2 PEOPLE AND PLANTS WORKING PAPER - MAY 1993 This series of working papers is intended to provide information and to generate fruitful discussion on key issues in the sustainable and equitable use of plant resources. Please send comments on this paper and suggestions for future issues Sustainability of harvesting Prunus africana bark in Cameroon A medicinal plant in international trade A.B. Cunningham and .T.Mbenkum to People and Plants working papers, Division of Ecological Sciences, UNESCO, 7 Place de Fontenoy, 75352 Paris CEDEX 07 SP, France.
Published in 1993 by the United Nations Educational, Scientific and Cultural Organization,7 Place de Fontenoy, 75352 Paris CEDEX 07 SP.Printed by UNESCO Presse on chlorine-free recycled paper.
Series editor: Alison SempleDesign and layout: Ivette FabbriSuggested citation: Cunningham, A.B.; Mbenkum, F.T. (1993). Sustainability of HarvestingPrunus africana Bark in Cameroon: A Medicinal Plant in International Trade.People and Plants working paper 2. Paris, UNESCO
The designations employed and the presentation of material throughout this publication do notimply the expression of any opinion whatsoever on the part of UNESCO concerning the legal statusof any country, territory, city, or area of its authorities, or concerning the delimitation of its frontiersor boundaries. The opinions expressed in this paper are entirely those of the authors and do notcommit any Organization.
Authors' addresses:
A.B. Cunningham84 Watkins Street - White Gum Valley, Fremantle 6162Western Australia - Australia
F.T. MbenkumCentre for the Study of Medicinal Plants,P.O. Box 193 - Yaoundé - Cameroon
Photos: Tony Cunningham; and G. Bockett (Photo 5).
Cover illustration: Prunus africana. Drawing preparedfor the Flora of East Tropical Africa, Royal BotanicGardens, Kew.
The Afromontane hardwood tree Prunusafricana (Rosaceae; African Cherry, RedStinkwood) is a multiple-use tree species withlocal and international economic and medici-nal value.
Bark is the major source of an extract usedto treat benign prostatic hyperplasia, an increas-ingly common health problem in older men.All bark is taken from wild Prunus africanapopulations in Afromontane forests ofCameroon, Zaire, Kenya and Madagascar. Barkor processed extracts are then exported toEurope (primarily to France or Italy) for prepa-ration of the drugs sold under the brand-names“Tadenan” (France) or “Pygenil” (Italy).
Despite assurances from senior manage-ment of the two major companies involved inthe harvest and processing of Prunus africanabark, considerable concern has been expressedby rural communities, traditional healers andgovernment departments in East and CentralAfrica about the sustainability of this interna-tional trade. Similar concern has also beenshown by international conservation agenciessuch as the International Council for BirdPreservation (ICBP) and Worldwide Fund forNature (WWF). Cameroon has been the majorsource of Prunus africana bark since 1972.
Prunus africana has a remarkable abilityto withstand bark removal. Despite attempts atsustainable bark harvesting from wild popula-tions, however, tree die-offs and felling of treesare frequent in high conservation priority sites.This occurs in Afromontane forest “islands”
surrounded by savanna that provide habitat forimportant endemic birds, mammals and plantsin both Madagascar and Africa. Prunusafricana is an important fruit-bearing tree inAfromontane forest providing a food source forendemic birds such as Bannerman’s Turaco andCameroon Mountain Greenbul, and endemic pri-mates such as Preuss’s Guenon. Research inMalaysian rain forests has shown that selectivelogging for hardwood timber results in reducednumbers and carrying capacity for fruit-eatingbirds such as hornbills. Destructive harvestingof Prunus africana may have a similar effect inAfromontane forest. This is made more seriousby the limited area this forest type covers inAfrica and Madagascar. Over the 6 yr period1986-1991, an annual average of 1923 metrictons of bark were processed. This represents atleast 63% of Prunus africana bark processedworldwide or an average of 35 000 debarkedtrees annually. Extrapolating from the density ofPrunus africana trees on Mt Cameroon (5.5 treeslarger than 20 cm DBH ha-1) this would affectat least 6300 ha of Afromontane forest each year.
Concern about overharvesting of Prunusafricana bark resulted in a partial ban on barkextraction in 1991. Despite the ban, during 1991over 3898 metric tons of bark ( twice the annu-al average) were processed.
An initial assessment is made of cultiva-tion as an alternative source of supply and rec-ommendations for practical action to promotethe sustainable use of Prunus africana bark aregiven.
Sustainability of harvestingPrunus africana bark
in CameroonA MEDICINAL PLANT IN INTERNATIONAL TRADE
$$������������������������������������������������������������������ ���������������� ������������Prunus africana timberTraditional medicinal usesInternational medicinal uses of Prunus africana barkVolume and economic value of the bark trade
��������������� ������������ ������������������������������������������� �����������������������Historical backgroundHarvesting by Special Permit holdersBark sources: CameroonViews of local bark harvesters
�������������������������������������������������������������������������� ��������������%%����Sustainable or not? Theory and practice of forest harvestPrunus africana recruitment on Mount CameroonHow many wild Prunus trees are debarked?Conservation issues in bark exploitation
Habitat destruction and changeReduction in bird and primate carrying capacitiesGenetic erosion?Environmental and cultural accounting
���������������������������������������������������������� ������%%���� ��������������������Bark yields: extrapolations from Acacia mearnsii cultivationMarket forces and Prunus cultivationCultivation
TechniquesLessons from Cinchona bark production in West CameroonPrunus africana planting by rural farmers in NW CameroonMedicinal tree cultivation planting by Cameroon governmentdepartments
Policies for achieving sustainable Prunus africana harvesting
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&&����������������������������Conservation by cultivationIn-situ conservation of representative viable populationsEx-situ conservationBark harvesting from wild populationsAwareness campaign Monitoring
88.6% of medicinal plant material acquired forexport between 1985/86 and 1990/91.
As early as 1976, the government ofCameroon first expressed concern about over-exploitation of internationally traded medicinalplants (United Republic of Cameroon, 1976).This resulted in establishment of a nursery andlarge-scale enrichment planting of Prunusafricana in West Cameroon. Despite this con-cern, harvesting from the wild continues. In 1987,the ICBP (International Council for BirdPreservation) drew attention to the problems thatover-exploitation of Prunus africana bark posedto important Afromontane forests in NWCameroon (MacCleod, 1987; Macleod andParrott, 1990) and was instrumental in workingtogether with the Forestry Department to addressthe problem. This resulted in a partial ban on thetrade in Prunus africana bark in February 1991(Ministry of Agriculture, 1991). This ban waslifted in February 1992 (Ministry of Agriculture,1992a). Neither the uncontrolled harvesting ofwild Prunus africana populations, nor the imple-mentation of cultivation as one of the alterna-tives, are easy problems to resolve. Much can belearnt however from an assessment of the extentof the trade in Prunus africana bark and a reviewof Prunus africana cultivation.
We hope that this paper will provide a basisfor recommendations for future action that willlead to a balance between bark harvesting, for-est conservation and economic development. Theresearch for this paper followed three approach-es: first, a review of published papers, govern-ment reports and weighbridge data from thePlantecam Medicam factory at Mutengene,Cameroon; second, discussions with harvesters,foresters and senior management of PlantecamMedicam, the sole processor and exporter ofPrunus africana bark or bark extract fromCameroon; third, field visits to the main areaswhere harvesting has taken place or where cul-tivation has been implemented in Cameroon.Although Prunus africana bark has been tradedfor twenty years, published information on theextent of the trade is scanty. Forestry Departmentrecords are a valuable source of information andwe are extremely grateful for the assistance thatwe received in obtaining copies of them. Despitethis assistance, however, we were not able tolocate reports prior to 1979.
