Response of Vegetation on Subantarctic Macquarie Island to Reduced Rabbit Grazing

Abstract

The responses of vascular plant species to a reduction in grazing pressure were monitored as part of a rabbit-control program on Macquarie Island. The initial response of the vegetation was more luxuriant growth with changes in abundance recorded after 2–3 years. After 8–10 years the relative abundance of several species had changed while species not previously recorded had appeared on study sites and others had disappeared. Of the 32 species recorded on study sites, 11 species (Agrostis magellanica, Deschampsia chapmanii, Festuca contracta, Juncus scheuchzerioides, Luzula crinita, Pleurophyllum hookeri, Poa annua, P. foliosa, Stilbocarpa polaris and Uncinia spp. (two species)) were found to form the major portion of the rabbits’ diet while another four species (Acaena magellanica, Cerastium fontanum, Isolepis aucklandica, Polystichum vestitum) were moderately grazed. The other species were either rarely grazed or occurred too infrequently to assess. Of the 25 species that were recorded over 30 times, 17 were considered to have benefited from the introduction of rabbits.