Hydrological and erosive effects of over-grazing at patch scale in humid mediterranean rangelands (Serranía de Ronda, South of Spain)

Abstract

The study focussed on the role played by over-grazing in the hydrological and erosive response of Mediterranean rangelands under humid climatic conditons. Two factors were considered to investigate such effect at patch spatial scale: hillslope exposure and soil surface component. A set of micro-plots (1.5 m2) were installed in the experimental area for recording runoff and soil loss during two-year period. The results indicated that exposure was a signifi cant factor controlling runoff generation and soil loss since it influenced soil surface component: i) soil completely bare in south facing hillslopes and ii) soil covered by annual plants and moss in the north facing ones. The consequence was that southern micro-plots showed hydrological and erosive response similar to those observed in more arid Mediterranean climatic conditions due to the impact of over-grazing in vegetation cover and soils, while the northern hillslopes seem to withstand better the grazing pressure.