“Pour notre part, et en parfaite entente avec lesautorités locales, nous veillons à ce que laperennité des espèces végétales concernées soitassurée, notamment par d’importantes mesuresde reboisement.” [For our part, and in perfectagreement with the local authorities, we arecareful that the sustainability of the species isensured, notably through major reafforestationmeasures].
J. Debat, Laboratoires Debat, 1992
“There are insufficient resources in terms ofpersonnel and vehicles to satisfactorily super-vise exploitation and enforce the legislation.”
Macleod and Parrott, 1990.
“He came here and paid a small amount to afew people. The result was major destructionof the forest, our cultural heritage. If he comesto this region he will not be welcome.”
Message from the Fon of Nso to the owner of Plantecam Medicam, 1992
For over a decade, the conservation implica-tions, economics and effects of tropical hard-wood logging have been the focus of consider-able attention. Until recently, however, similarinterest has rarely been shown in the values,economics or conservation implications of har-vesting “minor forest products”. Bark from theAfromontane canopy tree Prunus africana (andprobably also Prunus crassifolia) (Rosaceae) isone such product. Prunus africana bark extractwas patented in 1966 (Debat, 1966) andprocessed to provide a treatment for prostategland hypertrophy (Longo and Tira, 1981;Catalano et al, 1984). All of the bark harvest-ed in Africa (Cameroon, Kenya, Zaire) and east-ern Madagascar is taken from wild populations.As an internationally traded forest product har-vested from the wild, it provides a useful casestudy with practical implications for policy onharvesting and sale of forest products.
Cameroon is the major source of Prunusafricana bark, where it has been harvested since1972. Over a six year period (1986-1991),11 537 metric tons of bark were processed byPlantecam Medicam, a French owned compa-ny based in south-west Cameroon. Prunusafricana bark is the most important medicinalplant material to this company, representing
Geographical distribution and values of Prunus africana
P r u n u s a f r i c a n a ( H o o k . f ) K a l k m a n(Rosaceae)(formerly Pygeum africanumHook.f) is a widespread Afromontane foresttree in mainland Africa, Madagascar and theislands of Grand Comore, Sao-Tome andFernando Po (Kalkman, 1965; Vivien andFaure, 1985; this study; Figure 1). By contrast,Prunus crassifolia (Harm.) Kalkm. is endemicto Kivu (Zaire) although more specimens arerequired to confirm the status of this species(Kalkman, 1965). In Cameroon, Prunusafricana occurs in three major areas (Figure 2a)which have volcanic soils and a cooler high-land climate. These factors have resulted in
dense human populations in these areas (Figure2b), with clearing of forest for farming pur-poses the primary cause of Afromontane forestdestruction. As Afromontane forest “islands”have become smaller, the damage caused bydestructive bark removal and felling of Prunusafricana has become increasingly serious.
Prunus africana is an important multiple-use species throughout its range, primarily forits bark (traditional medicines) and hard tim-ber. In south-west and NW Cameroon, wheremost bark harvesting has taken place, Prunusafricana is known as iluo (Kom), vla (Oku),alumty (Bamenda), wotangue (Bakweri) orkirah (Banso). Prunus africana and Prunuscrassifolia are the only African species in thegenus Prunus, and are wild relatives of plums(Prunus domestica), cherries (Prunus avium),peaches (Prunus persica), almonds (Prunusdulcis) and apricots (Prunus armeniaca). Dueto the economic importance of these tree crops,the genus Prunus has been identified as one ofthe priority genera for in situ and ex-situ con-servation by the International Board for PlantGenetic Resources (IBPGR). Overexploitationof Prunus africana and P. crassifolia has con-sequences not only for forest habitat and genet-ic resource conservation, however. These treesare also valuable and increasingly scarceresources for rural communities.
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The hard, durable timber of Prunus africanamakes it a favoured of wood for household pur-poses, the type of use being dependent on treediameter and form (straightness) and locallifestyle. Small trees are a source of axe andhoe handles (Kom area, NW Cameroon) (Nsomand Dick, 1992) and grinding pestles (Bwindiforest, Uganda) (Cunningham, 1992). In west-ern Uganda, large Prunus africana trees are apopular source of “beer boats” for makingbanana beer (Cunningham, 1992). In southernAfrica the wood has been used for timber andwagon making (Palmer and Pitman, 1972).
Figure 1. World distribution of Prunus africana, showing itsoccurrence in Afromontane islands, where it can be alocally common tree (from Kalkman, 1965; Vivien and
Faure, 1985 and herbarium records (Kew)). Arrows indi-cate where commercial bark harvesting is taking place.
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Prunus africana is widely used in traditionalmedicine in southern, east and central Africa(Watt and Beyer-Brandwijk, 1962; Jeanrenaud,1991). The bark is not only used by tradition-al healers, but also by local people collectingtheir own medicinal plants, including for useas a purgative for cattle (Kalkman, 1965). Inthe Mount Cameroon area, for example, 88%of people collect traditional medicines includ-ing Prunus africana (Table 1). There are nopublished records on the traditional uses ofPrunus crassifolia.
Prunus africana was the fourth most pop-ular medicinal plant species amongst peopleinterviewed around Mount Cameroon, and wascollected by 14% of households surveyed(Table 2) (Jeanrenaud, 1991). Similarly, it is animportant medicine in the Ijim montane forestarea, where it is used to treat malaria, stomachache and fever (Nsom and Dick, 1992).
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Prostate gland hypertrophy and the closelyrelated but more serious condition benign pro-static hyperplasia (BPH) are common diseasesaffecting older men worldwide. They areexpected to become more common amongst theageing male population of western Europe andthe USA. It is now expected that one out ofevery two men in western countries will livelonger than 80 years, with the result that 88%have the chance of developing histologic evi-dence of BPH. In the USA, for example, a 40year old man has at least a 10% chance of need-ing surgery for BPH, and in a recent survey inScotland, 30.2% (492) of a random sample ofotherwise healthy men aged between 40 and 79years had prostatic enlargement and symptomsof BPH (Anonymous, 1992).
Figure 2. Location of Cameroon (inset) showing
African montane “islands” surrounded bysavanna and rural farmland which in (A),
the three main localities for Prunusafricana in Cameroon (Vivien and Faure,
1985) have a population density of wellover 100 people km-2 (from Neba, 1982).
Treatments for this disorder includesurgery, balloon dilation, hyperthermia (usingurethral probes), phytotherapy and pharmaceu-ticals containing anti-androgens and 5-alphareductase inhibitors. Although surgery is com-mon and effective, it is expensive, can causeimpotence and is potentially dangerous, with a1-3% post-operative mortality (Anon, 1992).For this reason, medical therapy and phy-totherapy are popular alternatives.
Nearly thirty years ago, Prunus africanabark extracts were identified and patented asactive in the treatment of benign prostatichypertrophy (Debat, 1966). Bark extracts con-
tain fatty acids, sterols and pentacyclic ter-penoids (Longo and Tira, 1981; Catalano et al,1984; Uberti et al, 1990). The sitosterol gluco-side content of Prunus africana bark is 11 mg100g-1 bark (Longo and Tira, 1981). Extracts ofPrunus africana bark have been shown to beeffective on rats (Thieblot et al, 1971, 1977) andin recent clinical trials conducted in Austria(Barlet et al, 1990). Capsules containing barkextracts have been marketed in Europe (mainlyAustria, France, Italy and Switzerland) for over20 years. By contrast with an earlier, small clin-ical trial which showed no significant differencebetween patients treated with “Tadenan” and a
placebo (Donkervoort et al, 1977), the recent,detailed clinical trial conducted by Barlet et al(1990) showed that 66% of patients treated with“Tadenan”, containing Prunus africana barkextract, had improved urine flow compared to31% with the placebo. Five patients out of the263 patients involved in the study showed gas-tro-intestinal side effects.
