Showing papers by "Clare H. Robinson published in 2001"

Global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass?

Abstract: Cornelissen, J. H. C., Callaghan, T. V., Alatalo, J. M., Michelsen, A., Graglia, E., Hartley, A. E., Hik, D. S., Hobbie, S. E., Press, M. C., Robinson, C. H., Henry, G. H. R. (2001). Global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass. Journal of Ecology, 89, (6), 984-994. Sponsorship: Swedish Natural Science Research Council (NFR)/Swedish Environmental Protection Agency (two grants)/ US National Science Foundation (four grants)/ the Danish Natural Science Research Council (two grants)/ NASA (Global Change Fellowship), NSERC (Canada, two grants)/the Natural Environment Research Council (UJ, two grants)/ the 'Stiftelse for Oscar & Lilli Lamms Minne' (Sweden) / ESRC (Global Change Research Council).

Cold adaptation in Arctic and Antarctic fungi

Abstract: Summary Growth and activity at low temperatures and possible physiological and ecological mechanisms underlying survival of fungi isolated from the cold Arctic and Antarctic are reviewed here. Physiological mechanisms conferring cold tolerance in fungi are complex; they include increases in intracellular trehalose and polyol concentrations and unsaturated membrane lipids as well as secretion of antifreeze proteins and enzymes active at low temperatures. A combination of these mechanisms is necessary for the psychrotroph or psychrophile to function. Ecological mechanisms for survival might include cold avoidance; fungal spores may germinate annually in spring and summer, so avoiding the coldest months. Whether spores survive over winter or are dispersed from elsewhere is unknown. There are also few data on persistence of basidiomycete vs microfungal mycelia and on the relationship between low temperatures and the predominance of sterile mycelia in tundra soils. Acclimation of mycelia is a physiological adaptation to subzero temperatures; however, the extent to which this occurs in the natural environment is unclear. Melanin in dark septate hyphae, which predominate in polar soils, could protect hyphae from extreme temperatures and play a significant role in their persistence from year to year.