The woodlands at Tireragan are moulded by the wind and have in the past been restricted to gullies and slopes to gain shelter. As trees grow older they reach a point where the wind stops them from getting taller so they grow outwards instead.
Gullies not only provided protection from the elements but in the past from grazing and burning as well. These small woodland patches are providing the seed for much of the regeneration that has occured in Tireragan.
Many of the oaks, which live longer than most of the other species, spread out to such an extent that they are several times wider than they are tall.
One such ancient oak at Tirergan is several hundred years old and rises not much more than twenty feet high but its limbs stretch more than fifty feet wide, filling the gully in which it rests.
Most numerous of the tree species found at Tireragan are birch and willow, which are the quickest growing and fastest spreading of all. Birch will flourish just about anywhere, except the deepest bogs, while willows are the first to colonise the wet, marshy areas. Rowans, though not as numerous, are also able to survive in most drier spots and have a particular ability to flourish from the smallest crevice on crags and cliffs.
The aspen is a solitary tree and tends to grow on steep slopes and crags away from other species. In contrast, the hazel and oak grow well together and once hazel is established, oak will usually follow.
All these trees had a place in the culture and ancient folklore of the Scottish Highlands and Islands.
* Hazel was coppiced extensively (coppicing is a process where by the trees are cut every 8 years to promote growth of numerous straight stems). These were used for many purposes including the production of woven fencing called hurdles.
* Birch is such a hardy and widespread tree that it became associated with fertility and love. Its abundant wood was a primary source of fire wood.
* Rowans were revered above all other trees. It was seen as bad luck to cut or even trim a rowan and one growing by your house was thought to ward off evil spirits.
* Oak’s great age and size combined with its usefulness for building and boats assured it a high status. Oak woods were once carefully managed, since a coppiced oak tree could produce wood for several hundred years.
* Aspen was held in esteem for its scarcity and its ability to grow up on a crag seemingly from nowhere, it’s tiny seed being carried great distances by the wind.
Since burning and grazing was stopped the regeneration has been remarkable. The process has benefited from the stands of remnant mature trees and the stunted, over grazed trees that are now able to grow unhindered. Although most of the regeneration spreads radially from the existing woodland, wind blown seed seem to be finding every possible area for growth.
It is difficult to know how far the regeneration will go. Areas of exposed moorland and blanket bog will take a very long time to regenerate, if they do so at all. Indeed, these areas are important habitats in their own right and may need some protection from the encroaching trees, to preserve the mixture of habitats that is so beneficial to wildlife. However it may be thirty or more years before that point is reached.