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At least four European companies have inter-ests in Prunus africana bark for medicinal pur-poses: Laboratoires Debat (France) and its sub-sidiary company Plantecam Medicam in
Cameroon; Madaus (Germany, Spain);Prosynthese (France); Inverni della Beffa andIndena Spa (Italy). Bark is bought for 150-170CFA kg-1 (US$ 0.6-0.7) in Cameroon and for11 French francs kg-1 (US$ 2) from Kenya.Capsules containing the bark extract are mar-keted in Europe, a 15 tablet box costing US$7-8. The market value of this trade has beenroughly estimated at US$ 150 million a year(A. Hamilton, pers. comm., 1992). The Italiancompanies import bark extract f romMadagascar and the other European companiesimport processed or unprocessed bark fromCameroon, Kenya, Uganda and Zaire. Extractin tablets or capsules are marketed under twomain trade names: “Tadenan”, produced byLaboratoires Debat (France) and “Pygenil” pro-duced by Indena Spa (Italy).
Prunus africana and medicinalplant trade from Cameroon
Internationally, Cameroon is the most impor-tant source of Prunus africana (Table 3). Allbark harvested in Cameroon is processed andexported by Plantecam Medicam, a subsidiaryof the French company Laboratoires Debat.Since 1972, Plantecam Medicam has focusedon four main medicinal plant species and iscurrently licensed to export a number of otherspecies with medicinal value (e.g. Tabernantheiboga, Myrianthus arboreus) or potentialsources of oils and fats from seeds (e.g.Allanblackia floribunda, Carapa procera).In the mid-1970s, the mass of Voacangaafricana (Apocynaceae) seed exports exceededthe mass of Prunus africana bark exported. In1976, for example, 500 tons of Voacanga seedwere sold (for production of the alkaloid taber-sonine, used to depress central nervous systemactivity in geriatric patients; Mabberley, 1987)compared to 10 tons of Prunus africana bark(United Republic of Cameroon, 1976). This sit-uation has changed in response to changingworld demand for medicinal plant material (E.Legendre, pers. comm., 1992). According todata from annual reports, 88.6% (9309 metrictons) of plant material brought to the PlantecamMedicam factory from 1985/86 to 1990/91 was
from Prunus africana (Table 4). The annualreport data are adequate to show the impor-tance of Prunus africana bark harvested rela-tive to other species. It should be noted, how-ever, that more accurate weigh-bill data showedthat a total of 11 537 tons of Prunus africanabark was sold during the six year period 1986-1991, compared to only 9 309 tons indicatedby annual reports over the period of six finan-cial years (1985/86-1990/91).
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Plantecam Medicam first started harvestingbark from forests on Mount Cameroon beforeexpanding into NW Cameroon (Macleod andParrott, 1990). According to discussions withvillagers during this survey, PlantecamMedicam visited Ntingue village, betweenDschang and Santchou in western Cameroon in1972, where they recruited at least 180 work-ers. Twenty years later, many of the bark har-vesters working for Plantecam Medicam arestill from the Dschang area. Minimum sizedbundles of 40 kg were expected from each
worker, with bonuses paid for heavier bundles.Harvesting was systematic and controlled, withbark removal on two opposing sides of the treetrunk to avoid girdling (or ring-barking) thetrees. Felling was not allowed. With thisapproach, some trees died, but the majority sur-vived.
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For fifteen years, Plantecam Medicam employedits own workers to harvest Prunus africana bark.Harvesting was controlled, with most trees sur-
viving. This system broke down in 1985 whenabout 50 additional licences were provided toCameroonian entrepreneurs. Bark harvestingwas no longer under monopoly control ofPlantecam Medicam although the companyremained the sole exporter of Prunus africanabark and bark extract. Although licensing oflocal contractors was intended to stimulateindustry, it also encouraged over-exploitation ofwild stocks. This has been a particularly seri-ous problem in NW Cameroon, where bark har-vesting has been in the hands of local busi-nessmen since 1987. In 1991/92, twenty-fourentrepreneurs supplied Plantecam Medicamwith Prunus africana bark (Table 5; DivisionalSection of Forestry, 1992). All Special Permit
holders, including Plantecam Medicam, pay a“Regeneration Tax” (2% of the value of the rawmaterial) and a “Transformation Tax” to theForestry Department. These are supposed tocover forest regeneration costs.
Data from annual reports for each financialyear (July to June) usually give an underesti-mate of bark mass harvested compared withweighbridge data (Figure 3). This is probablybecause the completion dates of these reportsvary (July to January the following year). Thereis no doubt, however, that the quantity of barkexploited has generally increased over the past12 years. The highest mass of Prunus africanabark was sold during the 1990/1991 financialyear, when the harvesting ban was supposed tobe in place (Figure 3). Most of this bark wasfrom NW Cameroon (Figure 4).
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Total annual quantities of bark processed inTable 4 are based on weighbridge data, whichis more accurate than that in ForestryDepartment annual reports (Ministry ofAgriculture, 1981-1992, Divisional Section ofForestry, 1986-1992). It is also more accuratethan the weighbills kept by entrepreneurs buy-ing Prunus africana bark from local people forsupply to Plantecam Medicam, as it is a recordof entering the factory as it is weighed and sup-pliers are paid (S. Eben Ebai, pers. comm.,1992). Annual bark masses (January-December) recorded on Plantecam Medicamweighbridge returns to the Forestry Departmentshow that whilst there has only been a slightincrease in quantity of bark harvested fromMount Cameroon (primarily by PlantecamMedicam), there has been a sharp increase inbark supplied from the NW province(Bamenda-Banso highlands) (Figure 4). Therehas also been a marked increase in bark quan-tity supplied from Bangem (South-Westprovince), but this represents a small propor-tion of total bark mass harvested.
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Apart from the permanently employed Prunusbark harvesters working from PlantecamMedicam, local villagers are also employed toshow harvesting teams where to find the Prunusafricana trees or to collect and carry bark. Oneof the aims of this survey was to work withlocal assistants to interview bark harvesters in
NW Province and Mount Cameroon. For tworeasons, this was only partly successful. First,at the time of this survey, the NW Provincewas under a State of Emergency in the periodfollowing the 1992 presidential election. Thisprecluded interview surveys at a time of socialtension and suspicion. Second, although meet-ings were held and permission obtained fromtraditional leaders in three villages aroundMount Cameroon (Bokwango, Bwassa andMapanja), bark harvesters were very reluctantto discuss this issue with Mr Stephen Ekema,a local villager and experienced interviewer.This reluctance was a result of three factors:(i) commercial harvesting by PlantecamMedicam was due to start at Mapanja, adjacentto Etinde Reserve; (ii) villagers had beenpromised results from a previous interview sur-
vey carried out to assess forest use, agricultur-al practices and villagers perceptions of the for-est near Etinde Forest Reserve. These resultswere not provided to villagers. For this reason,people were justifiably reluctant to participatein this survey; (iii) political tensions inCameroon after the presidential election.
Despite this, discussions and individualinterviews were completed with a limited num-ber of local people who had been involved inbark harvesting. Despite the small sample size,these interviews and earlier discussions withtraditional leaders provide useful insights intolocal perceptions of Prunus africana bark har-vesting. The results of the interview survey aresummarized in Table 6.
Concern about the killing of Prunusafricana trees was expressed by all traditionalleaders we spoke to (Chiefs Evakise, EwomeLinelo and S. K. Liwonjo, pers. comm., 1992).There was also widespread concern about thepreferential employment of outsiders to harvestbark, and the need to improve the terms of
Figure 3. Mass of Prunusafricana bark sold to, orharvested by PlantecamMedicam (1980/81 to1991/92) (Ministry ofAgriculture 1981, 1982,1983, 1984, 1985, 1986,1987, 1988, 1989, 1990,1991, 1992; unpublishedweighbridge data).
