An international team including Lancaster University and led by the University of Minnesota, found that plant diversity in natural ecosystems creates more stable ecosystems over time because of less synchronised growth of plants.

But the researchers also found that grassland diversity and stability are reduced when fertiliser is added.

Fertilisers are intentionally used in grassland to increase livestock fodder. Fertiliser addition is also occurring unintentionally in many places around the world because nitrogen, a common fertiliser, is released into the atmosphere from farming, industry, and burning fossil fuels.

Rainfall brings nitrogen out of the atmosphere and on to grasslands, changing the growth and types of plant species. This study placed measured amounts of fertiliser on a portion of their research sites and measured the changes that ensued.

Researchers found that the stabilising effect of species diversity was lost resulting in more synchronised growth of plants and a less stable ecosystem.

Dr Carly Stevens, of Lancaster University’s Lancaster Environment Centre, manages one of the experimental sites, located in Lancashire.

She said: “This research shows the serious negative effect that fertilisers can have on natural plant communities.  Understanding this is really important because the use of fertilisers and the addition of nitrogen in the form of atmospheric pollution are very widespread.”

The study was made possible due to the formation of the Nutrient Network, also known as NutNet. It is a ‘grassroots campaign’ supported by scientists who volunteer their time and resources. There are now 75 sites around the world that are run by more than 100 scientists participating in the NutNet experiment.

NutNet scientists collected data for this study for three years, measuring plant growth in 41 sites on five continents, so the researchers feel confident that their results have global applications.