Lenton, TM, Dahl, TW, Daines, SJ et al. (4 more authors) (2016) Earliest land plants created modern levels of atmospheric oxygen. Proceedings of the National Academy of Sciences, 113 (35). pp. 9704-9709. ISSN 0027-8424
Abstract
The progressive oxygenation of the Earth’s atmosphere was pivotal
to the evolution of life, but the puzzle of when and how
atmospheric oxygen (O2) first approached modern levels (~21%)
remains unresolved. Redox proxy data indicate the deep oceans
were oxygenated during 435-392 Ma, and the appearance of
fossil charcoal indicates O2>15-17% by 420-400 Ma. However,
existing models have failed to predict oxygenation at this time.
Here we show that the earliest plants, which colonized the land
surface from ~470 Ma onwards, were responsible for this mid-
Paleozoic oxygenation event, through greatly increasing global
organic carbon burial – the net long-term source of O2. We use
a trait-based ecophysiological model to predict that cryptogamic
vegetation cover could have achieved ~30% of today’s global
terrestrial net primary productivity by~445 Ma. Data from modern
bryophytes suggests this plentiful early plant material had a much
higher molar C:P ratio (~2000) than marine biomass (~100), such
that a given weathering flux of phosphorus could support more
organic carbon burial. Furthermore, recent experiments suggest
that early plants selectively increased the flux of phosphorus (relative
to alkalinity) weathered from rocks. Combining these effects
in a model of long-term biogeochemical cycling, we reproduce a
sustained +2‰ increase in the carbonate carbon isotope (δ13C)
record by ~445 Ma, and predict a corresponding rise in O2 to
present levels by 420-400 Ma, consistent with geochemical data.
This oxygen rise represents a permanent shift in regulatory regime
to one where fire-mediated negative feedbacks on organic carbon
burial stabilise high O2 levels.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2016, PNAS. This is an author produced version of a paper published in Proceedings of the National Academy of Sciences. Uploaded in accordance with the publisher's self-archiving policy. In order to comply with the publisher requirements the University does not require the author to sign a non-exclusive licence for this paper. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 25 Jul 2016 11:26 |
Last Modified: | 20 Jan 2021 12:51 |
Published Version: | http://dx.doi.org/10.1073/pnas.1604787113 |
Status: | Published |
Publisher: | National Academy of Sciences |
Identification Number: | 10.1073/pnas.1604787113 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:102812 |