Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies.
Bottom Line: Nonetheless, many models showed qualitative agreement with observed component processes.The results suggest that improved representation of above-ground-below-ground interactions and better constraints on plant stoichiometry are important for a predictive understanding of eCO2 effects.Improved accuracy of soil organic matter inventories is pivotal to reduce uncertainty in the observed C-N budgets.
Affiliation: Biogeochemical Integration Department, Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, D-07745, Jena, Germany.Show MeSH
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Mentions: Our study forms part of a model intercomparison (A. P. Walker et al., unpublished) looking at the effect of eCO2 on water (De Kauwe et al., 2013), C (M. G. De Kauwe et al., unpublished) and N cycling. Each of the participating models incorporates the major processes by which the N cycle affects the ecosystem's response to eCO2, such as plant N uptake, net N mineralization and the ecosystem N balance, as well as emergent ecosystem properties, such as the N-use efficiency (NUE) of plant production (Fig.1). The representation of these processes varies greatly among models (Table1), illustrating a lack of consensus on the nature of the mechanisms driving these processes. Our objectives in this study were as follows:
Affiliation: Biogeochemical Integration Department, Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, D-07745, Jena, Germany.