Productivity, composition and frequency of species in a grassland under two grazing regimes

Traditionally grasslands of the Ioannina plateau are cut for hay at the end of May and grazed till next March. (CG). The aim of this work was to examine how the continuous grazing (G) without clipping, as well as Nitrogen fertilization affect the productivity, species composition and frequency of species. Fertilization increased significantly the total biomass production (31%) during the first year due to the significant increase of grasses (40%). There were also similar results in the last year (2000) and the relative increments were 34% and 74% respectively. The dominant species Bromus hordeaceus and Alopecurus urticulatus increased 89% and 102% respectively. On the contrary, there was a significant reduction of forbs (63%) especially of Cichorium intybus, Tragopogon pratensis and Plantago lanceolata species. Finally there was a 50% reduction of the total forbs biomass in G treatment and N fertilization but not in the unfertilized treatment in which there was a significant increment. There were also similar results regarding species composition and frequency. A gradual change was observed for all the above species every year concerning productivity and composition, which was differentiated according to the whether conditions.