Über Pflanzenarten, die sich in den letzten 150 Jahren in der Stadt Zürich stark ausgebreitet haben
The results of a cartography of the flora of the political township of Zürich on a square kilometre base have been compared with earlier indications. More than 150 species have disappeared and many further species have decreased considerably within the last 150 years. On the other hand, more than 300 new species have arrived and several species have expanded. Of this last group 99 mostly frequent species have been compiled (Table 1). Of these species 15 % belong to the idiochorophytes, 9 % to the archeophytes and 75 % to the neophytes. In relation to their ecological origin they can be categorized in 8 % garden spring geophytes, 14 % garden woody plants, 19 % garden ornamental herbs, 5 % vegetable, spice and medicinal species, 37 % ruderals and weeds, 4 % introduced meadow and lawn species, 2 % aquaria species, and 12 % indigenous wood and swamp species. Thirty percent of these species originate from Central Europe and Eurasia, 26 % from Southern and Western Europe, 24 % from America, 6 % from Western Asia and 14 % from Eastern Asia. Similar to the indigenous vegetation, the main distribution area of most of the newly expanded city species is in suboceanic regions. In the more continental Berlin, 38 % of these species are missing or rare. On the other hand, many continental species which are today characteristic of Berlin can scarcely be found in Zürich. Most of the species of the investigated group are characterized by high indicator values for soil nitrogen, soil reaction and temperature.