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Keywords: which are associated to some degree with soil erosion (Diamond, 2005). In ecosystem ecology, ‘‘leakiness’ ’ refers to an ecosystem’s ability or inability to retain resources such as soil, nutrients and water and can be used as a negative index of ecosystem health 3 et al., 2003). Additionally, interacting biotic agents including vascular plants, and arbuscular mycorrhizal fungi (AMF) may account for a substantial proportion of soil aggregate stability (Tisdale and Oades, 1982) in most systems. But many drylands are distinctly different than other ecosystems in that there is a strong influence of biological soil crusts (BSCs), a complex community typically dominated by cyanobacteria, mosses and lichens, on soil stability (Warren, 2003; Chaudhary et al., in press). Because dry-lands account forw40 % of the terrestrial surface, and are the hom