Abstract: As an ornamental plant, Solidago canadensis was first introduced from North America to Shanghai and Nanjing in 1935, which has become one of the important invasive alien plants in China. Its seeds can diffuse by wind, its rhizomes can be cloned, and thus, the reproductive capacity of S. canadensis is very high. In 2006-2008, an investigation was made on the growth and reproductive characteristics of S. canadensis with different population densities (30-50, 60-80, and 90-120 plants per square meter) in Xiasha of Hangzhou, aimed to approach the grow and reproduction patterns of S. canadensis under natural conditions. At  the population density of 90-120 plants per square meter, the average plant height of  S. canadensis was higher than that at other population densities, with the biggest difference of 57.6 cm. At the population density of 60-80 plants per square meter, the stem diameter of S. canadensis was the largest, being averaged 10.3 mm, and 2 mm larger than that at the population density of 30-50 plants per square meter. The leaf number of S. canadensis increased most at population density of 60-80 plants per square meter, with the mean daily increment of 3.4 leaves. At the population density of 90-120 plants per square meter, S.canadensis bloomed earliest, being 8 and 3 days earlier than at the population densities of 60-80 and 30-50 plants per square meter, respectively. The seed dispersal was also the earliest at the population density of 90-120 plants per square meter, being 7 and 2 days earlier than that at the population densities of 60-80 and 30-50 plants per square meter, respectively. At the population density of 60-80 plants per square meter, S. canadensis produced the largest number (77896) of seeds, and the seeds had the highest germination rate. This study could provide scientific basis for preventing and controlling the invasion and dispersal of S. canadensis in China.

Key words: Carabid, Edge effect, Biodiversity, Agro-landscape