Nutrient pollution presents a serious threat to biodiversity conservation. In terrestrial ecosystems, the deleterious effects of nitrogen pollution are increasingly understood and several mitigating environmental policies have been developed. Compared to nitrogen, the effects of increased phosphorus have received far less attention, although some studies have indicated that phosphorus pollution may be detrimental for biodiversity as well. On the basis of a dataset covering 501 grassland plots throughout Europe, we demonstrate that, independent of the level of atmospheric nitrogen deposition and soil acidity, plant species richness was consistently negatively related to soil phosphorus. We also identified thresholds in soil phosphorus above which biodiversity appears to remain at a constant low level. Our results indicate that nutrient management policies biased toward reducing nitrogen pollution will fail to preserve biodiversity. As soil phosphorus is known to be extremely persistent and we found no evidence for a critical threshold below which no environmental harm is expected, we suggest that agro-environmental schemes should include grasslands that are permanently free from phosphorus fertilization.

(2009). Available soil phosphorus in semi-natural grasslands: assessment methods and community tolerances. Biological Conservation, 142 (5) To test which methods are most suitable for measuring available P in soils of mesotrophic 20 grasslands, a bioassay experiment was undertaken to compare seven extraction methods with 21 the growth and P uptake of grassland species. Five species were grown together on a soil treated 22 to create a range of conditions of pH, mycorrhizal infection and P availability. 23 24 Olsen P and Bray P were found to be significantly correlated with P uptake in plant growth 25 across the range of soil treatments whilst ion exchange membrane P and resin P were 26 significantly correlated with P uptake in plant growth in all but the calcareous soils. The acid 27 extractions of Truog, acetic acid and EDTA-ammonium acetate were found to be less correlated 28 with P uptake in plant growth. All extraction methods correlated more strongly with P uptake in 29 the sterilised treatments than in those inoculated with mycorrhizal spores. 30 31The method of Olsen was therefore selected to analyse P availability in soils supporting a range 32 of mesotrophic grassland communities from eleven sites across England. At each sampling 33 location, the species composition of the vegetation was assessed and classified using the British 34 National Vegetation Classification (NVC). Species-rich hay meadows across a range of 35 alliances were found to occur on soils with low phosphorus availability. Olsen's method of P extraction is recommended for analysing soils of areas identified for 41 habitat creation; values of less than 10 mg kg -1 will give the greatest potential for the restoration 42 of species-rich mesotrophic grassland. 43

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Reinstatement of vegetation to a similar condition to that prior to disturbance is often required in industrial restoration schemes. Seeding with specially prepared seed mixes containing species suited to local soils is often the preferred option on grounds of practicality and cost. Turf translocation is more difficult and costly but, if successful, meets the reinstatement requirement more precisely. In a pilot study at a proposed opencast coal site in Wales, we compared the effectiveness of whole-turf translocation of herb-rich mesic grassland communities, with a less technically demanding and more cost-effective technique involving spreading turf over twice the area at the receiver site and rotovating it into the underlying soil. The translocated whole turf and rotovated turf plots were cut annually and the vegetation removed to simulate grazing that had occurred prior to translocation. Both the whole-turf and rotovated turf transplant techniques gave successful re-establishment of 50% or more of the species originally present. After three years, the cover and species composition were similar in "whole-turf" and "spread and rotovated" plots. This suggests that the "spread and rotovate" tech-nique provides a satisfactory ecological alternative to whole-turf translocation. However, plant communities changed, in some cases substantially, after translocation using either technique. Altered soil hydrology and nutrition combined with the substitution of cutting for grazing are probably the main causes of these changes.