Abstract: Invasive alien species pose a severe threat to China’s biodiversity, economic development, and human health, yet research on the invasion mechanisms remains relatively insufficient. This study focused on the widely invasive Solidago canadensis in China, with the surrounding area of Ningbo Port as the study region. After investigating 270 quadrats, principal component analysis, multiple linear regression models, and generalized linear models were employed to explore the effects of species diversity, phylogenetic diversity, and environmental factors on the invasion of S. canadensis. The results showed that: (1) The invasion of S. canadensis was severe, accounting for 74.44% of the surveyed quadrats; (2) The influence of environmental factors on the invasiveness of S. canadensis was limited, with only the second factor composed of soil factors showing a significant positive correlation with the relative height of S. canadensis (P<0.05); (3) Species diversity had a significant inhibitory effect on S. canadensis, exerting a notably negative impact on relative height, relative abundance, relative cover, and ecological importance value (P<0.05), with contributions all exceeding 70%; (4) Phylogenetic diversity did not affect the invasiveness of S. canadensis (P>0.05), and the Darwinian naturalization conundrum requires further investigation. This study demonstrates that the invasiveness of S. canadensis in port areas is not affected by environmental factors, but is primarily suppressed by plant diversity, particularly species diversity. It is suggested that the “biotic resistance hypothesis” is the main mechanism explaining the invasion of S. canadensis in port areas. Our findings are of significant importance for the development of control strategies for invasive species in port regions.

Key words: diversity-invasiveness, environmental factor, Solidago canadensis, invasion mechanism