Pinus radiata

D. Don 1836

Common names

Monterey pine, insignis pine (Little 1980), radiata pine.

Taxonomic notes

Syn: Pinus tuberculata D. Don; P. insignis Douglas ex Loudon (Kral 1993, Millar 1986).

It hybridizes naturally with P. attenuata (P. × attenuradiata Stockwell & Righter; note that this name was applied to an experimental hybrid specimen).

One variety, Pinus radiata D. Don var. binata (Engelmann) Lemmon, the Guadalupe Island pine (syn: P. insignis var. binata Engelmann; P. muricata var. cedrosensis Howell; P. radiata var. cedrosensis (Howell) Silba) (Perry 1991).

Description

Trees 15-30(-64) m tall, 30-90(-280) cm in diameter, contorted to straight; crown broadly conic, becoming rounded to flattened, very shallow (10-20% of height) in closed stands. Red-brown, turning gray with age, furrowed between elongate-rectangular scaly ridges. Primary branches variably level, downcurved or ascending, often bearing old cones; twigs slender, red-brown, sometimes glaucous, aging gray, rough. Buds ovoid to ovoid-cylindric, red-brown, ca. 1.5 cm, resinous. Needles 2 (var. binata) or 3 (type variety) per fascicle, spreading-ascending, persisting 3-4 years, (8)9-15(20) cm × 1.3-1.8(2) mm, straight, slightly twisted, deep yellow-green, all surfaces with fine stomatal lines, margins serrulate, apex conic-subulate; sheath (1)1.5-2 cm, base persistent. Pollen cones ellipsoid-cylindric, 10-15 mm, orange-brown. Seed cones maturing in February, 2 years after pollination, persistent 6-20(-40) years, often serotinous, numerous, solitary to whorled, spreading to recurved, curved, mostly asymmetric (usually symmetric in var. binata and occasionally so in var. radiata), ovoid before opening, broadly ovoid when open, 7-15 cm, yellow-brown, lustrous, scales rigid, stalks to 1cm; apophyses toward outer cone base mostly increasingly mammillate (but not in var. binata), those on inward cone side and middle and apex of cone more level; umbo central, mostly depressed, with small central boss or occasionally with slender, deciduous prickle. Seeds compressed-ellipsoid; body ca. 6 mm, dark brown; wing 20-30 mm. 2n=24 (Little 1980, Kral 1993, M.P. Frankis e-mail 1999.03.05, pers. obs.).

Distribution and Ecology

The type variety occurs naturally only at three localities in a fog belt on the coast of central California (at 30-400 m elevation; one in San Mateo and Santa Cruz counties, one in Monterey County, and one in San Luis Obispo County), while variety binata is found on Islas Guadalupe and Cedros, off the west coast of Baja California Norte, Mexico (at 600-1200 m elevation) HERE is a Google Maps link to it on Isla Guadalupe, where the trees are restricted to steep slopes at the highest elevations at the northern end of the island (Rogers 2002). On Isla Cedros, Rogers (2002) reports that "the pines occur in two main populations: inland towards the center of the island and at the northern end of the island, separated by approximately 14 km. Their locations on the island may be moisture limited (Libby et al. 1968) because conditions are dry--lower elevations receiving less than 250 mm of precipitation annually. However, fogs and mist are common at higher elevations (Perry 1991) ... No census has been taken on the Monterey pines here--their numbers are far greater than those on Guadalupe Island--and no comprehensive map of their distribution has been made."

Distribution data from USGS (1999). Red polygons are the type variety and green, var. binata.

Due to its rarity, the species is of conservation concern, with some natural populations receiving protection (Kral 1993, Little 1980, Perry 1991); var. binata is classified Endangered. USDA hardiness zone 8. See also Thompson et al. (1999).

Its cones are serotinous, i.e. they remain closed until opened by the heat of a forest fire; the abundant seeds are then discharged to regenerate the burned forest. The cones may also burst open in hot weather (Little 1980).

Along the California coast it has escaped from cultivation, and from there into southern coastal Oregon it shows signs of naturalizing. It has been introduced as a timber tree in vast areas of New Zealand (where it is the most common tree), Australia, Chile, SW Europe and South Africa (Little 1980, Kral 1993, Lavery & Read in Richardson 1998). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001).

The three remaining native stands of var. radiata are infected and under threat of extinction from pitch canker, a fungal disease native to the southeast United States and found (in 1986) to have been introduced to California. When trees begin to die of the disease, they attract bark beetles which provide a pathway for infection of other trees. In some stands, 80-90% of trees are infected. If the disease is introduced in agroforestry areas dependent upon radiata pine, such as New Zealand, it could have catastrophic effects in those countries as well (Anonymous 1999).

In its native range, this species is a principal host for the dwarf mistletoe Arceuthobium littorum (Hawksworth and Wiens 1996).

Remarkable Specimens

Carder (1995) states that in its native range in California, the species seldom reaches 40 m in height. In the United States, a tree measured by Michael Kauffmann (2016) in spring 2016 is 178.7 cm dbh, height 48.77 m, crown spread 26.52 m; it grows in in Rohner Park, Fortuna, CA, and is about 100 years old. This tree is not within the species' native range, though it is in an area where the species is becoming naturalized.

Really exceptional specimens occur in the southern hemisphere. Of the many extraordinary specimens there, the thickest is 321 cm dbh (New Zealand Tree Register, accessed 2020.10.24). The tallest tree in New Zealand has been known for many years (Tree 33 in Burstall and Sale 1984), but it keeps growing! LIDAR data interpreted in July 2024 pegged it at about 70 m tall, shortly thereafter checked by laser measurement and found to be precisely 68.7 m tall (Matt Smillie, Facebook group "Great Trees of New Zealand, 2024.07.12). The tree was planted around 1927 in the Owen Road permanent sample plot on the edges of Kinleith Forest, near Atiamuri, so it has achieved this height in about 97 years; barring calamities, it can reasonably be expected to exceed 70 m in a few years.

