Population structure and traditional management patterns of two threatened medicinal tree species (Garcinia lucida and Pausinystalia johimbe) in the southern humid forest of Cameroon

Paper Details

Research Paper 01/07/2015
Views (231) Download (10)

Population structure and traditional management patterns of two threatened medicinal tree species (Garcinia lucida and Pausinystalia johimbe) in the southern humid forest of Cameroon

J.T. Makueti, A. Tsobeng, Z. Tchoundjeu, S. Tsafack, F. Numbissi
J. Bio. Env. Sci.7( 1), 459-481, July 2015.
Certificate: JBES 2015 [Generate Certificate]


Garcinia lucida and Pausinystalia johimbe are two medicinal tree species well-known in southern Cameroon as they provide non-timber forest products. Particularly, their barks and sometimes fruits, seeds and leaves of G. ludica are used to cure many ailments in local communities. Unfortunately, natural stands of both species are seriously threatened in Cameroon. The objectives of the study were to document use of the targeted species, their management patterns and assess their populations’ structure to establish better plans for the sustainable management and conservation. Ethnobotanical and quantitative ecological methods were used. The results showed that both species provided several products and services. The most mentioned services were the conservation of foodstuffs and medicine. Community responses indicated that the species became rare and there were no strategies developed to preserve them. The quantitative inventories supported this community’s view. Indeed, both species showed weak size classes’ distribution and low densities respectively 14.52 individuals/ha for G. lucida and 58.63 for P. johimbe. In addition, both species appeared to be threatened because of poverty and increasing demography, illegal logging, shifting cultivation, overexploitation and poor attitude to their conservation. Furthermore, because of the high value of these species of local, national and international levels, respondents claimed that they were interested in domesticating and conserving them but they lacked appropriate propagation techniques, materials and skills. Thus, the sensitization and the domestication of the species should urgently be considered in the farmer environment with strong sound of policy.


Abd El-Ghani MM, Abdou HM. 2007. Environment and vegetation of Randonia africana: an endangered desert plant in Egypt. African Journal of Ecology 45(4), 469- 475.

Adeniyi AA, Brindley GS, Pryor JP, Ralph DJ. 2007. Yohimbine in the treatment of orgasmic dysfunction. Asian Journal of Andrology 9, 403- 7.

Adou Yao YC, Dengueadhe KTS, Kouame D, N’Guessan KE. 2007. Diversité et distribution des ligneux dans le Sud du Parc National de Tai (PNT), Cote d’Ivoire. Agronomie Africaine 19(2), 113- 123.

Alemagi D, Duguma L, Minang PA, Nkeumoe F, Feudjio M, Tchoundjeu Z. 2014. Intensification of cocoa agroforestry systems as a REED+ strategy in Cameroon: hurdles, motivations, and challenges. International Journal of Agricultural Sustainability, http://dx.doi.org/10.1080/14735903.2014.940705

Alhamad MN. 2006. Ecological and species diversity of arid Mediterranean grazing land vegetation. Journal of Arid Environments 66, 698-715.

Appiah M. 2003. Domestication of an indigenous tropical forest tree: Silvicultural and socio-economic studies on Iroko (Milicia excelsa) in Ghana. Academic dissertation of the Faculty of Agriculture and Forestry of the University of Helsinki, Helsinki, 104 p.

Assogbadjo AE, Kakai RG, Adjallala FH, Azihou AF, Vodouhe GF, Kyndt T, Codjia JTC. 2009. Ethnic differences in use value and use patterns of the threatened multipurpose scrambling shrub (Caesalpinia bonduc L.) in Benin. Journal of Medicinal Plants Research 5(9), 1549- 1557.

Awono A, Ndoye O, Schreckenberg K, Tabuna H, Isseri F, Temple L. 2002. Production and marketing of safou (Dacryodes edulis) in Cameroon and internationally: Market development issues. Forest in the West Africa humid forest zone. Community Forestry Note N° 6, FAO, Rome, Italy, 232 p.

