Alien Vascular Plants of Kazakhstan: The First National Checklist and Spatial Distribution Patterns.

Biological invasions contribute to global biodiversity change, yet Kazakhstan's alien vascular flora remains insufficiently documented. We provide the first comprehensive verified inventory of alien vascular plants in Kazakhstan, synthesizing literature, herbarium collections, field observations, and iNaturalist and Plantarium records. The alien flora comprises 263 taxa in 181 genera and 54 families: 141 taxa (53.6%) are naturalized, 120 are casual, and two have unresolved establishment status. Neophytes predominate (218 taxa: 104 naturalized, 112 casual, two unresolved), whereas archaeophytes comprise 45 taxa (37 naturalized, eight casual). Asteraceae is the most taxon-rich family (47 taxa), followed by Poaceae (30), Brassicaceae and Fabaceae (20 each), Amaranthaceae (15), and Lamiaceae (14), while annual taxa dominate the life-cycle spectrum. Mediterranean-origin taxa form the largest biogeographical group (39.9%), followed by taxa native to the Americas (22.8%). Most taxa are associated with human-modified habitats; 75 taxa (28.5%) also occur in natural ecosystems. Twenty taxa are invasive; under the Environmental Impact Classification for Alien Taxa (EICAT), 17 have Moderate and three Major impacts. Alien taxon richness is spatially heterogeneous, with the highest values in the Trans-Ili Alatau, Altai, and Western Tian-Shan. This study establishes a national baseline for monitoring, invasion-risk assessment, biodiversity management, and conservation in Kazakhstan and Central Asia.