Map of the regions delimited for the regional threat classification of habitats (major landscape regions; red outlines). For ecological characterisation, Germany can be subdivided into natural units. The figure is based on the system of Meynen and Schmithüsen et al. (1953–1962). For the application in the habitats directive (Natura 2000) and the risk assessment of habitats Ssymank (1994) has restructured and generalised the system. The classification of major landscape units is based on physiographic units (black outlines; for a reference list see Annex V.6, Finck et al. [2017]) according to Ssymank et al. (1998) and Petersen et al. (2003).