So last year, Stevens, her UK colleagues David Gowing, Nancy Dise and Owen Mountford, and a team of experts from Germany, the Netherlands and France, embarked on a Europe wide project, part of the European Science Foundation (ESF) EuroDIVERSITY Programme. The projects aim is to see if the effects are the same on a wider range of grasslands, across the entire Atlantic side of Europe. The low countries and northern Germany are the epicentre of European nitrogen deposition, says Gowing.
70 new grasslands in at least nine countries have been added to the picture, including different types of grassland. So far, the first years field results seem to adhere to the pattern, showing that species loss is directly related to long term deposition of nitrogen. The loss in Great Britain is much larger than people had imagined, says Dise. Its almost 25% of species at the average deposition rate. If this is occurring across Europe, it will be a very important find. Wildflowers and other broad-leaved species, rather than grasses, are the hardest hit.
The team has started experiments to see if they can establish how extra nitrogen has these effects. They hope to predict what will happen in the future. Nitrogen deposition in Europe probably peaked in the 1990s, and is coming down now in many places, says Gowing. But it may not be appropriate for policymakers to relax. Having been accumulating nitrogen for 40 years, he continues, we might be near the edge of the cliff where communities will suddenly change. Perhaps well be able to say: you have another five years of accumulating at this rate, so now is the time to act.
What should be done" We are hoping for a clear signal that you can maintain species richness [under nitrogen deposition] by biomass stripping, says Gowing. That means extra mowing and grazing. If we find one, we can offer a management
|Contact: Sofia Valleley|
European Science Foundation