Excessive Fertilizer Use Decreasing Grassland Biodiversity: Scientists Discover Why
photo: Jeremy Carbaugh via flickr
Most TreeHugger readers probably a good handle on the concept that large monocropped fields have lesser biodiversity than more mixed cultivation, and that industrial agriculture uses excessive amounts of fertilizer to push crop yields to their maximum, even at the expense of decreasing soil fertility. But now scientists in Switzerland have identified why all that fertilizer use is decreasing biodiversity more broadly:Fast-Growing Plants Overwhelm Grasslands
The results of research done at the University of Zurich have been published in the latest issue of Science show that, looking at grasslands, the main reason is that all those extra nutrients allow faster growing plants to overwhelm an area, blocking sunlight from reaching smaller, slower-growing plants. This eventually causes many species to disappear.
Report co-author Andrew Hector calls this excess of nutrients "one of the main threats to biodiversity this century."
When Light Given to Slow-Growing Plants, They Were Fine
To test the hypothesis that it was access to light, and not increased competition among plants brought about by increased nutrients, the researchers devised a system wherein their could attach lights which would illuminate the understory of plants. When these plants received supplementary light to what they would ordinarily get--since the fast-growing plants were now blocking them--the biomass of slower-growing plants did not decrease or show loss in biodiversity.
In the past 50 years, the amount of nitrogen and phosphorus available to plants has doubled.
More: Competition for Light Causes Plant Biodiversity Loss After Eutrophication (subscription or one-time fee required)