Terminalia superba has a broad distribution in West and Central Africa. Range states are Angola, Benin, Cameroon, Central African Republic, Côte d'Ivoire, Congo, DR Congo, Equatorial Guinea, Gabon, Ghana, Guinea, Liberia, Nigeria, Sierra Leone, Togo.

Habitat

requirements of T. superba are discussed by Groulez and Wood (1985).

Population status and trends

Although the species is widespread, common and not generally threatened, it is becoming progressively impoverished by heavy exploitation, as pointed out by FAO (1984). Supplies in the southern parts of its range have dwindled so that forest management and restocking are now needed in those areas where the best quality wood occurs (Groulez and Wood, 1985). In situ conservation is considered to be a priority for the species by FAO (1990). Heavy exploitation is threatening natural populations in West African countries such as Ghana and Nigeria. N'Sosso (1990) notes that Limba is declining in Congo following 60 years of exploitation, and would benefit from trade controls. Terminalia superba has been recorded as threatened in Cameroon, based on assessments by local experts (WCMC, 1991).

Role of species in the ecosystem

Over-exploitation is the main recorded threat to the species in parts of its range. Forest clearance will also have caused population declines but the ability of T. superba to colonise agricultural land reduces the overall impact of this threat.

Depending on where it is grown, Limba is yellowish to brownish-black and of varying hardness and weight. The wood is not durable. It can be easily worked but has a tendency to split when nailed or screwed (Lamprecht, 1989). The timber is used for plywood, furniture, interior joinery and decorative veneers.

The market is mainly interested in Limba from the south of its range, especially from the Mayombe of Congo and DR Congo. Until 1955 DR Congo was the principal producer, followed by Angola and Congo. After 1955 exports from the first two countries declined as the forests became exhausted; whereas those from Congo rose annually (Groulez and Wood, 1985). Limba remains one of the most important commercial timbers of DR Congo and for the period 1983-1986 ranked eighth in terms of species production. In 1995, DR Congo exported 3,000 cu m of Limba logs; 1000 cu m of sawnwood and small quantities of veneer (ITTO, 1997).

Limba was one of the first species commercially exploited in Congo. It declined in importance from the 1950s to the early 1970s. In the 1960s Limba still represented more than 50% of Congo's log production but this had fallen to 4.55% in 1989. In 1989 the volume of log production for Limba in Congo was 45 525 m³ and log exports 22,910 m³, according to MEF and DREF statistics. In 1995, Congo exported 10,000 m³ of logs (ITTO, 1997).

Gabon exported 221 m³ of Limba logs through the ports of Libreville and Port Gentil, in 1989, and 1753 m³ were exported in the first nine months of 1990 (source: SEPBG). No exports from Gabon are reported in ITTO, 1997.

Côte d'Ivoire exported 17 072 235 kg of T. superba logs in 1988 (11 months). In 1995, 7,000 cu m of logs and a small amount of veneer were exported.

Cameroon exported 62,000 cu m of Limba logs in 1995 together with 15,000 cu m of sawnwood, 10,000 cu m of veneer and an unrecorded amount of plywood.

Ghana exported 18, 000 cu m of Limba logs, 3000 cu m of sawnwood and 1000 cu m of veneer during 1995 (ITTO, 1997). This compares with an average of 3,240 cu m during the period 1980- 1986 (WCMC, 1991).

Togo exported a small amount of limba sawnwood in 1995 (ITTO, 1997).

The wood of Terminalia superba is used particularly in Belgium, Germany and Switzerland (Groulez and Wood, 1985).

Conservation measures (source of information WCMC, 1991).

Legislation

Congo - Minimum exploitable diameter 0.6 m

Gabon - Minimum exploitable diameter 0.6 m

Ghana - Minimum exploitable diameter 0.7 m

Liberia - Minimum exploitable diameter 0.7 m

Presence in protected areas

Congo Odzala National Park, Conkouati Faunal Reserve, Lekoli-Pandaka Faunal Reserve, Mont Fouari Faunal Reserve, Nyanga Nord Faunal Reserve, Tsoulou Faunal Reserve, M'boko Hunting Reserve, Mont Maroumbou Hunting Reserve, Nyanga Sud Hunting Reserve

Gabon Sibang

DR Congo Réserve de la Biosphere de Luki

Provenance collections Seeds of provenances have been collected in various countries such as Cameroon, Congo, and Côte d'Ivoire for national and international provenance trials and for establishment of conservation stands in the countries of origin. Seed trees have been selected in the southern Congo provenances and seed orchards of grafted select clones have been established (FAO, 1984). Seventeen provenances are being tested in Côte d'Ivoire and are subject to regular measurements of 12 characteristics, including growth rate and wood characteristics (Anon., 1990). International provenance trials are being coordinated by CTFT and FAO's Forestry Department (Anon., 1987).

Forest management and silviculture

Groulez and Wood (1985) point out that successful natural regeneration of T. superba requires gaps in the forest canopy, sufficiently clean conditions for seed to reach the forest floor, lack of peasant cultivation and the absence of competition for several years. These conditions are seldom found and natural regeneration as a silvicultural system in forest management is possible, but expensive, and not without risk.

This species is widely used as a plantation species both within and outside its natural range. Plantations have been developed mainly in Congo, Côte d'Ivoire and DR Congo. The rotation age of this species in plantation varies from 30 to 40 years (Anon., 1987).