Pinus pinaster

Pinus pinaster, the maritime pine is a pine native to the south Atlantic Europe region and parts of the western Mediterranean. It is a fast growing hard pine with long needles and large cones with medium-sized seeds with large wings.

Description

thumb|left|Pinus pinaster foliage and cones

thumb|left|Pinus pinaster cones

Pinus pinaster is a medium-sized tree, reaching tall, exceptionally to , with a trunk diameter of up to , exceptionally .

The bark is orange-red, thick, and deeply fissured at the base of the trunk, somewhat thinner in the upper crown.

The leaves ('needles') are in pairs, long, very stout ( broad), and bluish-green to distinctly yellowish-green. The maritime pine features the longest and most robust needles of all European pine species. though not all authors consider them distinct:

Pinus pinaster subsp. pinaster – Atlantic Europe
Pinus pinaster subsp. escarena (Risso) K.Richt. – Mediterranean Europe
Pinus pinaster subsp. renoui (Villar) Maire – Northwest Africa (Atlas Mountains)

Distribution and habitat

Its range is in the western Mediterranean Basin and the southern Atlantic coast of Europe, extending from central Portugal and Northern Spain (especially in Galicia) to southern and Western France, east to western Italy, Croatia and south to northern Tunisia, Algeria and northern Morocco. It favours a Mediterranean climate, with cool, rainy winters and hot, dry summers. North of its native range, it is also naturalised (and locally invasive) in southern England.

Ecology

Dispersal, habitat loss, and fecundity are all factors that affect spread rate. The species favours acidic soils with medium to high-density vegetation,

Pests

Larvae of the moth Dioryctria sylvestrella feed on this pine. Their boring activity causes large quantities of resin to flow from the wounds which weakens the tree and allows fungi and other pathogens to gain entry.

Pestalotiopsis pini (a species of ascomycete fungi), was found as an emerging pathogen on Pinus pinea (Stone pine) and also on Pinus pinaster in Portugal. Evidence of shoot blight and stem necrosis were found in 2020. The fungus was found on needles, shoots and trunks of the pines.

Invasiveness

Pinus pinaster is a popular topic in invasion ecology because of its problematic growth and spread in South Africa for the past 150 years after being imported into the region at the end of the 17th century (1685–1693). It was found spreading in the Cape Peninsula by 1772. Towards the end of the 18th century (1780), P. pinaster was widely planted, and at the beginning of the 19th century (1825–1830), P. pinaster was planted commercially as a timber resource and for the forestry industry. The pine tree species invades large areas and more specifically fynbos vegetation. Fynbos vegetation is a fire-prone shrubland vegetation that is found in the southern and southwest cape of South Africa. It is found in greater abundance close to watercourses. P. pinaster is found in shrubland in South Africa; when compared to other environments, shrublands have the largest decline of species richness when invaded by an invasive species (Z=–1.33, p<0.001). Compared to graminoids, trees, annual herbs and creepers have a larger effect on decline of species richness (Z=–3.78; p<0.001). They deplete run-off in catchment areas and water flow in rivers. This depletes the resources available for other species in the environment. P. pinaster tends to grow rapidly in riparian zones, which are areas with abundant water where trees and plants grow twice as fast and invade. P. pinaster takes advantage of the water available and consequently reduces the amount of water in the area available for other species.

It is also sporadically naturalising in Oakland and San Leandro in northern California.

Ecological interactions

thumb|right|Bark of P. pinaster|upright=1.11

Pinus pinaster is particularly successful in regions with fynbos vegetation because it is adapted to high-intensity fires, thus allowing it to outcompete other species that are not as well adapted to high-intensity fires. In areas of fire-prone shrubland, the cones of P. pinaster will release seeds when in a relatively high-temperature environment for germination as a recovery mechanism. This adaptation increases the competitive ability of P. pinaster amongst other species in the fire-prone shrubland. Observations showed a mean of 25.25 seedlings per square metre within the first year and then slowly decreased the next two years due to intraspecific competition. These resins are produced as a defence mechanism against insect predators, such as the large pine weevil. According to an experiment done in Spain, the resin canal density was twice as high in the P. pinaster seedlings attacked by the weevils compared to the unattacked seedlings. Since P. pinaster has the ability to regulate their production of defence mechanisms, it can protect itself from predation in an energy-efficient manner. The resins make the P. pinaster less vulnerable to damage from insects, but they are only produced in high concentrations when P. pinaster is under attack. In other words, P. pinaster does not waste energy producing resins in safe conditions, so the conserved energy can be used for growth or reproduction. These characteristics enhance the ability of P. pinaster survive and flourish in the areas it invades. Both the traits of P. pinaster and the habitat in South Africa are conducive to the success of P. pinaster in this region of the world.

Options for biological control

Insects and mites that feed on the seeds and cones of P. pinaster can be effective biological control options. An insect or mite that acts as an ideal biological control should have a high reproductive rate and be host-specific, meaning that it preys specifically on P. pinaster. The life cycle of the predator should also match that of its specific host. Two key characteristics the predator should also exhibit are self-limitation and the ability to survive in the presence of a declining prey population. The uncertainties regarding the host-specificity of different types of P. validirostris, however, require more research to be completed before the introduction of the weevils into South Africa. An introduction of a species that is not host-specific to P. pinaster can lead to detrimental effects on both the environment and industries that are dependent on certain tree species. Two other biological control possibilities include the pyralid moth species Dioryctria mendasella and D. mitatella, but these species attack the vegetative tissue instead of just the seeds of P. pinaster, harming the plant itself. As of now, the eriophyid mite and cone-feeding weevil seem to hold the most potential to controlling the spread of P. pinaster in the regions it has invaded because they destroy the reproductive structures of the target invasive species.

Cultivation and uses

thumb|Maritime pine forest in the Coastal Park in [[Esposende, Northern Portugal as seen from the foredunes.]]

Pinus pinaster is widely planted for timber in its native area, being one of the most important trees in forestry in France, Spain and Portugal. Landes forest in southwest France is the largest man-made maritime pine forest in Europe. It has also been cultivated in Australia as plantation tree, to provide softwood timber. P. pinaster resin is a useful source of turpentine and rosin.

In addition to industrial uses, maritime pine is a popular ornamental tree, often planted in parks and gardens in areas with warm temperate climates. It has become naturalised in parts of southern England, Uruguay, Argentina, South Africa and Australia.

It is also used as a source of flavonoids, catechins, proanthocyanidins, and phenolic acids. A dietary supplement derived from extracts from P. pinaster bark called Pycnogenol is marketed with claims it can treat many conditions; however, according to a 2012 Cochrane review, the evidence is insufficient to support its use for the treatment of any chronic disorder.