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Headlines Published on 31 October 2007

Title Increased biodiversity leads to higher yields for farmers

Farmers across Europe could benefit from higher yields and fewer weeds in their grasslands if they planted a greater number of species. According to a new European study, this basic ecological principle holds true for planted pastures. It is now recognised within the science of biodiversity that when you lose a species from an ecosystem, it becomes less productive. Simple communities comprising only one or two species produce less biological material than a combination of species.

More species result in higher yields for grasslands.
More species result in higher yields for grasslands.
The question arises as to why farmers who grow grasses as fodder for animals continue to plant only one or two species of grass, when they could achieve higher yields by planting additional species? Farmers work mainly with monocultures, which are highly artificial plant communities containing only one species, and therefore, may fail to appreciate the relevancy of ecological research.

A project intended to bridge this knowledge gap is being coordinated by the European Science Foundation (ESF) and involves more than 20 European countries. 'If you want to communicate to farmers, you have to speak their language,' says ecologist John Finn from the Teagasc Environment Research Centre in Ireland, who presented the results of this research at a recent meeting of European biodiversity scientists.
The experiment was the largest ever of its kind and was carried out by scientists from 26 different universities and research institutes under the umbrella of the ESF’s EuroDIVERSITY Programme. There were 28 sites dotted across Europe, from the far north to the hot, dry south. At each site, experimental plots were planted with different combinations of four species that were familiar to local farmers. In central Europe, they comprised red clover, white clover, rye grass and cocksfoot, which is another type of grass.

The plots were managed in the same way as they would be on a farm and were fertilised and harvested by machine. Yields were calculated in tonnes per hectare, instead of grams per square metre, the units normally used by scientists. The results indicated that on average, when 4 species were planted instead of 1, an additional 3.5 tonnes per hectare of plant material could be achieved, as well as a reduction in weeds. At the majority of sites, the yield from a mix of species exceeded the yield from a monoculture of the most productive plant, an effect ecologists call “overyielding”. The most effective mix was found to be one that grew equal quantities of each of the four plants.

'Large areas of Europe are covered with intensive grasslands,' underlines Finn. He claims that if these grasslands contained four types of plants, rather than just one or two, there would also be definite benefits for wildlife. 'The research showed that more insects associate with the species-rich swards.' This, in turn, attracts the wild birds and small mammals that feed upon the insects.

More information:

  • European Science Foundation
  • 'Grassland plants disappear due to nitrogen, study suggests'

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