Ecological restoration is the repair of natural environments degraded by human activity. Its primary aim is to restore biodiversity – the richness of life in different places on the earth.
Carrifran was once clothed with diverse broadleaved woodland. The great altitudinal range of the site (165–821 m) provides a unique opportunity to re-create the full range of habitats that would have been in these hills before humans began to have a major impact.
Restoration of low-ground habitats is relatively straightforward, but treeline woodland and scrub habitats present a greater challenge, both because of the severe conditions and current lack of knowledge of what these habitats were like. One solution is to allow them to develop naturally, by the gradual upward spread of appropriate species planted lower down, but there is a case for trying to accelerate the process in a few places.
It is important to note, there is no plan to establish a continuous blanket of trees over the summits of the Moffat Hills. The aim is to create a natural looking woodland mosaic including much open ground, with patches of bent and wind-clipped dwarf trees, ribbons of woodland along watercourses and clumps of bushes hugging the ground in damp hollows. This will enhance the interest of the landscape and increase biodiversity, the woody species providing cover for several kinds of birds, along with resources for a whole array of insects and other animals. The work at Carrifran will play a significant role in achieving the goals set out in the Dumfries & Galloway Local Biodiversity Action Plan.
At Carrifran, active establishment of treeline woodland and scrub is being undertaken in two areas. The planting in the hanging valley of Firth Hope, between 600 and 750 m, is pushing the limits of broadleaf woodland establishment to heights where it has hardly been attempted in Britain. However, pollen records and analysis of exposure and predicted accumulated temperature suggest that scrubby woodland might once have grown there. Experience in a trial plot established in spring 2002 showed that a variety of trees and shrubs can survive and grow slowly as high as 690 m. Current planting involves screefing (clearing vegetation away prior to planting) and breaking up a peat layer to mix with mineral soil, together with use of a P-K fertiliser. Vole guards and wire netting reduce the impact of browsing, especially by mountain hares.
There will be no tree planting in the moss-heath communities higher up. Enriched flushes supporting special montane plants were mapped with support from Scottish Natural Heritage and wide unplanted zones have been left around them. Refer to the Montane restoration data for more detailed information.
Elsewhere, the species have been chosen to suit local conditions. The most widespread community, on peaty podzols and patches of well-drained mineral soil, will have dominant juniper (prostrate at the highest levels) along with downy birch, rowan, goat willow and aspen. Soligenous mires in the wet central part of Firth Hope will eventually have a patchy low canopy dominated by eared and grey willow, with occasional downy birch, bird cherry, aspen and goat willow in drier spots. Protected dry and sunny areas may carry a few hawthorn, hazel and holly, while flushed crags and shelves within the channels of the burns will be suitable for downy willow.
The second site is Rispie Lairs, an open corrie between 500 and 650 m below Saddle Yoke. It is suitable for establishment of juniper woodland with downy birch, rowan and perhaps Scots pine.
Public funding for recreating treeline woodland at Carrifran has not yet been obtained, in spite of useful discussions with Forestry Commission Scotland. Establishing trees and shrubs in such high and exposed situations is slow and difficult, making it unsuited for support by a conventional grant system. Costs are high, with walk-in times long and helicopter lifts sometimes needed to bring in trees and materials. Though independent funding is limited, it often gives us greater flexibility and thus a better final result is likely. Planting is being spread over several years and as much as possible is done by volunteers.
The challenge of establishing trees at Carrifran
The scarcity of seed sources on site (including the complete absence of sessile oak, wych elm and alder) meant that we could not rely on natural regeneration. The decision to plant 300 hectares of new native woodland on steep, rocky and remote hillsides, should produce appropriately diverse woodland within a foreseeable timescale.
Since the start of planting in 2000, over half a million saplings have been planted. These were derived from seeds collected locally by volunteers, which were mostly then cell-grown in compost plugs by commercial nurseries with stock control procedures rigorous enough to ensure that we received only plants from our own seeds. Five years is the period normally considered necessary to reach establishment, but on the high ground at Carrifran we find that seven or even more years are sometimes needed.
At Carrifran there has been minimal soil disturbance (except at the higher altitude plantings where some manual cultivation is used) and herbicide use has normally been restricted to a pre-planting spot spray of glyphosate. However, where tree growth is initially slow or browsing is severe, the saplings can be smothered by grass or bracken. Rigorous monitoring is necessary, followed by hand cutting of bracken and replacement of dead trees where necessary sometimes in 60 cm tubes. Spraying of bracken with herbicide has been used in a few places; this has now been discontinued.
Herbivore attack is a continual threat. Vole guards (20 cm) have been used throughout the site and have clearly saved the lives of many trees. Incursions by stray sheep have occasionally been troublesome. Rabbits are absent and damage by brown and mountain hares has been slight, perhaps because of the prevalence of foxes. No ‘vermin control’ is done at Carrifran.
Roe deer (the only deer species normally present) became abundant after a few years of planting and caused substantial damage in spite of a deer control programme. In 2004 more intensive culling (including night shooting) was initiated, with encouragement from the Deer Commission for Scotland.
This quickly reduced damage to a very low level, though continued extreme vigilance is necessary. At present, a professional stalker is retained to spend about three days per month on the site. A number of volunteer stalkers also make occasional visits, by arrangement with the Borders Forest Trust office, to help keep deer numbers under control.