Scotch Pine, Scot Pine, Scotís Pine, Scottish Pine; Pinaceae Family; Pinus sylvestris


    Scot Pine (Pinus sylvestris) is one of the most widely distributed conifers in the world. Its native range spans from western Scotland to eastern Siberia and from northern Scandinavia to southern Spain. In Scotland, Scot pine forests are unique and treasured due to the absence of any other native conifers (Sinclair et al 1999). Throughout Europe Scot pine is of great economic value as a lumber tree (Miller et al 1941).


    Scot pine is a monoecious evergreen reaching heights of 80 to 100 feet when mature. The vast geographic distribution of Scot pine has led to considerable variation of characteristics in the species, accounting for more than 20 different subspecies. Young Scot pine takes on a pyramidal shape, becoming round topped and irregular with age. The bark is smooth when young and becomes fissured at the lower portion of the trunk with age. One of its most distinguishing traits is the orange red bark on the upper branches. Needles are 1-3.5 inches long and found in bundles of two. There is a wide variation in needle color for subspecies of Scot pine; however they are usually dark green or yellow green. Male cones are yellow, and occur on branches just below the female cones, which are green in color. Both male and female cones point inward (Miller et al 1941). Female cones are 1-2.5 inches long, and mature after two years.


    Due to its wide geographic range, Scot pine can establish in a wide range of soils and climates, particularly in nutrient poor soils. Once introduced, Scot pine is known to persist (Kilgroe & Telewski 2004) and spread along roadsides, disturbed habitats, and into natural areas (forests, meadows and grasslands). Scot pine has been introduced extensively in regions where it is used on Christmas tree plantations, for erosion control or for land reclamation. Once abandoned, Scot Pine have been found to perform better or just as well as native species and to successfully recruit outside of the original plantings. In a common garden experiment in Michigan, after thirty years Scot pine was considered to have surpassed all of the other species in growth and was the only species to regenerate successfully by seed (Kilgore & Telewski, 2004).

    Scot Pine produces copious seeds which develop into mats that out compete other native species. These seedlings also grow more aggressively during their first few years, crowding out the roots of other species and shading them out as well. As with many pines, once reaching maturity Scot pine tends to dominate the community (Skilling 1990).

    Scot pine is listed as an ecological invader in several states; however surveys have demonstrated low ecological impact. A survey in Canada of thirty-five botanists found that although in the past Scot pine was frequently planted and known to escapes to old fields, roadsides, open bogs and open woods, the majority of respondents to the survey did not consider this species to be a problem. Those who did consider it a problem rated it as moderate, local, and spreading. In Southern Ontario, Scot Pine is classified as a category 2, a species that is "highly invasive but tend to only dominate certain niches or do not spread rapidly from major concentrations" and persist in dense populations for long periods (Urban Forest Associates 2002). In Wisconsin a similar survey was conducted rating Scot pine as having low ecological impact (IPAW 2003).

    Scot pine has at least 100 documented insect or disease issues resulting in potential ecological and economic impact by acting as a vector of spread to other tree species. Several of the pests affecting Scot pine are known to affect associated species such as oak allowing for the development of pure stands of Scot pine (Landowner Resource Centre 2005).


    Scot Pine has been documented in natural areas and disturbed environments of the Great Lakes Region, Mid Atlantic, North-central, and Northeast U.S., and Hawaii (Swearingen 2006).


    Scot pine can grow in a variety of soil types and climates due to the genetic diversity of species (Sinclair 1998), particularly when the best seed source is matched with site conditions. Several studies by the Forest Service were conducted to establish the best seed source for a region, with the objective to find the best Scot Pine for Christmas tree production (Cunningham 1991; Reads 1971). Scot Pine can grow in nutrient poor soils but does best in sunny fertilized soils. Being intolerant of shade, Scot pine is found to invade open areas and sandy soils, and is found to persist where introduced and to spread along roadsides, forest, meadows, grasslands, and open fields (Kilgore and Telewski 2004).


    Scot pine was among the first European tree species introduced in North America by European colonists. It is a valuable forestry species in Europe but not in the United States, where it is used primarily as a Christmas tree, and for ornamental plantings, erosion control, and as shelter belts. The species is also used in reclamation efforts since it grows in polluted and nutrient poor soils.

    Scot Pine makes up 30% of the 35 million Christmas trees sold in the United States each year. It is favored for this purpose due to its shape, color, fast growth, greater seed availability than native trees, ability to handle intensive plantation management, and capacity to retain needles (Skilling 1990; Richardson 1998). It has been used as an ornamental due to its ability to grow in compacted soils, reduce erosion, adapt to various climates and to grow fast. Scot pine is commonly used in the front lawns of newly built homes. The genetic variation of the species has allowed for the development of several cultivars (Conifer Garden Nursery).

    Scot Pine was introduced to Ontario in the 1920s when the first efforts to reforest abandoned agricultural lands began. It has been used for erosion control of large scale land clearing for agriculture. During the 1950s, Scot pine plantings on private land in Ontario peaked due to use for Christmas tree production, a market that soon declined. The drop in the market resulted in several abandoned plantations of Scot pine (Landowner Resource Center 2005).

    In New Zealand Scot Pine was introduced for erosion control and since became the third most wide-spread conifer in New Zealand (Richardson, Williams, & Hobbs, 1994).


    Scot pine is a monoecious perennial pine that reproduces by seed. Although a monoecious species, some shoots, branches and entire trees have been found to be predominantly of one sex. Male flowers are formed in late summer at the base of the bud that will make the next yearís growth. About two weeks after growth begins in the spring, the male catkins enlarge to 0.2-0.3 inches long and shed pollen. Because catkins replace leaves, an excess of pollen production leads to sparse foliage, a characteristic that is selected against by growers of Scot pine. Female flowers are formed in late summer but are microscopic. They develop on the tips of buds for the next yearís growth. They first flower becomes visible after the buds expand in the spring. Because of shearing involved in management of Scot pine for Christmas trees, female flowers are removed preventing the production of seeds. Christmas tree management reduces the invasive abilities of Scot pine. The abandonment of the plantations results in establishment of Scot pine and spread into natural areas. Scot Pine spreads through wind dispersion.

    Scot pine has the same biological characteristics that make pines good invaders: low seed mass, short juvenile period, short interval between large seed crops (Richardson D 1998). Scot Pine additionally grows fast and develops mats of seedlings that out compete native species. When invading sandy soils, Scot pine is able to develop a tap root (Skilling 1990).


    Best method of controlling regeneration and field infiltration of Scot Pine can be achieved through manual removal of trees and removal of seed source allowing natives to repopulate a location. Seeds can remain viable for a number of years (Landowner Resource Centre 2005).


    Depending on the region of the country, native alternatives exist that can be used for ornamental purposes, Christmas tree production or erosion control. Christmas Tree alternatives include Colorado blue spruce, white spruce, eastern white pine, Fraser fir, and Douglas fir.


    In Europe, information on the genetic variation of Scot pine is plentiful as a result of concern for an economically important tree for forestry and ecological benefits. Studies have illustrated the vast genetic diversity of the species and its original origins (Sinclair et al 1998). Both in Europe and the United States several hybrids have been developed by crossing subspecies to develop more resistant hybrids. In the United States several studies have been conducted by the forest service to determine the best seed source for a particular region or use of the species (Cunningham 1991; Reads 1971).


    Joy Cookingham, University of Massachusetts Boston, Boston, MA.


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    Swearingen, J. (2006). WeedUS: Database of Plants Invading Natural Areas in the United States. Retrieved 2007, from http://www.nps.gov/plants/alien/list/WeedUS.xls

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