LA VEGETACIÓN ANTÁRTICA, CENTINELA DEL CAMBIO CLIMÁTICO

Abstract

Antarctica is the coldest, driest, highest and windiest continent; the lichens and mosses grow where it is more warm, wet, low and protected. Overall productivity is strongly influenced by the length of period when water is available and the plants become, therefore, increasingly confined to areas of exceptionally good microclimate. It is this strong link between microclimate, water availability and productivity/growth that makes the system so potentially useful for monitoring global climate change, especially temperature increase. Even a small increase in temperature will markedly alter the areas over which such warm periods occur and bring with it a marked community shift. It is becoming clear that there are two Antarcticas, the Peninsula and the main continent. These differ in the controls on biodiversity distribution, there is a probably water unlimited but temperature-determined biodiversity cline in the Peninsula compared to a, water controlled, temperature-independent, fragmented vegetation in the continent. The reverse diel pattern of activity with the presence of very high light stress also seems to be confined to the continent. Several attempts have been made to use lichens as monitors of climate change especially in alpine and polar regions. The pristine Antarctica offers a unique opportunity to study the effects of climate change along a latitudinal gradient that extends between 62º and 87º S. Both lichen species diversity and thallus growth rate seem to show significant correlations to mean annual temperature and precipitation for gradients across the continent as well as to short time climate oscillation in the Antarctic Peninsula. Competition interactions appear to be small so that individual thalli develop in balance with environmental conditions and, as a result, can indicate the trends in productivity for discrete time intervals over long periods of time in a climate warming scenario.