ABSTRACT
Since the 1960s, most dryland ecosystems of the Mediterranean Basin have experienced a comprehensive land-use transition from complex and multifunctional agrosilvopastoral land-use systems to simplified and intensified forms of livestock husbandry and agriculture (Pinto-Correia and Vos, 2001). Intensified livestock husbandry is believed to shift rangeland ecosystems from equilibrium states and to initiate degradation processes (Iosifides and Politidis, 2005). In the Eastern Mediterranean, overgrazing has resulted in the removal of soil cover and the domination of undesirable plants, mostly Sarcopoterium spinosum (Bakker et al., 2005). These processes have been exacerbated by changes in the spatial configuration of grazing, which is now largely uncontrolled, continuous and all-season (Giourga et al., 1998). A remote-sensing survey showed that between 1977 and 1996 40 per cent of rangelands on Crete (Greece) suffered declining vegetation cover in consequence of increased grazing pressure (Hostert et al., 2003). However, grazing pressure is highly heterogeneous, so that over- and under-grazing can be observed even in immediate proximity of each other (Röder et al., 2007). Both over- and under-use can modify ecosystem structure and functions, as Mediterranean drylands are tightly coupled human—environment systems (Aranzabal et al., 2008). For example, a comprehensive cessation of livestock may involve loss of biodiversity and devastating wildfires (Papanastasis, 2009).
