Autobahnen als Wuchsorte und Ausbreitungswege von Ruderal- und Adventivpflanzen / von Dietmar Brandes
The ruderal vegetation is characterised by dynamic changes in relation to habitats and species combinations. Whereas classic habitats are reduced, corridors like river banks and traffic facilities are becoming more and more important. Numerous by-chance-observations support the impression that motorways are playing a big role as habitat as well as conduit for ruderal plants and alien species, however intensive investigations are missing. Therefore the ruderal vegetation of 8 exemplary parts of motorways in Lower Saxony, Saxony-Anhalt, Thuringia, Saxony and Bavaria with a length of 775 km was investigated. 145 ruderal and adventive plants have been identified clearly by mapping from the moving car. There was no correlation between the number of species and the length of the section of the motorway. Motorways in subcontinental rural landscapes show a relative high number of species on a relative short distance where as parts in lower mountains show fewer species. Therophytes and biennials are able to establish in the gaps of the vegetation. In a whole 73 therophytes and 43 biennials have been registered on the borders of German motorways. Very large populations of ruderal plants can establish at the sites of road works. The spreading of foreign plants along the motorways is demonstrated for selected species, mechanism and reasons for the migration are discussed. The German motor ways are habitat for ruderal plants which cannot be ignored. The spreading of some foreign plants along the motorways happens very quickly whereas the diffusion into the bordering landscape shows great delay.