Plants of extreme habitats in Antarctica

An account is given of phanerogams and cryptogams(bryophytes and lichens) growing in extreme habitats in Antarctica. These include high altitude and far southern sites, geothermal sites in volcanic areas, and deep water habitats, all of which confer considerable physiological stress on these organisms and represent the limits of non-microbial life in this biome and, to a large extent, on planet Earth

Species diversity and resource relationships of South Georgian fungi

The occurrence and distribution of the South Georgia fungal flora, particularly Ascomycotina and Basidiomycotina, is assessed in terms of habitat and substrate preference. The 113 taxa reported comprise 37 basidiomycetes, 49 ascomycetes, six myxomycetes and at least 21 lower fungi. Peat and litter substrata associated with tall tussock grassland have a rich macro-fungal flora, and numerous species occur in bog and mire communities, some in abundance from mid to late summer. Many micro-fungi and ascomycetes colonize dying leaves and inflorescences of specific vascular plants, and a few colonize bryophytes and lichens. At least a dozen species, probably non-indigenous, are associated with rotting timber and other imported materials at former whaling stations. An intensive survey of the South Georgia mycoflora is necessary to gain better understanding of their role in decomposition and nutrient cycling processes in the principal plant communities

Introduced plants in Antarctica: Potential impacts and conservation issues

The development of and compliance with the code of conduct embodied in the Antarctic Treaty to prevent or minimize the introduction of plants into the Antarctic is outlined. A chronological account of all known experimental and accidental introductions of higher plants in the field and their success and fate, if known, is given. The potential danger to the natural Antarctic ecosystem of importing plants rooted in their original soil is discussed with particular regard to the introduction of microorganisms, invertebrates and viable plant propagules. Unintentional dispersal of non-indigenous biota by human activities, and dispersal by natural agents (wind, birds) into and within the Antarctic, is assessed and numerous examples which contravened the measures of the Antarctic Treaty for the control of introduced biota are noted. The need for strict observance of the new Protocol on Environmental Protection to the Antarctic Treaty is emphasized

Biological and environmental characteristics of three cosmopolitan mosses dominant in continental Antarctica

Bryum argenteum, B. pseudotriquetrum and Ceratodon purpureus are the predominant mosses in Victoria Land, continental Antarctica. All have cosmopolitan distributions and are widespread throughout Antarctica with wide ecological amplitudes resulting in considerable morphological variation. They are well adapted to tolerate the physiological stresses imposed by the severe environment. This study investigates aspects of their growth, physiology and survival in response to habitat constraints, especially hydrology. Their distribution is controlled almost exclusively by moisture availability. Each species tends to predominate in a specific zone along hydrological gradients, with B. pseudotriquetrum on moist soil, C. purpureus on drier soil, and B. argenteum on unstable stream margins, fluvial deposits and the marginal capillary zone. Where conditions are optimal, each species can form a turf 6–10 cm thick. Nutrient status of the soil does not appear to be an important determinant in the distribution pattern within communities. The thermal regime of the moss turf varies according to its moisture content; for a period of ca. six weeks during the summer, with the frequent long spells of 24-h sunshine, temperatures remain above 0 °C for much of the time even though air temperatures are frequently below the freezing point. This allows growth and metabolic activity to proceed continuously at a relatively rapid rate for quite long periods. Annual shoot incremental growth can exceed 3.5 mm in each species. Growth of B. argenteum may be inhibited by UV- B radiation. The optimal temperature for photosynthesis in each species is around 15 °C, but significant carbon fixation occurs at 5 °C. Photosynthetic rates at 5, 10 and 20 °C were B. argenteum > B. pseudotriquetrum > C. purpureus

Vascular plants as bioindicators of regional warming in Antarctica

Monitoring selected populations of the only two native Antarctic vascular plant species (Colobanthus quitensis andDeschampsia antarctica) over a 27-year period has revealed a significant and relatively rapid increase in numbers of individuals and populations at two widely separated localities in the maritime Antarctic. There is strong evidence that this increase is a response to a warming trend in summer air temperatures, which has been evident throughout the region since the late 1940s, enhancing seed maturation, germination and seedling survival. This study provides the only known long-term monitoring data for any terrestrial organisms in Antarc-tica. Because their response to ameliorating conditions is more rapid than that of the dominant cryptogamic groups, Antarctic phanerogams may be useful bioindicators of climate change in West Antarctica