Baig BA, Ramamoorthy D, Wani BA. 2014. Population status and conservation prioritization of some threatened medicinal plants of Kashmir Himalayas. Journal of Applied Biology and Pharmaceutical Technology 5(4), 14 p.

Bationo BA, Ouedraogo SJ, Guinko S. 2001. Longévité des grains et contraintes à la survie des plantules d’Afzelia africana Sm. dans une savane boisée du Burkina Faso. Annals for Forest Science 58(1), 56- 75.

Bhawani BD, Poonam T, Sudha J. 2013. Conformational, chemical reactivity, thermodymanic properties and the sem study of yohimbine hydrochloride. Kathmandu University Journal of Science, Engineering and Technology 9 (1), 152- 160.

Cerutti PO, Lescuyer G, Nguibouri J, Essiane E, Ondoua J P, Robiglio V. 2010. The domestic timber market in Cameroon. Study preliminary results. CIFOR.

Chia M. 2004. Traditional forest-related knowledge as an instrument in sustainable forest management: a case study of the Kilum mountain forest project in Cameroon. FORAFRI Seminar, Libreville.

Cunningham AB. 2001. Applied ethnobotany. People, wild plant use and conservation. Earthscan Publications Ltd. London.

Chen Q, Li p, Zhang Z, Li K, Liu J, Li Q. 2008. Analysis of yohimbine alkaloid from Pausynistalia johimbe by non-aqueous capillary electrophoresis and gas chromatography-mass spectrometry. Journal of Separation Science 31(22), 2211- 2218.

Dale VH, Joyce LA, McNulty S, Neilson RP, Ayres MP, Flannigan MD, Michael Wotton B. 2001. Climate change and forests disturbances: climate change can affect forests by altering the frequency, intensity, duration, and timing of fire, drought, introduced species, insect and pathogen outbreaks, hurricanes, windstorms, ice storms, or landslides. BioScience 51(9), 723- 724.

Dawson Ik, Lengkeek A, Weber JC. 2009. Managing genetic variation in tropical trees: linking knowledge with action in agroforestry ecosystems for improved conservation and enhanced livelihoods. Biodiversity and Conservation 18, 969- 986.

Degrande A, Tadjio P, Takoutsing B, Asaah E, Tsobeng A, Tchoundjeu Z. 2013. Getting trees into framers’ fields: Success of rural nurseries in distributing high quality planting materials in Cameroon. Small Scale Forestry 12(3), 403- 422.

Dkamela GP. 2001. Les institutions communautaires de gestion des produits forestiers non ligneux dans les villages périphériques de la Réserve de Biosphère du Dja. Tropenbos-Cameroun, Document 7, 88 p.

Duminil J, Hardy OJ, Petit RJ. 2009. Plant traits correlated with generation time directly affect inbreeding depression and mating system and indirectly genetic structure. BMC Evolutionary Biology 9, 177.

Dzoyem JP, Guru SK, Pieme CA, Kuete V, Sharma A, Khan AI, Saxema AK, Vishwakarma RA. 2013. Cytotoxic and antimicrobial activity of selected Cameroonian edible plants. BMC Complement Alternatives Medicines 13, 78.

Elujoba AA, Odeleye OM, Ogunyemi CM. 2005. Traditional medicine development for medical and dental primary health care delivery system in Africa. African Journal of Traditional, Complementary and Alternative Medicines 2(1), 46- 61,

Emshwiller E. 2006. Genetic data and plant domestication. In: Zeder MA, Bradley DG, Emshwiller E and Smith BD, (Ed.), Documenting domestication, 99-122. University of California Press, Berkeley, California, USA.

Feyssa DH, Njoka JT, Asfaw Z, Nyangito MM. 2012. Uses and management of Ximenia americana, Olacaceae in semi-arid east Shewa, Ethiopia. Pakistan Journal of Botany 44(4), 1177- 1184.

