 |
| Titel |
Substrate heterogeneity and environmental variability in the decomposition process |
| VerfasserIn |
Carlos Sierra, Mark Harmon, Steven Perakis |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037451
|
|
|
|
|
|
| Zusammenfassung |
| Soil organic matter is a complex mixture of material with heterogeneous biological, physical,
and chemical properties. However, traditional analyses of organic matter decomposition
assume that a single decomposition rate constant can represent the dynamics of this
heterogeneous mix. Terrestrial decomposition models approach this heterogeneity by
representing organic matter as a substrate with three to six pools with different susceptibilities
to decomposition. Even though it is well recognized that this representation of organic matter
in models is less than ideal, there is little work analyzing the effects of assuming substrate
homogeneity or simple discrete representations on the mineralization of carbon and nutrients.
Using concepts from the continuous quality theory developed by Göran I. Ågren and
Ernesto Bosatta, we performed a systematic analysis to explore the consequences of
ignoring substrate heterogeneity in modeling decomposition. We found that the
compartmentalization of organic matter in a few pools introduces approximation error when
both the distribution of carbon and the decomposition rate are continuous functions
of quality. This error is generally large for models that use three or four pools.
We also found that the pattern of carbon and nitrogen mineralization over time is
highly dependent on differences in microbial growth and efficiency for different
qualities. In the long-term, stabilization and destabilization processes operating
simultaneously result in the accumulation of carbon in lower qualities, independent
of the quality of the incoming litter. This large amount of carbon accumulated in
lower qualities would produce a major response to temperature change even when
its temperature sensitivity is low. The interaction of substrate heterogeneity and
temperature variability produces behaviors of carbon accumulation that cannot be
predicted by simple decomposition models. Responses of soil organic matter to
temperature change would depend on the interacting effects of the sensitivity of different
pools to decomposition, the amount of carbon stored in the pools, the variability
of climatic drivers, and the degree and nature of the nonlinearities in the system. |
|
|
|
|
|
|