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Scotch pine is the most widely distributed pine in the world. It grows naturally from Scotland almost to the Pacific Ocean and from above the Arctic Circle in Scandinavia to the Mediterranean. Its altitudinal range is from sea level to about 2440 m (8,000 ft). Scotch pine is adapted to a wide variety of climates as indicated by its extremely large natural range. It grows in areas with an annual precipitation exceeding 1780 mm (70 in) and in areas with an annual precipitation as little as 200 mm (8 in). Scotch pine survives in the Verkhoyansk Mountains of eastern Siberia where winter temperatures have been recorded as low as -83° F. In some areas it grows where the subsoil is permanently frozen. Scotch pine can also survive high temperatures, and it is found at middle altitudes in the Mediterranean region. The primary distribution of Scotch pine, however, indicates that it is a tree of the continental climates. [2] |
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Scotch pine is the most widely planted pine introduced in North America. It is also the preferred large-volume Christmas tree in the United States. Approximately 30 percent of the 35 million Christmas trees harvested annually are Scotch pine. Scots pine's economic importance also consists of various products, among them: food flavoring; Environmental - agroforestry; ornamental; Materials: gum/resin; lipids; wood. (2) Because it survives on poor dry sites, Scotch pine has been used to control erosion in many areas. However, the poor vigor of many of these stands on dry, infertile sites has made them susceptible to serious insect attack and many of them have little potential to produce timber. Scotch pine has also been used to a large extent in ornamental plantings. It grows better than red pine on compacted clay soils frequently found around home sites. Because Christmas tree plantations are a ready source of trees, many trees are removed from these plantations as ornamental stock. Scotch pine is similar in fiber and wood characteristics to red pine and is usable for both pulpwood and saw logs. (1)
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Flowering and Fruiting- Although Scotch pine is primarily a monoecious species, some shoots, branches, and even entire trees are predominantly of one sex. Male flower primordia are formed in late summer at the base of the bud that will make the next year's growth. During the winter their presence can be noted as a slight swelling, and the preferred male catkins are easily visible if a bud is dissected. About 2 weeks after growth begins in the spring, the male catkins enlarge to 0.6 to 0.7 cm. (0.2 to 0.3 in) long and shed pollen. At this time they are yellow. The male catkins are borne at the base of the twigs, replacing leaf clusters. They are most common in the lower part of the crown and on short lateral twigs. Because they replace leaves, an excess of pollen production can lead to sparse foliage. A Pennsylvania breeder who selected for early flower production for two generations obtained a variety that produced plentiful pollen but few needles and it was worthless as a Christmas tree. Female flower primordia are also formed in late summer but are microscopic. They are borne at the tips of buds for the next year's growth. There may be one, two, or three on a single bud. They first become visible after the buds expand in the spring. The primordia enlarge into female flowers or strobili about 2 weeks after growth begins in the spring, at a time when the new growth has completed 75 percent of its elongation for the season. Because of this, shearing of the outside branches such as is practiced by Christmas tree growers removes all female flowers. Indeed, trees sheared in June will not produce seed for the next 3.5 years.
Flowering occurs in late May or early June. On any one tree nearly all pollen is shed and nearly all the female flowers are receptive during the same 2- or 3-day period. In any one stand most trees flower within a day or two of each other. Pollen production tends to be concentrated on short lateral twigs in the lower half of a tree crown. Female flowers are borne on the most vigorous shoots. They tend to be concentrated on upper branches but may occur in any part of the crown receiving full sunlight. (1) |
Damaging Agents- Scotch pine in North America is subject to a number of agents that can severely damage or kill the trees. Some of these agents are not present in Europe and Asia and, as a result, the species has not yet had an opportunity to develop genetic resistance. Fire and wind can damage the trees. Young stands have thin bark and are heavily damaged by fire. Older trees with thicker bark are moderately resistant. Scotch pine has more branches per whorl than red or white pine and this large number of branches makes the tree weak at the nodes. During severe wind storms, trees may snap off at the nodes 3 to 6 m (10 to 20 ft) above the ground. The pine root collar weevil (Hylobius radicis) is a major cause of tree death in young plantations in the Lake States. The weevil girdles the tree at the base, killing it within 3 to 4 years. The damage is especially severe on dry sandy soils. The fast-growing central European trees are particularly susceptible (26). In Michigan, on low quality sites, mortality frequently reaches 70 to 80 percent. The pine root tip weevil (Hylobius rhizophagus) causes serious damage in Michigan on Scotch pine Christmas trees grown from stump culture. These trees result from leaving the lower limbs on cut trees to grow into a second tree crop. The pine root tip weevil larvae feed on the roots and root tips, resulting in reduced height growth and flagged shoots, and eventual death. In some cases the pine root tip weevil and the pine root collar weevil attack some Scotch pine stands simultaneously, causing more mortality than expected from either insect alone. The European pine sawfly (Neodiprion sertifer) causes moderate damage in Christmas trees and ornamental plantings. Heavy defoliation reduces growth from 10 to 20 percent. The fast-growing Scotch pine variety uralensis shows some resistance to this insect while the slow-growing variety iberica is most susceptible. (1) |
 26-year-old Scotch Pine
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Morton Arboretum accession 661-65*2 Waterer Scots Pine - Pinus sylvestris 'watereri'
| References: 1. USDA Forest Service Pinus sylvestris - Scotch Pine 2. USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN) |
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