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| Titel |
Evapotranspiration partitioning in a semi-arid African savanna using stable isotopes of water vapor |
| VerfasserIn |
K. Soderberg, S. P. Good, M. O'Connor, E. G. King, K. K. Caylor |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250069996
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| Zusammenfassung |
| Evapotranspiration (ET) represents a major flux of water out of semi-arid ecosystems. Thus,
understanding ET dynamics is central to the study of African savanna health and
productivity. At our study site in central Kenya (Mpala Research Centre), we have been
using stable isotopes of water vapor to partition ET into its constituent parts of
plant transpiration (T) and soil evaporation (E). This effort includes continuous
measurement (1 Hz) of δ2H and δ18O in water vapor using a portable water vapor isotope
analyzer mounted on a 22.5 m eddy covariance flux tower. The flux tower has been
collecting data since early 2010. The isotopic end-member of δET is calculated
using a Keeling Plot approach, whereas δT and δE are measured directly via a
leaf chamber and tubing buried in the soil, respectively. Here we report on a two
recent sets of measurements for partitioning ET in the Kenya Long-term Exclosure
Experiment (KLEE) and a nearby grassland. We combine leaf level measurements of
photosynthesis and water use with canopy-scale isotope measurements for ET partitioning.
In the KLEE experiment we compare ET partitioning in a 4 ha plot that has only
seen cattle grazing for the past 15 years with an adjacent plot that has undergone
grazing by both cattle and wild herbivores (antelope, elephants, giraffe). These
results are compared with a detailed study of ET in an artificially watered grassland. |
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