Alien invasive organisms and their distribution in forest, grassland and wetland ecosystems in Anji County, Huzhou City

As the birthplace of the concept of ' lucid waters and lush mountains are invaluable assets ', the problem of alien invasive organisms in Anji County has attracted much attention. The forest, grassland and wetland ecosystems in Anji County were investigated by sample line and sample plot survey methods. The species and hazards of alien invasive organisms in the region were comprehensively understood, and the risk level of invasion was evaluated.The survey results showed that there were 13 species of alien invasive organisms in Anji County, including Eichhornia crassipes、Ambrosia artemisiifolia、Alternanthera philoxeroides、Amaranthus spinosus、Solidago canadensis、Dysphania ambrosioides、Hydrocotyle vulgaris、Ipomoea triloba、Bidens frondosa、Bidens alba var. Radiata、Pomacea canaliculata、Pseudomonas syringae pv.actinidiae and Corythucha ciliate. Among them, there were 4 species of Asteraceae plants, accounting for 30.8%, followed by 2 species of Amaranthaceae plants, accounting for 15.4%. From the perspective of geographical distribution, most of these alien invasive organisms are native to the Americas, with the largest number of 6 species in tropical America, accounting for 46%. From the perspective of township distribution, Dipu Town and Baofu Town had the most abundant alien invasive species, with 10 species, accounting for 76.9%, while Xilong Town and Guishan Town had the least, with only 5 species, accounting for 38.5%. From the perspective of biological distribution, Solidago canadensis, Alternanthera philoxeroides, Amaranthus spinosus and Pennisetum grandiflorum are distributed in all townships in the county, Corythucha tabaci is only distributed in Baofu Town, and Pseudomonas syringae pv.actinidiae is only distributed in Tianzihu Town ;In terms of habitat distribution, it was mainly distributed in shelter forest land and shrub land, with 418 and 412 points respectively, accounting for 34.4% and 33.9% respectively. Risk level analysis showed that there were 5 first-level risk alien invasive organisms and 8 second-level risk alien invasive organisms. The risk of alien invasive biological invasion in Anji County is relatively high. Therefore, it is recommended to take comprehensive control measures according to its risk level, and carry out scientific prevention and control of alien plant invasion hazards to maintain the stability and ecological security of the ecosystem.