Figure 4. Quantity ofPrunus africana barkharvested from differentparts of Cameroon (1985 -1992), showing the largequantity exploited fromAfromontane forest in NWProvince. Data for 1992are incomplete. Thisrepresents a total of11 537 tons of bark soldduring the period 1986-1991 or an average of1923 tons of bark year-1.
employment for temporary workers. Thepermanently employed bark harvesterswho were outsiders to the community,were said to be starting fires and robbingbeehives in the forest.
Bark harvesting was generally con-sidered to be very hard work most suit-able for strong young men due to the dif-ficulty of climbing Prunus trees and car-rying 50-70 kg loads of bark through themountain forest. No women are involvedin bark harvesting. All respondents wereaware of the requirement that bark shouldonly be removed from opposing quartersof the trunk, starting a “cutlass length”above the ground, and that 4-5 yearsshould elapse before the trees aredebarked again. Although no respondentswere cultivating Prunus africana, allexpressed an interest in this, but requiredsupport with materials (implements,fencing) and information on plantingmethods.
Although it is commonly believed that mosttree species completely regenerate their barkafter it has been damaged, this is the excep-tion, rather than a common response to seriousbark damage (>10% of trunk bark removedbelow head height). Trees in the Proteaceaefamily, for example, are thick-barked and with-stand fire damage, but are very vulnerable to
Photo 1. Stripping of Prunusafricana bark from one of twoopposing quarters of the trunk.
fungal or borer attack once their bark isremoved. The fact that Prunus africana was thetarget species for bark removal was extremelylucky. Prunus africana, together withWarburgia salutaris (Canellaceae) and somelatex producing Ficus species (such as Ficusnatalensis; Moraceae) are among the fewAfrican tree species that exhibit complete barkregrowth and are even able to withstand com-plete bark removal (Cunningham, 1991; unpub-lished records). The ability to withstand barkdamage offered the potential for sustainableharvesting of Prunus africana bark. What ispossible in theory, however, is difficult toimplement in practice.
It is to the credit of Plantecam Medicamthat a real effort has been made to ensure thatall of the bark harvesters they have employedare shown the collecting procedure of remov-ing bark “quarters” from opposing sides of thetree trunk, starting the bark removal aboveground level and not debarking above the levelof the first branch (Photo 1). Workers also knowthat if they are caught removing all bark fromthe trees, they face dismissal. All bark har-vesters encountered during this survey wereaware of these conditions.
Despite these commendable efforts, thereare many cases where these guidelines are notfollowed and harvesting is not sustainable, par-ticularly in NW Province. This is due to boththe loss of monopoly control by PlantecamMedicam, with a resultant opportunistic scram-ble for wild stocks in NW Province by licensedentrepreneurs and also the felling and/or com-plete stripping of Prunus africana trees by somebark harvesters.
In 1991, Plantecam Medicam funded theForestry Department to carry out a survey todetermine the availability and distribution ofPrunus africana on Mount Cameroon (EbenEbai et al, 1992). Trees within 25 x 500 m sam-ple plots at six sites around Mount Cameroonwere measured, covering a total sample area of45 ha. The number of seedlings m-2 was count-ed in three 2 x 2 m sub-samples in each plot,to get an estimate of regeneration rate, and avisual assessment was made of the extent ofbark removal. The study showed that Prunusafricana was most abundant in disturbed sites,with 63% of Prunus africana trees found alongforest margins on the upper slopes of MountCameroon. Average density of trees >20cmDBH was only 5.5 trees ha-1. Seedlings weremost abundant where there was good light pen-etration into the forest and undergrowth wassparse, with seedling density usually 5 seedlingsm-2, but with patches of up to 50 seedlings m-2 (Eben Ebai et al., 1992). Both of theseobservations are as expected from a light-demanding, secondary forest species such asPrunus africana.
The Eben Ebai et al. (1992) study high-lighted the relatively low density of Prunusafricana trees and the high proportion (83%)of trees >20cm DBH (n = 130 020) within allsample plots. It should be noted here that sam-pling was not random, but was based on theguidance of knowledgeable local people to siteswhere Prunus africana occurred. Thus, it is rea-sonable to expect an even lower natural popu-lation density if sampling were to be random.Second, the study showed a low level of recruit-ment of Prunus africana trees at four of the sixsample sites (Figure 5). In all six sample sites,size class distributions are unusual, showinglow or sporadic recruitment. Whether this isdue to episodic events, limited forest distur-bance, 20 years of bark harvesting on MountCameroon or a combination of these factors isunknown and needs further investigation.
These data clearly show the destructiveeffects of felling or killing large Prunusafricana trees in a situation where there is botha low density and low recruitment of large trees.They also suggest the need for bark harvestingto be excluded from Etinde Forest Reserve sothat it can be maintained as a control area forcomparison with other sites on MountCameroon where commercial bark removal istaking place. Although Eben Ebai et al. (1992)recorded some trees killed by debarking, the
majority of debarked trees had survived. Fromfield observations it would appear that a farhigher mortality rate due to debarking andfelling has occurred in forest in NW Provincethan on Mount Cameroon.
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To appreciate the extent of damage to wildPrunus africana populations, and the scale ofcultivation required to replace harvesting ofwild stocks, we need to know how many treesare debarked currently. Estimates of the num-ber of Prunus africana trees that would haveto be planted to ensure sustainable rotation tomeet current demand can be obtained fromestimates based on bark production by wildpopulations on Mount Oku (Table 7).
Photo 2. Limited bark regeneration and subsequent borer attack in a dry site (Mount Oku).
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Field observation suggests that bark gatherersselectively harvest bark from the largest treesavailable. Where over-exploitation of largetrees occurs, there is a shift to trees with asmaller and smaller diameter at breast height(DBH). Although Prunus africana showsremarkable bark regrowth in moist sites, this isnot always the case and trees are attacked bywood-borers (Photo 2) and exhibit crown die-back. Forests are dynamic systems with 4-10%in canopy-gap phase at any one time, and aturnover rate of approximately 100 years(Brokaw, 1985). As a secondary forest, lightdemanding species, Prunus africana recruitmentwould normally be favoured by disturbance. Thisis not the case, however, when species selectiveover-exploitation is taking place. Prunusafricana die-off or a shorter lifespan of treesattacked by fungi and wood-borer after poor barkregrowth will result in changes in species com-
Mean bark yield was 55 kg tree-1, withvariation in yields of 38-73.8 kg tree-1 with theexception of April 1985 when mean bark yieldsare suspiciously high (128.2 kg tree-1), eitherdue to taking too much bark from each tree orunderenumerating the trees harvested. Theannual quantity of Prunus africana bark har-vested (1923 metric tons), would representalmost 35 000 trees year-1 assuming that reg-ulations were followed and bark on opposingquarters of the trunk only was removed. Fromfield experience and the observations of others(Besong et al., 1991; Macleod and Parrott,1990) we can confidently assert that these reg-ulations are not always observed today.
Figure 5. Prunus africana diameter size class distributionsfrom sample plots surveyed by Eben Ebai et al (1992) on MtCameroon. Unfortunately, data for trees less than 20cm DBHare lumped together. Histograms nevertheless show poorrecruitment at four sites (Munyenge, Ekona Lelu, Bokwangoand Mapanja) and unusual size class distributions at all sites.
From studies in Malaysia, it is known thatselective removal of tropical forest treesreduces its carrying capacity for hornbills(Johns, 1987). It is likely that this is also truefor Bannerman’s Turaco in Oku forest, whichonly has 0.08-0.12 pairs ha-1 (an estimated 800-1000 pairs) and is the major locality for thisspectacular endemic bird (Fotso and Parrott,1991). At an average Prunus africana densityof 5.5 trees ha-1 (Eben Ebai et al., 1992) anda bark yield of 55 kg tree-1, the commercialharvesting of 1923 tons of bark each year wouldaffect over 6300 ha of Afromontane forestannually.
