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

Juul Limpens (1) , Goran Granath (2) , Rien Aerts (3) , Monique M.P.D. Heijmans (1) , Lucy Sheppard (4) , Luca Bragazza (5, 6, 7) , B.L. Williams (8) , H. Rydin (2) , J. Bubier (9) , T. Moore (10) , Line Rochefort (11) , Edward A.D. Mitchell (12) , A. Buttler (13, 14) , Leon Jl van den Berg (15) , Urban Gunnarsson (2) , Andre-Jean Francez (16) , Renato Gerdol (7) , M. Thormann (17) , Philippe Grosvernier (18) , Magdalena M. Wiedermann (19) , M.B. Nilsson (19) , M. R. Hoosbeek (20) , S. Bayley (21) , Jorn-Frode Nordbakken (22) , M.P.C.P. Paulissen (23) , Stephan Hotes (24) , A. Breeuwer (1) , Mati Ilomets , H.B.M. Tomassen (25) , Ian Leith (26)

1 Nature Conservation and Plant Ecology group
2 Department of Plant Ecology and Evolution
3 Dept of Systems Ecology
4 CEH - NERC Centre of Ecology and Hydrology
5 ECOS - Laboratoire des systèmes écologiques
6 WSL Lausanne
7 UniFE - Università degli Studi di Ferrara = University of Ferrara
8 Soils Group
9 Mount Holyoke College
10 Department of Geography [Montréal]
11 Centre de Recherches Nordiques
12 Institute of Biology - Laboratory of Soil Biology
13 EPFL - Ecole Polytechnique Fédérale de Lausanne
14 LCE - Laboratoire Chrono-environnement (UMR 6249)
15 Aquatic Ecology and Environmental Biology
16 ECOBIO - Ecosystèmes, biodiversité, évolution [Rennes]
17 Aquilon Environmental Consulting Ltd
18 LIN'eco
19 Umeå University
20 WUR - Wageningen University and Research [Wageningen]
21 University of Alberta
22 The Norwegian Forest and Landscape Institute
23 ALTERRA - Alterra Wageningen University & Research Centre
24 JLU - Justus-Liebig-Universität Gießen = Justus Liebig University
25 B-Ware Research Centre
26 CEH - Centre for Ecology and Hydrology [Edinburgh]

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.

Mots clés: experiments; meta-analysis; mires and peatlands; nitrogen deposition; productivity; Sphagnum.; climate; carbon (C); Sphagnum

Domaines: Biodiversité et Ecologie

Juul Limpens, Goran Granath, Rien Aerts, Monique M.P.D. Heijmans, Lucy Sheppard, et al.. Glasshouse vs field experiments: do they yield ecologically similar results for assessing N impacts on peat mosses?. New Phytologist, 2012, 195 (2), pp.408-418. ⟨10.1111/j.1469-8137.2012.04157.x⟩. ⟨hal-00736089⟩