Many old stories include warnings to beware of nasty surprises that can appear harmless, like the wolf disguised as a sheep to better sneak up on the unknowing flock. But what if the sheep themselves are actually the nasty surprise? In some parts of Iceland, extensive land degradation has been linked to overgrazing by livestock, as well as land clearing and natural processes including a harsh climate and frequent volcanic activity. Identifying the factors responsible for ecosystem changes in these environments is essential for making good management decisions. In this paper, we use state-and-transition models, a simple representation using boxes and arrows, to describe ecosystem changes in Iceland over three periods with different human influence, from pre-settlement times to present days. The results suggest increasing complexity in recent decades where the models include stronger human influences, particularly sheep grazing. These models can be used to make predictions about possible management interventions, so they can help farmers, managers and researchers identify realistic and achievable restoration goals.
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Reference: Barrio, I.C., Hik, D.S., Thórsson, J., Svavarsdóttir, K., Marteinsdóttir, B., Jónsdóttir, I.S. (2018) The sheep in wolf’s clothing? Recognizing threats for land degradation in Iceland using state‐and‐transition models. Land Degradation and Development 29:1714-1725.
Picture: Icelandic sheep (photo: David Hik)