Partitioning evapotranspiration across gradients of woody plant cover: Assessment of a stable isotope technique

Lixin Wang, Kelly K. Caylor, Juan Camilo Villegas, Greg A Barron-Gafford, David D Breshears, Travis E. Huxman

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Abstract

In water-limited ecosystems, partitioning ecosystemscale evapotranspiration fluxes between plant transpiration and soil/canopy evaporation remains a theoretical and technical challenge. We used the Biosphere 2 glasshouse to assess partitioning of evapotranspiration across an experimentally manipulated gradient of woody plant cover using continuous measurements of near-surface variations in the stable isotopic composition of water vapor (δ2H). Our technique employs a newly-developed laser-based isotope analyzer and the Keeling plot approach for surface flux partitioning. The applicability of the technique was verified by comparison to separate, simultaneous lysimeter and sap flow estimates of ET partitioning. The results showed an expected increase in fractional contribution of transpiration to evapotranspiration as woody cover increased-from T/ET = 0.61 at 25%woody cover to T/ET = 0.83 at 100% cover. Further development of this technique may enable field characterization of evapotranspiration partitioning across diverse woody cover gradients, a central issue in addressing dryland ecohydrological responses to land use and climate change.

Original languageEnglish (US)
Article numberL09401
JournalGeophysical Research Letters
Volume37
Issue number9
DOIs
Publication statusPublished - May 2010

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ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Geophysics

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