| 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 eg 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. |