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| Titel |
Untangling climatic and autogenic signals in peat records |
| VerfasserIn |
Paul J. Morris, Andrew J. Baird, Dylan M. Young, Graeme T. Swindles |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123137
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| Publikation (Nr.) |
 EGU/EGU2016-2337.pdf |
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| Zusammenfassung |
| Raised bogs contain potentially valuable information about Holocene climate change.
However, autogenic processes may disconnect peatland hydrological behaviour
from climate, and overwrite and degrade climatic signals in peat records. How can
genuine climate signals be separated from autogenic changes? What level of detail
of climatic information should we expect to be able to recover from peat-based
reconstructions?
We used an updated version of the DigiBog model to simulate peatland development and
response to reconstructed Holocene rainfall and temperature reconstructions. The model
represents key processes that are influential in peatland development and climate signal
preservation, and includes a network of feedbacks between peat accumulation,
decomposition, hydraulic structure and hydrological processes. It also incorporates the
effects of temperature upon evapotranspiration, plant (litter) productivity and peat
decomposition.
Negative feedbacks in the model cause simulated water-table depths and peat
humification records to exhibit homeostatic recovery from prescribed changes in rainfall,
chiefly through changes in drainage. However, the simulated bogs show less resilience to
changes in temperature, which cause lasting alterations to peatland structure and function and
may therefore be more readily detectable in peat records. The network of feedbacks
represented in DigiBog also provide both high- and low-pass filters for climatic information,
meaning that the fidelity with which climate signals are preserved in simulated peatlands is
determined by both the magnitude and the rate of climate change. Large-magnitude climatic
events of an intermediate frequency (i.e., multi-decadal to centennial) are best preserved in
the simulated bogs. We found that simulated humification records are further degraded by
a phenomenon known as secondary decomposition. Decomposition signals are
consistently offset from the climatic events that generate them, and decomposition
records of dry-wet-dry climate sequences appear to be particularly vulnerable to
overwriting.
Our findings have direct implications not only for the interpretation of peat-based records
of past climates, but also for understanding the likely vulnerability of peatland ecosystems
and carbon stocks to future climate change. |
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