East Antarctica has shown little evidence of warming to date 1-3 with no coherent picture of how climate change is affecting vegetation 4-6 . In stark contrast, the Antarctic Peninsula experienced some of the most rapid warming on the planet at the end of the last century 2,3,7,8 causing changes to growth and distribution of plants 9-11 . Here we show that vegetation in the Windmill Islands, East Antarctica is changing rapidly in response to a drying climate. This drying trend is evident across the region, demonstrated by changes in isotopic signatures measured along moss shoots 12,13 , moss community composition and declining health, as well as long-term observations of lake salinity 14 and weather. The regional drying is possibly due to the more positive Southern Annular Mode (SAM) in recent decades. The more positive SAM is a consequence of Antarctic ozone depletion and increased greenhouse gases, and causes strong westerly winds to circulate closer to the continent, maintaining colder temperatures in East Antarctica despite the increasing global average 15-18 . Colder summers in this region likely result in reduced snow melt and increased aridity. We demonstrate that rapid vegetation change is occurring in East Antarctica and that its mosses provide potentially important proxies for monitoring coastal climate change.Climate change is causing many species to shift poleward in response to increasing global temperatures 19 . Antarctic continental vegetation, however, is unlikely to exhibit such simple and predictable responses, as warming is inconsistent over the continent 1,3 , and species distributions are largely determined by local availability of ice-free habitats and water, rather than temperature per se 6,[20][21][22] . Small changes in microclimate (temperature, precipitation, wind or humidity) can impact the water balance or freeze-thaw cycles 23 and thus impact vegetation, even in the absence of regional warming.

BackgroundAntarctic bryophytes (mosses and liverworts) are resilient to physiologically extreme environmental conditions including elevated levels of ultraviolet (UV) radiation due to depletion of stratospheric ozone. Many Antarctic bryophytes synthesise UV-B-absorbing compounds (UVAC) that are localised in their cells and cell walls, a location that is rarely investigated for UVAC in plants. This study compares the concentrations and localisation of intracellular and cell wall UVAC in Antarctic Ceratodon purpureus, Bryum pseudotriquetrum and Schistidium antarctici from the Windmill Islands, East Antarctica.ResultsMultiple stresses, including desiccation and naturally high UV and visible light, seemed to enhance the incorporation of total UVAC including red pigments in the cell walls of all three Antarctic species analysed. The red growth form of C. purpureus had significantly higher levels of cell wall bound and lower intracellular UVAC concentrations than its nearby green form. Microscopic and spectroscopic analyses showed that the red colouration in this species was associated with the cell wall and that these red cell walls contained less pectin and phenolic esters than the green form. All three moss species showed a natural increase in cell wall UVAC content during the growing season and a decline in these compounds in new tissue grown under less stressful conditions in the laboratory.ConclusionsUVAC and red pigments are tightly bound to the cell wall and likely have a long-term protective role in Antarctic bryophytes. Although the identity of these red pigments remains unknown, our study demonstrates the importance of investigating cell wall UVAC in plants and contributes to our current understanding of UV-protective strategies employed by particular Antarctic bryophytes. Studies such as these provide clues to how these plants survive in such extreme habitats and are helpful in predicting future survival of the species studied.Electronic supplementary materialThe online version of this article (10.1186/s40659-018-0196-1) contains supplementary material, which is available to authorized users.

Polar ecosystems, and particularly Antarctica, are one of the few environs in which bryophytes dominate the flora. Their success in these regions is due to bryophytes' ability to withstand an array of harsh conditions through their poikilohydric lifestyle. However, the unique conditions that allow bryophytes to proliferate over other forms of vegetation also create considerable limitations to growth and photosynthetic activity. High latitude areas are already experiencing some of the most pronounced and rapid climatic change, especially in the Arctic, the Sub-Antarctic Islands and Maritime Antarctica, and these are predicted to continue over the next century. This climatic change is already impacting the flora of the polar regions both via direct and/or indirect impacts on plant species. Water availability and temperature are undoubtedly the most influential factors that determine bryophyte productivity in the Antarctic, but the ozone hole is also having an impact either directly via increased ultraviolet-B radiation and/or indirectly through the increasing wind speeds associated with ozone depletion. In a time of shifting climate the dominance of bryophytes in these regions may be threatened.