Studies in the Grazing of Heather Moorland in North-East Scotland. I. Site Descriptions and Patterns of Utilization

Abstract

Dung deposition by cattle, sheep, red deer, lagomorphs and red grouse was measured at 32 sites representative of different altitudes, land-uses and soil types. Fixed plots were visited every 3 wk for at least 4 yr. Use of the main plant species at the sites was assessed 4 times each year. Rates of dung deposition ranged from < 60 ml m-2 yr-1 at a quarter of the sites to a 6 yr mean of 810 ml m-2 yr-1 at 1 grassy site. The heaviest deposition was by cattle and occurred at lower altitudes. At over half the sites, herbivores other than the main ruminant species contributed at least 20% of the dung. Occupance by cattle and sheep was much affected by the role of each moorland tract in farm management and by nearness to reseeded grasslands or swards with attractive graminoids; soil type was unimportant. Red-deer usage was controlled by annual movements between high ground and valleys. Grouse and lagomorphs showed seasonal trends dependent on reproduction and mortality and, at higher sites, snow cover. Ericoid plants were most heavily used in autumn and winter; in spring and summer they were used less than graminoids. In year-round ranking, Molinia caerulea and Trichophorum cespitosum had high positions despite being grazed almost entirely in spring and summer. Juncus squarrosus and Nardus stricta ranked low, being eaten mainly in spring when new growth appeared and in late winter when other food was scarce.