Water stable isotopes (2H and 18O) are a widely applied tool to study ecohydrological processes in the soil-plant-atmosphere continuum. However, isotope-based field studies are often constrained by a lack of temporally explicit data, usually related to the choice of destructive sampling in the field and subsequent analysis in the laboratory. In the last decade, laser-based techniques have been advanced to measure water stable isotopic composition directly and at high temporal resolution. Novel techniques have been developed to sample different ecosystem water pools in-situ to monitor, for instance, the isotopic composition of soil water, transpired water, and xylem water.” Angelika/ I will give an overview of recent in-situ methods to study ecohydrological processes in grassland and forest ecosystems, with the focus on drought responses.