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| Titel |
High potential for chemical weathering and climate effects of early lichens and bryophytes in the Late Ordovician |
| VerfasserIn |
Philipp Porada, Tim Lenton, Alexandre Pohl, Bettina Weber, Luke Mander, Yannick Donnadieu, Christian Beer, Ulrich Pöschl, Axel Kleidon |
| 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 |
250134788
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| Publikation (Nr.) |
 EGU/EGU2016-15553.pdf |
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| Zusammenfassung |
| Non-vascular vegetation in the Late Ordovician may have considerably increased global
chemical weathering, thereby reducing atmospheric CO2 concentration and contributing to a
decrease in global temperature and the onset of glaciations. Usually, enhancement of
weathering by non-vascular vegetation is estimated using field experiments which are limited
to small areas and a low number of species. This makes it difficult to extrapolate to the global
scale and to climatic conditions of the past, which differ markedly from the recent
climate.
Here we present a global, spatially explicit modelling approach to estimate chemical
weathering by non-vascular vegetation in the Late Ordovician. During this period, vegetation
probably consisted of early forms of today’s lichens and bryophytes. We simulate these
organisms with a process-based model, which takes into account their physiological diversity
by representing multiple species. The productivity of lichens and bryophytes is then related to
chemical weathering of surface rocks. The rationale is that the organisms dissolve rocks to
extract phosphorus for the production of new biomass. To account for the limited supply of
unweathered rock material in shallow regions, we cap biotic weathering at the erosion
rate.
We estimate a potential global weathering flux of 10.2 km3 yr−1 of rock, which is around
12 times larger than today’s global chemical weathering. The high weathering potential
implies a considerable impact of lichens and bryophytes on atmospheric CO2 concentration
in the Ordovician. Moreover, we find that biotic weathering is highly sensitive to atmospheric
CO2, which suggests a strong feedback between chemical weathering by lichens and
bryophytes and climate. |
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