Bare soil forms an important part of the surface cover in Mediterranean arid and semiarid areas dominated by Stipa tenacissima L. tussock grass. Some studies have stressed the relevance of the spatial arrangement of this species in the improvement of sediment dynamic and soil characteristics close to the tussock. Reciprocally, bare soil condition has been considered as a key factor in the physiological performance of S. tenacissima stands. On the other side, other studies have neglected the capacity of the root system of this species to explore and consume resources from bare soil surrounding the tussock. In the present work we show some evidences that suggest the importance of bare soil near to the tussock in the water status of this species, especially in the high water stress season. We have found that water gains in bare soil from water vapour adsorption were highly coincident with the S. tenacissima stand transpiration. Furthermore, S. tenacissima sub-populations living in rock outcrops with lower connectivity with the surrounded bare soil showed higher signs of physiological water stress than those stands in areas with more soil availability. We believe that an interaction of water dynamics between bare soil and S. tenacissima tussocks would have to be reconsidered to fully understand ecophysiology of this species. © 2012 Nova Science Publishers, Inc. All rights reserved.