Vegetation monitoring of recently protected tussock grasslands in the southern South Island, New Zealand

An increasing number of areas of native grassland and shrubland, previously under pastoral farming use, are being transferred to public conservation land in southern New Zealand, posing questions concerning their effective management. In particular, managers need to know more about the general effects of release from pastoral grazing and periodic burning on protected tussock grasslands and associated communities, especially with respect to naturalised plant species. Permanently marked height-frequency vegetation monitoring sites in the Bain, Rock and Pillar, Lauder, and Eyre conservation areas, established at or about the time of their formal protection, were resampled after intervals of 5-6 years. Removal of grazing by domestic stock aids recovery of the dominant tussock species, as indicated by data from monitoring tall- and short-tussock grasslands. As the height and canopy cover of the tall tussock increased, there was a corresponding, although variable, decline in the diversity and biomass of native and naturalised inter-tussock plant species at most sites. In the short-tussock grasslands, removal of grazing also aided recovery of native shrubs and inter-tussock grass and herb species. Over the time interval of the study, there was no significant increase in abundance of naturalised pasture species following removal of grazing from these four conservation areas.