Fotie J, Bohle DS, Olivier M, Gomez MA, Nzimiro S. 2007. Trypanocidal and antileishmanial dihydrochelerythrine derivatives from Garcinia lucida. Journal of Natural Products 70, 1650- 1653.

Foundjem-Tita D, Tchoundjeu Z, Speelman S, D’haese M, Degrande A, Asaah E, van Huylenbroeck G, Van Damme P. 2012. Policy and legal frameworks governing trees: Incentives or disincentives for smallholder tree planting decisions in Cameroon? Small Scale Forestry 12, 148- 505.

Gangoue-Pieboji PJ. 2007. Caractérisation des béta-lacmatases et leur inhibition par les extraits de plantes médicinales. Thèse de Doctorat en Biochimie, Université de Liège, Belgique.

Guedje NM, Fankap R. 2001. Uses and management potential of Garcinia lucida Vesque (Clusiaceae) in the south Cameroon region. Systematics and Geography of Plants 71, 747-758.

Guedje NM, Nkongmeneck BA. 2001. Demographic study on non-timber species for sustainable use and management of forest resources: the case of Garcinia lucida Vesque. In: Jonkers WBJ, Foahom B and Schmidt P (Ed.). Seminar proceedings ‘Sustainable management of African rain forest’, held in Kribi, Cameroon, November 1999. Part II. Symposium. The Tropenbos Foundation, Wageningen, the Netherlands, 125- 131.

Guedje MN, Lejoly J, Nkongmeneck BA, Jonkers WBJ. 2003. Population dynamics of Garcinia lucida (Clusiaceae) in Cameroonian Atlantic forests. Forest Ecology and Management 177, 231-241.

Guedje NM, Zuidema PA, During H, Foahom B, Lejoly J. 2007.Tree bark as a non-timber forest product: The effect of bark collection on population structure and dynamics of Garcinia lucida Vesque. Forest Ecology and Management 240, 1- 12.

Gopalakishnan G, Banumathi  B,  Suresh  G. 1997. Evaluation of the antifungal activity of natural xanthones from Garcinia mangostana and their synthetic derivatives. Journal of Natural Products 60, 519- 524.

Hall P, Bawa K. 1993. Method of assess the impact of extraction of Non-Timber tropical Forest products on Plant Populations. Economic Botany 47(3), 234-247.

Hamawa Y, Mapongmetsem PM, Nkongmeneck BA, Dongok ND, Ntoupka M. 2012. Sustainable management of a natural threatened resource: the case study of Vepris heterophylla (Engl.) Letouzey (Rutaceae) in the soudano-sahelian zone of Cameroon. Ethiopian Journal of Environmental Studies and Management 5(4), 461- 469.

Hasan MK, Gatto P, Jha PK. 2013. Can environmental income from wild medicinal plants contributes to annual household income: a case study from Makawanpur district in Nepal. International Journal of Medicinal and Aromatic Plants 3(1), 18-26.

Ickowitz A. 2011. Shifting cultivation and forest pressure in Cameroon. Agricultural Economics 42(2), 207-220.

International Union for Conservation of Nature (IUCN) Red List, Version 2012. 2. Retrieved June 2014. http://www.iucnredlist.org

Ingram V, Schure J. 2010. Review of non-timber forest products (NTFPs) in Central Africa: Cameroon, edited by FORENET. Yaoundé, CIFOR.

Jamnadass RH, Dawson IK, Franzel S, Leakey RRB, Mithofer D, Akinnifesi FK, Tchoundjeu Z. 2011. Improving livelihoods and nutrition in sub-Saharan Africa through the promotion of indigenous and exotic fruit production in smallholders’ agroforestry systems: a review. International Forestry Review 13(3), 338- 354.

