The relative grassland species richness was estimated using depositions on Natura 2000 [ 3 ] areas since 1980 computed with the Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe ( EMEP ) model [ 4 ] on a 50 square kilometre ( km2 ) x 50 km2 grid ( figure 3 ) . The average species richness in Natura 2000 grasslands ( European Nature Information System ( EUNIS ) [ 5 ] classes E1 , E2 , E3 ) was estimated to be 72 per cent in 1990 , 78 per cent in 2005 and 81 per cent in 2020 under the revised Gothenburg Protocol .