The species composition and distributional characteristics of invasive alien plants along the new Sichuan-Tibet railway (Ya'an to Changdu section).
Hengduan Mountains is a hotspot of global biodiversity and serves as an important part of the national ecological barrier. The new Sichuan-Tibet Railway (Ya'an to Changdu section) crosses the core area of the Hengduan Mountains. The transportation network formed by the railway connects the biodiversity hotspots along the route to the outside world, leading to an increased risk for biological invasions. In order to obtain information on the composition and distributional characteristics of the invasive alien plants in this region and provide references for upcoming railway construction, ecological protection, and ecological restoration, we selected 43 representative sites (1 km × 0.02 km) in the area to conduct surveys. A total of 58 invasive alien species were identified, belonging to 18 families and 42 genera. The three most frequently occurring species were Galinsoga parviflora, Cosmos bipinnatus, and Bidens pilosa. Ten species were considered to be the malignant invasive species, 16 serious invasions, 8 local invasions, and 15 general invasions. The damage of the remaining 9 species needs further observation. The Americas are the primary geographical origin of invasive alien plant species in this region. A comparative study based on altitude and major rivers found that with increasing altitude and geographic extension, the number of invasive alien plants decreased significantly, and the distributional pattern was the result of the combined effects of environmental factors and human activities. Based on the status and habitat characteristics of the invasions along the railway, this study analyzed the risk of alien plant invasion caused by railway construction, and we make corresponding suggestions to prevent further invasion.