Colline Mbokdoum

Mbekoum

CMNTIPA014
Colline Mbokdoum

Country: Cameroon

Administrative region: Centre (Region)

Central co-ordinates: 3.85720 N, 11.44430 E

Area: 6.7km²

Qualifying IPA Criteria

A(i)Site contains one or more globally threatened species

IPA assessment rationale

Mbokdoum hill qualifies as a potential IPA under criterion A(i) due to the presence of three globally threatened (all critically endangered) species known only from here and one or two other sites. Other globally threatened species recorded from "N'kolbisson" may also occur here.

Site description

Mbokdoum hill (Mbogdoumy, Mbekoum) is a steep-sided inselberg, one of the "seven hills" of Yaoundé (Tiafack & Mbon, 2017) rising to around 1,000 m and part of a larger group of mountains which form a natural barrier on the western side of the city. Included in the proposed IPA perimeter is the unnamed hill to the south east (895 m) and the low lying riverine zone in between. The site is close to the N'kolbisson neighbourhood where IRAD and other scientific institutes are based and is adjacent to the Mt Eloumden proposed IPA which in turn extends west almost to the Mt Kala proposed IPA.

Botanical significance

The site is significant for three critically endangered species that have been recorded there, two of which are endemic to the Yaoundé inselbergs. Multidentia saxicola has only been recorded from here, another site north of N'kolbisson, possibly Mont Minloua, and one location in DRC. Psychotria yaoundensis is only otherwise recorded from neighbouring Mont Akokndoué and from Mont Eloumden 3 km to the south (Lachenaud et al., 2013). Coffea sp. "Nkolbisson" is a possibly undescribed, morphologically distinct taxon known only from this record and other non-specific "N'kolbisson" locations. Treated as Coffea heterocalyx, which might otherwise be extinct, it was demonstrated to be distinct from Coffea canephora ("Robusta" coffee) by a recent molecular study (Davis et al., 2020). As apparently the closest "wild relative "of C. canephora, it is of potential economic importance as a possible source of useful genetic traits. Conserving it in the wild should therefore be a priority.
Several other threatened species, including Chlorophytum staudtii (EN), Cyphostemma camerounense (EN) and Momordica camerounensis (EN) may occur here, having been recorded from N'kolbisson without a precise location. Many threatened species were also recorded by Zenker and Staudt from "Yaunde station" and some of these might also occur at this site.

Habitat and geology

The hills around Yaounde rise from the South Cameroon Plain between the Sanaga fault and the north-thrusting Congo craton. They are formed from high grade metamorphic rocks, mainly granulites and migmatites also referred to as embrichite gneiss (Achoundog, 1985), formed from sedimentary and igneous protoliths and apparently dating from around 600 mya (Nzenti, 1988; Tchouatcha et al., 2018; Ngnotue et al., 2012).
Precipitation in Yaoundé is 1,605 mm per annum, falling in a bimodal pattern with a small (March–June) and greater (September–November) wet season interspersed with a drier period (July–August) and a second more severe dry period between December and February when mean monthly rainfall drops below the relatively flat mean monthly temperature curve (range: 22.8–25.47 °C) on a Walter-Leith type chart (Simo et al., 2009; Bissaya et al., 2014; Noumi, 2015). This is below the level of rainfall normally thought necessary to sustain evergreen tropical forest (Cheek et al., 2011), although the level maybe higher on the summits with orographic precipitation likely (Noumi, 2015; Simo et al., 2009). The original forest was probably semi-deciduous (Achoundong et al. 1985; O. Lachenaud, 2021, pers. comm. 29 June) but has been heavily degraded through timber and wood extraction and cultivation.
The Mbokdoum hill is especially steep sided on its northeast and southern faces, with outcrops of bare rock. There is low-lying marshy habitat between Mbokdoum and the hill to the southwest.

Conservation issues

The vegetation has been considerably degraded by logging and cultivation. Settlements surround the Mboukdoum hill and have crept up the lower slopes on all sides but are especially dense to the north where they reach up to 850 m. The site appears to be privately owened and botanists visiting the site encountered surveyors demarcating the boundary (O. Lachenaud, 2021, pers. comm. 29 June). On the other hill a road and sparse buildings ascend to nearly the summit. There is also evidence of cultivation on the lower slopes.
Elsewhere in Yaoundé, such as nearby Mont Minloua, similar inselbergs have been partly destroyed by quarrying activity.
Yaoundé's population is rapidly growing and all pressures are therefore likely to intensify (Nkwemoh et al., 2018; United Nations, 2018). However, despite the considerable habitat degradation, sites such as these present an opportunity for recreational and educational spaces in the expanding city, improving quality of life and prestige of the city while also conserving what remains of the original vegetation. They provide convenient fieldwork sites for students at Yaoundé's universities and, for other urban residents, a potential connection to the country's rich biodiversity.
A program of tree-planting has been initiated in Yaoundé in the last decade, including planting of Eucalyptus trees, with the aim of drying up marshy areas (Nkwemoh et al., 2017). Such wetland areas may be important for some species and planting fast-growing native species might be a better option where reforestation is desirable because of the invasive, flammable and allelopathic traits of Eucalpytus.
Mbokdoum, Mt Eloumden and Mt Kala could be connected to form a continuous forest habitat.

