Stavi, I., Dead Sea and Arava Science Center, Ketura 88840, Israel
Lavee, H., Geography and Environment Department, Bar-Ilan University, Ramat-Gan, Israel
Ungar, E., The Agricultural Research Organization, Bet-Dagan, Israel
Sarah, P., Geography and Environment Department, Bar-Ilan University, Ramat-Gan, Israel

Many semi-arid regions are composed of mosaics of woody vegetation patches and interpatch spaces. Source-sink relations occur between these two phases, enabling primary production. Recent studies from the rangelands of the semi-arid Negev in Israel reveal that bimodal distribution of stocking density creates an additional phase-livestock trampling routes. The objectives of this commentary were to highlight the impact of this modification on primary productivity, and to provide a new insight regarding the functioning of these rangelands. © 2012 Copyright Taylor and Francis Group, LLC.