Why do historians call the global exchange of plants and animals the Colombian exchange?

It is known fact that with the discovery of America got a lot of plants and animals, radically transforming the European food, which has made many biological species in biocoenoses and made amendments to habitual methods of cultivation Agricultural culture and in growing domestic animals.

The term "Colombian Exchange" was first published in 1972 by Alfred Crosby. The essence of the concept of "Colombian exchange" is the mutual influence of the discovery of the American continent on ecology, environment, culture, agro-technical methods and even medical factor (mutual exchange of illnesses, including rare).