Prota 7(1): Timbers/Bois d’œuvre 1
Trans. Acad. Sci. St. Louis 4(1): 186–190, pl. 1–3 (1880).
2n = 24
Slash pine, pitch pine, yellow pine (En). Pin d’Elliott, pin à aiguilles longues (Fr).
Origin and geographic distribution
Pinus elliottii occurs naturally in the south-eastern United States (Florida and adjacent coastal plains). It has been introduced into many parts of the southern hemisphere, including Africa, South America, Australia and New Zealand. In Africa it is recorded from Burundi, Tanzania, Malawi, Zambia, Zimbabwe, Madagascar, Mauritius, Réunion, South Africa and Swaziland. It also occurs as an escape.
The lightweight and soft wood from younger trees is mainly used for pulping, whereas the heavier and harder wood of older trees is used as timber. The straightness of the bole makes it particularly suitable for poles, piles and solid-wood products, but treatment with preservatives is often necessary. The wood is also suitable for construction, flooring, frames, joinery, interior trim, furniture, cabinet work, ship and boat building, vehicle bodies, toys, turnery, boxes, crates, veneer, plywood and particle board. It is used as fuelwood.
Oleoresin is tapped from the trees and distilled to obtain turpentine and rosin. Turpentine is used in the paint industry, and rosin is used in the production of paper, soap and glue.
The heartwood is yellow to red-brown, and not clearly demarcated from the 5(–15) cm wide yellowish white sapwood. The grain is straight, sometimes spiral; texture medium. Growth rings are distinct. The resin content of the wood is high. The wood has a density of 420–700 kg/m³ at 12% moisture content. It dries with little degrade, although some surface checking and splitting down the centre may occur. The rates of shrinkage from green to oven dry are 4.2–5.5% radial and 7.9–8.5% tangential. At 12% moisture content, the modulus of rupture is 71–123 N/mm², modulus of elasticity 7800–14,700 N/mm², compression parallel to grain 37–59 N/mm², compression perpendicular to grain 6 N/mm², shear 8–9 N/mm², Janka side hardness 2930–4630 N and Janka end hardness 3800–5920 N.
The wood is relatively difficult to work. Resin may adhere to sawteeth and cutting edges, but the use of long-pitched sawteeth reduces this problem. The wood holds nails and screws well, and it glues, finishes and paints satisfactorily. It is moderately durable to non-durable, being susceptible to attacks by Anobium borers, marine borers and termites. The sapwood is not susceptible to Lyctus borers. The heartwood is resistant to impregnation with preservatives, the sapwood is permeable.
The wood fibre cells are 2.1–4.0 mm long, with a diameter of 39–54 μm and a cell wall thickness of 4.2–6.5 μm. The chemical composition of the oven-dry wood is: holocellulose 57–73%, α-cellulose 36–42% and lignin 28–32%. The solubility in cold water is 1.4–3.3%, in hot water 1.9–4.7%, in alcohol-benzene 0.5–6.6% and in 1% NaOH 8.5–15.8%. Pulping with the sulphate (kraft) process yields 40–51% screened pulp, with a kappa number of 23–56, giving paper with satisfactory tensile and bursting strengths, but relatively low tearing strength.
In Zimbabwe the oleoresin yields 12–13% turpentine, with as main components α-pinene (54.3%) and β-pinene (34.0%). The main components of essential oil distilled from the needles of Pinus elliottii from Mozambique were α-pinene (43.0%), β-pinene (27.1%) and α-terpineol (9.6%).
Evergreen, monoecious, medium-sized tree up to 30(–40) m tall; bole slender, straight, up to 90(–100) cm in diameter; outer bark greyish and furrowed in young trees, later brownish red with a plate-like pattern; crown ovoid. Leaves crowded towards the ends of branches, in bundles of 2–3, needle-shaped, 17–30 cm long, stiff, dark green. Male cone in dense clusters, up to 6 cm long. Mature female cone usually solitary, sessile, ovoid-conical, 7–15 cm long, greyish or reddish brown, lustrous, with scales with a blunt greyish prickle. Seeds c. 6 mm × 3 mm, with wings c. 25 mm long, dark brown mottled with black. Seedling with epigeal germination.
