Partitioning Evapotranspiration in Tallgrass Prairie under Woody Encroachment

Graduate Student: Xiangmin Sun 

PI: Chris Zou (OSU), Brad Wilcox

Site: Tall Grass Prairie, Oklahoma State University, Stillwater

Labs: Stable Isotope Lab TAMU (SIBS)

Description:

Evapotranspiration accounts for large quantities of water and energy (as latent heat) between the land surface and the atmosphere. Eddy covariance system is used to measure vertical fluxes  in tallgrass prairie for water vapor, heat, and momentum between the soil, vegetation, and the atmosphere. These fluxes is calculated as a covariance of instantaneous deviations in vertical wind speed and instantaneous deviations in the entity of interest.  Both evaporation and transpiration involves water phase transition. The water vapor fluxes by soil evaporation (δ_E) is highly fractionated, but plant water vapor in transpiration (δ_T) is less fractionated (via an isotopic steady state), so this difference is the principle for ET partitioning between evaporation and transpiration components within an ecosystem. As such, combining these continuous isotopic analyzer and micrometeorological techniques to partition ET is feasible and promising. As such, combining these continuous isotopic analyzer and micrometeorological techniques to partition ET is feasible and promising.