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| Titel |
Cold ecosystems in a warmer climate: carbon fluxes at the alpine treeline under experimental soil warming |
| VerfasserIn |
Sonja Wipf, Frank Hagedorn, Melissa Martin |
| 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 |
250044911
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| Zusammenfassung |
| The impact of climatic warming on the C balance of terrestrial ecosystems is uncertain
because rising temperature increases both C gains through net primary production, but also
respiratory C losses. ‘Cold’ ecosystems such as treeline ecotones will respond particularly
sensitive to climatic changes because many processes are limited by temperature and soils
store particular large amounts of labile soil organic matter. In our study, we investigate
ecosystem responses to 9 years of elevated atmospheric CO2 and to 3 years of experimental
soil warming by 4Ë C. The added CO2 contains another δ13C signature than normal air,
which allows the tracing of new carbon through the plant and soil system. This provides new
insight into carbon cycling at the treeline and it shows which C flux respond most sensitive to
climatic changes.
Results showed that soil warming increased soil CO2 effluxes instantaneously
and persisted for at least three vegetation periods (+35-45%; +80 to 120 g C m
y-1). In contrast, DOC leaching showed a negligible response of less than 5%
increase. Annual C uptake of new shoots was not significantly affected by elevated
soil temperatures, with a 10 to 20% increase for larch, pine, and dwarf shrubs,
respectively, resulting in an overall increase in net C uptake by plants of 20 to 40 g C
m-2y-1. The Q10 of 3.0 measured for soil respiration did not change compared to a
three-year period before the warming treatment started, suggesting little impact
of warming-induced lower soil moisture (-15% relative decrease) or a depletion
in labile soil C. The fraction of recent plant-derived C in soil respired CO2 from
warmed soils was smaller than that from control soils (25 vs. 40% of total C respired),
which implies that the warming-induced increase in soil CO2 efflux resulted mainly
from mineralization of older SOM rather than from stimulated root respiration. In
summary, the 4 Ë C soil warming led to C losses from the studied alpine treeline
ecosystem by increasing SOM decomposition more than C gains through plant growth. |
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