Jiofack T, Fokunang C, Guedje N, Kemeuze V, Fongnzossie E, Nkongmeneck BA, Mapongmetsem PM, Tsabang N. 2010. Ethnobotanical uses of medicinal plants of two ethnoecological regions of Cameroon. International Journal of Medicine and Medical Sciences 2(3), 60-79.

Kalaba KF, Chirwa P, Syampungani S, Ajayi OC. 2010. Contribution of agroforestry to biodiversity and livelihoods improvement in rural communities of Southern African regions. In: T. Tscharntke et al. (Ed.), Tropical Rainforests and Agroforests under Global Change, Environmental Science and Engineering, 461- 476.

Kamatenesi M, Remigius B. 2002. Ethnobotanical survey methods to monitor and assess the sustainable harvesting of medicinal plants in Uganda, In: Plant conservation in the Tropics: Perspectives and Practice. Maunder M. Colin, C. Clare, H. Madeleine, G. (Ed.). The Cromwell Press Ltd. Britain.

Kuete V, Efferth T. 2010. Cameroonian Medicinal Plants: Pharmacology and Derived Natural Products. Frontiers in Pharmacology 1, 123.

Kumar S, Kumar R, Khan A. 2011. Medicinal plant resources manifestation and prospects of life-sustaining healthcare system. Continental Journal of Biological Sciences 4(1), 19- 29.

Lacmata ST, Kuete V, Dzoyem JP, Tankeo SB, Ngo Teke G, Kuiate JR, Pages JM. 2012. Antibacterial activities of selected Cameroonian plants and their synergistic effects with antibiotics against bacteria expressing MDR phenotypes. Evidence-Based Complementary and Alternative Medicine 11 pp, http://dx.doi.org/10.1155/2012/623723.

Larson AM, Barry D, Dahal GR, Colfer CP (Ed.). 2010. Forests for People: community rights and forest tenure reform. London: Earthscan.

Lawas MCM. 1997. The Resource User’s Knowledge, The Neglected Input in Land Resource Management International Institute for Aerospace Survey and Earth Sciences (ITC), Enschede, The Netherlands, 6-7.

Lehoux H, Chakib. 2012. Produits forestiers non ligneux. Rapport national (http://www.fao.org/forestry/nwfp/78836/cmr.Retrieved 23 October 2014.

Leakey RRB, Tchoundjeu Z, Schreckenberg K, Shackleton, SC, Shackleton CM. 2005. Agroforestry Tree Products (AFTPs): targeting poverty reduction and enhanced livelihoods. International Journal of Agricultural Sustainability 3, 1- 23.

Lescuyer G, Eba’a Atyi R. 2009. Consommations nationales de bois d’œuvre en Afrique centrale: un enjeu majeur pour la gestion forestière durable. World Forestry Congress. Buenos Aires, Argentine.

Lescuyer G, Mvondo SA, Essoungou JN, Toison V, Trebuchon JF, Fauvel N. 2012. Logging concessions and local livelihoods in Cameroon. From indifference to alliance? Ecology and Society 27(1), 7.

Letouzey R. 1985. Notice de la carte phytogéographique du Cameroun au 1:500 000. Domaine de la forêt dense humide toujours verte. Carte Internationale. Végétation, Toulouse, France.

Magalula J, Tewtrakul. 2010. Anti-HIV-1 protease activities of crude extracts of some Garcinia species growing in Tanzania. African Journal of Biotechnology 9(12), 1848- 1852.

Mahonge CPI, Nsenga JV, Nenget EJ, Mattee AZ . 2006. Utilization of medicinal plants in East Uluguru Mountains, Tanzania. African Journal of Traditional, Complementary and Alternatives Medicines 3(4), 121- 134.

Makueti JT, Tchoundjeu Z, Tsobeng A, Numbissi F, Tsafack S. 2015. Local communities’ perception and willingness on sustainable management of a natural threatened resource: case study of Baillonella toxisperma Pierre in Eastern Cameroon. Journal of Biodiversity and Environmental Sciences 6(5), 74- 92.

