Ecohydrology is an emerging and synthetic discipline in the biogeosciences aimed at understanding connections between the ecological dynamics of vegetation and the hydrological cycle, and how vegetation-water interactions influence elemental cycling and energy exchange. An ecohydrology perspective is especially relevant and important for understanding dynamics of arid and semiarid ecosystems and landscapes. In these water-limited ecosystems, highly variable patterns of precipitation, geomorphology, and soils strongly influence vegetation structure, dynamics, and function. These systems are pulse-driven; bursts of biological activity commence with discreet inputs of precipitation. These short-lived and highly active periods are separated by periods of extreme water limitation and vegetation stress. The duration and spatio-temporal dynamics of precipitation pulses and plant-available soil moisture are key features in these ecosystems, controlling vegetation composition, nutrient biogeochemistry, and energy exchange.