The greatest variety of moorland plants occurs in areas where there is variation in grazing impact over the moorland, usually where there is light to moderate grazing pressure overall. In addition, disturbance to the vegetation and soil by fire or swiping, or intermittent heavier grazing will also increase diversity. Some areas of moorland should be moderately frequently disturbed while other areas should be relatively free from disturbance. Moderately frequent disturbance favours diversity of flowering plants, including the full range of characteristic dwarf-shrubs of upland heathland including bell heather, cross-leaved heath, blaeberry, cowberry and bearberry. Freedom from disturbance favours diversity and abundance of mosses, liverworts and lichens, and, sometimes, an overwhelming dominance by heather. Heather is an important and characteristic plant of Scottish moorlands, but if it remains very dense and tall for prolonged periods, other moorland plants can be much reduced or eliminated. The abundance and diversity of mosses and liverworts is a characteristic feature of moorlands in Scotland. Freedom from disturbance by fire or grazing animals may favour some flowering plants, such as twinflower, lesser twayblade or crowberry, but this is much more important for maintaining the diversity of the mosses, liverworts and lichens. This is most likely to be beneficial in areas of steep, rocky or broken slopes which are moist and shaded, wet areas of bog, areas with scattered trees, scrub or woodland, and high altitude or exposed areas with a vegetation mat kept short by the wet and windy climate. These are often areas that are difficult, and uneconomic, to try to manage more intensively. Such areas are also most likely to retain species that are sensitive to disturbance. Avoiding burning these sorts of areas will favour BAP priority species such as some liverworts and juniper since the mature bushes are killed by fire, and seedlings are sometimes heavily browsed. The diversity of invertebrates will be strongly influenced by the diversity of plants and variation in vegetation structure and disturbance. The netted mountain moth larvae feed on bearberry on moorland and mountainside. High stocking rates could have a detrimental effect upon bearberry and therefore upon the netted mountain moth. The northern brown argus will benefit from careful muirburn in areas of herb-rich heath in which rock rose occurs. It will also benefit from moderate levels of grazing - very heavy grazing will tend to reduce the rock rose but very light grazing could lead to loss of rock rose through suppression by heather or bracken. In such instances, bracken control may be beneficial. However, care should be taken that other sensitive ferns, e.g. moonwort and adder's tongue fern, do not occur in the area. The skylark will be assisted by managing moorland grasslands so that they become neither very long and rank nor extremely short. Areas of short, and more herb-rich, heath may provide some additional benefit for this species and will also provide feeding grounds for a variety of other moorland birds such as lapwing, golden plover, and ring ouzel. Red grouse, perhaps the most characteristic bird of upland heathland, feeds in areas of shorter heath but requires taller heather in which to find cover for shelter and nesting. Food availability and quality is improved if there is some variation in the range of dwarf-shrubs present: blaeberry flushes earlier than heather in the spring, and in autumn blaeberry, cowberry, bearberry and crowberry are a source of energy-rich berries. In the spring, cottongrass flower heads in bogs are an important source of nutrients. Black grouse, a declining BAP priority species, has similar requirements to red grouse but also requires flushes or rushy areas (where invertebrates are usually most abundant) for feeding chicks, and areas of scrub and woodland for shelter and forage (for buds) in the winter and spring. Although some moorland birds, like the golden plover, favour short heath and bog vegetation for nesting, most moorland birds require some taller vegetation to provide nesting cover. Control of grazing and burning to provide this will favour black grouse, red grouse and scarce or declining species like ring ouzel, twite, hen harrier and merlin. |