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| Titel |
Both biocrust cover and soil warming increased inorganic and organic P fractions in a semi-arid ecosystem of Central Spain |
| VerfasserIn |
Laura García-Velázquez, Antonio Gallardo, Fernando T. Maestre |
| 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 |
250138394
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| Publikation (Nr.) |
 EGU/EGU2017-1387.pdf |
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| Zusammenfassung |
| Semi-arid and arid ecosystem represents 41% of Earth’s surface, and climate change is
expected to increase this percentage of drylands. The increase in aridity has a profound effect
on biogeochemical cycles, inducing an imbalance in the soil nitrogen (N): phosphorus (P)
ratio, with subsequent impacts on ecosystem services. In addition, primary productivity in
terrestrial ecosystems can be destabilized by the increase of atmospheric N deposition, and P
may become the most limiting nutrient in these altered ecosystems. Some studies have
shown that aridity and climate change influence N cycling in drylands, however the
resilience of labile and recalcitrant, inorganic and organic fractions of P in semi-arid
ecosystems is still unknown. Our main hypothesis stipulates that soil warming might
induce an increase of the inorganic P fractions versus the organic ones because of a
rise of biological activity in drylands, but these variations may be modulated by
the presence of Biological Soil Crust (BSC) and counteracted by the predicted
precipitation decrease. We tested how warming (ambient vs. ∼2.5 ˚ C increase), rainfall
exclusion (ambient vs. ∼30% reduction in total annual rainfall) and biocrust cover
(incipient vs. well-developed biocrusts) alter organic and inorganic P fractions (resin-P,
NaHCO3-P, NaOH-P, HCl-P and residual P) in a 5-yr field experiment. We performed a
combination of classic methods of soil P fractionation to determine proportions of
organic and inorganic P, representing different indexes related to availability and
recalcitrance of P. The presence of BSC had a great influence through an increase
in all P fractions. Soil warming increased inorganic P (NaHCO3-P, NaOH-P and
HCl-P) but also organic P fractions (NaHCO3-P and NaOH-P) f. In addition, we
detected an increase in the recalcitrance-to-labil P ratio over time possibly due to
microbial immobilization. The rainfall exclusion experiment had no effect on any
P fractions. Our results suggest that global warming may alter significantly the
P biogeochemistry both directly and indirectly by influencing the BSC cover in
drylands.
Key-words: P fractionation, global warming, rainfall exclusion, biocrust |
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