Commercial harvesting of Prunus africanabark has been taking place in all of Cameroon’sthree most important forests for bird conserva-tion - (Mount Oku, Mount Cameroon andMount Kupe; Collar and Stuart, 1988). Forthese reasons alone, it is important that Prunusafricana cultivation becomes an alternative toexploiting wild stocks.
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Two issues are of particular concern for speciesconservation. First, the apparently heavyexploitation of Prunus crassifolia, which is cur-rently recognized as a separate species endem-ic to Kivu, Zaire. Kalkman (1965) stressed thatmore material was required to be sure. With
position in Afromontane forest where Prunusafricana was formerly a dominant tree.
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Selective felling or girdling and die-off of thelarger trees in a population results in lower seedproduction for the next generation of trees(Connell et al., 1984). It also represents lowerproduction of food for frugivorous birds andmammals. This has important implications forbird and probably primate populations inAfromontane forest islands where over-exploitation of Prunus africana is taking place.
Afromontane forests of Cameroon containsome of the most important habitat in Africafor bird conservation, with a high number ofendemic bird species (Collar and Stuart, 1988).Examples are the endangered Bannerman’sTuraco (Tauraco bannermani) and the near-threatened Cameroon Mountain Greenbul(Andropagus montanus). These birds and thenear-threatened primate Preuss’s Guenon(Cercopithecus preussii) are all endemic to theBamenda Highlands. All feed on Prunusafricana fruits in addition to the fruits of othertrees (Fotso and Parrott, 1991; S. Tame, pers.comm.). Prunus africana fruits are probably animportant dietary component which would belost with Prunus africana over-exploitation.
commercial exploitation of Prunus bark fromthe wild in Kivu, Zaire, further taxonomic studyis now an urgent requirement.
Second, the removal of large, reproduc-tively mature Prunus trees reduces seed dis-persal and genetic flow between already iso-lated montane “islands”, further increasing theirisolation. A project aimed at determining genet-ic variation in and between Prunus africanapopulations on montane islands using DNA fin-gerprinting (RAPD) techniques is curently inprogress. If genetic erosion is taking place, thenex-situ field gene banks need to be established.
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The Global Biodiversity Strategy (WRI, 1992)points out that national governments currentlyconsider forest and wetland ecosystems as “freegoods”, where their degradation does not countas depreciation on a nation’s basic capital stockin calculations of Gross National Product.Prunus africana is a good example of this: quo-tas were given for bark exploitation withoutadequate knowledge of the quantities or con-sequences involved. The result has been the“mining” of natural resource capital rather thanmanaged use. The quantity of bark harvestedhas increased annually (Figure 4), and fromfield observation and other reports (Macleodand Parrott, 1990; Besong et al., 1991) it isclear that this increase has been at the expenseof wild Prunus africana stocks.
Although environmental accounting is inits infancy, it would be useful to make a studycomparing the economic benefits of Prunusafricana bark harvesting with the real costsinvolved. Local people and traditional leadersare aware of many of these costs: the waste ofPrunus timber from felled or girdled trees thathave been debarked, leaving the trees to die
and timber to rot; reduced access to Prunusafricana for traditional medicine, and the con-tribution that heavy vehicles transporting thebark make to degradation of country roads. Itwould also appear that benefits from the 2%regeneration tax are insufficient to cover eventhe direct costs of replanting Prunus africanatrees. Macleod and Parrott (1991) observe thatthe permits issued to four contractors to exploit600 tons of Prunus africana bark from Kilumforest could represent the death of 75 000 treesat an average bark yield of 8 kg tree-1. Thecost to the Cameroon government of replanti-ng these trees would be an estimated 11.5 mil-lion CFA (US $ 43 000), compared to“Regeneration tax” benefits of only 1.7 millionCFA (US $ 6300). It would be at least 15-20years before replanted trees could be harvest-ed. Bark yields tree-1 may be higher than esti-mated (see Table 7), but it would still beextremely informative to carry out a detailedcost-benefit analysis with the estimates alreadyavailable.
The problem needs to be seen from a cul-tural as well as an environmental perspective.According to the Fon of Banso, debarking anddie-off of Prunus africana trees has evenoccurred within a sacred forest which is theburial site of 17 previous Fons (traditional lead-ers). The Fon also considered that commercialharvesting of Prunus africana bark had stimu-lated forest clearing, by changing local per-ceptions of the forest from being a communi-ty asset to being a resource to be exploited forpersonal gain (A. Hamilton, pers. comm.,1991). This was given as a major reason forthe surge in forest destruction after 1985. It isdifficult to evaluate whether this is correct ornot. There is no doubt, however, that massiveforest clearing took place after 1985 when cof-fee prices collapsed and farmers expanded theirfields to grow alternative crops such as beansand potatoes.
Alternatives to bark harvesting from wild populationsUnder their current special licence, it is speci-fied that Plantecam Medicam should plant 5 haof Prunus africana per year for the next 5 years.At most, the Forestry nursery at Buea onlyholds 1000 seedlings on behalf of PlantecamMedicam. This is only enough to plant 1 ha.Only 2 ha have been planted at Buea, at theexcessively wide spacing of trees 5 m apartwith 5 m between rows. There is little doubtthat the requirement to plant 5 ha of Prunusafricana per year has not been fulfilled. It isalso clear that even if this were achieved, itwould not be sufficient to replace the wild har-vested trees. The question is: how many treesneed to be planted if bark production is to besustainable?
Two approaches can be taken to answeringthis question given that no data exist on barkproduction yields from cultivated Prunusafricana trees. First, we can estimate plantingrequirements for the well-documented Acaciamearnsii (Mimosaceae; Black wattle), anAustralian tree cultivated worldwide for its tan-nin producing bark. This can then be linked toPrunus africana bark production data from wildcollections in the Mount Oku forests, NWCameroon, during a period when records werekept of total bark yields and the number of treesfrom which bark was harvested.
Black wattle (Acacia mearnsii) bark productionfrom 12 year old stands with a mean densityof 1363 trees ha-1 is 28.1 tons ha-1 (Schonau,1973; 1974). Unlike the recommended Prunusafricana bark harvesting methods, Acaciamearnsii bark production is from successiveplantings of trees felled and totally stripped oftheir bark. Timber is then sold as fuelwood.Mean bark thickness at breast height in theseAcacia mearnsii trees was 5.46 mm, with amean DBH of 14.4 cm and a mean height of16.4 m at 12 years old (Schonau, 1973; 1974).
Field observation suggests a similar barkthickness in Prunus africana. Probably due tosite differences, the diameters of Prunusafricana in the enrichment planting at Ntinguevaried considerably (7.9 - 42.3 cm DBH), withtrees up to 17 m high. This short initial surveyof this 15 yr old planting gave mean DBH of15.8 cm (n = 49 trees). These preliminary datasuggest that comparisons between Prunusafricana and Acacia mearnsii bark productionare reasonable.
The mean quantity of Prunus africana barkprocessed annua l ly f rom 1986-1991by Plantecam Medicam was 1923 metric tonsyear-1 (see above). Assuming that bark pro-duction and growth rates in Acacia mearnsiiplantations would be the same as those forPrunus africana, this quantity of bark wouldbe produced by 68.4 ha of trees felled and total-ly stripped of bark each year. These would be12 year old stands with 1363 trees ha-1. Currentannual demand would thus represent 93 229trees each year. A 12 year rotation would there-fore require 820.8 ha of trees. Even if the plant-ing of 5 ha of Prunus africana trees each yearfor 5 years was being carried out by PlantecamMedicam as stipulated in their current licenceagreement, this would be totally inadequate tosupply the existing demand for bark. In brief,current efforts to cultivate Prunus africana aretotally inadequate and can not be expected totake the harvesting pressure off wild stocks.
