Checklist of Austrian neophytes (2nd edition)

Twenty-two years after publishing the first edition of the checklist of alien vascular plants introduced to Austria after 1492 (i.e. neophytes), we present a completely revised second edition. For the update presented here, we collected, compiled and standardized data on all known neophytes in Austria with data collection ending September 2022. In addition, we provide information on the regional distribution in the federal states, invasion status, habitat affiliation, the first records, the regions of origin, pathways of introduction and spread, and impacts. The second edition of the Austrian neophyte checklist contains 1,615 taxa – 1,388 species, 7 aggregates, 138 hybrids, 70 subspecies, and 12 lower infraspecific taxa distributed across 135 families. Of these taxa, 548 were newly added in the second edition, which constitutes an increase of 45% of recorded neophyte plant taxa compared to the first edition. A total of 99 taxa included in the first edition of the checklist of neophytes were removed in the edition presented here due to erroneous or doubtful records, or due to being considered native or archaeophytic. The majority of neophytes (1,180) have only casual occurrences in Austria, while 207 taxa are locally established and 226 taxa have become widely established. The habitats showing the highest numbers of neophytes were ruderal (1,420 taxa) and segetal habitats (204 taxa). The most important donor regions for neophytes in Austria are temperate Asia (761 species), followed by Europe (607), North America (389), and Africa (311). While 118 neophytes were known by 1850 in Austria, this number increased to 265 in 1900, 514 in 1950, 1,084 in 2000, and currently 1,615 taxa. Reports of newly introduced taxa show a particularly pronounced increase since the mid-20th century, as 1,056 (65%) were first found after 1950, and 496 (31%) were first recorded after 2000. The most important introduction pathways into Austria are known for 1,016 taxa, with escape (912) and stowaway (118 taxa) being by far the most common pathways. In total, 73 taxa were assessed to have negative impacts in Austria. Specifically, 48 have negative impacts on biodiversity, 26 on agriculture, nine on silviculture, six on human health, three on water management and one taxon negatively impacts animal health. To conclude, the revised inventory of neophytes in Austria documents the extraordinary dynamics of neophyte accumulation and spread in a botanically well-explored country and provides a wealth of data for research and environmental management.