Background: In ethnobotanical research, the investigation into traditional knowledge of medicinal plants in the context of migration has been of increasing interest in recent decades since it is influenced and changed by new environmental and social conditions. It most likely undergoes transformation processes to match the different living circumstances in the new location. This study compares the traditional knowledge of medicinal plants held by Tyroleans - and their descendants - who emigrated to Australia, Brazil and Peru at different time scales. The study's findings allow a discussion of the complexities and dynamics that influence this knowledge within the context of long-distance migration.
Methods: Information was obtained from 65 informants by free-listing, semi-structured interviews and non-participatory observation in Tyrol (Austria) and the migrants' countries: Australia, Brazil and Peru. The collected data was analysed using different quantitative approaches, including statistical tests, and compared between the countries of investigation.
Results: All respondents in all four investigation areas claimed that they had knowledge and made use of medicinal plants to treat basic ailments in their day-to-day lives. Informants made 1,139 citations of medicinal plants in total in free lists, which correspond to 164 botanical taxa (genus or species level) in Tyrol, 87 in Australia, 84 in Brazil and 134 in Peru. Of all the botanical taxa listed, only five (1.1%) were listed in all four countries under investigation. Agreement among informants within free lists was highest in Tyrol (17%), followed by Peru (12.2%), Australia (11.9%) and Brazil (11.2%). The proportion of agreement differs significantly between informants in Australia and Tyrol (p = 0.001), Brazil and Tyrol (p = 0.001) and Peru and Tyrol (p = 0.001) and is similar between informants in the migrant countries, as indicated by statistical tests. We recorded 1,286 use citations according to 744 different uses (Tyrol: 552, Australia: 200, Brazil: 180, Peru: 357) belonging to 22 different categories of use. Use values are significantly different between Tyrol and Australia (p < 0.001) but not between Tyrol and Brazil (p = 0.127) and Tyrol and Peru (p = 0.853). The average informant agreement ratio (IAR) in Tyrol is significantly higher than in Australia (p = 0.089) and Brazil (p = 0.238), but not Peru (p = 0.019).
Conclusions: Changing ecological and social conditions have transformed and shaped traditional knowledge of medicinal plants through adaptation processes to match the new circumstances in the country of arrival. Continuation, substitution and replacement are strategies that have taken place at different rates depending on local circumstances in the research areas. Traditional knowledge of medicinal plants acquired in the home country is continuously diminishing, with its composition influenced by urbanisation and ongoing globalisation processes and challenged by shifts from traditional healing practices to modern healthcare facilities.