Arid Dune Ecosystems

Abstract

The Nizzana area has experienced periods of heavy grazing which resulted in the destruction of a cryptogamic soil crust and vegetation cover which, in turn, led to increased aeolian sand movement (Tsoar and M ller 1986). The influence of cryptogamic soil crusts on deflation has been the focus of several studies mainly in drylands used or suitable for grazing (Harper and Marble 1988; West 1990; Eldridge and Greene 1994; Belnap 1995; Belnap and Gillette 1998; Leys and Eldridge 1998). The resistance of such crusts against wind erosion has been tested in wind tunnel studies (McKenna Neuman et al. 1996; McKenna Neuman and Maxwell 1999, 2002). The results of these studies show that intact crusts inhibit deflation of sandy soils, while a destruction (e.g. trampling by grazing animals) leads to a sharp increase of aeolian transport rates (Leys and Eldridge 1998; Allgaier 2005). Aeolian sand transport rates over crust-covered areas at the Nizzana site have been found to be negligible, and experimental studies showed that current wind energy at the site is not sufficient to destroy the crust (Allgaier 2005).