Effects of reducing the ambient UV-B radiation in the high Arctic on Salix arctica and Vaccinium uliginosum

K.R. Albert, H. Ro-Poulsen, Teis Nørgaard Mikkelsen, L. Bredahl, K.B. Haakansson

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    Abstract

    Effects of reducing the ambient UV-B radiation on gas exchange and chlorophyll fluores-cence of two dwarf shrub species, Salix arctica and Vaccinium uliginosum, was studied in a high arctic heath in North East Greenland during two growing seasons. Films (Mylar, transmitting λ > 320 nm, and Lexan, transmitting λ > 400 nm) were used to reduce UV-B radiation and UV-B+A respectively. A UV transparent film (Teflon, transmitting λ > 280 nm) and no film were used as controls. Field measurements showed that the plants under Teflon, Mylar and Lexan received app. 91%, 39% and 17% of the ambient UV-B irradiance, respectively. UV radiation decreased the maximal photochemical efficiency (Fv/Fm) and other fast fluorescence transient derived parameters in both species, despite an increased level of leaf flavonoid content. The responses varied in signifi-cance according to species and site. The relation of these effects to a significantly decreased stomatal conductance (gs) and intercellular CO2 concentration (Ci) pointed to respiration as an im-portant factor in the interpretation of the observed unaffected net CO2 assimilation (Pn) in UV- re-duced treatments. It is concluded that the studied species have not fully acclimatized to the level of ambient UV-B radiation, and that ambient UV-B level is an important stress factor for the investi-gated plants in High Arctic.
    Original languageEnglish
    JournalPhyton. Annales Rei Botanicae
    Volume45
    Issue number4
    Pages (from-to)41-49
    ISSN0079-2047
    Publication statusPublished - 2005

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