Fertilisers destabilise diverse grasslands

Wednesday, February 19, 2014 - 10:15

Fertilisation of grasslands significantly reduces their ability to cope with changing conditions even when they contain a diverse mix of plants, finds a global study involving Oxford University. The research, published this week in Nature, showed that diverse grasslands were more stable over time but that this effect was weakened when the plots were artificially fertilised.

"More diverse areas are generally more stable because different plants will benefit from different things at different times," said Professor Andrew Hector of Oxford University's Department of Plant Sciences, senior author of the study. "To take a simple example, if you have plants that thrive in heavy rain and plants that prefer lighter rain in the same field, then the total amount of plant matter in the field in a given year will be less dependent on rainfall as both types will balance each other out."

Fertilisers are known to drive down grassland diversity over time, but this study found that fertilised plots were less stable even before their diversity decreased. This effect was not expected based on previous results. As fertilisation boosts total yields, it was expected to increase short-term stability by making small variations less significant. However, the study found that fertilisation disproportionately increased yearly variations in yield, particularly in the most diverse grasslands.


Photo of fieldwork in Finley (OR, USA) from the Nutrient Network Global Research Cooperative.

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