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In Spain, desertification has been-and is still-mainly associated with soil erosion, particularly in natural and semi-natural systems. Such association cannot be supported either from the scientific or the socio-economic point of view. Most average values of erosion rates in Spain have been overestimated, especially in the case of natural systems. High rates of soil erosion in natural systems are usually restricted to spatially limited areas like badlands, most of them generated through active natural geomorphologic processes. The main erosion problems are not found in natural environments but in agricultural systems, especially in marginal agricultural areas on steep slopes and with bad agricultural practices and also in intensively irrigated lands, especially greenhouses. The association of and zones with the ancient destruction of vegetation is rooted in simplistic ideas considering areas with scarce vegetation, little biomass or limited height to be generated by negative human interventions. However, in and and semiarid systems this is not always true. The simplistic ideas linking scarce vegetation with desertification is also deeply negative for the conservation of the outstanding biodiversity of and systems, most of them included in the European Habitat Directive. The main desertification problem in Spain is generated by unsustainable water management. The current expansion of irrigated lands outside the areas suited for agriculture is increasing the intensity of aquifer exploitation, already causing serious problems of salinization, the loss of springs and wetlands and associated biodiversity and the exhaustion of non-renewable groundwater resources. Copyright (c) 2005 John Wiley & Sons, Ltd.