Abstract:

In order to understand factors regulating the distribution of invasive plants in Wenzhou, we used route-checking and fixed-plot sampling to evaluate the distribution of invasive species and associated agrotype, topographical and anthropological factors. Relationships between the distribution of invasive plants and the environmental factors were assessed using canonical correspondence analysis (CCA). Analysis of variance was used to test for differences in species composition and abundances of the invasive plants among different parts of the region, and to explore the major factors responsible for the differences. Our investigations showed: (1) 64 invasive plant species from 28 families and 51 genera were found in Wenzhou. More than 70% of those species were either annual or biennial dicotyledonous, and 68.8% of them were of American origin. (2) The number of invasive plant species differed among the 11 investigated counties of the region, among which Yueqing County had the highest number of species (51 spp.), followed by Cangnan (43 spp.), while Dongtou had the fewest (27 spp.). (3) The distribution of exotic invasive plants in Wenzhou was most affected by traffic frequency, the degree of settlement, and landform type. (4) The distribution of common eurychoric species was not affected strongly by any single environmental factor. The distribution of rare species with limited distributions, however, was affected significantly by both traffic frequency and landform; (5) Human activities played an important role during the initial stage of the invasion for the successfully invaded plants. Environmental factors were critical to the invading plants during the establishment stage of the invasion, while their biological characteristics had the major effect on their successful spread and on the extent of the damage they would cause in the areas they invaded.

Key words: invasive plants, environmental factors, canonical correspondence analysis, spatial distribution pattern, life forms, invasive stages