Composition and distribution of invasive alien plants in Suzhou area.
In order to understand species composition and distribution of invasive alien plants in Suzhou, invasive alien plants in different habitats of 26 sample plots in six counties or cities (including Changshu, Kunshan, Suzhou, Taicang, Wujiang and Zhangjiagang) of Suzhou area were investigated and analyzed. The investigation results show that there are 7-25 species of invasive alien plants in these plots with the average of 17.9 species per plot. There are 57 species of invasive alien plants observed in 26 sample plots, belonging to 45 genera in 19 families. In which, species number in Compositae (23 species) is the most, which accounts for 40.4% of total species number. And species number in Leguminosae, Scrophulariaceae, Poaceae, Apiaceae, Amaranthaceae and Convolvulaceae is also more. Number of species originated from North America and Europe is 20 and 12 with the percentage of 35.1% and 21.0% of total species number, respectively, there are 17 species originated from other regions of America and a few species originated from Africa, West Asia and Mediterranean. In 57 species of invasive alien plants, there are 55 herb species and 44 non-perennial plants accounting for 96.5% and 77.2% of total species number, respectively. There are 18 species with the frequency over 50%, in which, frequency of Solidago canadensis L. and Erigeron annuus (L.) Pers. is the highest with the value of 96.15% and 92.31%, respectively, and their abundances belong sociales scale (Soc). And also, frequency of Alternanthera philoxeroides (Mart.) Griseb. and Trifoliutn repens L. is over 80% with an abundance of sociales scale (Soc). It is concluded that the invasive phenomenon of alien plants in Suzhou area is very serious.