Monterey pine

Monterey pine, (Pinus radiata), economically important conifer species (family Pinaceae), the most widely planted pine in the world. The tree is endemic to three locations along the central coast of California—including one population on the Monterey peninsula—and to Guadalupe Island and Cedros Island in Baja California, Mexico. It is an endangered species in its native range. Despite their very limited natural distribution, the trees do well in cultivation and grow rapidly. They have been introduced throughout the world—especially in New Zealand, Australia, South Africa, and Chile—and are grown for timber, pulp, and other commercial uses.

Physical description

Monterey pines are evergreen trees with deeply furrowed bark. They can grow 2 meters (6.5 feet) per year, often reaching a height of 12–18 meters (39–59 feet) within 25 years of their planting. Wild Monterey pines have an average life span of 80 to 90 years, and the largest specimens in nature are about 38 meters (125 feet) in height. Plantation pines can grow even taller and reach heights of 40–50 meters (131–164 feet) before they are harvested. Young Monterey pines typically have a pyramidal shape, while the adult canopy may be rounded or flat-topped. Although plantation-grown trees have straight trunks, many of the iconic Monterey pines of California and Mexico grow in twisted, contorted, and knotted shapes as a result of coastal winds.

Monterey pine needles are glossy and dark green in color, sometimes appearing blueish-green on older trees. The needles occur in groups of two or three and are 9–15 cm (3.5–6 inches) in length. Monterey pines are monoecious, meaning both male and female cones grow on a single individual. The male, pollen-producing cones are small and borne in clusters at the tips of the branches. The pale brown female cones are solitary or grow in clusters of three to seven and reach maturity after two years. They are asymmetrically oval, measure some 6–15 cm (2–6 inches) in length, and feature smooth, rounded scales that are sometimes sealed with resin. Such sealed, serotinous cones require fire or high air temperatures in order to open and release the numerous black-brown winged seeds housed within.

An important source of timber and wood products, Monterey pines produce a pale softwood with a straight grain and an even, medium texture. It is characterized by very wide growth rings and is free of knots. Easily workable, the wood is used as a veneer, as construction lumber, and as material for boxes and crates, plywood, and paper (pulpwood).

Threats

Although the tree is cultivated extensively in the Southern Hemisphere, the five natural populations of Monterey pine trees in California and Mexico are severely fragmented and decreasing. Threats to native-range Monterey pines include urbanization and development, though they are now a protected species. For the California populations, a history of fire suppression has impeded the release of seeds from cones and permitted the growth of a thick understory that crowds out pine seedlings.

The trees are also threatened by numerous pests and diseases. One of the most serious is pine pitch canker, a novel and potentially fatal fungal disease caused by Fusarium circinatum and spread by pine cone beetles, twig beetles, and engraver beetles. Other pests and diseases include Monterey pine midge, western dwarf mistletoe, and various needle blights. The population on Guadalupe Island was heavily damaged by a feral goat population that virtually eliminated all the young trees, though the goats have since been eradicated from the island.