Current status of the Antarctic herb tundra formation in the central Argentine Islands

Changes in the higher plant populations of the Argentine Islands over the last four to five decades have been central to developing an understanding of the likely biological responses to the globally exceptional rates of regional climate change, in particular warming, experienced along the western Antarctic Peninsula over the same period. In this study, we reassessed local populations and distribution of the two indigenous flowering plants on two islands in this archipelago, the grass Deschampsia antarctica and the pearlwort Colobanthus quitensis, in order to compare with previous partial and detailed surveys carried out by the British Antarctic Survey between 1963 and 1990. Our major finding was that the strong trend of recent increase in population size documented in 1990 has not continued, with current population sizes of both higher plants now being slightly lower than but still comparable with those recorded in the last survey in 1990. We discuss reasons underlying this, including possible limits imposed by the suitability of available habitat, and a recent plateauing of the local climate warming trend in comparison with that seen before the 1990 survey, with no significant short-term warming apparent in annual or seasonal meteorological data since 1990.