Silviculture is the term for the cultivation of forest trees. At Carrifran, our aim is to restore the native trees to a whole valley which was once a primeval forest. Our intention is to mimic the original forest as much as possible, within the limits of our knowledge and other constraints.
We know which tree species were in the original wild wood at Carrifran, as we have a complete pollen record from the peat bog at Rotten Bottom. We also know what conditions each species prefers, and we considered several important variables such as soil type, moisture, slope, aspect, altitude, accumulated soil temperature and windiness, when deciding which trees to plant in different parts of the site.
Tree planters were also encouraged to think of the ‘microsite’ when planting a tree. For example, a sheltered spot behind a rock may give some extra shelter from winds to help the tree become established. We soon learned that planting trees among rocks was most easily done using a ‘spear’. This is a robust, narrow and pointed spade which can be used to lever a small space between rocks.
The trees and shrubs we consider native to Carrifran are; ash, downy birch, sessile oak, rowan, hazel, bird cherry, aspen, hawthorn, blackthorn, holly, wych elm, guelder rose, dog rose, burnet rose, juniper, alder, elder, Scots pine, yew and several of willows (goat, eared, downy, tea-leaved, bay-leaved, dark-leaved).
Getting native trees established at Carrifran to the point where they need only protection from domestic stock and excessive deer browsing has proved a practical challenge over the last eight years. Firstly we start with the right kinds of tree, by selecting seeds from ancient woodland remnants as close as possible to Carrifran and in similar situations. We are fortunate to have this genetic resource, often perched in steep gullies (known as cleuchs in southern Scotland) where trees have escaped browsing by sheep, cattle, goats, deer, hares and rabbits.
Each tree species has its own routine for producing seed, and our Seed Collection and Propagation sub-group has been dedicated to gathering the right amount of seed and root cuttings at the right time of year from often remote trees for over ten years. Acorns are our furthest travelled seeds, with some coming high oak woodlands in the Lake District. Most of the trees were grown in non-peat compost in 200ml cells by Alba Trees of Haddington. Once the young trees are big enough they are sent to Carrifran in bundles of 15 and if necessary can survive like this from November to April if kept moist. Frozen blocks of trees were one of the main causes of delay when planting, and tree planters often took home a few hundred trees to thaw out at home!
We entered into a Woodland Grant Scheme contract with the Forestry Commission (FC) to plant a total of 299ha of land at Carrifran (roughly up to the 500m contour). The contract gave us £1,050 per hectare, with an initial 70% being paid when the trees were planted, and the remaining 30% in year five, if the trees were considered by the Forestry Commission to be established.
This payment also allowed for up to 20% open ground to protect places with archaeological remains, scree or interesting plants and to create open glades, conserving the views and increasing habitat diversity. We agreed that the average tree density would be 1600 per hectare, with an average distance between trees of 2.5m, but that we would try to mimic a natural distribution, including dense clumps, sparse areas and small open areas.
Around 40ha of trees were planted each year, around 60,000 trees. The costs of raising all trees at Carrifran has been paid for by the David Stevenson Trust. A 12 km fence around the perimeter of Carrifran, to keep out neighbouring sheep and goats, was completed in August 2000, with funding from the Millennium Forest for Scotland Trust.
Each tree is protected by a 20cm wrap-around plastic vole guard, supported by a 30cm cane. This is the essential as short-tailed field voles can have a devastating effect on young trees. Vole numbers tend to increase when the removal of grazing lets grass grow longer, providing more cover for them. In the winter when the grass dies back, the trees would be vulnerable if not protected.
A 1m diameter spot spray of ‘glyphosate’ herbicide is applied before planting, as slow growing trees can become smothered by grasses. Bracken is also a threat to small trees, and much volunteer time is spent cutting back bracken in June and July. Deer control continues all year round, following Deer Commission for Scotland best practice. Deer browsing became a serious problem up to 2003, when deer control was increased. A professional deer stalker walks the valley most weeks, and other qualified volunteer deer stalkers help on occasion.
We have now had second instalments of the Woodland Grant Scheme payments from the FC on all areas where they are due, apart from a 7ha compartment on the steep side of Peat Hill which was deferred for two years. Here, bracken smothering, drought and deer browsing took their toll, and we have planted 10,000 extra trees protected by 60cm guards. This will stop the trees being smothered and give more protection from deer.
In 2007, with funding from LloydsTSB bank we planted a further 10,000 trees on the area known as Todcastles, the long stony slope above the road towards Moffat. Trees were planted using 60cm tubes and bracken was sprayed by helicopter. This approach was necessary due to the dense bracken and the challenge of deer control. On this site, we planted a large proportion of hazel, though at lower densities than on the FC funded areas.
At Firth Hope, the hanging valley above the waterfall, planting montane scrub between 600m and 750m was approved by Scottish Natural Heritage. A small trial at 690m of downy willow, juniper and other species which survive at high elevations was started in 2002 and showed that suitably adapted trees could thrive at this height. By summer 2008, over 8000 trees and shrubs had been planted, protected by 40cm mesh shelters, with a small amount of fertiliser as advised by the FC. Most of these trees were planted by volunteers who camped at these altitudes during the springs of 2007 and 2008.
At Carrifran, we took a calculated risk in planting trees without deer fences and with only very small individual tree protection. We initially suffered a lot of browsing from deer, some from brown hare, and even from escaping sheep the years when they still shared the valley, though enclosed in temporary fence. Weed control was also a problem until we spot sprayed� with herbicide in summer the areas where trees would be planted the following autumn.
With more rigorous deer control (between 10 and 20 deer culled per year) tree growth has been good. We will be able to relax a bit more when all the planted areas have received their second stage payments, which will be in 2013 at the earliest. In the meantime, volunteer Boundary Wardens check that the fence is in good order, and volunteers plant trees and do various tasks to nurture the trees, such as bracken control - and remove temporary fences to make the valley look more like a Wildwood.