Mapongmestem PM, Nkongmeneck BA, Rongouni G, Dongock DN, Dongmo B. 2011. Impact des systèmes d’utilisation des terres sur la conservation de Vitellaria paradoxa Gaertn. F. (Sapotaceae) dans la région des savanes soudano-guinéennes. International Journal of Environmental Studies 68(6), 851- 872.

Marieke V, Cuny P, Zagt R, Bauer T. 2012. The formalization and integration of the domestic market into LAS: Cameroon. Tropenbos International, April 2012.

Maundu PP, Eyog-Matig O. 2006. Threats to medicinal plant: An african perspective. Pp 47-63 In: Conserving medicinal species: securing a healthy future. Mithapala S. (Ed.) IUCN: Ecosystems and Livelihoods Group, Asia, 184 p.

Momo IJ, Kuete V, Dufat H, Michel S, Wandji J. 2011. Antimicrobial activity of the methanolic extract and compounds from the stem bark of Garcinia lucida vesque (Clusiaceae). International Journal of Pharmacy and Pharmaceutical Sciences 3(3), 215- 217.

Muchugi-Mwangi A, Kadu C, Kindt R, Kipruto H, Lemurt S, Olale K, Nyadoi P, Dawson I, Jamnadass R. 2008. Molecular markers for tropical trees, a practical guide to principles and procedures. ICRAF technical manual N° 9. Dawson I. & Jamnadass R. (Ed.) Nairobi: World Agroforestry Centre.

Nduwamungu J, Munyanziza H. 2012. Agroforestry practice in villages surrounding Nyamure former refugee camp, Nyanza District: tree species and purpose. Rwanda Journal of Agricultural Sciences 28 (E), 64- 75.

Ngo Mpeck ML, Tchoundjeu Z, Asaah E. 2003. Vegetative propagation of Pausinystalia johimbe (K. Schum.) by leaf stem cuttings. Propagation of Ornamental Plants 3(2), 3- 10.

Ngo Mpeck ML. 2004. Contribution to domestication of local high-value tree species: case of Pausinystalia johimbe (K. Schum Pierre ex Beille). PhD thesis, University of Yaoundé I, Yaoundé, Cameroon, 167 p.

Nji A. 2004. Why poor people remain poor: Key elements for poverty alleviation and sustainable development. Buma Kor Publishers Ltd. Yaoundé, Cameroon.

Nyemba AM, Mpondo TN, Connolly JD, Rycroft DS. 1990. Cycloarthane derivatives from Garcinia lucida. Phytochemistry 20, 994- 997.

Oldfield S, Lusty C, MacKiven A. 1998. The world list of threatened trees. Cambridge: World Conservation Press.

Olivry JC. 1986. Fleuves et rivières du Cameroun. Collection Monographies Hydrologiques d’ORSTOM N˚ 9. MESRES-ORSTOM, Paris, France.

Policegoudra RS, Saikia S, Das J, Chattopadhyay P, Singh L, Veer V. 2012. Phenolic content, antioxidant activity, antibacterial activity and phytochemical composition of Garcinia lancifolia. Indian Journal of Pharmaceutical Sciences 74(3), 268- 271.

Robiglio V, Lescuyer G, Ceruti PO. 2012. From farmers to loggers: the role of shifting cultivation landscapes in timber production in Cameroon. Small Scale Forestry 12(1), 67- 85.

Sakala T. 2002. Assessing the sustainability of harvest of Pterocarpus angolensis in Rukwa region. Tanzania. Forest Ecology and Management 170 (1-3), 259- 269.

Samant SS, Dhar U, Rawal RS. 1996. Conservation of rare endangered plants: the context of Nanda Devi Biosphere Reserve In: Conservation and management of biological resources in Himalaya (Ramakrishman PS, Ed.). Oxford & IBH Publishing Co, New Delhi, India, 521-545.

