The effect of removing grazing pressure on grassland reserves: three Canterbury examples

Grazed and ungrazed silver tussock grassland on the Port Hills and Rytidosperma-bryophyte-lichen grassland on the Canterbury and Culverden Plains were studied. Removal of grazing resulted in an increase in the cover of naturalized plants, especially grasses (cocksfoot and sweet vernal), and a decrease in the number and/or cover of indigenous herbaceous species (including non-vascular species). The extent of change was greater at the higher rainfall sites and/or at the sites with the longer period since the cessation of grazing. It is suggested that controlled grazing is a desirable management technique for these grasslands where maximum indigenous species diversity is the objective, however, mowing or cutting may be preferable when highly palatable species are involved. Other conservation goals in these grasslands would require different management techniques.