Does arctic vegetation change when grazed by barnacle geese?:A pilot study

The effects of grazing by barnacle geese Branta leucopsis on arctic vegetation was studied. Two plots where grazers had been excluded five and six years previously were compared with grazed vegetation nearby. The exclosed plots contained more live biomass than the area with grazed vegetation. However, there was no significant difference in density of shoots and number of leaves per shoot in the heavily grazed Poa arctica. Within the exclosed plots, there was a slow build-up of dead material and the moss carpet had grown thicker than in the grazed plots. The number of inflorescences was the most prominent feature, which differentiated the exclosed vegetation from the sated surrounding. There is no evidence for habitat deterioration caused by increased grazing pressure from the expanding barnacle goose population as has been reported for the snow goose on the Hudson Bay lowlands in Canada. The increased activity of nitrogen fixation by cyanobacteria in grazed vegetation might be a mechanism which compensates for the nitrogen deficit caused by the migratory geese.