Shackleton S, Paumgarten F, Kassa H, Husseelman M, Zida M. 2011.Opportunities for enhancing women’s economic empowerment in the value chains of three African non timber forest products. International Forestry Review special issue 13.

Soares AM, Ticli FK, Marcussi s, Lourenco MV, Januario AH, Sampaio SV, Giglio JR, Lomonte B, Pereira PS. 2005. Medicinal plants with inhibitory properties against snake venoms. Current Medicinal Chemistry 12, 2625- 2641.

Sofowora A, Ogunbodede E, Adedeji OA. 2013. The role and place of medicinal plants in the strategies for disease prevention. African Journal of Traditional, Complement Alternatives Medicines 10(5), 210- 229.

Stoffelen P, Robbrecht, Smets E. 1996. A revision of Corynanthe and Pausinystalia (African Rubiaceae-Coptosapelteae). Botanical Journal of the Linnean Society 120, 287- 326.

Subedi M. 2010. Aromatic plant trade and livelihood strategies in rural Nepal: A case of Wintergreen in Dolakha District. Occasional Papers in Sociology and Anthropology 11, 84- 103.

Sunderland TCH, Njiamnshi A, Koufani A, Ngo-Mpeck ML, Obama C. 1997. The ethnobotany ecology and natural distribution of johimbe (Pausinystalia johimbe K. Shum.) and evaluation of the sustainability of current bark harvesting practices and recommendations for domestication and management. A report prepared for ICRAF, Nairobi.

Sunderland TCH, Tchoundjeu Z, Ngo-Mpeck ML. 2000. The exploitation of Pausinystalia johimbe. Medicinal Plant Conservation 6, 22- 30.

Sunderland TCH. 2011. Food security: why is biodiversity important? International Forestry Review 13(3), 265- 274.

Sunit S, Narisara S, Piniti R, Nantana A, Apichart S. 2002. Xanthones from the green fruit hulls of Garcinia mangostana. Journal of Natural Products 65, 761- 763.

Tabuti JRS, Mugula BB. 2007. The ethnobotany and ecology status of Albizia coriaria (Welw. ex Oliv.) in Budondo Sub-country, eastern Uganda. African Journal of Ecology 45 (Supplement 3), 126- 129.

Takoutsing B, Tchoundjeu Z, Degrande A, Asaah E, Gyau A, Nkeumoe F, Tsobeng A. 2013. Assessing the quality of seedlings in small-scale nurseries in the highlands of Cameroon: the use of growth characteristics and quality thresholds as indicators. Small Scale Forestry 12(1), 1- 15.

Takoutsing B, Tchoundjeu Z, Degrande A, Asaah E, Tsobeng A. 2014. Scaling-up sustainable land management practices through the concept of the Rural Resource Centre: Reconciling farmers’ interests with research agendas. Journal of Agricultural Education and Extension, 1- 21, http://dx.doi.org/10.1080/1389224X.2014.913984.

Tasse BD. 2007. Impact écologique de l’exploitation de l’écorce de Prunus africana (Hook.f.) Kalkman dans la région du mont Cameroun: cas de la zone de Bokwango-Mapanja. Mémoire de fin d’études : Faculté d’agronomie et des Sciences Agricoles. Université de Dschang, Cameroun, 95.

Tchoundjeu Z, Duguma B, Tientcheu ML, Ngo-Mpeck ML. 1999. The domestication of indigenous agroforestry trees: ICRAF’s strategy in the humid tropics of west and central Africa. In: Sunderland TCH, Clark LE and Vantomme P (Ed.). The non-wood forest products of central Africa. Current Research Issues and Prospects for Conservation and Development, pp 161- 169. FAO, Rome.

Termote C, D’heda B, Van Damme P. 2011. Eating from the wild: Turumbu, Mbole and Bali traditional knowledge on non-cultivated edible plants, Tshopo District, DR Congo. Genetic Resources and Crop Evolution 58, 585- 618.

