Plant cover as a tool for monitoring desertification in mountain Mediterranean rangelands

Plant cover was measured for three years in the rangelands of Psilorites mountain of Crete, located at a mean altitude of 1,200m and overgrazed by sheep and goats from May to October. Rangelands consist of phryganic ecosystems dominated by dwarf shrubs, often subjected to occupational burning, and secondarily by grasslands. Herbaceous cover was significantly lower in the overgrazed than in the protected sites, but woody cover was higher unless the dwarf shrubs were palatable to animals. When overgrazing was combined with occupational burning then both plant groups were reduced with total cover reaching threshold values for potential soil erosion and desertification. On the contrary, no substantial differences were found between years indicating that overgrazing and burning were much more important than environmental changes. The results suggest that plant cover is an effective tool for monitoring the impact of pastoral activities on rangeland vegetation and therefore on desertification of mountain Mediterranean rangelands.