2. From the Pic du Mas de la Grave refuge to the refuges of Les Mouterres and Le Fay

2 points of interest

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  Fauna

  A “plague” of voles

  The European water vole, also called the rat taupier (mole-like rat) in French, is one of the biggest species of voles. Its breeding cycle is such that the species can undergo phases of infestation. Although the causes are not fully understood, this cyclic problem started a few years ago in the valley of La Buffe, at an altitude of 2,000 metres. Although the first signs of the presence of voles in a meadow are undoubtedly the "molehills" they create, when they constitute a plague, they can completely overturn the earth, which could be mistaken for ploughed land.

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  Flora

  The wetlands of the Rif Tort

  Temperatures on the Emparis plateau are characteristic of a cool steppe climate. It is a very windy plateau with an average annual temperature only just above zero degrees. Winter lasts for eight months, during which it freezes almost every day. The particularly severe temperature constraints in the Rif Tort catchment area have favoured the maintenance of a relic flora adapted to these extreme conditions since the last ice age. «Arctic-Alpine»plant formations are found here. This is a relic flora inherited from advancing glaciers in the Quaternary period, comparable to the flow found on the coasts of the Far North. These formations are particularly rare in Europe and are of very high heritage value. You might see numerous protected species here: bicoloured sedge, sweet grass (a boreal relic species, sole colony in Isère) and the sago pondweed. Livestock grazing in the marsh is necessary because it limits the development of herbaceous plants which could squeeze out the Arctic-Alpine species. A delicate balance needs to be found between the trampling likely to destroy the plant species growing in the low marshes and the passage of the flocks to encourage rejuvenation of the area, and thus maintain this habitat.