Initial growth of Pinus elliottii is fast, but over the whole rotation cycle growth is not as fast as that of Pinus patula Schltdl. & Cham. In Zambia 30-year-old trees were on average 24 m tall. In Malawi 30-year-old trees in a thinned plantation with a density of 296 trees/ha were 30 m tall, with a mean bole diameter of 37 cm. In Madagascar 40 year-old-trees were on average 31 m tall with a bole diameter of 41 cm. In South Africa 20-year-old trees (density 320 trees/ha) were 23 m tall, with a bole diameter of 22 cm, and 33-year-old trees (density 320 trees/ha) 33 m tall with a bole diameter of 42 cm. Pinus elliottii is notable for the straightness of the bole. Self-pruning is common, resulting in a relatively short crown. Pollination is by wind. Female cones mature in 3 years, and trees start bearing seed when 7–8 years old.
Pinus is a large genus comprising over 110 species, almost all restricted to the northern hemisphere. Many Pinus species are cultivated outside their natural distribution area, in tropical, subtropical and temperate regions. In the tropics 2 species are of outstanding importance: Pinus caribaea Morelet in the lowland humid tropics and Pinus patula in the cooler highland tropics and subtropics. Pinus elliottii is often confused with Pinus caribaea, and the 2 species hybridize.
Pinus elliottii is grown at (500–)700–2500 m altitude, in areas with a mean annual temperature of 15–24°C, a mean maximum temperature of the warmest month of 23–32°C, a mean minimum temperature of the coldest month of 4–12°C, an average annual rainfall of 650–2500 mm, and a dry season of 1–4 months. It can be grown on a wide variety of soils, but does best on deep, well-draining, acid soils. Pinus elliottii is fairly tolerant to frost and salt winds. Young trees are quite susceptible to fire injury until they are 3–4.5 m tall, but then the bark becomes thick enough to insulate the cambium from high temperatures. It is a light-demanding species, competing well with weeds.
Pinus elliottii is usually propagated by seed. The 1000-seed weight is 25–50 g. In Zimbabwe seeds are collected after sun-drying the cones in open-sided sheds covered with plastic roofs, sometimes supplemented by kiln-drying at a maximum temperature of 48°C. The seeds can be stored for years under dry, cold and airtight conditions. Germination normally takes 15–20 days, and the germination rate of fresh seeds is usually 80–95%. The presence of mycorrhizae is highly beneficial for survival and early growth, so it is recommended to inoculate with spores or to add soil from near established trees. Seedlings can be planted out 4–8 months after germination, when they are about 30 cm tall. Common spacings are 2.5 m × 2.5 m. Vegetative propagation is possible using grafting, air-layering or cuttings, but branch cuttings do not root easily, especially those from older trees. In-vitro regeneration systems have been developed using embryogenesis or organogenesis.
Weed control is necessary during the first 2 years after sowing. There are no conclusive experiments of fertilizer use. Rotation cycles depend on production aims: the optimum rotation for pulpwood is about 25 years, whereas for sawn timber longer rotations are applied, e.g. 45–55 years to obtain trees with a bole diameter of about 40 cm. Thinning is normally practised. In plantations in Malawi with an initial density of 1250 trees/ha the first thinning takes place when the mean bole diameter of the trees is 24 cm, so that the wood of felled trees can be commercialised; this is usually when the trees are about 13 years old. The second thinning is carried out when the trees are 19 years old, and the third when they are 25 years old, with a final density of 270 trees/ha. For the production of sawn wood prunings are required at 5–10-year intervals, starting at age 8–12, but even for pulp production pruning to a height up to 2 m is recommended when the trees are 6 m tall, to reduce fire hazard. Pinus elliottii is reported to coppice well.
Of all pines, Pinus elliottii is considered the most resistant to the important fungal pine pathogen Sphaeropsis sapinea (synonym: Diplodia pinea) causing Sphaeropsis blight or die-back. The most serious disease is fusiform rust caused by Cronartium fusiforme. In Malawi Pinus elliottii is susceptible to honey fungus (Armillaria sp.), particularly below 1300 m altitude. In nurseries damping off may occur. Pests include the grasshopper Mecostibus pinivora in Zimbabwe. Pinus elliottii is also attacked by the southern pine bark beetle (Dendroctonus frontalis).
