Study area - The Lorraine district
The Lorraine district (Lorr.) is a part of the large sedimentary basin of Paris and corresponds to geological rocks of the Mesozoic, in particular sandstone, sand and clay of the Triassic and Lower Jurassic periods. Its relief in cuesta is highly characteristic and has permitted the conservation of forest blocks, which are well preserved and of prime importance for the lichen flora. The gorges near Berdorf in Luxembourg are also a Mecca for lichenology in the area of study. Semi-natural habitats rich in lichens are now rather rare in the district, but roadside trees have so far been able to maintain locally quite interesting epiphytic communities. The ‘Moselle’ subdistrict corresponds to the calcareous outcrops of the Muschelkalk (Trias).