THE CONTRIBUTION OF GRAZING TO PLANT DIVERSITY IN ALPINE GRASSLAND AND HEATH

Grazing on transplants of a grass, a forb and a tree was examined in l ow-diversity grassland and more diverse heath in Australia's Snowy Mou ntains. Transplants were surrounded by 2 mm mesh netting. In one grass land plot, grazers (probably soil invertebrates) attacked 40-90% of tr ee and forb seedlings but no grass seedlings. In heath, which had abou t half the grass cover of grassland, grazers consumed grasses but not trees or forbs. The results suggest that grazers can depress diversity in grassland by attacking species other than grass. In heath, they ma y promote diversity by attacking only grass and releasing other specie s from competition.