Bauer, J., Kirschbaum, M.U.F., Weihermüller, L., Huisman, J.A.,
Herbst, M., Vereecken, H. (2008). Temperature response of
wheat decomposition is more complex than the common approaches of most
multi-pool models. Soil Biology and Biochemistry 40:
2780-2786.
Abstract.
The temperature response of heterotrophic soil respiration is crucial
for a reliable prediction of carbon dynamics in response to climatic changes.
Most multi-pool models describe the temperature dependence of carbon
decomposition by a response function which uniformly scales the decomposition
constants of all carbon pools. However, it is not clear whether the temperature
response does, indeed, conform to such a simple formulation. In this study, we
analysed measured CO2 efflux from wheat decomposition experiments under six
different temperatures (5°C, 9°C, 15°C, 25°C, 35°C and 45°C). Data were
interpreted by assuming that litter could be sub-divided into two pools, a
labile and a more recalcitrant one, that would each decay exponentially. We
found that the observed patterns of carbon loss were poorly described if we used
the same relative temperature response functions for the decomposition of both
pools and assumed the same chemical recalcitrance (expressed as the ratio of
labile and recalcitrant pool sizes) at all temperatures. Data prediction could
be significantly improved by using different temperature response functions for
the decomposition of the two different organic-matter fractions. Even better
data prediction could be achieved by assuming that chemical recalcitrance varied
with temperature. The data could also be well described by the more
sophisticated carbon-dynamic models RothC and CenW/CENTURY, again, provided that
the ratio of litter fractions in the initial input material was modified with
temperature. Our findings thus suggest that the temperature dependence of
organic matter decomposition cannot be fully described with the simple
approaches usually employed but that there is a more complicated interplay
between the temperature dependence of decomposition rates and temperature
effects on the chemical recalcitrance of different organic matter fractions.
Keywords:
CENTURY, CenW, decomposition, exponential decay, RothC, soil carbon,
temperature, temperature dependence, 14C-carbon