Azobe  (Lophira alata)

Classified as Vulnerable (VU) on the IUCN Red List (1).

The alternative name for this large rainforest tree, ‘ironwood’, refers to the very heavy and hard nature of its valuable timber (2) (3). The trunk of the azobe is usually straight, without buttresses, but sometimes with a swollen base (2) (4) (5), and is usually clear of branches up to about 30 metres (5). The bark is typically red-brown in colour, up to two centimetres thick, and has a bright yellow layer underneath. Young trees under four metres in height have greenish-grey bark, which becomes pink or light brown as the tree matures (2). Inside, the living sapwood is pale pink or whitish in colour, while the inner heartwood is dark red-brown to chocolate brown, with conspicuous white deposits of silica (2) (4) (5). The leaves of the azobe are up to 25 centimetres long and are tough, fairly narrow and elongated, with a rounded or slightly indented tip, and tend to occur in clusters at the ends of the twigs (2) (4).

Azobe occurs in western and central Africa, from Sierra Leone to Ghana, and in Nigeria, Cameroon, Congo, Democratic Republic of the Congo, Equatorial Guinea, Gabon, Sudan and Uganda (1) (6) (7).

Found in wet evergreen forest, moist deciduous forest, freshwater swamp forest and gallery forest, azobe is a pioneer species, able to colonise open and disturbed areas, such as forest edges, clearings, the sides of roads and rivers, and even savannas and abandoned cultivated areas (1) (2) (7). Azobe adapts to a range of soil types and tends to prefer fairly flat ground, generally at elevations below 800 metres (2).

The azobe sheds all its leaves during a short period of one to two weeks, usually in December, and the re-growth of bright red young leaves, often simultaneously on all azobe trees in an area, can set the canopy ablaze with colour (2). The flowers of the azobe are white, fairly large, strong-smelling, and grouped in loose, branched, terminal inflorescences. Flowering occurs in adult trees with trunks over 50 centimetres in diameter, and takes place from the time the new leaves appear. Azobe is monoecious, meaning that male and female flowers are found on the same tree, and the flowers are insect-pollinated (2) (4) (6). Fruiting takes place between January and March, the fruits becoming mature around March to April, although fruits do not always appear every year (2). The fruits, which are wind-dispersed, contain a single, oil-rich seed in a conical capsule, which is brown when mature and is surrounded by two unequally-sized membranous ‘wings’, one up to six centimetres long and the other twice the size, at up to twelve centimetres (2) (4) (7). Although the azobe needs full sunlight to grow (2) (7), seedlings can persist for some time in the shady undergrowth and resume growth if and when sunlight again becomes available (2).

Although common and widespread in Cameroon, where it regenerates well (1) (7), azobe is under threat in other parts of its range as a result of large-scale forest destruction and over-exploitation for its timber (1), which is popular for heavy construction work, harbour works and railway sleepers (2) (3) (7). The species is also used locally in traditional medicine, for treating backache, toothache, respiratory and stomach problems, and as a treatment for yellow fever. The leaves can be used in mulch to help control termites, and an edible and odourless oil from the seeds is used as a food and to make ointments and soaps (2) (7) (8). This heavy exploitation, together with azobe’s slow growth rate and poor regeneration when conditions are not optimum, is contributing to a population decline throughout most of its range (1).

The azobe is protected by law in Ivory Coast (7), and occurs in protected areas in some parts of its range, such as in Odzala National Park in Congo (9). However, improved protection, better management of existing forest reserves, and intensified regeneration work are all considered essential conservation measures to protect this heavily utilised rainforest tree (1) (7).

For more information on the conservation of threatened tree species and for advice on responsible timber buying, see:

• Global Trees Campaign:
  http://www.globaltrees.org/
• Forest Stewardship Council:
  http://www.fsc.org/