The aim of the FENCES experiment is to assess the impact of sheep grazing on summer rangelands in the highlands of Iceland. The experiment was established in 2016 by setting up fences that exclude sheep grazing at two sites and in two contrasting habitats that differ in their susceptibility to soil erosion. The basis of site and habitat selection lays on two of the main features that determine the ecological conditions in Iceland: volcanic activity and vegetation cover. We regularly monitor vegetation composition inside and outside the fences, as well as many other parameters that inform us of ecosystem changes associated with sheep grazing.