Changes in the Flora and Fauna of the City Frankfurt/Main in the last 200 years:
Due to their diversity of biotopes, large cities in Central Europe usually house a higher species diversity than rural areas of comparable size. Flora and fauna are highly dynamic, with species disappearing or being introduced continuously. Appearance of new species in an area is in almost all of the cases due to the impact of man.
In cities like Frankfurt/Main, a substantial part of the plant species growing outside cultivation is formed by these introduced or alien species. Many alien plant or animal species, especially insects, originate from regions with a warmer climate.
In spite of many introduced species, the total plant species diversity has substantially decreased in the last 200 years in Frankfurt. Considering the plants, that have disappeared in Frankfurt in the last centuries, there is no case that can unequivocally be attributed to warmer climate. The basic causes are changes in agriculture and forestry.