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The commercial value of the bark is well knownto small farmers in Cameroon. Farmers are alsoaware of the damage to wild Prunus africanapopulations that has occurred in some areas,and the resultant scarcity of bark. This hasencouraged farmers in NW Cameroon to culti-vate Prunus africana from seed on a much larg-er scale than Plantecam Medicam. Ideally, cul-tivation by Plantecam Medicam and SpecialPermit holders could be supplemented with pro-duction from farmers in montane Cameroon.As a fast growing indigenous tree, Prunus
for a synthetic compound which acts as a testos-terone 5-alpha-reductase inhibitor (Rasmussonet al., 1988). Trials with new medicines con-taining 5-alpha reductase inhibitors show areduction in prostatic mass, improved urineflow and reduction in symptoms in about a thirdof patients with BPH (Anon., 1992). The effectof these new drugs on phytotherapy and themarket for treatments based on Prunus africanaextracts is difficult to estimate. On one hand,there is a resurgence in popularity for herbaltreatments, but on the other, Prunus africanabased products have been on the market for 20years, and may lose ground to newer treatments.This question should be resolved as far as pos-sible before small farmers are encouraged tospend time and money producing a long-termcrop for which they may not have a market.Small farmers have much to lose. Market fail-ure could result in many disappointed and jus-tifiably angry farmers, and might damage thecredibility of the conservation and rural devel-opment organizations involved.
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Cultivation of Prunus africana is easier thanother forest trees with slower grow rates andmore specific habitat requirements. Prunusafricana seed appears to be recalcitrant. Freshseed germinates readily, however (Table 8). Itis a light tolerant, secondary forest species thatmakes an ideal tree for reafforestation, bound-ary markers or plantations, and has been used
africana also has great potential for reaf-forestation and tree-based permaculture sys-tems on steep slopes where current maize andbean production is unsustainable due to highrates of soil loss.
If small farmers are to become involved inPrunus africana cultivation, however, thereneeds to be a guaranteed market for the barkthey produce at a price that makes productionprofitable. Plantecam Medicam can offer a mar-ket for Prunus africana bark for the next 5years, but are unable to give any guaranteebeyond that (E. Legendre, pers. comm., 1992).The 15 year old enrichment planting nearDschang gives us the opportunity to calculateannual bark yields ha-1, and what profits couldbe reasonably be expected, based on standardforestry input costs in Cameroon. Another pos-sibility (A. Hamilton, pers. comm. 1991) wouldbe for farmers to cultivate only young Prunusafricana trees (2-3 years old) for processing.This would give farmers a shorter rotation cropto cultivate, but feasibility depends on the levelof active ingredient in young trees. Samples of30 young (2-3 yr old) trees, and a 1 kg sam-ple of bark from two 15 year-old cultivatedtrees were supplied to Plantecam Medicam inDecember 1992 as part of this study for test-ing.
The size of the market for “Tadenan” and“Pygenil”, produced from Prunus africanabark, is uncertain. Continued demand for theseherbal preparations will depend on competitionfrom new treatments for benign prostatic hyper-plasia (BPH), such as anti-androgens, 5-alphareductase inhibitors and hyperthermia usingurethral probes. A recent patent was taken out
by the ICBP Mount Kilum project to mark theforest boundary around Mount Oku (over 15 000 trees were planted on the forest bound-ary in 1990-1991).
Prunus africana has also been propagatedfrom cuttings in Cameroon, with a root-strikeof 10% of cuttings after 3 weeks (G. Bockett,pers. comm., 1992). This was done in sand,without the use of rooting hormone. A muchgreater percentage of rooted cuttings could beexpected with the use of commercially avail-able auxin-based rooting hormones. Leakey(1987) has emphasized the opportunities thatclonal forestry can offer for enhancing yieldand quality of forest products and the oppor-tunities for implementing this in the tropics.Although this has mainly been applied toindigenous timber and fruit trees in West andCentral Africa (Leakey et al., 1990), there ispotential to develop faster growing, high active-ingredient yielding varieties of Prunusafricana. This expertise already exists inCameroon, where timber trees are being massproduced in low-technology propagators(Photo 3).
In the late 1970s, in an effort to reduce depen-dency on imported anti-malarial drugs, consid-erable effort and expense were put into estab-lishing Cinchona plantations in the MenoueDivision, W Cameroon with an accompanyingfactory at Dschang. The aim was to establisha 200 ha plantation at Bansoa, initially throughinvolvement of the Ministry of Agriculture,with the project then handed over to UCCAO(Union de Coopérative de Cacao et de Café del’Ouest) (United Republic of Cameroon, 1981).From an initial 10 ha planting in the first year,expansion was planned to 20 ha by 1982/83and 30 ha year-1 in the following years (UnitedRepublic of Cameroon, 1976). From 1983, itwas also planned to cultivate 30 ha of small-holdings in W and NW Cameroon. Bark pro-duction was projected to be 300 kg ha-1 after5 years.
A fully equipped factory was built atDschang with support funding from the inter-national community, accompanied by staffhousing and imported equipment for process-ing of Cinchona bark right through to the pro-duction of quinine. In many ways, this factorysymbolized an ideal often expressed in Africa:to reduce dependency on expensive importedpharmaceuticals and produce effective drugs forcommon and often fatal tropical diseases (inthis case malaria). In addition, as Cinchona isan exotic species, production had to be based
on cultivated stocks rather than exploitationfrom the wild.
Despite the infrastructure and ideals, theproject failed entirely after a few years. Today,the factory and its processing equipment arederelict. The Cinchona plantation has beenfelled for housing and bean fields. Only a sin-gle, debarked Cinchona tree remains. If culti-vation is to provide a viable alternative to har-vesting of wild Prunus africana stocks, theincredible waste of energy and expenditure onthe Cinchona project must not be repeated. Barkyields from cultivated stocks must not be under-estimated and cultivation has to be an economicproposition, with fair prices for bark producedso that small farmers are involved. PlantecamMedicam needs to ensure that large scale pro-duction takes place on land with secure tenurein a similar way to oil palm and rubber plan-tations. At present, Prunus africana trees in thetrial plot at Buea are already being felled tomake space for beans that farmers are growingunderneath them. While there is nothing wrongwith an agroforestry approach, uncertainty overtenure appears to have been a major factor inCinchona plantations being replaced by beansand cocoyams. The same could happen withPrunus africana plantations if these mistakesare repeated.
The commercial importance of Prunus africanain NW Province has been an important stimu-lus to rural farmers to start growing this treefrom seed. Although some farmers in the Okuarea started planting Prunus as early as 1977,
most Prunus cultivation has taken place since1990 with encouragement from the KilumMountain Forest Project (KMFP) of ICBP andthe “Trees for the Future” project. KMFP hasassisted around 70 nurseries in the Oku area,all of which propagate Prunus africana. Severalthousand trees have been planted in small plan-tations (Table 9) and around compounds andon farmland. These figures are probably anunderestimate - Prunus africana fruited heavi-ly in 1991 and planting figures for 1992 shouldbe much higher (J. Parrott, pers. comm., 1993).
More trees are under cultivation by ruralfarmers in either Oku (Table 9) or Nso(Table 10) than in the Plantecam Medicam sup-ported nursery at Buea, which in December1992 only contained about 1000 seedlings.Among other advantages, cultivation mayreduce the efforts entailed in bark transport(Photo 4).
Over the past 17 years, ONADEF (OfficeNational de Devéloppement des Forets) hasapplied its experience of indigenous (e.g.Terminalia superba) and exotic timber species(e.g. Pinus, Eucalyptus) to four tree specieswith medicinal value: three species cultivatedfor bark production (Prunus africana and twoexotic Cinchona species) and Voacangaafricana cultivated for its seed. The foresightof ONADEF in implementing medicinal treecultivation in plantations and through enrich-ment planting is exceptional in Africa, and isa source of valuable information applicable notonly in Cameroon, but in other African coun-tries as well.
