Summary
Bryophytes (mosses and liverworts) are sensitive indicators of environmental change and with climate change expected to occur first at high latitudes, Antarctic bryophytes are ideal study systems for the detection of climate change effects. Tolerance of desiccation is crucial for plant survival in Antarctica, where water availability is the most important environmental characteristic limiting bryophyte distributions. If predicted fluctuations in water availability occur in this sensitive community, relative species distributions are likely to change in the future. In earlier work, we have found differences in tolerance of desiccation for three Antarctic moss species, and these physiological differences are reflected in their ecological distributions. The present study was designed to test for changes in tolerance of desiccation across a summer season for the three Antarctic moss species, Bryum pseudotriquetrum, Grimmia antarctici and Ceratodon purpureus. Chlorophyll fluorescence and water content were measured during desiccation and subsequent recovery, under laboratory conditions, for the three moss species, at three intervals over a summer growing season. Changes in the concentration of soluble carbohydrates were also determined over the season as osmotically active solutes may play a role in desiccation tolerance. Significant differences occurred between the three moss species over the season, during desiccation, recovery from desiccation and in soluble carbohydrate contents. These results suggest that the three species utilise different strategies for tolerating desiccation and have variations in their resource availability. This work has contributed to predictions for species relative dynamics under a changing climate and has implications for conservation of species diversity.