Distribution

This widespread species is found in Angola, Burundi, Cameroon, Ethiopia, Equatorial Guinea - Bioko, Sao Tome & Príncipe, Kenya, Madagascar, Mozambique, Rwanda, South Africa (Cape Province, Natal, Transvaal), Sudan, Swaziland, Tanzania, Uganda, Zaire and Zambia.

Habitat

This species occurs at altitudes above 1500m in Kenya (Marshall & Jenkins, 1994). In Madagascar this species occurs above 1000m. In Zimbabwe P. africana is restricted to montane rainforest (CITES proposal, 1994)

Population Status and Trends

In Cameroon, where P. africana is restricted to the montane forests of the western highlands, the high level of trade has greatly depleted this species (Dawson & Rabevohitra, 1996). This species is relatively rare in Zimbabwe (CITES proposal, 1994). In South Africa, P. africana colonises open sites and the species is regenerating well, with younger trees growing along the roads (African Regional Workshop comm., 1996).

Regeneration

This is a fast growing species and the seeds germinate easily, however the seeds are recalcitrant (African Regional Workshop, 1996).

Role of Species in its Ecosystem

P. africana trees are an important part of the montane ecosystem; tree deaths from bark stripping affects the integrity of the forest and reduces food resources for rare birds (Cunningham & Mbenkum, 1993 in CITES proposal, 1994).

Threats

High demand for P. africana has led to over-exploitation of this species for its medicinal properties and to a lesser degree its timber (Dawson & Rabevohitra, 1996). Bark removal is most extensive in Cameroon and Madagascar (Dawson & Rabevohitra, 1996). In Madagascar, trees are being felled for the bark in protected areas (100-200 trees along the western boundary of the National Park of Mantadia) (Dawson & Rabevohitra, 1996).

Regeneration from cut young trees appears to be low in Cameroon (Dawson & Rabevohitra, 1996)

Tree bark can regenerate if care is taken not to damage the cambium. The forestry procedures for bark removal in Cameroon are as follows, the bark is to be stripped from the two opposite quarters of the trunk and the tree is then left to regenerate its bark for four years, after this time the remaining quarters are then stripped (Parrott & Parrott, 1989).

This species is not under threat in South Africa, as there is regeneration and limited exploitation in rural areas where ring barked trees are dying (African Regional Workshop, 1996).

Utilisation

This species has excellent timber for construction, furniture and household utensils. It is used especially in the informal sector, although it is also used commercially (Marshall & Jenkins, 1994). The bark of P. africana is highly valued for its medicinal properties; it is used as a purgative and as a medicine for benign prostatic hyperplasia and prostate gland hypertrophy, diseases that commonly affect older men in Europe and N. America (Dawson & Rabevohitra, 1996). Bark extracts were patented about 30 years ago (CITES proposal, 1994).

Trade

P. africana is exported from Africa to Europe where the active compounds in the bark are used for drug production (Walter & Rakotonirina, 1995). Between 1988 and 1993 in Madagascar, the amount of bark harvested doubled from 300 tonnes/year to 600 tonnes/year; in 1995, the estimated figure doubled again to 1200 tonnes (Dawson & Rabevohitra, 1996). Between 1986 and 1991 Cameroon exported an average of 1923 tonnes/year to France, Zaire exported 300 tonnes/year (of P.africana and P.crassifolia) to Belgium and France, Kenya exported 193 tonnes {in 1993?} to France and Uganda exported 96 tonnes {in 1993?} (various sources in Walter & Rakotonirina, 1995).

There have been reports of illegal harvesting in Uganda (Anon, 1993 in CITES proposal, 1994). There is evidence of complete stripping of trees or felling in Cameroon and Madagascar (Dawson & Rabevohitra, 1996). Trade bans in Cameroon have led to massive illegal trade (Cunningham & Mbenkum, 1993 in CITES proposal, 1994). P. africana is being removed from the Kakamega Forest Reserve, Kenya (Marshall & Jenkins, 1994)

Conservation Status

IUCN Category and Criteria: Cr (A1c,d) - This category was applied at the Regional Workshop for the Conservation and Sustainable Management of Trees project. It may, however, apply to populations of the species in parts of its range rather than to the entire population.

In many areas, P. africana is severely threatened (Dawson & Rabevohitra, 1996). In Madagascar, trees are cut down and completely stripped of bark; this heavy exploitation is causing the species to be severely threatened (Dawson & Rabevohitra, 1996). This species has been listed as Endangered to Extinction by the department of forestry in Cameroon (CITES proposal, 1994).

Conservation Measures

This species is listed on Appendix II of the CITES convention.

There are 153 ha of this species in plantations in Kenya (Marshall & Jenkins, 1994). Seed has been collected and substantial planting of P. africana is underway in Cameroon (Dawson & Rabevohitra, 1996). There are no conservation measures in practice in Madagascar (Dawson & Rabevohitra, 1996). P. africana is no longer harvested in Zimbabwe, it is only used locally in South Africa and it has not entered international trade in Malawi (CITES proposal, 1994).

Intensive regeneration is required (African Regional Workshop comm., 1996).

Additional Information

P. africana is an important source of income for the villagers employed by licence holders to collect the bark (Walter & Rakotonirina, 1995).

P. africana is a fast growing species that can be cultivated on steep slopes, however, farmers are reluctant to plant unless they can be assured that there is a market (CITES proposal, 1994).

References