Technical Abstract: In order to better understand energy, water and carbon cycling in ecosystems, ecological, hydrological, and meteorological measurements can be combined in creative ways to illuminate the myriad of component processes that control these exchanges. This talk with feature examples of this approach from experiments carried out in semiarid south-western U.S. In the first experiment, multiple eddy covariance systems were deployed to partition ecosystem water fluxes into their overstory and understory components in riparian woodland in order to partition ecosystem evapotranspiration into its groundwater or surface water sources. In the second experiment, sap flow sensors were deployed on lateral (surface) and tap (deep) roots of trees and borehole ground penetrating radar was used to quantify deep vadose zone soil moisture changes in order to assess the hydraulic redistribution activity of trees. In the final example, a combination of eddy covariance and sap flow were used to partition ecosystem evapotranspiration in a Chihuahuan desert shrubland. By determining the transpiration and evaporation, a more complete picture of the timing and interplay between these fluxes is given and the relationship between these fluxes and ecosystem carbon exchange is shown.