Summary
Bryophytes are sensitive indicators of environmental change and with climate change being expected to occur first at high latitudes, Antarctic bryophytes are ideal study systems for the detection of climate change effects. Antarctica is the driest continent on Earth and so it follows that water availability is one of the most important environmental characteristics limiting bryophyte (moss and liverwort) distribution in continental Antarctica. Tolerance of desiccation is crucial for plant survival in such environments and unlike most vascular plants, Antarctic bryophytes have the ability to survive complete desiccation of their tissues. In earlier work, we have found differences in the tolerance of desiccation for the three moss species (Bryum pseudotriquetrum, Grimmia antarctici, and Ceratodon purpureus) occurring in the Windmill Islands, East Antarctica, and these physiological differences are reflected in the ecological distributions of these species. A more detailed understanding of the dynamics of tolerance of desiccation between these species will contribute to the development of predictions for species distributions under a changing climate. The aim of the present study is to test if the three moss study species (Bryum pseudotriquetrum, Grimmia antarctici, and Ceratodon purpureus) show a seasonal response to tolerance of desiccation. Chlorophyll fluorescence and water content were measured during desiccation under laboratory conditions for the three moss study species at three intervals over a summer growing season. Osmotically active solutes may play a role in desiccation tolerance. An analysis of osmotically active soluble carbohydrates was included in this work and it is hoped that the results will contribute to an explanation for physiological differences of the three study species.