Ecosystem services

As is the case with the other hills around Yaoundé, there is a high risk of landslides and soil erosion due to steep terrain and impervious clay beneath porous laterite soil. Such events have claimed lives and caused extensive damage such as the Oyom Abang landslide in western Yaoundé in September 1990 which killed five people (Zogning et al., 1900; Mukenga et al., 2016; Bissaya et al., 2014). Flooding is also a danger due to the dramatic rise in unplanned settlements and deforestation of slopes and naturally flood prone areas such as swamps (Tiafack & Mbon, 2017). Preservation of existing forest and primary vegetation is important to preventing such disasters and flash flooding (Lachenaud et al., 2013), especially since the land adjacent to the site is densely settled in places.
In a rapidly growing metropolitan area such sites are also an important recreational and educational resource for the growing population and the survival of rare species and primary vegetation greatly increases the value of such sites. The site has long been important for education and training of botanists and forestry students at the city's universities and institutes.
Picathartes oreas (VU) used to occur here. Although it is not know if this is still the case, Mbokdoum is one of several sites which, with restoration, could serve as satellites to Mbam Minkom and help protect and enlarge the Yaoundé populations of this rare bird and other fauna.

Site assessor(s)

Bruce Murphy, Royal Botanic Gardens, Kew

Martin Cheek, Royal Botanic Gardens Kew

Olivier Lachenaud, Meise Botanic Garden

IPA criterion A species

Species Qualifying sub-criterion ≥ 1% of global population ≥ 5% of national population 1 of 5 best sites nationally Entire global population Socio-economically important Abundance at site
Multidentia saxicola O.Lachenaud & Séné A(i) True True True False False
Psychotria yaoundensis O.Lachenaud A(i) True True True False False
Coffea sp. 'nkolbisson' Charr et al. A(i) True True True True False

Multidentia saxicola O.Lachenaud & Séné

Qualifying sub-criterion:
A(i)
≥ 1% of global population:
True
≥ 5% of national population:
True
1 of 5 best sites nationally:
True
Entire global population:
False
Socio-economically important:
False
Abundance at site:

Psychotria yaoundensis O.Lachenaud

Qualifying sub-criterion:
A(i)
≥ 1% of global population:
True
≥ 5% of national population:
True
1 of 5 best sites nationally:
True
Entire global population:
False
Socio-economically important:
False
Abundance at site:

Coffea sp. 'nkolbisson' Charr et al.

Qualifying sub-criterion:
A(i)
≥ 1% of global population:
True
≥ 5% of national population:
True
1 of 5 best sites nationally:
True
Entire global population:
True
Socio-economically important:
False
Abundance at site:

General site habitats

General site habitat Percent coverage Importance
Artificial - Terrestrial - Subtropical/Tropical Heavily Degraded Former Forest No value
Forest - Subtropical/Tropical Moist Lowland Forest No value

Artificial - Terrestrial - Subtropical/Tropical Heavily Degraded Former Forest

Percent coverage:
No value
Importance:

Forest - Subtropical/Tropical Moist Lowland Forest

Percent coverage:
No value
Importance:

Land use types

Land use type Percent coverage Importance
Harvesting of wild resources No value
Residential / urban development No value

Harvesting of wild resources

Percent coverage:
No value
Importance:

Residential / urban development

Percent coverage:
No value
Importance:

Threats

Threat Severity Timing
Residential & commercial development - Housing & urban areas High Ongoing - increasing
Agriculture & aquaculture - Annual & perennial non-timber crops - Shifting agriculture High Ongoing - increasing
Agriculture & aquaculture - Annual & perennial non-timber crops - Small-holder farming High Ongoing - increasing
Energy production & mining - Mining & quarrying Medium Future - inferred threat
Geological events - Avalanches/landslides Medium Future - inferred threat
Biological resource use - Logging & wood harvesting - Unintentional effects: subsistence/small scale (species being assessed is not the target) [harvest] High Ongoing - trend unknown
Natural system modifications - Fire & fire suppression - Increase in fire frequency/intensity High Ongoing - trend unknown

Residential & commercial development - Housing & urban areas

Severity:
High
Timing:
Ongoing - increasing

Agriculture & aquaculture - Annual & perennial non-timber crops - Shifting agriculture

Severity:
High
Timing:
Ongoing - increasing

Agriculture & aquaculture - Annual & perennial non-timber crops - Small-holder farming

