Scots Pine (Pinus sylvestris) is a species of pine native to Europe and Asia, ranging from Scotland, Ireland and Portugal in the west, east to eastern Siberia, south to the Caucasus Mountains, and as far north as well inside the Arctic Circle in Scandinavia (including Sápmi). In the north of its range, it occurs from sea level to 1,000 m, while in the south of its range it is a high altitude mountain tree, growing at 1,200–2,600 m altitude. It is readily identified by its combination of fairly short, blue-green leaves and orange-red bark.^[2][3][4][5]

Botany

Leaves and cones, Poland.

Seedling with flater, non paired juvenile leafs.

Ripe pollen cones, Poland.

Pinus sylvestris is an evergreen coniferous tree growing up to 35 m in height^[6] and 1 m trunk diameter when mature, exceptionally to 45 m tall and 1.7 m trunk diameter^{[citation needed]} and on very productive sites (in Estonia, there are some 220 year old trees that are 46 metres tall in the forests of Järvselja^[7]). The bark is thick, scaly dark grey-brown on the lower trunk, and thin, flaky and orange on the upper trunk and branches. The habit of the mature tree is distinctive due to its long, bare and straight trunk topped by a rounded or flat-topped mass of foliage. The lifespan is normally 150–300 years, with the oldest recorded specimens (in Sweden and Norway) just over 700 years.^[2][3][4][8]

The shoots are light brown, with a spirally arranged scale-like pattern. On mature trees the leaves ('needles') are a glaucous blue-green, often darker green to dark yellow-green in winter, 2.5–5 cm long and 1–2 mm broad, produced in fascicles of two with a persistent grey 5–10 mm basal sheath; on vigorous young trees the leaves can be twice as long, and occasionally occur in fascicles of three or four on the tips of strong shoots. Leaf persistence varies from two to four years in warmer climates, and up to nine years in subarctic regions. Seedlings up to one year old bear juvenile leaves; these are single (not in pairs), 2–3 cm long, flattened, with a serrated margin.^[2][4][8]

Mature open cones and seeds - MHNT

The seed cones are red at pollination, then pale brown, globose and 4–8 mm diameter in their first year, expanding to full size in their second year, pointed ovoid-conic, green, then grey-green to yellow-brown at maturity, 3-7.5 cm in length. The cone scales have a flat to pyramidal apophysis, with a small prickle on the umbo. The seeds are blackish, 3–5 mm long with a pale brown 12–20 mm wing; they are released when the cones open in spring 22–24 months after pollination. The pollen cones are yellow, occasionally pink, 8–12 mm long; pollen release is in mid to late spring.^[2][4][8]

Taxonomy

Pinus sylvestris var. hamata, Crimea

Over 100 Pinus sylvestris varieties have been described in the botanical literature, but only three or four are now accepted; they differ only minimally in morphology, but with more pronounced differences in genetic analysis and resin composition. Populations in westernmost Scotland are genetically distinct from those in the rest of Scotland and northern Europe, but not sufficiently to have been distinguished as a separate botanical variety. Trees in the far north of the range were formerly sometimes treated as var. lapponica, but the differences are clinal and it is not genetically distinct.^{[2][3][5][9][10][11][12][13][14][15]}

• Pinus sylvestris var. sylvestris. The bulk of the range, from Scotland and Spain to central Siberia. Described above.
• Pinus sylvestris var. hamata Steven. The Balkans, northern Turkey, Crimea, and the Caucasus. Foliage more consistently glaucous all year, not becoming duller in winter; cones more frequently with a pyramidal apophysis.
• Pinus sylvestris var. mongolica Litv. Mongolia and adjoining parts of southern Siberia and northwestern China. Foliage duller green, shoots grey-green; leaves occasionally up to 12 cm long.
• Pinus sylvestris var. nevadensis D.H.Christ. The Sierra Nevada in southern Spain and possibly other Spanish populations (not considered distinct from var. sylvestris by all authors) Kalenicz. Ex Kom. Cones often with thicker scales, but doubtfully distinguishable on morphology.
• Pinus sylvestris var. cretacea Kalenicz. ex Kom. From border regions between Russia and Ukraine.^[16]

Distribution

Scots Pine is the only pine native to northern Europe, forming either pure forests or alongside Norway Spruce, Common Juniper, Silver Birch, European Rowan, Eurasian Aspen and other hardwood species. In central and southern Europe, it occurs with numerous additional species, including European Black Pine, Mountain Pine, Macedonian Pine, and Swiss Pine. In the eastern part of its range, it also occurs with Siberian Pine among other trees.^[3][4]

British Isles

Scattered survivors (two recently dead) of extensive deforestation at Glen Quoich, Scotland

The tree spread across the British Isles after the Last Glacial Maximum. Pollen records show that pine was present locally in southern England by 9,000 years ago having entered from northeast France and that it had spread as far north as the Lake District and North Pennines 500 years latter.

