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10 March 2015

Impact of reindeer grazing shows major variations

Reindeer grazing affects plant life in the Swedish montane landscape, but local variations are large. This is clear from the first systematic review of the area by the Mistra Council for Evidence-based Environmental Management (EviEM). This review is a key piece in the jigsaw puzzle of government agencies’ work to achieve the environmental quality objective of A Magnificent Mountain Landscape.

Perceptions of how reindeer grazing affects the mountain landscape differ. Among scientists, too, there is uncertainty as to whether the grazing harms the vegetation or, on the contrary, contributes to biodiversity. A group of Nordic researchers have therefore, on behalf of Mistra EviEM, examined all existing knowledge in this area.

After an extensive search of the academic literature, they compiled data from 41 studies performed in the Nordic region, North America, Russia, Greenland and elsewhere. Analysis of the results confirms that forbs (herbaceous flowering plants that are not grasses, sedges or rushes) and lichens are under duress, while mosses are less vulnerable.

‘Individual effects on the vegetation are as we expected. What surprised us was that the impact varied so much from one place to another. I’d thought we would get a more clear-cut result,’ says Jon Moen, professor at Umeå University and chair of the review group.

No unequivocal answer to the question of how reindeer grazing affects the flora can be obtained, at least on the basis of current knowledge.

‘There’s no universally valid patent solution. The impact of reindeer grazing depends on the context. You have to understand how reindeer influence the vegetation in each individual case,’ Moen points out.

Difficulties due to research variation

One important conclusion from the review is that the impact of reindeer grazing on plant life varies greatly. This is both because of differences in the management of reindeer husbandry around the world and because the studies cover many different habitats that react differently to being grazed and trampled on by reindeer. A factor impeding clear conclusions, too, is that the researchers behind the various studies included in the review have, in Jon Moen’s view, used differing methods and described their findings in such a way as to make them hard to summarise.

Mistra EviEM was founded in 2012. Its task is to assist Swedish environmental agencies by providing decision data with a scientific foundation in various fields. Similar organisations have been set up in the past few years in the UK, South Africa, Australia and Canada. The model is derived from the care sector, where evidence-based documentation on suitable medical treatment has long been drawn up.

The study of the impact of reindeer grazing is the first systematic review carried out by Mistra EviEM. This extensive study was published just the other day, which gave pleasure to Sif Johansson, programme director at Mistra EviEM.

‘The researchers involved in the review have done a superb job, and their extensive knowledge is a guarantee that the review is of high scientific quality,’ says Johansson.

More knowledge needed

The knowledge foundation proved to be inadequate to guide environmental policy and management of the reindeer stocks in detail. But this does not represent failure: one important lesson learnt is the conclusions about what research is needed are just as important as the research results to date, thinks Sif Johansson.

The review will promote efforts to achieve A Magnificent Mountain Landscape, one of Sweden’s 16 national environmental quality objectives.

‘Throughout the review, we held ongoing discussions with the Swedish Environmental Protection Agency and other stakeholders. This enabled us to contribute to their work on the environmental quality objectives,’ says Johansson.

Text: Henrik Lundström, Vetenskapsjournalisterna


More reviews under way

Later in the spring, EviEM will present another systematic review — of whether water quality in eutrophic lakes can be improved by reducing the number of fish feeding on zooplankton. A further four reviews are in progress. Also later in the spring, three new reviews will start on the following topics:

  • the effects of buffer zones around arable land
  • how management of road verges affects flora and fauna
  • how human activities in shallow marine areas influences fish reproduction.

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