Pinus radiata D.Don

Pinaceae

Distributed on the Pacific coast of California and on two islands off the coast of Mexico, it is threatened by feral goats on the islands and by an introduced pathogen, and competition from other trees in the absence of periodic fires on the mainland

Associated Names:

Distribution

The typical variety of Monterey Pine occurs along the coast of California in three disjunct populations in San Mateo and Santa Cruz counties, Monterey County, and San Luis Obispo County. Pinus radiata var. binata occurs on Guadalupe and Cedros islands, Mexico. Although trees on these islands differ in morphology from those in the United States, they have been shown to be most closely related to P. radiata.

Sub-populations exist on the mainland coast of California (3) and on two islands off the coast of Mexico (2–3); only one of these is healthy and regenerating well.

Habitat and Ecology

Pinus radiata is confined to promontories and strips of rocky coast as well as two offshore islands; it is rarely found more than 11km from the sea. The cold ocean water moving down the Californian coast substantially influences the local climate, raising humidity, tempering heat from the sun and causing almost daily summer fogs. On a rare clear day in summer temperatures can quickly rise to 40º C, coming down to only 15º C on the next foggy day. On Guadalupe Island, which lies ca. 250km offshore surrounded by deep, cold water, fog is nearly perpetual during the growing season. Rainfall is erratic and fog drip provides most of the moisture to the soil and the trees. On the islands the species does not grow below 300 m and ascends to the summit ridges at 1100 metres above sea-level on Guadalupe Island, but on the mainland it grows from sea level to the base of inland hills and does not ascend higher than 400 metres above sea-level. The island populations form pure stands with some undergrowth of Quercus tomentella (Guadalupe Island) or Juniperus californica (Cedros Island). On the mainland it forms pure stands or mixed stands with Cupressus macrocarpa, Pinus attenuata (both like P. radiata with serotinous cones adapted to fire), Arbutus menziesii, and Quercus agrifolia. In the absence of fire, Pseudotsuga menziesii establishes itself, especially in the southernmost population at Año Nuevo, and would become dominant to the exclusion of P. radiata. In stands with Cupressus macrocarpa there is very little or no undergrowth.

Human Uses

Radiata pine, as it is commonly called, is the most widely planted tree species in the world. Its tiny natural relict stands fall into insignificance to the millions of hectares planted in Australia, New Zealand, Chile, Argentina, Uruguay, South Africa, Kenya, and Spain. Provenance is almost exclusively from mainland California. Its spectacularly rapid growth under plantation conditions is the main reason for its success in commercial forestry and for many of the above mentioned countries it is the most important timber tree. The wood is rather brittle and coarse grained and most suitable for pulp wood, but in many countries where it has been introduced it is also put to other uses. These are e.g. construction, carpentry and joinery, veneers, furniture, laminated wood, and crates and boxes. This species has been widely planted as a landscape tree in urban areas, parks and large gardens, where it can grow to huge size in relatively short time. It is a very suitable tree to form a living screen against wind and traffic noise and tolerates relatively high levels of air pollution.

Conservation Status

Global status

Endangered B2ab(ii,iii)

Global rationale

Based on the assessments of the two varieties separately, it is considered that although the large subpopulation on Cedros Island (var. binata) appears stable, the situation on the mainland (var. radiata) is more severe and in total the population is in continuing decline. There are no more than five locations and the population is severely fragmented. With a combined area of occupancy of less than 30km² the species meets B2 for Endangered.

Global threats

Threats are (were) logging, feral goats, an introduced pathogen, and competition with other trees in the absence of periodic fires.

Conservation Actions

Legal protection and inclusion in protected areas are in place. Eradication of goats on Guadalupe Island has been undertaken. Fire management needs to be implemented in an ecologically responsible way. Research for immunity or resistance against pathogen needs to be undertaken.