Veränderungen der Flora der Stadt Zürich in den letzten 150 Jahren

Abstract

Out of 970 species mentioned by Kölliker (1839) from the area of the township of Zürich 130 (13%) died out and 170 (18%) became endangered. The reduction of the number of species is predominantly due to the changing methods of agricultural and forestry management and to built-over land. Thanks to the great variability of different ecological niches within the city which compensates some of the lost agricultural biotopes, the decline is not stronger. Since 1839 nearly 350 new species became introduced out of which at least 20 colonized more than half of the squares and are frequent. A great amount of species is only locally established or dependent on a steady flux of reproduction units from gardens. Today the flora of Zürich consists of almost 600 originally native species (idiochorophytes) (decline of about 30 species), 150 archaeophytes (decline of about 100 species), 350 more or less integrated neophytes (increase of over 250 species) and more than 100 ephemerophytes.