Ambrosia trifida

This study was carried out to investigate the on the fitness of Polygonatum stenophyllum Maxim. along the coverage of Ambrosia trifida L. We were measured the number of species, death rate of P. stenophyllum, vegetative and reproductive growth of P. stenophyllum and analyzed from June 2015 to October 2016. The coverage gradient of A. trifida was divided none removed control (Control, C), 40 ~ 60% removed treatment (Treatment 1, T1) and 100% removed treatment (Treatment 2, T2) of A. trifida. As a result, When the more than 40% of removal coverage of A. trifida, the number of plant speciecs, the number of P. stenophyllum and vegetative and reproductive growth of P. stenophyllum were higher than none removed the A. trifida during the two years. (Kim et al. 2018)

The shading effect of A. trifida negatively affects native species; in the Seoul metropolitan area, A. trifida can grow to about 3 m in height prior to September/October. A. trifida dominated the DMZ of Paju City, forming monocultures in fields by road edges, abandoned paddy fields, and military training areas. (Kim, 2017)

Vegetation dominated by the giant ragweed showed differences in terms of both species composition and diversity from the typical riparian vegetation and that restored by introducing willows as dominant species of riparian vegetation (Figs. 5 and 6). These results can be viewed as evidence that the invasion of giant ragweed generally influences on riparian ecosystems. In reality, the giant ragweed produces rhizomes although it is an annual plant, induces shading by extending many branches, and inhibits the establishment of the other plants by secreting allelochemic substances (Korean Association for Nature Conservation 1999, Ministry of Environment 2006). Therefore, species diversity of the sites that this plant established was quite low (Fig. 7) (Lee et al. 2010) Tha authors conclude that due to its superior ability to suppress and eliminate most associated species, A trifida 'behaves' as an organizer or keystone species by controlling species composition, biomass and diversity of the community (Abul-Faith and Bazzaz, 1979-A). (Megyeri, 2011)

The results showed the difference of nematode taxa and dominant genera under exotic A. trifida and native C. serotinum during the study period. Nematode taxa reflect biodiversity of soil habitat (Ou et al., 2005). There are some differences in soil nematode community structure under C. serotinum and A. trifida. Soil nematode communities under A. trifida were characterized by a high proportion of plant parasites (69.3 %), while those under C. serotinum dominated by plant parasites (62.4 %) and bacterivores (32.6 %). (Liang et al. 2007)