UNASSIGNED: Soil CO2 efflux, fine root biomass, ground vegetation biomass, tree increment and litter input were assessed in (i) an undisturbed section of a ~ 110 years old Norway spruce stand, (ii) in a disturbed section which was clear-cut six years ago (no tree regeneration), and (iii) in a disturbed section which was clear-cut three years ago (no tree regeneration).
UNASSIGNED: Total soil CO2 efflux was similar across all stand sections (8.5 ± 0.2 to 8.9 ± 0.3 t C ha-1 yr.-1). The undisturbed forest served as atmospheric C sink (2.1 t C ha-1 yr.-1), whereas both clearings were C sources to the atmosphere. The source strength three years after disturbance (-5.5 t C ha-1 yr.-1) was almost twice as high as six years after disturbance (-2.9 t C ha-1 yr.-1), with declining heterotrophic soil respiration and the high productivity of dense graminoid ground vegetation mitigating C loss.
UNASSIGNED: C loss after disturbance decreases with time and ground vegetation growth. Dense non-woody ground vegetation cover can hamper tree regeneration but simultaneously decrease the ecosystem C loss. The role of ground vegetation should be more explicitly taken into account in forest C budgets assessing disturbance effects.