PHOTOECOLOGICAL CHARACTERIZATION OF AN EPILITHIC ECOSYSTEM AT A HIGH MOUNTAIN LOCALITY (CENTRAL SPAIN)

摘要

We selected the most abundant lichen strain at the Plataforma de Gredos and Circo de Gredos (1.819 m ― 2.000 m a.s.l., N 40° 16.529'-W 005° 14.008', Sierra de Gredos, Central Spain) to test the effects of UV-B radiation on Rhizocarpon geographicum, in a growing season. Using lichen samples with- and without cortex, we observed a substantial protection of the cortex against high stress conditions (mainly microclimate), specially at summer solstice. Application of the UV Ecodosimeter Biofilm TKJ 6312 of DLR closed to lichen samples provide ratios of UV-B/UV-A irradiances demonstrating the high biological effectiveness at the UV range. Because of this high resistance of R. geographicum against environmental UV-radiation, it might be an ideal model system for studies on the possibility of interplanetary transfer of life, like micro organisms. Therefore, its sensitivity to the space environment will be tested during the upcoming BIOPAN Mission 2002 of ESA.