It was present in Ireland over 8,800 years ago but absent from Wales at that time which suggests that Scots Pine in Ireland had a separate Iberian origin. Pine expanded into Scotland between 8,000 and 8,500 years ago either from an independent refuge, from Scandinavia (via ‘Doggerland’) or from Ireland. As the climate warmed it became extinct from most of the British Isles around 5,500 years ago except in Scotland and at Kielder, Northumberland.

The Irish and Western Scottish populations went through a massive decline around 4000 years ago which ultimately led to the extinction of the Irish population between 2,000 and 1,000 years ago. It was replaced by large areas of blanket bog in Western Scotland and Ireland though the reasons for its decline nor its extinction in England are clear, but it may have been influenced by human activities. ^[17]

In Britain it now occurs naturally only in Scotland, but historical and archaeological records indicate that it also occurred in Wales and England until about 300–400 years ago, becoming extinct there due to over-exploitation and grazing; it has been re-introduced in these countries. Similar historical extinction and re-introduction applies to Ireland, Denmark and the Netherlands.^{[4][5][8][18]} Whether it truly became extinct in England is unknown; it has been speculated that it may have survived wild long enough for trees used in cultivation in England to derive from native (rather than imported) sources.^[19] Shakespeare (in Richard II) was familiar with the species in the 1590s, as was Evelyn in the early 1660s (Sylva), both around the time when Scots Pine was thought to become extinct in England, but when landowners were also beginning ornamental and forestry planting.^[19]

It is the national tree of Scotland, and it formed much of the Caledonian Forest which once covered much of the Scottish Highlands. Overcutting for timber demand, fire, overgrazing by sheep and deer, and even deliberate clearance to deter wolves have all been factors in the decline of this once great pine and birch forest. Only comparatively small areas (17,000 ha, only just over 1% of the estimated original 1,500,000 ha) of this ancient forest remain, the main surviving remnants being at Abernethy Forest, Glen Affric, Rothiemurchus Forest, and the Black Wood of Rannoch. Plans are currently in progress to restore at least some areas and work has started at key sites.^[4][8]

Cultivation and uses

Pinus sylvestris - Botanical plate

Pinus sylvestris - Scots Pine wood

Bark on a mature Pinus sylvestris tree.

Looking up into the branch structure of a Pinus sylvestris tree

Scots Pine is an important tree in forestry. The wood is used for pulp and sawn timber products. A seedling stand can be created by planting, sowing or natural regeneration. Commercial plantation rotations vary between 50–120 years, with longer rotations in northeastern areas where growth is slower.

In Scandinavian countries, Scots Pine was used for making tar in the pre-industrial age. There are still some active tar producers, but mostly the industry has ceased to exist.^[8][9] The pine has also been used as a source of rosin and turpentine.

The wood is pale brown to red-brown, and used for general construction work. It has a dry density of around 470 kg/m³ (varying with growth conditions), an open porosity of 60%, a fibre saturation point of 0.25 kg/kg and a saturation moisture content of 1.60 kg/kg.^[9]

Scots Pine has also been widely planted in New Zealand and much of the colder regions of North America; it was one of the first trees introduced to North America, in about 1600.^[20] It is listed as an invasive species in some areas there, including Ontario,^[21] Michigan^[22] and Wisconsin.^[23] It has been widely used in the United States for the Christmas tree trade, and was one of the most popular Christmas trees from the 1950s through the 1980s. It remains popular for that usage, though it has been eclipsed in popularity, by such species as Fraser Fir, Douglas-fir, and others. Despite its invasiveness in parts of eastern North America, Scots Pine does not often grow well there, partly due to climate and soil differences between its native habitat and that of North America, and partly due to damage by pests and diseases; the tree often grows in a twisted, haphazard manner if not tended to (as they are in the Christmas tree trade).^[3][24] Scots Pines may be killed by the pine wood nematode, which causes pine wilt disease. The nematode most often attacks trees that are at least ten years old and often kills invaded trees within a few weeks.^[25]

Several cultivars are grown for ornamental purposes in parks and large gardens, and the following have gained the Royal Horticultural Society's Award of Garden Merit:-

• P. sylvestris^[26]
• 'Aurea group'^[27]
• 'Beuvronensis'^[28]

Names

In the past (pre-18th century) this species was more often known as "Scots Fir" or "Scotch Fir".

Other names sometimes used include Riga Pine and Norway Pine, and Mongolian Pine for var. mongolica. "Scotch Pine" is another variant of the common name, used mostly in North America.^[29]

The timber from it is also called red deal or yellow deal.

Another name, although less common, is European Redwood ^[30]

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References