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| Titel |
The role of tectonic uplift, climate and vegetation in the long-term terrestrial phosphorous cycle |
| VerfasserIn |
Corina Buendia, Axel Kleidon, Amilcare Porporato |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035815
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| Zusammenfassung |
| Phosphorus (P) is a crucial element for life and therefore for maintaining ecosystem
productivity. Its local availability to the terrestrial biosphere results from the interactions
between climate, tectonic uplift, atmospheric transport and biotic cycling. To understand to
what extent terrestrial productivity may feed back on the atmospheric CO2 concentration and
climate change, a model that is capable of synthesizing the P-cycle is essential. Here we
present a mathematical model that describes the terrestrial P-cycle considering the
interactions between climate, tectonic uplift, atmospheric transport and the biologically
controlled P re-cycling. The resulting dynamical system can be solved analytically for
steady-state conditions, allowing us to test the sensitivity of the simulated P-availability to
key model parameters and processes.
We find that humid ecosystems in steady-state will normally exhibit lower P availability
due to higher runoff and losses. Tectonic uplift is a fundamental constraint as it is
the main source of P for terrestrial ecosystems through weathering. Our model
represents this fundamental constraint and clearly shows the difference between the P
dynamics on volcanic islands and continental crusts. We demonstrate this using the
time-dependent P dynamics for the Franz Josef and Hawaii chronosequences as an
example. While tectonic uplift is an important constraint on ecosystem productivity,
hydroclimatic conditions control the rate P-losses and speed of convergence towards
a steady-state. For the case of the Amazon Basin, the model also illustrates that
ecosystems with limited uplift and atmospheric P input must rely on mechanisms
that enhance P-availability and retention to sustain their productivity. Our analysis
underlines the need to include P dynamics in global vegetation-atmosphere models for a
reliable representation of the response of the terrestrial biosphere to global change. |
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