Cell Structure and Physiology of Alpine Snow and Ice Algae

Due to climatic and orographic reasons, the occurrence of vascular plants in high alpine regions is limited. At locations that are not suitable for the establishment of higher plants because of exposure, substrate or other abiotic factors, cryptogams can be the dominant life forms. Mosses, lichens and algae particularly thrive on places such as bare rocks, permafrost soils or, exceptionally, even in melting snow and permanent ice. Since these lower plants are poikilohydric and lack complex morphological tissues like the cormophytes, unfavourable conditions (like drought) can be overcome by physiological inactivity, and structural damage is not the critical issue for these poikilohydric organisms. The vegetation period of cryptogams can be very short (from days to a few weeks per year), and growth and reproduction have to be adapted to limiting factors such as low temperatures, limited water-availability or irradiation stress.