The influence of microclimate on the composition of lichen communities along an altitudinal gradient in the maritime Antarctic

The influence of microclimate on diversity and abundance of lichen communit ies was studied along an altitudinal gradient on Livingston Island, South S hetland Islands, maritime Antarctic. Whilst biodiversity overall is high, i t appears to decrease drastically within a few hundred meters from the coas t towards higher altitudes. Microclimatic data and community composition we re investigated at different sites and slope exposures from near sea level to the summit of Mount Reins Sofia. (274 m a.s.l.) near the Spanish Antarct ic research station Juan Carlos I. Microclimatic measurements were made ove r a period of 43 days during a summer. A remarkable decrease in lichen dive rsity and biomass was found with increasing altitude which correlated with a decrease in 2.37 degreesC mean thallus temperature over an altitudinal ra nge of 266 m. Neither air humidity nor irradiance seems to influence lichen biodiversity over this altitudinal range. The results indicated slight cha nges in air temperature as limiting the distribution of lichens, the major photosynthetic organism in this area.