The effects of fertilization on part of the Keen of Hamar Serpentine, Shetland

Summary

Winter feeding of stock has caused eutrophication of the lower part of the Keen of Hamar. A nutrient addition experiment is reported which shows that grass cover of the serpentine debris increased greatly following phosphorus fertilization. Long-term observations have shown a substantial increase in grass cover over c. 35% of the lower part of the Keen and in one limited area the complete elimination of a rare species. It is suggested that the effects of eutrophication are likely to persist indefinitely and that it poses a major threat to this habitat and its rare plant species, although it seems that the site could be restored by removal of newly accumulated soil.