The vast majority of water on Earth's terrestrial surface is lost through evapotranspiration (ET; vaporization processes that include evaporation [E] of intercepted water, E from free-water surfaces, and transpiration [T] from vegetation [Savenije 2004]) (Jasechko et al. 2013). Management and conservation of water resources require explicit understanding of ET, particularly due to the potential for global change to alter water fluxes. Although mostly considered by its hydrological nature, ET is the result of a suite of both physical and biological processes interacting at multiple spatial and temporal scales (Jarvis 1995) and constitutes a key driver of ecosystem function via the effects of T on ecosystem water and energy balance, impacting productivity (Jackson et al. 2001).