Species composition and distribution pattern of invasive plants in the Ili River Valley region, China.

To understand the species composition and distribution patterns of alien invasive plants within the Ili River Valley region, we conducted field investigations and specimen collections from 2022 to 2024 using route survey methods. Combined with digital herbarium data and literature review, we clarified the species composition of invasive alien plants in this region and analyzed their floristic geographic elements, life forms, origins, invasion pathways, invasion grades, and distribution patterns. There were 58 invasive plant species in the region, belonging to 38 genera and 18 families. The dominant families were Asteraceae (13 species), Fabaceae (9 species), and Amaranthaceae (6 species). The geographic floristic elements of the 38 genera could be classified into 7 types and 2 subtypes, with temperate geographic elements (64.3%) being predominant. Life forms were mainly annual herbs (34 species, 58.6%), followed by perennial herbs (14 species, 24.1%). Most invasive plants originated from America and Europe (61.1%), followed by Asia and Africa. Regarding invasion pathways, 39.7% were intentionally introduced, 56.9% unintentionally introduced, and only 3.4% spread naturally. Invasion grade analysis revealed 24 species (41.4%) showing significant invasiveness, with grade 1 (5 species) and grade 2 (14 species) being predominant, indicating a relatively severe overall invasion status. The geographical distribution of invasive alien plants in the Ili River Valley region was uneven, exhibiting significant spatial variations, with Xinyuan County being the most severely affected.