This investigation examines the influence of fertilization with organic and mineral fertilizers on the biodiversity of grasslands containing Festuca rubra, Agrostis capillaris and Nardus stricta. Permanent meadows were studied in terms of production of food, and of biodiversity. The current strategy of using organic fertilizers has raised concerns about resource conservation and environmental protection. The increase in the number of species is due to the fertilizers that have been applied leading to changes in the soil fertility status. This change in soil fertility has allowed other mesotrophic and eutrophic species to become established in fertilized meadows. In Romania, meadows belonging to this category occupy an area of approximately 1,600,000 hectares and have relatively low production rates. The experiment was located at Pojorata, Suceava County (Romania), in two different natural grasslands that had different floristic compositions. Manure improved the growth of a number of species, especially in the "plants from other botanical families" category, because of the pool of seeds that it contains. Using a management system based on fertilization with small amounts of organic and mineral fertilizers can help preserve the biodiversity of these meadows. The results of this study, in an area considered representative for large parts of the mountainous areas of Romania, indicated that fertilization treatments were able to maintain a high species diversity.