Survival rates in the Czech Republic of introduced plants known as wool aliens
In Brno, Czech Republic, was located a factory processing wool imported mostly from Australia and South America. Its employees used the processing refuse to fertilize their allotments. From 1958 to 1961, Dvořák and Kühn (1966) observed the plants which were growing in these gardens. Their 5 year record constituted a reasonably complete set of species which might have been introduced with wool imports and which were able to germinate under the local Czech conditions. This set of data was revisited by Pyšek in 2005. To obtain a list of species specifically introduced with wool, archeophytes were excluded from the original list, as well as neophytes known not to be associated with wool. 56 species were identified as associated with the wool processing industry in Brno, and were checked against the recent Czech alien flora to estimate their fate, almost 40 years after their introduction.
Of the 56 species, 18 still occur in the Czech Flora and 38 are considered extinct. Most of the 18 species still occurring are casual and have been frequently reintroduced in different places in the Czech Republic, not only through the wool pathway, though it remains typical of these species. Only 3 species naturalized: Chenopodium pumilio (Chenopodiaceae), Panicum capillare (Poaceae) and Xanthium spinosum (Asteraceae). The extinction rate is therefore 77.9%, survival rate is 22.1%, and naturalization rate is 5.4%. These data fit the ‘tens rule” predicting that 10% of the species entering a country naturalize, with confidence limits comprised between 5 and 20%. It should nevertheless be kept in mind that the number of species in this study is rather small.
Wool aliens originating from Australia, Africa and South and Central America were over represented in comparison with neophytes from other continents. There is a remarkable under representation of North American species.
Poaceae was the most represented family, constituting 62.5% of wool aliens, while they only represent 7.9% of the neophyte in the flora of Czech Republic. Fabaceae were also well represented (12.5% versus 7%).
The wool alien flora contained 48 annuals (72.7%), 8 perennials (27.3%), and no woody species (i.e. shrubs, trees or climbers). All surviving species were annuals. This can be associated with the habitat in which the species grew, i.e. gardens.
Height and flowering time did not appear to be good indicators of whether the species would survive or not.
Sources
Pyšek P (2005) Survival rates in the Czech Republic of introduced plants known as wool aliens. Biological invasions 7: 567-576.