Effect of Rotational and Continuous Grazing on Vegetation of an Upland Grassland in the Jizerské Hory Mts., Czech Republic

The effect of different grazing regimes on pasture vegetation was studied during the intensive grazing of heifers in the Jizerské hory mountains during 1993-1997. The vegetation was monitored in 3 pairs of permanent 1 × 1 m plots using a continuous grid of nine 0.33 × 0.33 m subplots. We applied continuous stocking and rotational grazing. Vegetation varied as a result of time and differences between treatments. Several prostrate dicotyledonous species (Trifolium repens, Taraxacum sp., Bellis perennis and Leontodon autumnalis) increased under continuous stocking. This treatment also promoted the growth of the perennial grass Lolium perenne, which was able to cope with frequent defoliation. Tall grasses sensitive to frequent defoliation (Poa travialis, Holcus mollis, Alopecurus pratensis, Dactylis glomerata and Elytrigia repens) were more abundant in rotationally grazed paddocks. Species diversity was not significantly influenced by the different grazing systems. The decrease in the potential sward height under continuous stocking revealed the replacing of tall dominants by lower species. Our results indicate that different grazing systems alter the composition and structure of grassland vegetation. Defining the intensity of grazing under continuous stocking or rotational grazing is complex due to the different stocking rates and the heights of sward during a grazing season. Information about pasture management should therefore involve not only grazing intensity but also the grazing system used.