The situation of common ragweed (Ambrosia artemisiifolia L.) in the Düzce province of Turkey.
Common ragweed (Ambrosia artemisiifolia L.) is an invasive alien species in many areas where it has been introduced other than its native range, which affects negatively biological diversity and ecosystem services. It has spread abundantly in Eastern Black Sea and Trace subregions, and partly in Middle Black Sea for the last 10 years although its existence has been known in Turkey since 1990s. This study was conducted to determine common ragweed populations in the Düzce Province in the west part of the Black Sea Region in 2017 where is located in between two common ragweed invaded territories. Forty-one populations of common ragweed is determined, which are all in roadsides and empty areas except one. The size of habitats invaded by common ragweed varied between 1 and 4375 m2 and two third of a habitat as an average was covered with common ragweed. In the communities with common ragweed populations, 23 plant species belongs to 15 families were determined. Horseweed (Conyza sp.) was the most distributed species, which has seen in 18 out of 38 communities. The following species to horseweed. as the most distributed species were the alien species for Turkey as well and had importance as weeds and/or invasive alien species in other countries as well as Turkey. Common ragweed could be introduced in Düzce in 1999 earthquake with aids came from overseas or international and national transport activities, and then it naturalized and spread due to disturbed habitats after the earthquake. Common ragweed might invade agricultural areas in the Düzce Province although it was not determined in agricultural areas in the province. It is shown with the populations determined in Düzce that common ragweed can be seen any suitable habitat from east to west through the north of Turkey.