Excess Nutrients Lead to Biodiversity Loss

A U.S. study of experimental grasslands suggests giving plants too many nutrients can lead to long-term biodiversity loss.

The study by W. Stanley Harpole of the University of California-Irvine and David Tilman of the University of Minnesota finds such actions as over-enriching water with nutrients can have detrimental impacts on ecosystem function.

The researchers altered the levels of nitrogen, phosphorus and various cations in water used to irrigate an experimental grass plot in California. When nutrients were plentiful, productivity increased but species number declined — the most successful species were those that could grow quickly and eliminate the competition.

In contrast, when resources were limited, productivity decreased but biodiversity increased — the conditions favored the existence of species adapted to cope with the various nutrient deficiencies.

The scientists said their finding also helps explain the diversity changes seen in the long-running Park Grass Experiment at Rothamsted, England, and parallels similar results seen in aquatic systems.

The study appears in the journal Nature.