Effects of nitrogen enrichment, plant litter removal and cutting on a species-rich Mediterranean calcareous grassland

Semi-natural calcareous grasslands are of great interest in conservation because of their high species richness, but presently they are threatened by both land abandonment and nitrogen eutrophication. The paper reports on a three-year field experiment conducted in a species-rich Mediterranean grassland to study the effects of nitrogen application coupled with removal of plant litter and artificial cutting on plant species diversity. Vegetation treatments were applied both to abandoned and adjacent long-term mowed grassland, to evaluate their restoration value and impact of management abandonment. Cutting significantly increased species diversity in the abandoned area by positively affecting the cover of almost all annual and biennial species and several perennial forbs. Cutting strongly reduced the dominance of perennial grasses. Litter removal had similar effects to cutting, although it was far less effective in increasing species diversity. In the mowed area, cutting abandonment did not reduce species diversity, although the perennial grasses started to increase their cover, while several rare species reduced their abundance. Surprisingly, nitrogen enrichment did not affect species diversity both in the abandoned and mowed area. Our results provided evidence that, within three years, annual cutting can partially restore the species diversity of abandoned grasslands.