Technical Abstract: In arid and semi-arid ecosystems (drylands), soil moisture abundance limits biological activity and mediates the effects of anthropogenic global change factors such as atmospheric CO2 increases and climate warming. Moreover, climate variability and human activities are interacting to increase the abundance of woody plants in drylands worldwide. How woody plants interact with rainfall to influence patterns of soil moisture through time, at different depths in the soil profile and between neighboring landscape patches is poorly known. In a semi-arid mesquite savanna near Tucson, Arizona we deployed arrays of sensors located in distinct microsites (beneath a mesquite canopy and in an open area) to measure volumetric soil water content (') every 30 minutes at several depths between 2004 and 2007. In addition, to quantify temporally dynamic variation in soil moisture between microsites and across soil depths we analyzed ' time-series using Fast Fourier Transforms (FFT).