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| Titel |
Effects of bryophyte and lichen cover on permafrost soil temperature at large scale |
| VerfasserIn |
Philipp Porada, Altug Ekici, Christian Beer |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148735
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| Publikation (Nr.) |
 EGU/EGU2017-13016.pdf |
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| Zusammenfassung |
| Bryophytes and lichens covering the soil surface at high latitudes act as an insulating layer,
which has a net cooling effect on the soil and thereby protects permafrost. Climate change,
however, may lead to changes in the average surface coverage of bryophytes and lichens. This
can result in thawing of permafrost and an associated release of soil carbon to the
atmosphere, which may cause a positive feedback on atmospheric CO2 concentration. Hence,
it is crucial to predict the future large-scale response of bryophyte and lichen cover to
climatic change at high latitudes. Current global land surface models, however, contain
mostly empirical approaches to represent the surface cover of bryophytes and lichens,
which makes it difficult to quantify its future extent and dynamics. Therefore, we
integrate a process-based model of bryophyte and lichen growth into the global
land surface model JSBACH (Jena Scheme for Biosphere–Atmosphere Coupling
in Hamburg). Thereby, we explicitly simulate dynamic thermal properties of the
bryophyte and lichen cover and their relation to environmental factors. To quantify the
insulating effect of the cover on the soil, we compare simulations with and without
simulated bryophyte and lichen cover. We estimate that the bryophyte and lichen
cover exerts an average cooling effect of 2.7 K on temperature in the topsoil for the
region north of 50o N under current climatic conditions. Locally, a cooling of up
to 5.7 K may be reached. Furthermore, we show that using a simple, empirical
representation of the bryophyte and lichen cover instead of a dynamic one results only
in an average cooling of around 0.5 K. We conclude that bryophytes and lichens
have a significant impact on soil temperature in high-latitude ecosystems and that
dynamic thermal properties are necessary for a realistic representation of the cooling
effect. |
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