the diversity will be reduced, compromising its value for birds and other taxa.
Unpalatable, eg thorny, species will develop thickets beneath gaps in the canopy or on the woodland edge, even under moderate grazing pressure (although some livestock, eg old pony breeds, are adept at taking holly and gorse). Such thickets provide some shielding of palatable species, eg oak from grazing, and so could be important in regenerating grazed woodland in addition to providing nesting habitat for birds. However, intense grazing can prevent such thickets from developing, and it is important to note that hardier breeds of livestock can adopt less palatable species in their diet when more palatable species are limited.
Impacts of different livestock at low stocking levels
Cattle are not very selective grazers, older breeds even less so. They tend to leave a tussocky structure across a wide area. They dung randomly, and dung sites are then avoided when grazing, increasing the tussocky nature of the sward.
Sheep are selective grazers, tending to produce a tight sward by favouring the most palatable species. Dunging is largely random; although concentrations develop where gatherings occur, eg at night. Some older breeds readily browse on woody growth.
Ponies are selective and graze palatable vegetation tightly. They are communal dungers, so local alteration of fertility and vegetation can occur. Certain breeds have a high propensity for browsing.
Impacts of browsing animals
Goats eat almost anything, seemingly at random. They browse more than other livestock and can, even at a low density, cause damage to saplings and the shrub layer. Goat browsing in woodlands has become a problem in some parts of Wales.
Deer Browsing has become a potentially major problem in some woodland areas of the UK. To date, deer browsing has not been considered a major issue across
Managing woodland for birds
Plate 5 Thorny scrub will offer protection from grazing.
Wales, although they can have an impact locally. They may be increasing in Wales, so there is the potential for deer browsing to become a more significant problem in Welsh woodlands.
Issue: managing grazing
Identify objectives in the woodland planning process (Chapter 4).
Identify appropriate grazing regime including type of stock and timing of grazing. In Wales, closed canopy upland oak woods have been traditionally grazed and support birds favouring little or no shrub layer and a low field layer, eg wood warbler, pied flycatcher. A reduction or cessation in grazing should only be considered if these species are not a priority, or if a reduction in grazing is the preferred option to promote canopy regeneration. If a reduction in grazing is required, eg for species that require a more substantial shrub layer, some control of grazing or browsing will be required. Total stock exclusion may be necessary depending on the management objectives, eg if rank vegetation is required.
Consider other managements that may be necessary, eg in closed-canopy grazed oak woods, it may be necessary to protect seedlings and saplings by encouraging development of unpalatable scrub or using tree tubes.
Controlling unwanted grazing pressure, eg by trespassing livestock by fencing.
Forestry Commission Picture Library/Isobel Cameron