Effects of heifers and sheep grazing on herbage production on a previously abandoned grassland

摘要

Large areas of cultivated grassland are annually abandoned and no longer used for production in Norway. Such areas will over time be encroached by shrubs and trees, which is regarded as undesirable. We assessed plant community development, pasture production, herbage quality and pasture utilization by sheep and heifers of a grassland that has been unmanagcd for 12 years. The experiment was run for two consecutive years. Sheep grazed the whole area for one month in spring and autumn. During the summer, the area was assigned to three replicated treatments: (1) control with no management; (2) grazing heifers; and (3) grazing sheep with offspring. The stocking rate was 1.8 LU ha"1, in both b and c, for a duration of one month. The area was left restingfor a month after treatment and before autumn sheep grazing. Pasture production and herbage intake was estimated using grazing exclosure cages. Herbage consumed during summer period was on average 211 g DM m"2 and the pasture utilization was 55%. The annual consumption and utilization was 336 g DM m and 62% in the grazed treatments and 28 g DM m"2 and 15% in the control, respectively. Total annual pasture production was on average 72% higher in the grazed treatments compared to the control. Ihere was nodifference between the grazed treatments on annual production, herbage intake or pasture utilization. Grazing stimulated herbage production, and such abandoned grasslands are valuable forage resources.