Phytodiversität jüngerer Verkehrswege
In historical times the system of waterways was overlayed only by historical courses (Dietwege, Heerwege, long distance trails of flocks, later also causeways). Nowadays overlaying nets of traffic systems like roads, motorways, railway tracks and inland waterways facilitate the spreading of ruderal plants and invaders. The “globalization” results also in a till now unknown exchange of species. Migration phenomena happen very quickly along linear structures. Traffic areas can be very rich in species even on small areas. E.g. railway systems can be seen as “hot spots” with respect to the diversity of cormophytes. Inner-city railway fallow grounds are important as a refugium for low competitors on poor nutrient soils. It is to assume that also the micro evolution is speeding up at such places. But detailed investigations are very seldom.
A change of the ruderal vegetation happened nearly unnoticed. In the mean while in Central Europe the largest connected ruderal areas are to be found along traffic systems. Besides all floristic differences between road edges and railway stations resp. inland harbours, the grassland matrices of the slopes of roads, motorways, railway tracks and channels are very similar to each other. Actually inner-city railway fallow lands and the whole roadsides are characterized by a high phytodiversity and a high nature protection value.
Remark: This paper is the slightly modified version of an oral presentation of a survey lecture on the meeting „Landnutzungssysteme und pflanzliche Biodiversität“ at the university of Jena in May 2011. Unfortunately the publication of the proceedings is however delayed till now (more than 10 years). Therefore the presentation from 2011 is published here updated to some extent (approximately 2013).