Abstract:

 The impacts of alien species invasion on wetlands are an important issue in ecological research, but there are few reports on reservoir wetlands. Based on field investigation of 10 sampling transects across five landuse types, we analyzed species composition, flora characteristics and hazard degree of alien plants in Huangjinhe National Wetland Park in Pingjiang, Hunan Province. The results showed that: (1) A total of 46 alien plant species belonging to 37 genera and 17 families were recorded, with the dominant growthform of annual and biennial herb (33 species) accounting for 71.74% of the total alien species. Asteraceae (9 species) and Poaceae (7 species) were the most speciesabundant families, accounting for 19.57% and 15.22% of the total species richness, respectively. (2) South America and North America were mainly the origins of alien species, indicating that alien plants originated from American continent have better adaptability in the park. (3) The proportions of tropical families and genera were significantly higher than those of temperate families and genera, indicating that flora of the alien plants had a strong tropical nature. (4) 42 alien plant species showed different degrees of invasive hazards. The species (32 species) with the first three levels of invasive hazards accounted for 69.57% of the total species, five species out of which, including Bidens frondosa,Eichhornia crassipes, caused the malignant invasive hazards. (5) America was the main origin of alien plants in the park and in other wetlands (Dongting Lake, Nanjishan and Xuanmenwan) from the same latitude. Plant species of Compositae and annual herbs were most dominant. The similarity coefficients of species between Huangjinhe and other wetlands decreased with the increases of distance, with the highest similarity being with Dongting Lake. The proportion of species only found in Huangjinghe was 32.61% (15 species). The long history of human disturbance, diverse land use types and complex habitat characteristics are the main reasons for the composition and invasion hazards of alien plants in reservoir wetlands. To prevent and control the invasion of alien plants, it is suggested to combine strict control of human introduction and timely treatmentaccording to different habitat types.

Key words: Huangjinhe National Wetland Park, wetland ecosystem, reservoir wetland, flora, Hunan.