomposition, which may mask hypothesised shifts in the effect of N fertilisation on litter decomposition dynamics. In this meta-analysis, we compared the performance of four empirical decomposition models and showed that N fertilisation consistently accelerates early-stage but slows late-stage decomposition when the model structure allows for flexibility in decomposition rates through time. Within a particular substrate, early-stage N-stimulation of decomposition was associated with reduced rates of late-stage decay. Because the products of early- vs. late-stage decomposition are stabilised in soils through distinct chemical and physical mechanisms, N-induced changes in the litter decomposition process may influence the formation and cycling of soil C, the largest terrestrial C pool.
Bibliographical noteFunding Information:
Members of the Hobbie Research Group, EJ Sayer and three anonymous reviewers provided comments which improved this manuscript. Funding support was provided by the Grand Challenges in Biology Postdoctoral Fellowship Program from the University of Minnesota (to ALG), and the NSF Long‐Term Ecological Research (DEB‐1234162) and Ecosystem Studies (DEB‐1556529) Programs.
© 2021 John Wiley & Sons Ltd.
- decomposition model
- soil organic matter