Abstract:

Aims Amaranthus retroflexus is the most harmful, widely distributed invasive species in its genus. Our objective was to determine its potential worldwide distribution and compare that with its present distribution.

Methods We selected 28 environmental factors including climatic, topographic and soil factors as GIS layers and determined their quantitative relationship with the actual global distribution of the species, based on 4 207 herbarium records. Principal component analysis (PCA) was used to select the environmental factors influencing the distribution of the species. Based on these results, we estimated the central and maximum potential distribution of A. retroflexus and compared them to its actual geographical distribution.

Important findings Fourteen environmental factors importantly affected the distribution of A. retroflexus. The central potential distribution range was southern New Zealand, southeastern Australia, some areas in northern South America, northwestern and southeastern North America, most of Europe and southeastern China. The maximum potential distribution range was southcentral South America, most of North America, some areas in northern Africa, most of Europe, some areas in southern and northern Australia and most of Asia including most of China except Tibet, Qinghai Province, Xinjiang and western Sichuan Province. The potential central distribution of the species matched its actual distribution, whereas the potential maximum distribution was much larger.

Key words: invasive species, Amaranthus retroflexus, environmental factors, maximum distribution, central distribution, actual distribution