Abstract:

Solidago canadensis, a plant listed on the second batch of alien invasive species in China, was first detected in Wenzhou in 2003. In the present study, typical coastal habitats in Wenzhou were strategically selected, and the survey data collected from 40 quadrats were used to to meticulously investigate the variations in the community structure and species diversity of S. canadensis invasions under diverse invasion intensities and habitat types, to reveal the invasion characteristics and underlying mechanism of S. canadensis in coastal areas. It was shown that within the invaded communities of S. canadensis in Wenzhou, there were 34 species of vascular plants, which were taxonomically classified into 28 genera across 13 families. Notably, invasive plants accounted for 26.5% of the total species. As the invasion degree of S. canadensis intensified, the number of community species, encompassing both native and invasive plants, declined gradually. Concomitantly, the proportion of invasive species increased, and the cumulative importance value of invasive plants steadily rose. Further in-depth analysis demonstrated that S. canadensis boasted the highest importance value and niche breadth within invaded communities. In comparison to native species, the importance value and niche breadth of other invasive plants predominantly ranked among the top positions in these commuties. Furthermore, the species diversity indexes of the severely invaded communities were significantly (p<0.05) lower than those of the slightly and moderately invaded ones. There was negative correlation within S. canadensis and both invasive and native plants in the relative abundance, and this correlation strenthened as the invasion degree escalated. The analysis of niche overlap index further corroborated that the increasingly competitive relationships between S. canadensis and other invasive as well as native species within moderately and severely invaded communities were the root causes underlying the aforementioned outcomes. Among different habbitats, garden and transportation land facilitated the dissemination of alien species. In contrast, cultivated land might offer certain protection against alien invasive plants.

Key words: biological invasion, habitat, Solidago canadensis, species diversity, niche