Invasion dynamics of three allergenic invasive Asteraceae (Ambrosia trifida, Artemisia annua, Iva xanthiifolia) in central and eastern Europe.

We analyzed the history of the invasion, spread dynamics and habitat affiliation of three allergenic wind-pollinated species (Ambrosia trifida, Artemisia annua, Iva xanthiifolia; tribe Heliantheae, Asteraceae) in central and eastern Europe (CEE) using distribution data from a wide range of sources. In addition, we used niche-based ensemble modelling techniques to assess current invasion risk of the region studied. We collated 1804 records of A. annua, 1063 of I. xanthiifolia and 324 of A. trifida. All species were first recorded in the 19th century, remained rare until the middle of the 20th century, but have spread rapidly in recent decades. Iva xanthiifolia spread the fastest followed by A. annua. The latter species is now abundant in northern Italy, along the Elbe river in Germany and the Danubian Lowland in Slovakia and Hungary, while I. xanthiifolia occurs most frequently in the warm and continental parts of CEE. Ambrosia trifida spread slowly and its current distribution consists of relatively few and mostly isolated localities in CEE. Ambrosia trifida and I. xanthiifolia occur primarily in ruderal habitats, whereas I. xanthiifolia has also increasingly invaded fields. Initially confined to ruderal habitats, A. annua has expanded its habitat niche during the invasion and has invaded riverine vegetation and (semi-)natural habitats. Ensemble species-distribution models show that the current distribution of A. trifida and A. annua in CEE is closely related to temperature and precipitation, whereas land use is only important for I. xanthiifolia. Under the current climate, substantial fractions of the study area provide suitable habitat for these species: A. trifida (16% of CEE), A. annua (28%) and I. xanthiifolia (26%). Because of their significant potential impact on public health, future spread of these species should be monitored and management strategies (e.g. raising awareness, early control) should urgently be implemented.