Soil temperature synchronisation improves representation of diel variability of ecosystem respiration in Sphagnum peatlands

Benoît D’angelo (1, 2, 3) , Sébastien Gogo (1, 3) , Fatima Laggoun-Défarge (1, 3) , Franck Le Moing (1, 3) , Fabrice Jégou (2) , Christophe Guimbaud (2)

1 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
2 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
3 Biogéosystèmes Continentaux - UMR7327

tThe temperature dependence of Ecosystem Respiration (ER) is often assessed based on the temperatureof one specific layer. Air temperature or temperatures in the first ten centimetres of the soil profile are themost frequently used temperatures in models. However, previous studies showed that the relationshipbetween ER and temperature is depth dependent, making depth selection for temperature measurementsan important issue, especially at short time-scales. The present study explores one possible way to assessthis relationship by synchronising the ER and temperature signals and to test if the relationship betweenER and temperature differs between daytime and nighttime. To do so, ER measurements were undertakenin 2013 in four Sphagnum-peatlands across France using the closed chamber method. The ER fluxes weremeasured hourly during 72 h in each of four replicates in each site. Synchronisations between ER and Tsignal were determined for each depth (from surface to 30 cm depth) by selecting the time-delay leadingto the best correlation between ER and soil temperatures and ER was then modelled. Our results showedthat: (i) the delay between ER and soil temperature is greater in peat than in mineral soils; (ii) at a dailytime-scale synchronisation can improve the model representation using soil temperatures.

Mots clés: CO2; Q10; Chamber; Temperature depth; Time-delay

Domaines: Planète et Univers [physics]; Interfaces continentales, environnement

Benoît D’angelo, Sébastien Gogo, Fatima Laggoun-Défarge, Franck Le Moing, Fabrice Jégou, et al.. Soil temperature synchronisation improves representation of diel variability of ecosystem respiration in Sphagnum peatlands. Agricultural and Forest Meteorology, 2016, 223, pp.95-102. ⟨10.1016/j.agrformet.2016.03.021⟩. ⟨insu-01303659⟩