Is the proportion of alien species in man-made habitats influenced by city size?
Little is known about the possible relationships between the proportion of alien plant species and the size of cities. A study was carried out in 3 types of human settlements all located in Central Europe: cities with more than 100;000 inhabitants, towns with populations between 20;000 to 50;000 inhabitants and villages with less than 5000 inhabitants. In each settlement, 3 types of habitats were chosen: paved settlement centre, residential area and abandoned area with perennial grassland and shrubs. Alien species were categorized as native, archaeophytes (species introduced before 1500) and neophytes.
This study highlighted that the total number of alien plant species in studied habitats was affected by city size. The proportion of neophytes increased with city size especially in residential areas, where human activities serve as a source of propagules of neophytes. In contrast, the proportion of archaeophytes did not depend on the population size of the city. Archaeophytes represented a well-established part of the flora of settlements and their surroundings because these species are not dependent on the repeated human introduction to urban habitats.
Sources
Čeplovà N, Lososovà Z, Kalusovà V (2014) Is the proportion of alien species in man-made habitats influenced by city size? Abstract of the 4th International Symposium on Environmental Weeds and Invasive Plants, Montpellier (FR), 2014-06-19/23.