Due to its slower growth, wood yields of Pinus elliottii are lower than those of Pinus patula. However, Pinus elliotti can produce higher pulpwood yields because of its higher wood density. Mean annual volume increments in plantations are usually 10–20 m³/ha, but for Malawi annual increments of up to 36 m³/ha have been recorded. Annual oleoresin yields of 3 kg/tree have been recorded from Zimbabwe.
Genetic resources and breeding
Pinus elliottii has been crossed with Pinus caribaea, Pinus patula and other Pinus spp. A hybrid of Pinus elliottii and Pinus caribaea var. hondurensis has become important in plantations in Queensland (Australia) because of its superior growth and shape. Genetic linkage maps of Pinus elliottii have been made using RAPD, AFLP and microsatellite markers.
Pinus elliottii is a useful plantation tree for the production of poles, piles and solid-wood products, and for paper making. It tolerates a wide range of climates and soils, and is relatively resistant to Sphaeropsis sapinea. Drawbacks are its relatively slow growth and the low durability of its wood.
• Barnett, J.P., 2002. Pinus elliottii Engelm. In: CAB International. Pines of silvicultural importance. CABI Publishing, CAB International, Wallingford, United Kingdom. pp. 115–131.
• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
• Lamprecht, H., 1989. Silviculture in the tropics: tropical forest ecosystems and their tree species, possibilities and methods for their long-term utilization. Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH, Eschborn, Germany. 296 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Theron, J.M., Paterson, D.N., Mjuweni, L.S., Joab, H. & Ng’Ambi, G.L., 1971. Growth and yield of Pinus elliottii in Malawi. Research Record No 53. Malawi Forest Research Institute, Zomba, Malawi. 27 pp.
• Banks, C.H. & Schoeman, J.P., 1963. Railway sleeper and crossing timbers. Bulletin 41. The Government Printer, Pretoria, South Africa. 54 pp.
• Busby, R.W., 1982. Naval stores in Zimbabwe. South African Forestry Journal 121: 93–94.
• Foot, D.L., 1967. Note on the planted conifers of Malawi. Silvicultural Research Record No 9. Forestry Research Institute (FRIM), Dedza, Malawi. 53 pp.
• Morris, A.R., Palmer, E.R., Barnes, R.D., Burley, J., Plumptre, R.A. & Quilter, A., 1997. The influence of felling age and site altitude on pulping properties of Pinus patula and Pinus elliottii. Tappi Journal 80(6): 133–138.
• Pagula, F.P. & Baeckström, P., 2006. Studies on essential oil-bearing plants from Mozambique: part 2. Volatile leaf oil of needles of Pinus elliottii Engelm. and Pinus taeda L. Journal of Essential Oil Research 18(1): 32–34.
• Palmer, E.R. & Gibbs, J.A., 1974. Pulping qualities of plantation grown Pinus patula and Pinus elliottii from Malawi. Report L37. Tropical Products Institute, London, United Kingdom. 30 pp.
• Palmer, E.R., Ganguli, S. & Gibbs, J.A., 1984. Pulping properties of Pinus caribaea, Pinus elliottii and Pinus patula growing in Tanzania. Report L66. Tropical Development and Research Institute, London, United Kingdom. 31 pp.
• Parant, B., Chichignoud, M. & Curie, P., undated. Présentation graphique des caractères technologiques des principaux bois tropicaux. Tome 8. Bois du Burundi. CTFT, Nogent-sur-Marne, France. 82 pp.
• Shepherd, M., Cross, M., Dieters, M.J. & Henry, R., 2003. Genetic maps for Pinus elliottii var. elliottii and P. caribaea var. hondurensis using AFLP and microsatellite markers. Theoretical and Applied Genetics 106(8): 1409–1419.
• Tang, W., Newton, R.J. & Charles, T.M., 2006. Plant regeneration through multiple adventitious shoot differentiation from callus cultures of slash pine (Pinus elliottii). Journal of Plant Physiology 163(1): 98–101.
Correct citation of this article:
Brink, M., 2008. Pinus elliottii Engelm. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
obtained from Plants of Hawaii
obtained from Plants of Hawaii
obtained from Carlton McLendon, Inc.