Soil CO2 efflux in a beech forest:: the contribution of root respiration

The contribution of root respiration to soil carbon efflux in a young beech stand was estimated by comparing soil CO2 efflux from small trenched plots to efflux from undisturbed areas (main plot). Soil CO2 efflux was measured every 2-4 weeks in 1997. An empirical model (y = A q(v) e(BT)) was fitted to the soil CO2 efflux data and was used to calculate annual soil carbon efflux from soil temperature (T) and soil volumetric water content (q(v)). The annual soil carbon efflux were 0.66 kg(c) m(-2) year(-1) in the main plot and 0.42 kg, m-2 year(-1) in the trenched plots. The difference between these two estimations was corrected for the decomposition of roots that were killed following trenching. The heterotrophic component of soil carbon efflux accounts for 40 % of total soil carbon efflux (0.26 kg(C) m(-2) year(-1)) while root respiration accounts for 60 % of soil C release (0.40 kg(C) m(-2) year(-1)). ((C) Inra/Elsevier, Paris.).