Prunus africana trees have been planted intwo main areas of Cameroon. There is a small(2 ha) Prunus africana plantation at Buea anda Voacanga africana plantation of 100 ha (E.Legendre, pers. comm., 1992) on PAMOL landin the Fako division, SW Cameroon. A large-scale (c. 60 ha) enrichment planting has been
undertaken in Menoua Division, W Cameroon.In 1974/75, two years after Plantecam Medicamstarted commercial harvesting of Prunusafricana bark, Fond Forestière established anursery at Ntingue near Santchou in MenoueDivision, W Cameroon. At this early stage, theGovernment of Cameroon had recognized theneed for cultivation of medicinal plants andallocated 75 million CFA francs to inventory,harvesting and marketing and 25 million CFAfrancs to experiments and regeneration as partof a 5 year plan (1976-1981) (United Republicof Cameroon, 1976). Review of past experi-ence from the 60 ha Prunus africana enrich-ment planting and the failure of the Cinchonabark production and its associated quinine pro-duction project is essential in order to avoid themistakes, and benefit from the successes ofthe past.
Several previous studies have resulted in rec-ommendations for measures to bring wildPrunus bark harvesting to a sustainable leveland to implement cultivation.
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In 1976, the government of Cameroon notedthat “There also exist in Cameroon a numberof foreign companies (Plantecam, Hollando,Sodex, Sodexpharm, Continaf, etc.) whichexport medicinal plants such as Voacanga,Strophanthus gratus, Yohimbe [Pausinstyliajohimbe], Rauwolfia vomitoria, Vinca rosea,Funtumia elastica, Pygeum and aromatic plants.
The result of this disorderly exploitation isa gradual reduction of the potential supply ofmedicinal plants. For example, 800 tons ofVoacanga and 50 tons of Pygeum are tradedeach year (United Republic of Cameroon,1976)”.
To resolve this problem, the governmentrecommended that a para-statal corporationshould be set up “to control the production andmarketing of medicinal plants, and to absorbthe companies and private individuals nowengaged in those activities”. In addition, 100million CFA francs were set aside for invento-ry, organization of harvesting, marketing andregeneration. The enrichment planting nearDschang was implemented as part of this five-year plan and is a useful source of information
on yields and economics of Prunus africanacultivation. The quantity of Prunus africanabark extracted from the wild annually hasincreased, however, from 50 tons (UnitedRepublic of Cameroon, 1976) to an average of1923 tons.
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Detailed resource management recommenda-tions were made by Macleod and Parrott (1990)as the problem worsened and affected impor-tant conservation areas in NW Province. Theirreport stressed the need for prompt action and: (1) a complete ban, pending further study; (2) an inventory to determine the status of
Prunus throughout Cameroon’s forests;
Photo 4. Bark harvester with 50 - 60 kgload of Prunus africana bark.
vesting had taken place, meeting with har-vesters, conservation NGO’s and representa-tives of Plantecam Medicam (Besong et al.,1991). Their report highlights the risk that hadbeen taken by permitting the exploitation ofPrunus africana bark when the extent or pro-ductivity of the resource was unknown. Besonget al. (1991) also record the insufficient con-trol of bark exploitation, lack of respect forquotas or forestry regulations and consequentresource degradation (Photo 5). A major rea-son identified for this is that people did not feelresponsible for the forest resource, resulting inopportunsitic over-exploitation. Key recom-mendations were :(1) To reduce quotas and limit the number of
permits given out.(2) To restrict the activities of permit holders
to the forest zones allocated to them.Inventories should be done in these areasby the permit holders, and their accuracycertified by the local Conservator ofForests.
(3) To hold permit holders responsible for thedamage caused to the trees. Bark harvest-ing techniques should be respected (i.e.bark removal from opposing quarters of thetrunk up to the first branch). Killing of treesis forbidden in forestry legislation. Thisgives adequate power to Conservators tocontrol this situation.
(4) To increase minimum exploitable diameterto 40 cm DBH.
(5) To limit the total volume of bark harvest-ed annually to 1500 tons year-1.
(6) To introduce reafforestation.(7) To raise forest regeneration taxes and link
them to this exploitation in order to financea silviculture programme.
(8) To encourage Plantecam Medicam to cre-ate its own plantations, following the exam-ple of private oil palm and rubber compa-nies such as HEVECAM and SOCOPALMin Cameroon.
(9) To start an education campaign to raiseawareness of the importance of trees andtheir value as a source of revenue.
(10)To organize a meeting with all interested par-ties (government, Plantecam Medicam, per-mit holders, etc.) to discuss the problems ofproduction, allocation of permits, pricing andthe role of each permit holder.
In addition to the above recommendations,Eben Ebai et al. (1992) recommended enrich-ment planting with wild grown Prunus africanaseedlings in order to avoid the costs of nurs-ery establishment, and argued against the fellingPrunus africana trees.
(3) an independent study should be made todetermine the best harvesting techniquesand intervals for sustainable harvesting ofPrunus bark;
(4) on the basis of points (2) and (3), annualharvesting quotas should be calculated foreach forest area and each Division; and
(5) on the basis of points (2), (3) and (4), per-mits should be issued against a licence feeand a deposit. The deposit would bereturned when the Forestry Department wassatisfied that the contractor had compliedwith recommended harvesting procedures.
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In January 1991, three senior members of theForestry Department visited areas of SW, Wand NW Cameroon where Prunus africana har-
Photo 5. Prunus africana felled for total barkremoval, Mount Oku forest reserve (photo :G Bockett).
The market for “Tadenan” in France has gen-erated a massive commercial demand forPrunus africana bark in Cameroon. In contrastto companies producing palm oil and rubber,which are both produced from large commer-cial plantations or small-holder production,Prunus africana continues to be taken from thewild. Plantecam Medicam deserves credit forattempting sustainable bark harvesting byremoving opposing quarters of trunk bark ratherthan girdling the trees. However, quotas havebeen awarded by the Forestry Department with-out adequate forest inventories, and with lim-ited resources to control exploitation.Overexploitation of Prunus africana in NWCameroon has worsened since bark harvestingpermits were awarded to 50 entrepreneurs andPlantecam Medicam lost its monopoly overbark harvesting. As the sole exporter of barkand bark extract, however,Plantecam Medicammust bear a large degree of responsibility forthe over-exploitation taking place and needs totake steps to remedy this situation.
Despite the assurances of LaboratoiresDebat that measures for conservation and sus-tainable use Prunus africana have been takenby its subsidiary Plantecam Medicam, this hasnot applied to the entrepreneurs who are itsmain suppliers. Plantecam Medicam buys barkfrom Special Permit holders regardless of howthe bark was harvested. Plantecam Medicam
has also not fulfilled afforestation requirementsfor cultivation of 5 ha each year under its cur-rent licence agreement. The ForestryDepartment has limited money and manpower,which has restricted forest inventory and con-trol of bark exploitation. These factors are wors-ened by corruption and the poor economic sit-uation in Cameroon. This situation casts seri-ous doubt on managed, sustainable harvestingfrom wild populations and probably enrichmentplantings. The 1991 “ban” on bark harvestingis a good example of this. Despite the ban, in1991, double the usual quantity of bark wassold to Plantecam Medicam. The elaborate sys-tem of controls devised to ensure legal har-vesting proved totally ineffectual (J. Parrott,pers. comm. 1993). What are the future optionsunder these circumstances ? There are four mainalternatives to the destructive harvesting ofPrunus africana bark. First, managed sustain-able use of wild populations after stock assess-ments and preparation of management plans.This could only take place if the managementcapacity of the Forestry Department wasstrengthened. Second, a complete ban on barkharvesting from wild populations, rather thanthe unsuccessful partial ban instituted in 1991.Third, phasing out harvesting of wild stocks infavour of cultivation. Fourth, promotion of othermedical treatments to Prunus africana phy-totherapy to treat prostate gland hypertrophy.