Severity:
High
Timing:
Ongoing - increasing

Energy production & mining - Mining & quarrying

Severity:
Medium
Timing:
Future - inferred threat

Geological events - Avalanches/landslides

Severity:
Medium
Timing:
Future - inferred threat

Biological resource use - Logging & wood harvesting - Unintentional effects: subsistence/small scale (species being assessed is not the target) [harvest]

Severity:
High
Timing:
Ongoing - trend unknown

Natural system modifications - Fire & fire suppression - Increase in fire frequency/intensity

Severity:
High
Timing:
Ongoing - trend unknown

Management type

Management type Description Year started Year finished
No management plan in place No value No value

No management plan in place

Year started:
No value
Year finished:
No value

Bibliography

Cheek, M., Harvey, Y. & Onana, J.M., 2011

The Plants of Mefou Proposed National Park, Yaoundé, Cameroon

Zogning, A., Ngouanet, C. & Tiafack, O., 2007

The catastrophic geomorphological processes in humid tropical Africa: A case study of the recent landslide disasters in Cameroon

Sedimentary Geology, Vol 199, page(s) 13 – 27 Available online

Mukenga, W,. Havenith, H.B., Dewitte, O. & R.M. Eko, 2016

Spatial Analysis of the Landslide Risk in the Cameroon Volcanic Line (CVL)

Available online

Bissaya, R., Ghogomu, R.T., Moundi, A., Njom, B. & N.S. Kanouo, 2014

Utilisation des données géologiques et gestion des informations multi-sources pour l’analyse de l’aléa glissement de terrain/éboulement dans le secteur Nord-Ouest de la région de Yaoundé

Afrique SCIENCE, Vol 10(3), page(s) 113 - 133

Charra, J.-C., Garavito, A., Guyeux, C., Crouzillat, D., Descombes, P., Fournier, C., Ly, S.N., Raharimalala, E.N., Rakotomalala, J.-J., Stoffelen, P., Janssens, S., Hamon, P. & Guyot, R., 2020

Complex evolutionary history of coffees revealed by full plastid genomes and 28,800 nuclear SNP analyses, with particular emphasis on Coffea canephora (Robusta coffee)

Molecular Phylogenetics and Evolution, Vol 151, page(s) 106906

Emmanuel (Cameroon Tribune), 2020

Yaounde development: Great Transformation

Cameroon Tribune, Vol 4th March 2020 Available online

Tiafack, O. & Mbon, A.M., 2017

Urban Growth and Front Development on Risk Zones: GIS Application for Mapping of Impacts on Yaounde North Western Highlands, Cameroon

Current Urban Studies, Vol 5(2), page(s) 217-235

Nkwemoh, C.A., Tchindjang, M. & Afungang, R.N., 2017

The Impact of Urbanization on the Vegetation of Yaounde, (Cameroon)

International Journal of Innovative Research & Development, Vol 6(5), page(s) 6-18

Lachenaud, O., Droissart, V., Dessein, S., Stévart, T., Simo, M., Lemaire, B., Taedoumg, H. & Sonké, B., 2013

New records for the flora of Cameroon, including a new species of Psychotria (Rubiaceae) and range extensions for some rare species

Plant Ecology and Evolution, Vol 146 (1), page(s) 121–133

Nzenti, J.P., Barbey, P., Macaudiere, J. & Soba, D., 1988

Origin and evolution of the late Precambrian high-grade Yaounde gneisses (Cameroon).

Precambambrian Research, Vol 38, page(s) 91-109

Tchouatcha, M.S., Kouske, A.P., Njiosseu, E.L.T., Ngouem, P.A., Ngnotue, T., Njinchuki, D.N. & Nzenti, J.P., 2018

Preserved Sedimentary Features in the Pan-African High-Grade Metamorphic Rocks from the Yaoundé Series (Cameroon)

Journal of Geosciences and Geomatics, Vol 6(3), page(s) 94-102

Ngnotué, T., Ganno, S., Nzenti, J.P., Schulz, B., Tchaptchet T.D. & Suh, C.E., 2012

Geochemistry and geochronology of Peraluminous High-K Granitic Leucosomes of Yaoundé Series ) Cameroon. Evidence for a Unique Pan-African Magmatism and Melting Event in North Equatorial Fold Belt.

International Journal of Geosciences, Vol 3, page(s) 525-548

Davis, A., Gargiulo, R., Fay, M., Sarmu, D. & Haggar, J., 2020

Lost and Found: Coffea stenophylla and C. affinis, the Forgotten Coffee Crop Species of West Africa

Frontiers in Plant Science, Vol 11, page(s) article 616

United Nations, Department of Economic and Social Affairs, Population Division, 2018

World Urbanization Prospects: The 2018 Revision, Online Edition

Available online

Recommended citation

Bruce Murphy, Martin Cheek, Olivier Lachenaud (2024) Tropical Important Plant Areas Explorer: Mbokdoum hill (Cameroon). https://tipas.kew.org/site/colline-mbokdoum/ (Accessed on 21/05/2024)