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| Titel |
Vertical and Lateral Carbon Flux in a Larrea/Cardón Ecosystem near La Paz, BCS, Mexico |
| VerfasserIn |
Thomas Bell, Walter Oechel |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045886
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| Zusammenfassung |
| Arid ecosystems comprise about 30% of terrestrial cover and are projected to increase by
17-20% in area during this century due to global climate change. Likewise, the dynamics of
carbon sequestration under extreme water and temperature stress provides important
information about carbon exchange in relation to water use efficiency in the context of rising
atmospheric CO2 levels, global temperature increase, and precipitation shifts. The technique
of Eddy Covariance has emerged as an important tool to measure fluxes of carbon dioxide
between terrestrial ecosystems and the atmosphere over extended periods of time. Carbon
loss through lateral transfer is missed by this method and may play an important role in
regional carbon balance.
The objective of this study is to quantify the lateral transport of carbon in aboveground
litter fall in comparison to the annual net ecosystem exchange (NEE) measured by the Eddy
Covariance tower in the arid Larrea/Cardón ecosystem on the preserve of the Centro de
Investigaciones Biológicas del Noroeste (CIBNOR) near La Paz, BCS, Mexico. Using the
tower based Eddy Covariance method and litter fall and transport measurements, an accurate
measure of lateral carbon transport can be made along with its importance to the overall
ecosystem carbon cycle.
By analyzing the Eddy Covariance data from 2004-2008, along with previously published
data from 2001-2003, an 8-year data set of seasonal and annual carbon flux can be produced.
These data show decreasing carbon sinks in the years 2001-2003, to increasing carbon
sources to year 2006, after which the annual carbon source begins to decrease. Seasonally,
fall and winter show general carbon sinks following large late summer hurricane events,
switching to monthly carbon sources in early spring and increasing through summer. There is
a strong control of annual NEE by the previous year’s precipitation event strength.
The lack of a large precipitation pulse prevents an annual carbon sink in future
years.
Lateral carbon transport experiments show lateral transport of leaf litter in quantities that
exceed local production. The distance traveled of litter transported by wind is greater than an
area of 2500Â m2. Carbon stored in litter fall is transported over large distances throughout the
year and may be subject to respiration or storage outside of the measured footprint of the
Eddy Covariance tower. Depending on the geographic and meteorological conditions of the
ecosystem, this lateral transport of carbon may distort the annual NEE of the measured
ecosystem. |
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