Influence Of Sheep Research Articles

The Influence of Sheep, Cattle and Horse Grazing on Soil Mites (Acari) of Lowland Meadows

The Influence of Sheep, Cattle and Horse Grazing on Soil Mites (Acari) of Lowland Meadows

The Influence of Sheep on Pattern and Process in Atriplex vesicaria Populations From the Riverine Plain of New South Wales

The application of multiple pattern analysis (multiscale ordination) to a phase-differentiated sample of perennial saltbush (Atriplex vesicaria) rangeland, along with assessments of the vegetative and reproductive states of individual plants, served to indicate the importance of sheep in determining some scales of distributional pattern in the shrub population. By comparison with conventional pattern analysis, it is shown that multiple pattern analysis can be used to provide an economic description of 'total' pattern in temporally related phases of a monospecific plant population. It is demonstrated that the pattern-determining interaction between sheep and saltbush individuals is dependent on plant size, sex and location with respect of other shrub individuals, in particular due to the trampling of seedling and pioneer phases and the selective grazing of sexually mature shrubs by sheep.

Trends in Montane Grasslands in Snowdonia, expressed in Terms of “Relative Entropy”

BETWEEN 1957 and 1960 a series of experiments was set up at four sites in Snowdonia, North Wales, to study the influence of sheep grazing on two widely distributed plant communities characterized by the dominance within them of Nardus stricta (on soils of peaty podsol/peaty gley character), and Agrostis tennis and Festuca ovina (on soils of brown earth character), respectively. Some of the experiments were established by M. J. Chadwick1. The experimental sites cover an altitude range of 1,300–3,000 feet O.D. (396–914 m) and, at each site, three treatments are set out in a randomized design incorporating four replicates per treatment. The experimental treatments were: (i) Normal grazing: open to the sheep from the surrounding mountain pastures (most of the breeding ewes and yearling sheep are removed from the mountain in winter); (ii) winter protection from grazing: the plots were protected by fencing from October to April each year; normal grazing took place during the summer; (iii) no grazing; the plots were ungrazed throughout the period of the experiment. (The approximate densities of the sheep populations grazing the experimental plots, expressed in ewe units/acre (hectares), are set out in Tables 1 and 2.)

The Influence of Sheep on the Vegetation of Hill Grazings in Scotland

SHEEP graze over a very large proportion of the total land surface of Britain, even excluding temporary and permanent pastures. According to Stamp & Beaver (1933) the proportion of rough grazings to the total area of land is as follows: England 11, Wales 32, and Scotland 62 per cent. Although occasionally other stock may be found on rough grazings, their numbers are almost negligible in comparison with the high total of sheep, and the areas where only sheep graze make up much the greatest portion. Sheep have been the chief and, in many parts of Scotland, virtually the only grazing animals on some of these rough grazings for centuries (Ritchie, 1919, 1920). In consequence of this the vegetation has been, and still is, changing to a rather grassy type, which in certain areas has now reached a biotic climax. These rough grazings show considerable variation both in flora and in capacity to carry stock (Smith, 1918 a). In the past cattle as well as sheep prevented the natural regeneration of trees (First and Second Statistical Accounts of Scotland, 1791-9, 1845 (Ritchie, 1920)). Then heather (Calluna vulgaris) began to feel the effects of the constantly increasing pressure of sheep grazing. Nearly two centuries ago sheep replaced cattle on the more remote hills and rough grazings, and also dispossessed a scattered rural population. From that time dates the beginning of the bracken menace (Ritchie, 1909; Fenton, 1936a). Previously bracken was held in check as it had many uses for man and beast (Fenton, 1936 a). Since then it has virtually got out of control. Sheep also kill out broom (Cytisus scoparius), which often competes with bracken (Fenton, 1926, 1937). The destruction of heather and the overgrazing of the better areas have led to an extensive spread of mat grass (Nardus stricta) (Fenton, 1936b). In many parts of the Southern Uplands of Scotland and in the southern parts of the Central Highlands this grass is still spreading, and presents a very difficult and serious problem. It is a fact of great significance that these two regions show the densest sheep population in Scotland (Wood, 1930). In Boghall Glen (Midlothian) experiments have been conducted now for over 10 years, and several of these indicate very clearly what has occurred in other parts of Scotland. In the past there has been far more heather than there is at present, and it also covered much of the lower part of the valley (Fenton, 1933). Owing to continual sheep grazing, and at times unskilful burning, the heather has been largely replaced by a grassy vegetation, with heather confined chiefly to the higher levels and the tops of the hills. As a result of this