I study the exchanges of energy, water and carbon dioxide at the soil, vegetation, and atmospheric interface and the interactions between hydrology and ecology. I focus on these exchanges and interactions in water-limited areas. Some of my specific research topics include: 1) understanding the consequences of land-cover and climate change on ecosystem water and carbon cycling, 2) improving models of ecosystem fluxes, 3) determining the role that vegetation plays on vadose zone soil water redistribution and carbon dioxide respiration, and 4) partitioning water vapor and net carbon dioxide flux into their component fluxes.