Eutrophic means well nourished, rich in nutrients, mainly nitrogen compounds. This word is often used in the sense of hypertrophic, which means, overrich in nutrients. The opposite is oligotrophic, with a little amount of nutrients. These words are often used for lakes and rivers but are as well usable for other ecosystems like pastures and meadows.
Eutrophication leads to an increase of primary production and often to a vanishing of organisms that are weak in competition. The value of oligotrophic ecosystems like oligotrophic pastures lies in the fact that rare plants appear, which elsewhere are pushed away by stronger plants. As a consequence also rare animals, like certain species of grasshoppers find better living conditions.