Improved UV-B screening capacity does not prevent negative effects of ambient UV irradiance on PSII performance in High Arctic plants. Results from a six year UV exclusion study

Kristian Rost Albert, Teis Nørgaard Mikkelsen, H. Ro-Poulsen, Anders Michelsen, Marie F. Arndal, Linda Bredahl, Kirsten B. Håkansson, Kristine Stove Boesgaard, Niels Martin Schmidt

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Long-term responses of ambient solar ultraviolet (UV) radiation were investigated on Salix arctica and Vaccinium uliginosum in a High Arctic heath ecosystem in Zackenberg, northeast Greenland. Over a period of six years, UV exclusion was conducted in the growing season by means of filters: 60% UV-B reduction, 90% UV-B + UV-A reduction, UV transparent filter control, and an open control without filter. Plant responses were evaluated using specific leaf area, leaf content of UV-B absorbing compounds and PSII performance parameters derived from chlorophyll-a fluorescence induction curves. Based on the JIP-test, we calculated the total performance index PItotal, which includes the integrating antennae, the PSII reaction center, intersystem electron transport and reduction of PSI end acceptors-dependent parameters. In both species, UV exclusion significantly decreased the content of UV-B-absorbing compounds. Salix increased its specific leaf area, while Vaccinium decreased it. UV exclusion increased the PItotal in both species during all six years of experimentation. This response was governed by a significantly decreased RC/ABS, a marginally non-significant increased ETo/TRo and a significantly increased TRo/ABS = FV/FM and REo/ETo. These results demonstrate the current level of ambient UV-B to decrease PSII performance significantly in these High Arctic plants. It appears that the two plant species both have improved their UV-screening capacity, but through different strategies, although this did not sufficiently prevent negative effects of the ambient UV radiation. We argue the decreased PSII performance to be part of a response decreasing plant carbon uptake. We speculate the negative effects on PSII performance mediated by ambient UV irradiance to be present in years where warming induces early snowmelt, exposing the vegetation to high spring UV-B, and to be present in the future to the degree the ozone layer is not fully recovered.
    Original languageEnglish
    JournalJournal of Plant Physiology
    Volume167
    Issue number18
    Pages (from-to)1542-1549
    ISSN0176-1617
    DOIs
    Publication statusPublished - 2010

    Keywords

    • Bio systems
    • Environment and climate

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