Publication details

Vliv nepůvodních druhů na biotickou homogenizaci středoevropských měst

Title in English Alien species affect biotic homogenization of Central European cities


Year of publication 2009
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description Urbanization and associated spread of alien species in cities is presumed to result in biotic homogenization, i.e. increase of between-site similarity in floristic composition. Level of biotic homogenization may vary between cities of different climatic regions and also between different urban habitats. We studied the effect of alien species on floristic similarity among fifteen large cities in Central Europe, with the aim to determine patterns of biotic homogenization. We used standardized sampling design to obtain floristic data for each surveyed city. In each of the 15 cities, species composition of all vascular plants except those deliberately planted was recorded in seven 1 ha plots, each representing one urban habitat. In total, we recorded 892 plants on 105 (15 x 7) plots. Of them, 451 species were native and 441 species were alien. We calculated the Sorensen index of similarity separately for all species, native species and alien species and used these values for expressing a homogenization index for each pair of studied cities and for each pair of studied habitats. Homogenization index was obtained by subtracting similarity index for native species from that for all plant species. We related Sorensen indices and homogenization indices to geographic and climatic distances between pairs of cities and between pairs of selected urban habitats. We found that more than 70 %of compared pairs of plots were homogenized due to the invasion of alien species and that the level of biotic homogenization differed between urban habitats. Biotic homogenization increased with increasing climatic dissimilarity of cities. Our results do not show a clear relationship between geographical distance of studied cities and the homogenization index.
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