• 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.
- nitrogen deposition
- sphagnum mosses
Limpens, J., Granath, G., Gunnarsson, U., Rydin, H., Aerts, R., Heijmans, M. M. P. D., Hoosbeek, M. R., Paulissen, M. P. C. P., & Breeuwer, A. J. G. (2012). Glasshouse vs field experiments: do they yield ecologically similar results for assessing N impacts on peat mosses. New Phytologist, 195(2), 408-418. https://doi.org/10.1111/j.1469-8137.2012.04157.x