Changing dispersal processes in the central European landscape since the last ice age: an explanation for the actual decrease of plant species richness in different habitats?

During the evolution of the Central European landscape and especially since the settlement of man there has been a permanent change of processes affecting dispersability of plants. In a traditional man-made landscape there was the highest diversity of dispersal processes combined with a high diversity of land use practices. In the actual man-made landscape most of these processes became lost or changed. Due to the rules of seed prescription many weeds became extinct, which were spread in former times with uncleaned seed. Traditional manure contained huge amounts of diaspores whereas today animal slurry with low contents of diaspores or mineral fertilizer are used. Changing harvest methods have selected the dominance of weeds which ripen later and have light diaspores. Herded and transhumant domestic livestock decreased or became locally extinct, which was probably the most important dispersal vector in the Central European man-made landscape. Artificial flooding practices favoured the migration of species in meadows of mountain and floodplain regions. Whereas in the traditional man-made landscape all habitats were more or less connected due to alternating management or grazing, today most habitats are isolated. With respect to restoration efforts in habitats dispersal processes or vectors should be included before planning. If there is no possibility of restoring traditional or similar dispersal processes, artificial reintroduction of species is the only option.