Understanding the drivers of extensive plant damage in boreal and Arctic ecosystems: Insights from field surveys in the aftermath of damage

Jarle W. Bjerke, Rachael Treharne, Dagrun Vikhamar-Schuler, Stein R Karlsen, Virve Ravolainen, Stef Bokhorst, Gareth K. Phoenix, Zbigniew Bochenek, Hans Tømmervik

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    Abstract

    The exact cause of population dieback in nature is often challenging to identify retrospectively. Plant research in northern regions has in recent decades been largely focussed on the opposite trend, namely increasing populations and higher productivity. However, a recent unexpected decline in remotely-sensed estimates of terrestrial Arctic primary productivity suggests that warmer northern lands do not necessarily result in higher productivity. As large-scale plant dieback may become more frequent at high northern latitudes with increasing frequency of extreme events, understanding the drivers of plant dieback is especially urgent. Here, we report on recent extensive damage to dominant, short, perennial heath and tundra plant populations in boreal and Arctic Norway, and assess the potential drivers of this damage. In the High-Arctic archipelago of Svalbard, we recorded that 8-50% of Cassiope tetragona and Dryas octopetala shoots were dead, and that the ratios of dead shoots increased from 2014 to 2015. In boreal Norway, 38-63% of Calluna vulgaris shoots were dead, while Vaccinium myrtillus had damage to 91% of shoots in forested sites, but was healthy in non-forested sites. Analyses of numerous sources of environmental information clearly point towards a winter climate-related reason for damage to three of these four species. In Svalbard, the winters of 2011/12 and 2014/15 were documented to be unusually severe, i.e. insulation from ambient temperature fluctuation by snow was largely absent, and ground-ice enforced additional stress. In boreal Norway, the 2013/14 winter had a long period with very little snow combined with extremely low precipitation rates, something which resulted in frost drought of uncovered Calluna plants. However, extensive outbreaks of a leaf-defoliating geometrid moth were identified as the driver of Vaccinium mortality. These results suggest that weather and biotic extreme events potentially have strong impacts on the vegetation state of northern lands.

    Original languageEnglish
    Pages (from-to)1965-1976
    Number of pages12
    JournalScience of the Total Environment
    Volume599-600
    Early online date23 May 2017
    DOIs
    Publication statusPublished - 1 Dec 2017

    Funding

    This study was funded by the Polish-Norwegian Programme of the EEA Norway Grants (WICLAP, project 198571), by the Research Council of Norway (225006/E10), and by FRAM–High North Research Centre for Climate and the Environment through its terrestrial flagship program (project 362222). We thank Geraldine Mabille, Sidsel Grønvik, Trond V. Johnsen, John K. Bjerke and Laura Stendardi for assistance in the field.

    FundersFunder number
    Polish-Norwegian Programme of the EEA Norway198571
    Norges forskningsråd225006/E10
    Framsenteret362222

      Keywords

      • Journal Article

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