In the course of six years (1979-1984), a Magallanes tussock grassland ("Coironal") was repeatedly set stocked during spring, summer, autumn or winter. The animal effect was imposed by five stocking rates (0.25, 0.5, 1.0, 1.5, and 2.0 sheep units/ha/year). Inter-tussock vegetation was markedly depleted by repeated spring grazing. The same, though less notorius was observed when grazing occured in summer, autumn and winter, decreasing in the same order. Increasing stocking rates determined a negative effect on forage availability, botanic composition and pasture regrowth.