Utilisation frequency was studied on three typical grasslands of Hungary between 2006 and 2012. One wet, one dry located lowland and one hilly, dry located grassland were studied. Grass yield, diversity of species and local weather conditions were monitored and correlations were studied. Utilisation frequency was determined in three versions, when grasslands were utilised 2, 3 and 4 times a year, which fit to the utility of grasslands (reaping, meadow (reaping and pasturage) and pasturage). The experimental set was as follows: sample area was 4×4 m data were collected in 3 replicates, in block arrangements. Plant diversity (10.85 species) was slightly changed (compared to planting conditions) on wet grassland at Mende, under stable ecological conditions. Climatic factors varied considerably on dry located natural grasslands and plants had adapted to this condition. Therefore, more diverse (26.34 species) plant composition was developed. Yield fluctuations were strongly correlated to annual rainfall, but coverage ratio changes could not be statistically correlated to changes in rainfall. On the basis of trends, higher temperature and more intensive solar radiation than ever experienced can increase the size of the uncovered areas and reduce the number of plants valuable for feeding on dry areas.

Keywords: grasslands, utilisation frequency, plant population, biodiversity, climatic factors