The Effect of Winter Grazing by Barnacle Geese on Grassland Yields on Islay

作者：Steve M. Percival, David C. Houston · 发表于：Journal of Applied Ecology · 年份：1992 · 被引用次数：41 · 研究领域：Ruminant Nutrition and Digestive Physiology、Animal Nutrition and Physiology、Isotope Analysis in Ecology

1. The effect of different intensities of winter grazing by barnacle geese, Branta leucopsis, on the yields of agricultural grasslands was studied on the island of Islay on the west coast of Scotland. Exclosure cages were used to compare yields of ungrazed plots with those grazed by geese. 2. The geese caused a large reduction in the grass standing crop in the early spring on all the study fields. Up to 82% of the yield was lost to the geese in the most heavily grazed areas. 3. Some pastures on which the geese had grazed through the winter showed substantial reductions in the yield of silage cut in mid-June. The effect was particularly marked on heavily grazed, newly reseeded fields where as much as 38% of the yield was lost. However, other less heavily grazed areas showed no significant loss attributable to the geese. 4. There was a correlation between yield loss and goose grazing intensity, but this explained only 28% of the variance in yield loss in April and only 19% in June: other factors were also responsible for reducing yields below their possible maximum. 5. The standing crop at the end of April and the silage yield in mid-June were correlated with goose grazing intensity, but this relationship varied greatly between years. In 1986 there was a strong negative relationship but in 1987 the trend was in the opposite direction. The difference in weather conditions in the two years may have been responsible for this result: in 1986 the spring was colder than in 1987.