The old man has been rather out of his element recently, visiting the largely treeless landscapes of the north.
There is now no naturally occurring woodland on Shetland, although small bushes of birch, hazel, aspen and sallow can sometimes be found in places inaccessible to sheep and burning such as on inland cliffs and on islands in freshwater lochs. However, when the first settlers arrived there was at least a scattered cover of trees and scrub; no doubt highly wind-pruned in exposed areas but with more substantial trees where conditions were more sheltered.
Pollen records from different parts of Shetland indicate that from about 9,000 – 10,000 years ago birch and hazel woodland developed with some juniper and aspen. Alder and oak may have been present locally, possibly even some elm and ash, although some of the pollen recovered may be that blown across from the Continent. The woods were probably quite open as there are also records for various tall herbs and ferns, such as are now found with the patches of remnant scrub. By between 6,000 and 4,000 years ago (depending on the locality) most of the tree cover had been lost. High levels of charcoal (indicating burning) and evidence for farming settlements suggest humans were partly responsible, although the spread of peat would have also been encouraged by cooler wetter conditions.
The rich archaeological record of these past settlers attracted us to the islands; there is an outstanding collection of prehistoric remains through to those of the Norse settlers. The surviving features are mainly stone, but trees and wood were by no means unimportant in the lives of their builders.
The early settlers could have used locally cut birch poles, to help support the roofs of their roundhouses, but even when much of the native tree cover had been lost, wood was still available. Large quantities of timber were once swept into the sea from the forests of North America and some would eventually have been washed up on the shores of these Atlantic islands. These could have provided the large timbers needed to support the floors of brochs or the spruce logs that held up the roof of the Neolithic Stanydale ‘temple’. Driftwood could also have been used for firewood. In later times after the spread of peat use for domestic burning, fuelwood may still have remained important as a source of charcoal for the smelting of metal.
The Norse settlers may have imported wood from time to time for special projects and re-used timbers from decommissioned boats built elsewhere, a tradition that continued into much later times. However use of driftwood and any surviving local sources continued. The stone built long-houses are thought to have had internal paneling while birch bark provided a water-proof underlay to the turfs that covered the roofs.
What of current and future tree cover? A few small planted shelterbelts were seen and wind-sculpted trees and bushes in gardens. Our local guide commented that there were more of these around than when he was growing up – evidence of climate change or simply more appreciation of the shelter trees and shrubs provide? Sycamore has come into its own, as around Pennine farmhouses; willow, alder, various conifers were also seen. Roses formed thickets one-two metres high around some gardens but I did not see any brambles – there are only half-a-dozen spots on the BSBI atlas for the islands. I had been told there were recent records for oak on Yell and Unst (the most northerly inhabitated islands of the archipelago) but I did not see those either.
Given some initial protection from the elements and from sheep there are probably many more places where trees and shrubs could grow. At the moment lack of a seed source could often be limiting but as the garden patches mature further woody encroachment seems likely.