摘要：A number of forest and grassland studies indicated that stimulation of the soil respiration
by soil warming ceases after a couple of years (Luo et al 2001 Nature413 622–5). Here we
present results from a long-term soil warming lysimeter experiment in southern Germany
showing sustained stimulation of soil respiration after 10 years. Moreover, both warmed
and control treatments exhibited a similar temperature response of soil respiration,
indicating that adaptation in terms of temperature sensitivity was absent. Carbon dioxide
concentration measurements within the profiles are supporting these findings.
The increased soil respiration occurred although vegetation productivity in the
warmed treatment was not higher than in the control plots. These findings strongly
contrast with current soil carbon modeling concepts, where carbon pools decay
according to first-order kinetics, and thus a depletion of labile soil carbon pools
leads to an apparent down-regulation of microbial respiration (Knorr et al 2005
Nature433 298–301). Consequently, the potential for positive climate carbon cycle
feedback may be larger than represented in current models of soil carbon turnover.