The largest and tallest specimen in Australia is a tree at Blackwood Recreation Reserve in Victoria, measured in 2010 as 314 cm dbh and 53.0 m tall (National Register of Big Trees 2020). In South Africa, a tree from a plantation at Tokai Forest, near Cape Town, was 53.0 m tall when climbed and measured on 2008.01.25 (Leon Visser email 2014.11.05). So far, I have no data from other southern hemisphere locations.

Ethnobotany

"Radiata", as it is generally known, is probably the most widely-planted and commercially-important plantation conifer in the world (depending on your interpretation of the word "plantation"; Pseudotsuga menziesii is even more economically important, but is mostly harvested within its native range, where it is supported by both plantings and natural regeneration). This industry is almost entirely in the southern hemisphere. New Zealand alone has nearly than 1.6 million hectares of radiata plantations, which is 88% of all the tree plantations in the country (Ministry for Primary Industries 2021). In 1998 New Zealand had about 1.4 million hectares of plantations, while Australia had 0.75 million and Chile had 1.4 million. It is also one of the most important plantation species in Argentina, Chile, Kenya, South Africa, Spain, and Uruguay; there are over 4 million hectares of radiata plantations around the world (Lavery and Mead 1998). This popularity derives from the species' capacity to grow rapidly to large sizes, producing a wood usable for timber, pulp, and a variety of processed wood products. The species was introduced in Europe by the 1830s, but at that time the interest was horticultural. More pragmatic introductions took place in South Africa in 1850, soon thereafter in Australia, and in 1876 it was used for housing timbers in New Zealand; introduction to Chile finally happened in 1886. By 1900 all of these countries supported commercial plantations. The radiata genome has probably been more radically modified than that of any other economically important conifer, excepting certain ornamental cultivars. It has been selectively bred at southern hemisphere sites, yielding a very uniform stock with spectacular growth rates (Lavery and Mead 1998), and now genomic selection techniques are being used to further select suitable trees (Klápště et al. 2022). It is not hard to imagine that radiata may become the first synthetic forestry species.

Observations

It can most easily be seen on the Monterey Peninsula, where it occurs on the hills in the interior of the peninsula. Most peninsular stands have suffered the depredations of axe and bulldozer, and nowadays the species is most comonly visited at Point Lobos State Park (Peattie 1950).

Remarks

The epithet radiata refers to radial markings visible on the apophyses of some cones (Farjon 2010).

This is the most common pine in the southern hemisphere, where no pines are native (except that Pinus merkusii barely crosses the Line in Sumatra).

Citations

Anonymous. 1999. Fungus threatens pines worldwide. American Forests, Autumn 1999, page 14.

Don, D. 1836. Descriptions of five new species of the genus Pinus discovered by Dr. Coulter in California. Trans. Linn. Soc. London 17:439-444.

Klápště, Jaroslav, Ahmed Ismael, Mark Paget, Natalie J. Graham, Grahame T. Stovold, Heidi S. Dungey, and Gancho T. Slavov. 2022. Genomics-enabled management of genetic resources in radiata pine. Forests 13(2):282. https://doi.org/10.3390/f13020282.

Lavery, Peter B. and Donald J. Mead. 1998. Pinus radiata: a narrow endemic from North America takes on the world. Pp. 432-449 in D. M. Richardson (ed.), Ecology and Biogeography of Pinus. Cambridge University Press.

Libby, W. J., M. H. Bannister and Y. B. Linhart. 1968. The pines of Cedros and Guadalupe Islands. J. Forest. 66:846-852.

Kauffmann, Michael. 2016.06.09. Record Monterey pine (Pinus radiata). blog.conifercountry.com/2016/06/record-pinus-radiata/, accessed 2016.06.10.

Millar, C.I. 1986. The Californian closed-cone pines; a taxonomic history and review. Taxon 35: 657-670.

National Register of Big Trees. 2020. Tree details. https://www.nationalregisterofbigtrees.com.au/pages/tree-register-view, accessed 2012.10.24.

Ministry for Primary Industries. 2021. National Exotic Forest Description. Available: https://www.mpi.govt.nz/dmsdocument/43540-2021-NEFD-report, accessed 2023.02.28.

Rogers, Deborah L. 2002. In situ genetic conservation of Monterey pine (Pinus radiata D. Don):Information and recommendations. Report no. 26. Genetic Resources Conservation Program, Division of Agriculture and Natural Resources, University of California. 92pp.

Rogers, D.L., J.J. Vargas Hernández, A.C. Matheson, and J.J. Guerra Santos. 2002. The Mexican island populations of Pinus radiata: an international expedition and ongoing collaboration for genetic conservation, in Forest Genetic Resources No. 30. www.fao.org/docrep/005/y4341e/Y4341E07.htm, accessed 2011.02.25.

See also

Elwes and Henry 1906-1913 at the Biodiversity Heritage Library. This series of volumes, privately printed, provides some of the most engaging descriptions of conifers ever published. Although they only treat species cultivated in the U.K. and Ireland, and the taxonomy is a bit dated, still these accounts are thorough, treating such topics as species description, range, varieties, exceptionally old or tall specimens, remarkable trees, and cultivation. Despite being over a century old, they are generally accurate, and are illustrated with some remarkable photographs and lithographs.

FEIS database.

The species account at Threatened Conifers of the World.

Burns and Honkala (1990).

Farjon and Styles (1997) provide a detailed account of var. binata, with illustrations.