Variability of sward structure and plant species composition of pastures at low stocking rate

Grazing at a low stocking rate is considered a promising option to meet both the requirement for a reasonable agronomic output and the maintenance and enhancement of biodiversity. Such grazing creates a mosaic pattern of patches of variable defoliation and resulting sward height and structure. An extended rising-plate-meter method was developed to investigate the spatial and temporal variability of the grass sward and the resulting pasture and animal performance. Along permanent transect lines, a high number of fixed points is established and the following recordings are made repeatedly during the grazing season: compressed sward height, dominating plant species, development of the plant (vegetative, reproductive growth). Additional sampling at random points was used to establish a relationship between sward height and herbage mass. The nutritive value of the herbage samples was analysed. Live weights of grazers and quality of ingested herbage were measured. The data were analysed to provide information on the variability of the amount and the quality of the herbage on offer, the percentage of different dominating species in the different grazing patches, the contribution of the different patches to the nutrition of the grazing animals, and the percentage of patches with reproductive plant growth which indicates the opportunity for seedling recruitment.