National and regional capacities to manage coreconservation areas need to be strengthenedtogether with pro-active rural development andresource managment options in buffer zonesaround these core areas. The Kilum MountainForest project (ICBP) is a good example of this.The general requirements for this institutionbuilding, including international funding forequipment, infrastructure and training are wellknown to conservation agencies. Long-termcommitment to address the rapid growth inhuman needs and numbers that is the drivingforce behind forest clearing and habitat destruc-tion in Africa is also essential (see Cunningham,1990).
Managed sustainable harvesting of Prunusafricana is theoretically possible thanks to theremarkable bark recovery of a high proportionof debarked trees. In practice, however, the highinputs of Forestry Department money and man-power required are not available and are unlike-ly to become available with the current eco-nomic situation in Cameroon. Provided therecontinues to be a market for Prunus africanabark, cultivation is the major long term alter-native to rather than “mining” Cameroon’s nat-ural resource capital.
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(1) Plantecam Medicam and other SpecialPermit holders should take responsibilityfor establishment of large enough Prunusafricana populations to replace harvestingof wild stocks, following the example ofrubber and palm oil plantations such asPALMOIL, SOCOPALM, HEVECAM.Plantecam Medicam or Laboratoires Debatshould acquire land to cultivate Prunusafricana, rather than expecting land to beprovided by the Forestry Department.Prunus africana grows well at low alti-tudes, and active ingredient yields could beincreased through clonal selection. Thisshould be done in addition to enrichment
planting, and should be the main focus ofbark production for future needs (seeBesong et al., 1991).
(2) The commercial viability of convertingsome of the oilpalm plantations aroundMount Cameroon to Prunus africana andtropical timber agroforestry systems needsto be investigated. At present the econom-ic viability of palm oil production appearsto be seriously affected by higher yieldingoilpalm estates in south-east Asia.
(3) Research needs to be unertaken on theselection of fast growing, high active-ingre-dient yielding Prunus africana cultivars.This could be done through joint workbetween the Forestry Department,ONADEF, the Cameroon Centre for theStudy of Medicinal Plants (CEPM) and theU.K. Institute of Terrestrial Ecology andUniversity of Edinburgh, following theMbalmayo example.
(4) If it is economically viable, small-holderfarmers should play a greater role in Prunusafricana cultivation, including agro-forestry/permaculture systems and usingPrunus africana trees as hedges in tea plan-tations.
(5) Prunus africana cultivation using selectedhigh active-ingredient yielding varieties(rather than from wild collected seed/cut-tings) should only take place if this posesno threat to the genetic integrity of wildpopulations in core conservation sites.
(6) Nurseries and extension support should beestablished to assist small-holder farmers,following the Kilum Mountain Forest(ICBP) example (Besong et al, 1991)
populations continues to take place.Disturbed sites should be used to monitorforest recovery and Prunus africana regen-eration. It is recommended that no Prunusafricana harvesting should take place with-in the areas set aside for Afromontane for-est conservation (see Gartlan, 1989). Thereshould be an immediate withdrawal of barkharvesters working within these high con-servation priority sites.
(2) Community forests should be recognizedand more established, as ICBP are doing.This could include the support from localcommunity leaders and traditional healersfor forest conservation.
(3) Good fertile material of Prunus crassifolianeeds to be collected in Kivu, Zaire to con-firm Kalkmans’ (1965) identification of thisas a separate species. The effects of theinternational bark trade on Prunus popula-tions in Zaire and Madagascar need to beinvestigated. The Kenyan situation is con-sidered to be a lower priority due to thelow volume of the trade, which is report-edly based on bark harvested from depro-claimed forests, pipelines and new tea plan-tations where the forest would be destroyedanyway (J Leakey, pers. comm., 1992).
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Provenance collections in secure field banksshould be established for Prunus africana geno-types. The same should apply to provenancecollections for Prunus africana and Prunuscrassifolia from other sites, particularly wherecommercial bark harvesting is taking place.Where these field banks occur outside the coun-tries of origin of the material, they should beaccompanied by legal agreements that covercontrol and compensation for the use of thematerial.
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(1) Current Special Permits should be revokedand reissued after comprehensive invento-
ries have been established prior to furtherbark exploitation from the wild. It is sug-gested that prospective Special Permit hold-ers should fund these inventories, whichshould be carried out independently.
(2) Strong support should be given to the fol-lowing recommendations made by Besonget al. (1991):(i) to reduce quotas and limit the number
of permits given out;(ii) to restrict the activities of permit hold-
ers to the forest zones allocated tothem;
(iii) that permit holders should be heldresponsible for the damage caused tothe trees; bark harvesting techniquesneed to be respected;
(iv) the minimum exploitable diametershould be increased to 40 cm DBH;
(v) forest regeneration taxes need to beraised and linked to this exploitation inorder to finance a silviculture pro-gramme.
(3) The volume of bark harvested annually willdepend on the results of the forest inven-tories. Besong et al. (1991) suggested thatthis should not exceed 1500 tons year-1.From this study, annual report data over thesix year period (1985/86-1990/91) showedthat this was the recorded annual average(1551 tons year-1), with more accurateweighbridge data giving a figure onlyslightly higher than this (1923 t year-1). Ifbark harvesting were excluded from coreconservation areas, and given that over-exploitation has depleted wild stocks in themajor supply area (NW Cameroon), wesuggest that a limit of 1500 tons year-1 istoo high and should be greatly reduced fol-lowing inventory work (see Macleod andParrott, 1990).
(4) In conjunction with the reduced number ofSpecial Permit holders and controls overharvesting recommended by Besong et al.(1991), and a drastic reduction in annualexpected bark quotas following thoroughinventories, the price paid for the barkshould be increased to stimulate Prunusafricana cultivation.
(5) Special emphasis should be placed on fieldassessment of bark damage (Cunningham,1991) in addition to more detailed work onpopulation structure of Prunus africana inCameroon, following the work done byEben Ebai et al. (1992).
“Trees for Health” or “Forests are Wealth” cam-paigns that are designed to promote under-standing of the importance of habitat and med-icinal plant conservation and encourage the cul-tivation of medicinal plants should be institut-ed (see Besong et al., 1991) through WWF,WHO, UNESCO and national governmentDepartments of Environment, Forestry andHealth or local NGOs in countries where com-mercial harvesting of Prunus africana or othermedicinal plant species is taking place
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(1) Permanent plots or transect lines need tobe set up outside and within core conser-vation areas;
(2) A timetable needs to be set by the ForestryDepartment for the implementation of cul-tivation, and a register needs to be kept ofthe land area that this involves, with morepractical spacings between trees than thoseimplemented at Buea.
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This survey could not have been produced with-out the assistance and hospitality of C. A.Asanga, J. B. Besong, G. Bockett, M. Bovey,C. Dig, S. Eben Ebai, S. Ekema, B. N. Ewusi,F. C. Foncham, S. Gartlan, E. Legendre, R.Ordot, N. Ndam, B. N. Nkongo, S. Tame andV. Tame. We would also like to acknowledgethe help and advice of Chief S. K. Liwonjo(Mapanja), Chief Evakise (Bokwango) andChief Ewome Linelo (Bwassa). Particularthanks go to A. Hamilton for his great interestand encouragement in this project, J. Gillet, for
drawing our attention to the Austrian clinicaltrial conducted with Prunus africana extract,G. Bockett for photographs, Royal BotanicGardens, Kew for the cover illustration, M.Cunningham for data processing and graphics.Thanks also to J. Parrott for his comments onearlier versions of this paper. Financial assis-tance for this study was provided by WWF,UNESCO and the Tropical Forest Programme(USDA Forest Service) (Grant no. 93-G-001).This study was carried out as part of the WWF-UNESCO-RBG, Kew “People and Plants” ini-tiative, in collaboration with WWF-Cameroonand the Centre for the Study of MedicinalPlants, Yaoundé.
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Already published in this series:
1. Cunningham, A.B. 1993. African medicinal plants: setting priorities at the interface betweenconservation and primary healthcare.
