Segoli, M., Mitrani Department of Desert Ecology, BIDR, Ben-Gurion University, Sede Boker Campus, Israel
Ungar, E.D., Department of Agronomy and Natural Resources, Institute of Plant Sciences, Agricultural Research Organization - the Volcani Center, Bet Dagan, Israel
Shachak, M., Mitrani Department of Desert Ecology, BIDR, Ben-Gurion University, Sede Boker Campus, Israel

In arid ecosystems, shrub patches are regarded as "islands of fertility," enriched in resources that facilitate growth of herbaceous vegetation. It is often assumed that the modulation of resources and the effect that it has on herbaceous vegetation are homogeneous within each shrub patch. We examined the modulated resources in terms of their fine-scale spatial extent, level, and response to anthropogenic disturbances, that is, canopy removal and grazing. We defined three patch types-core of shrub patch, periphery of shrub patch, and intershrub patch-and recorded their levels of soil nutrients (organic matter, potassium, phosphorus, nitrate, and ammonium) and temperature regimes, with and without canopy removal, and/or grazing. Overall, our study found higher soil-nutrient contents and lower maximum temperatures at the core of the shrub patch than in the intershrub matrix. However, we also found that resource modulation was not spatially homogeneous within the shrub patch: soil nutrient levels were higher in the core than at the periphery. Anthropogenic disturbances did not affect soil nutrients within the 2-year time scale of our study. Our results emphasize the importance of examining the landscape at the spatial scale of the modulated resources, in order to develop patch management that increases productivity and diversity, and prevents desertification. © 2012 Copyright Taylor and Francis Group, LLC.