Fertilizing a grassland will cause plant biodiversity there to decrease. It’s not known why this is so, and one theory says that it is because some fast-growing species shade out slower-growing species. A recent study in the journal Ecology Letters says that it’s not a lack of light, or at least not just a lack of light, that is stifling diversity. The study found that the impact of light availability varied greatly in years when there were droughts.
In dry years more light meant less diversity, but in wet years, more light meant more diversity. Either way, fertilization meant species diversity went down, no matter what the light situation was.
With nutrient pollution such a widespread problem, getting to the bottom of this would be useful in protecting rare plants and threatened ecosystems.This paper doesn’t offer the answer, but adds another piece to the puzzle.
A previous paper on the subject appeared in the journal Science two years ago. Find that paper here.
Photo: Bobolink, a grassland bird, courtesy of the US Fish and Wildlife Service