How fertilisers reduce biodiversity

Researchers in Switzerland say they have identified why excessive fertilisation of soils results in a loss of plant diversity, the BBC reported. Extra nutrients, the team wrote in the journal Science, allow fast-growing plants to dominate a habitat, blocking smaller species’ access to sunlight. Consequently, many species are disappearing from affected areas.

The University of Zurich scientists said it was widely recognised that an increase of chemical nutrients in an ecosystem led to a loss of diversity, but exactly how it was occurring had been difficult to determine. After experimentation, said study co-author Andrew Hector, the team concluded that a lack of access to light – rather than an increase in the strength of competition among plants – is what affects diversity.

Hector noted, however, that the findings did not offer a “magic bullet” for conservationists. “What our research shows is that competition for light is very asymmetric,” he said. “So if a plant can get between the sun and its competitors, not only can it get all the light it needs but it can also block its competitors’ access to light. Because this competition for light is such a ‘winner takes all’, it emphasises how important it is that we control nutrient enrichment.”

Tighter controls were needed in order to prevent widespread biodiversity loss, the scientists warned. Estimates suggest that the global level of nitrogen and phosphorous available to plants has doubled in the past 50 years.

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