© 2001 Heron Publishing—Victoria, Canada
Seasonal dynamics of soil carbon dioxide efflux and simulated rhizosphere respiration in a beech forest
Daniel Epron (1), Valerie Le Dantec (2), Eric Dufrene (2) and Andre Granier (3)
1. Laboratoire de Biologie et Ecophysiologie, Institut des Sciences et des Techniques de l'Environnement, Universitéde Franche-Comté,
BP 71427, 25211 Montbéliard cedex, France / 2. Laboratoire d'Ecophysiologie Végétale, Bâtiment 362, CNRS-UA 8079, Université de Paris XI, 91405 Orsay cedex, France / 3. Laboratoire d'Ecophysiologie Végétale, Bâtiment 362, CNRS-UA 8079, Université de Paris XI, 91405 Orsay cedex, France / Received November 6, 1999
Summary
Respiration of the rhizosphere in a beech (Fagus sylvatica L.) forest was calculated by subtracting microbial respiration associated with organic matter decomposition from daily mean
soil CO2 efflux. We used a semi-mechanistic soil organic matter model to simulate microbial respiration, which was validated against
“no roots” data from trenched subplots. Rhizosphere respiration exhibited pronounced seasonal variation from 0.2 g C m–2 day–1 in January to 2.3 g C m–2 day–1 in July. Rhizosphere respiration accounted for 30 to 60% of total soil CO2 efflux, with an annual mean of 52%. The high Q10 (3.9) for in situ rhizosphere respiration was ascribed to the confounding effects of temperature and changes in root biomass and root and shoot
activities. When data were normalized to the same soil temperature based on a physiologically relevant Q10 value of 2.2, the lowest values of temperature-normalized rhizosphere respiration were observed from January to March, whereas
the highest value was observed in early July when fine root growth is thought to be maximal.
Keywords:
Fagus sylvatica, root respiration, soil CO2 efflux, temperature.