Thirakul S. 1985. Manuel de dendrologie. Groupe Poulin. Quebec: Theriault Ltee.

Tieguhong JC, Ndoye O, Grouwels S, Mala WA, Betti JL. 2012. Rural enterprise development for poverty alleviation based on non-wood forest products in Central Africa. International Forestry Review 14(3), 363- 379.

Tsafack S, Degrande A, Franzel S, Simpson B. 2014. Farmer-to-farmer extension in Cameroon: a survey of extension organizations. ICRAF Working Paper No.182. Nairobi, World Agroforestry Centre, pp 53.

Tuxill J, Nabhan GP. 2001. People, plants and protected areas. A guide to in situ management. Earthscan Publication Ltd. UK.

Uprety Y, Poudel RC, Assselin H, Boon EK, Shrestha KK. 2011. Stakeholder perspectives on use, trade and conservation of medicinal plants in the Rasuwa District of Central Nepal. Journal Mountain of Science 8(1), 75- 86.

van Dijk JFW. 1999. Non-timber forest products in the Bipindi-Akom II region, Cameroon: a socio-economic and ecological assessment. Tropenbos Cameroon Program.

van Gemerden BS, Hazeu GW. 1999. Landscape ecological survey (1:100.000) of the Bipindi-Akom II-Lolodorf Region, Southwest Cameroon. Tropenbos Cameroon Documents 1. The Tropenbos Cameroon Programme, Kribi, Cameroon.

van  Tassel  DL,  DeHaan  LR,  Cox  TS.  2010. Missing domesticated plant forms: Can artificial selection fill the gap? Evolutionary Applications 3, 434- 452.

Venter SM, Witkowski ETF. 2011. Baobab (Adansonia digitata L.) fruit production in communal and conservation land-use types in Southern Africa. Forests Ecology and Management 261, 630- 639.

Vermeulen WJ. 2009. The sustainable harvesting of non-timber forest products from natural forests in the Southern Cape, South Africa: Development of harvest systems and management prescriptions. PhD thesis, Stellenbosch University, Stellenbosch, South Africa.

Vichai R, Natthinee A, Manat P, Samaisukh S, Chalobon Y, Jittra L, Chanita N, Thawatchai S, Patoomratana T. 2006. Cytotoxic and anti-HIV caged xanthones from the resin and fruits of Garcinia hanguryi (2006). Planta Medica 73, 33- 40.

Vivien J et Faure JJ. 1985. Arbres des forêts d’Afrique Centrale, R.C. Ministère français des Relations Extérieures, de la Coopération et du Développement / CTFT, 565 p.

Yakeu DSE. 2012. Local knowledge and socio-economic values of Picralima nitida ((Stapf) th. & H. Durand) in the humid forest zone of Cameroon. Master thesis, Ghent University, Belgium, 94 p.

Yakubu MT, Bilbis LS, Lawal M, Akanji MA. 2003. Evaluation of selected parameters of rat liver and kidney function following repeated administration of yohimbine. Biokemistri 15(2), 50-56.

Yirga G. 2010. Use of traditional medicinal plants by indigenous people in Mekele town, capital city of Tigray regional state of Ethiopia. Journal of Medicinal Plants Research 4(17), 1799- 1804.

Yobo MC, Ito K. 2015. Trade of the most popular indigenous fruits and nuts, threats and opportunities for their sustainable management around the Ivindo national Park (INP), Gabon. International Journal of Biodiversity and Conservation 7(2), 85- 102.

Zanolari B, Powers MB, Ndjoko K, Loset JR, Marston A, Hostettman K. 2003. Qualitative and quantitative determination of yohimbine in authentic yohimbe bark and commercial aphrodisiacs by HPLC-UV-API/MS methods. Phytochemical Analysis 14(4), 193- 201.