Araucaria angustifolia

Araucaria angustifolia, the Paraná pine, Brazilian pine or candelabra tree (, or ), is a critically endangered species in the conifer genus Araucaria. Although the common names in various languages refer to the species as a "pine", it does not belong in the genus Pinus.

Description

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A very young A. angustifolia

It is an evergreen tree usually growing to tall and diameter at breast height. The tree is fast growing; as much as in 14 years in a plantation at Puerto Piray, Misiones Province, Argentina.Template:Rp The leaves are thick, tough and scale like, triangular, long, broad at the base, and with razor-sharp edges and tip. They persist 10 to 15 years, so cover most of the tree except for the trunk and older branches. The bark is uncommonly thick, up to 15 cm (6 in) deep. The inner bark and resin from the trunk of the tree is reddish.

It is usually dioecious, with the male and female cones on separate trees. The male (pollen) cones are oblong, long at first, expanding to long by broad at pollen release. Like all conifers it is wind pollinated. The female cones (seed), which mature in autumn about 18 months after pollination, are globose, large, in diameter, and hold about 100–150 seeds. The cones disintegrate at maturity to release the approximately long nut-like seeds, which are then dispersed by animals, notably the azure jay, Cyanocorax caeruleus.

Similar species

It can be distinguished from its close relative A. araucana (found further southwest in South America), by its narrower leaves, seed with a much shorter bract scale, brown inner bark and white resin.

Taxonomy

The genus Araucaria was part of terrestrial flora since the Triassic and found its apogee in Gondwana. Today, it is restricted to the Southern Hemisphere and has 19 species.

Distribution and habitat

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A. angustifolia in Campos do Jordão

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Araucarias at Floresta Nacional de Caçador, Santa Catarina, Brazil

The prehistoric distribution of A. angustifolia in earlier geologic periods was very different to the present day; fossils have been found in northeastern Brazil. The species moved into its present-day range in southern Brazil during the later Pleistocene and early Holocene. This chorological shift may possibly be due to climatic change and the migration of mountain flora by way of river courses. Covering an original area of , it has now lost an estimated 97% of its habitat to logging, agriculture, and silviculture.

Besides southern Brazil, it is also found in high-altitude areas of southern Minas Gerais, in central Rio de Janeiro and in the east and south of São Paulo, but more typically in the states of Paraná, Santa Catarina and Rio Grande do Sul. According to a study made by Brazilian researcher Reinhard Maack, the original area of occurrence represented 36.67% of the Paraná state (), 60.13% of the Santa Catarina state (), 21.6% of the São Paulo state () and 17.38% of the Rio Grande do Sul state (). It is also found in the northeast of Argentina (Misiones and Corrientes), locally in Paraguay (Alto Paraná), growing in low mountains at altitudes of and in northern regions of Uruguay where it was thought to be extinct until recent discoveries.

It prefers well drained, slightly acidic soil but will tolerate almost any soil type provided drainage is good. It requires a subtropical/temperate climate with abundant rainfall, tolerating occasional frosts down to about .

Ecology

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Araucaria angustifolia in Cerro Largo, Uruguay

The seeds are very important for the native animals. Several mammals and birds eat the , and it has an important ecological role in Araucaria moist forests (a sub-type of the Brazilian Atlantic Forest).

In a long term study observing the feeding behaviour throughout the year of the squirrel Guerlinguetus brasiliensis ingrami in a secondary A. angustifolia forest in the Parque Recreativo Primavera in the vicinity of the city of Curitiba, Paraná, of the ten plant species of which the squirrel ate the seeds or nuts, seeds of A. angustifolia were the most important food item in the fall, with a significant percentage of their diet in the winter consisting of the seeds as well.

The squirrels cache seeds, but it is unclear how this affects recruitment.

Role in forest expansion

Studies show the crucial contribution of Araucaria trees in promoting forest expansion. Araucaria angustifolia trees play a pivotal role in shaping the landscape and fostering ecological diversity in southern Brazilian highlands. These conifers act as a facilitator species, also known as nurse trees, significantly increasing species richness and abundance of other trees beneath their crowns. The crowns of these iconic trees foster a unique microenvironment that positively influences the structure and diversity of plant communities

Conservation

According to one calculation it has lost an estimated 97% of its habitat to logging, agriculture, and silviculture in the last century. People also eat the seeds, which may reduce recruitment. It was therefore listed by the IUCN as 'vulnerable in 1998 and 'critically endangered' in 2008.

Uses

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Araucaria angustifolia cones () and nuts ()

Two dry male cones lie side by side on a table

Dry male cones

Araucaria angustifolia is a popular garden tree in subtropical areas, planted for its unusual effect of the thick, 'reptilian' branches with a very symmetrical appearance.

The seeds of A. angustifolia, similar to large pine nuts, are edible, and are extensively harvested in southern Brazil (Paraná, Santa Catarina and Rio Grande do Sul states), an occupation particularly important for the region's small population of natives (the Kaingáng and other Southern Jê). The seeds, called are popular as a winter snack. The city of Lages, in Santa Catarina, holds a popular fair, in which mulled wine and boiled Araucaria seeds are consumed. of seeds are collected annually in Brazil.

It is also used as a softwood timber in stair treads and joinery. The species is widely used in folk medicine.

While A. angustifolia is a main species and dominant in South Brazil, it's also grown as an ornamental plant in parks of towns and cities of Chile, from Santiago to Valdivia. It grows better in low altitudes than the local Araucaria araucana, hence its use as a substitute in the Central Valley and coastal regions of Chile. In some places like the town of Melipeuco A. angustifolia can be seen growing side by side with A. araucana.

The hybrid Araucaria angustifolia × araucana is thought to have first arisen "in a plantation forestry environment in Argentina sometime in the late 19th or early 20th century". It is thus not a natural hybrid as there are more than 1000 km between the natural stands of the two species.