Infiltration through three contrasting biological soil crusts in patternedlandscapes in the Negev, Israel

We examined the role of soil crusts in infiltration processes in three cont rasting environments in thc Northern, Central, and Central-Western Negev, I srael. The removal of a thin cyanobacterial-dominant crust from a sandy dun e at Nizzana in the Central-Western Negev and of a well-developed lichen-do minant and a cyanobacterial-dominant crust from a loess-covered hillslope a t Sayeret Shaked in the Northern Negev resulted in three to fivefold increa ses in sorptivity and steady-state infiltration under both pending and tens ion. The removal of a depositional crust colonised by cyanobacteria from a loess floodplain at Sede Zin in the Central Negev resulted in an increased infiltration under tension, bur had no significant effect under pending. We attribute the lack of effect under pending to exposure of surface silts to water, which resulted in the clogging of matrix pores and surface sealing. The removal of the crusts in all three landscapes influences resource flow s, particularly the redistribution of runoff water, which is essential for the maintenance of desert soil surface patterning. It would also have marke d effects on germination, establishment and survival of vascular plants and soil biota, leading ultimately to desertification. (C) 2000 Elsevier Scien ce B.V. All rights reserved.