Faculté des sciences

Glasshouse vs field experiments: do they yield ecologically similar results for assessing N impacts on peat mosses?

Limpens, J. ; Granath, G. ; Aerts, R. ; Heijmans, M. M. P. D. ; Sheppard, L. J. ; Bragazza, L. ; Williams, B. L. ; Rydin, H. ; Bubier, J. ; Moore, T. ; Rochefort, L. ; Mitchell, Edward A. D. ; Buttler, A. ; van den Berg, L. J. L. ; Gunnarsson, U. ; Francez, A. -J. ; Gerdol, R. ; Thormann, M. ; Grosvernier, P. ; Wiedermann, M. M. ; Nilsson, M. B. ; Hoosbeek, M. R. ; Bayley, S. ; Nordbakken, J. -F. ; Paulissen, M. P. C. P. ; Hotes, S. ; Breeuwer, A. ; Ilomets, M. ; Tomassen, H. B. M. ; Leith, I. ; Xu, B.

In: New Phytologist, 2012, vol. 195, no. 2, p. 408-418

• Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating... Mehr

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    Summary

    • Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating multifactorial experiments.
    • We investigated whether glasshouse experiments are reliable proxies for field experiments for assessing interactions between N deposition and environment as controls on Sphagnum N concentration and production. We performed a meta-analysis over 115 glasshouse experiments and 107 field experiments.
    • We found that glasshouse and field experiments gave similar qualitative and quantitative estimates of changes in Sphagnum N concentration in response to N application. However, glasshouse-based estimates of changes in production – even qualitative assessments – diverged from field experiments owing to a stronger N effect on production response in absence of vascular plants in the glasshouse, and a weaker N effect on production response in presence of vascular plants compared to field experiments.
    • Thus, although we need glasshouse experiments to study how interacting environmental factors affect the response of Sphagnum to increased N deposition, we need field experiments to properly quantify these effects.