Effects of reducing sheep grazing in the Scottish Highlands.

Abstract

The effects of reducing sheep grazing on upland vegetation and wild herbivores was studied at 11 sites in the Scottish Highlands. Areas where sheep had been removed for periods of up to 25 years were compared with areas where stocking rates had remained unchanged. At 5 sites, removal of sheep was associated with taller vegetation and more signs of vole activity. While the removal of sheep appeared to have resulted in relatively few changes in floristic composition at these sites, patches of dwarf shrub-dominated vegetation tended to be larger and patches of grassland to be smaller where sheep had been removed. One previously open site was being invaded by birch woodland after sheep removal. At the remaining 6 sites removal of sheep appeared to have had little or no effect on vegetation or on wild herbivore activity. This was probably due to an increase in grazing by red deer, along with continued heather burning, at these sites. It is concluded that sheep removal is only likely to cause significant changes in vegetation composition and structure in the Scottish Highlands where red deer numbers are low and heather burning infrequent. When this occurs, vole numbers are likely to increase.