Akokndoué hill, N’kolbisson, Yaoundé

Mont Akok Ndoé

CMNTIPA011
Akokndoué hill, N’kolbisson, Yaoundé

Country: Cameroon

Administrative region: Centre (Region)

Central co-ordinates: 3.85700 N, 11.46540 E

Area: 1.6km²

Qualifying IPA Criteria

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

IPA assessment rationale

Akokndoué hill qualifies as a potential IPA site under criterion A(i) through the presence of several globally threatened species which have been recorded here and are known from very few other sites. While the considerably degraded nature of the site is noted and the continued presence of some of these taxa would need to be confirmed, populations at other potential sites are also at risk. For those species endemic to the Yaoundé inselbergs, preserving a network of these neighbouring sites is the best hope for their survival.

Site description

Akokndoué hill (Mont Akok Ndoe) and the associated ridge leading to Mvog-Betsi summit a short distance to the northeast, is a partially forested prominence located in the N'kolbisson area of west Yaounde, immediately west of the Institute of Agricultural Research for Development (IRAD) and associated buildings. It is part of a chain of c. 1, 000m inselbergs in and around the western part of Yaoundé, the capital of Cameroon.

Botanical significance

Many specimens were collected in the Yaoundé area by Zenker and Staudt as far back as the 1890s but unfortunately few of these can be located to precise areas. Subsequent collecting has recorded several rare or important species from the inselberg hills, including rediscovery of many of the earlier collections. The N'kolbisson area has been a particular locus for collecting, partly due to the proximity of the IRAD headquarters and other institutions. Once again, some of these collections, particularly a number made by de Wilde and colleagues in the 1960s can not be further located within this region. However, others are pinpointed to Mont Akokndoué, Mont Minloua or one of the other hills.
Notable amongst the globally threatened species at this site are Psychotria yaoundensis (CR), which is endemic to Yaounde, Pristimera bilhongii and P. breteleri (both CR) which are both narrowly endemic to the N'kolbisson area. Pterorachis zenkeri (VU), first described from Zenker and Staudt's "Yaunde station" collections, has also been subsequently recorded here as well as at a few other sites including the neighbouring inselbergs of Mont Minloua and Mont Febe.
Callichilia monopodialis (VU) and Commelina zenkeri (EN) are other threatened species recorded at this site, while several others, including Chlorophytum staudtii (EN), Cyphostemma camerounense (EN) and Momordica camerounensis (EN), may also occur here, having been recorded from N'kolbisson without a precise location.

Habitat and geology

The hills around Yaoundé 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 (Achoundong., 1985), derived from sedimentary and igneous protoliths and apparently dating from around 600 mya (Nzenti et al., 1988; Tchouatcha et al., 2018; Ngnotue et al., 2012).
Preciptiation 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 may be higher on the summits due to orographic precipiation (Madiapevo et al., 2014; Simo et al., 2009). The original forest was probably semi-deciduous (Achoundong, 1985) but has been heavily degraded.

Conservation issues

The vegetation has been considerably degraded by logging and cultivation. Dense settlements cover the lower slopes and have spread high up the flanks in places. Buildings are visible on satellite imaging to the top of the connected northeast ridge at c. 885 m. Elsewhere in Yaoundé, such as nearby Mont Minloua, similar inselbergs have been partly destroyed by quarrying activity. Yaoundé's population is rapidly growing and such pressures are therefore likely to intensify.
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.

Ecosystem services

As is the case with the other hills around Yaoundé, there is a high risk of landslides due to steep terrain and impervious clay beneath permeable laterite soil. Such events have claimed lives and caused extensive damage. For example, the Oyom Abang landslide in western Yaoundé in September 1990 killed five people (Zogning et al 1900; Mukenga et al 2016; Bissaya et al 2014). Preservation of existing forest and primary vegetation is important to preventing such disasters and limiting flash-flooding (Lachenaud et al 2013).
The site provides a recreational and educational opportunity for the city's residents, as well as improving air quality.
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 their value. The site has been important historically to botanists and forestry students at the city's universities and institutes for educational and training purposes and continues to be so.

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
Pterorhachis zenkeri Harms A(i) True True True False False
Commelina zenkeri C.B.Clarke A(i) True True True False False
Pristimera biholongii N.Hallé A(i) True True True True False
Pristimera breteleri N.Hallé A(i) True True True True False
Psychotria yaoundensis O.Lachenaud A(i) True True True False False
Callichilia monopodialis (K.Schum.) Stapf A(i) True False False False False
Oxyanthus doucetii Sonké & O.Lachenaud A(i) True False False False False

Pterorhachis zenkeri Harms

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:

Commelina zenkeri C.B.Clarke

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:

Pristimera biholongii N.Hallé

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:

Pristimera breteleri N.Hallé

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:

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:

Callichilia monopodialis (K.Schum.) Stapf

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

Oxyanthus doucetii Sonké & O.Lachenaud

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

General site habitats

General site habitat Percent coverage Importance
Forest - Subtropical/Tropical Moist Montane Forest No value
Artificial - Terrestrial - Plantations No value

Forest - Subtropical/Tropical Moist Montane Forest

Percent coverage:
No value
Importance:

Artificial - Terrestrial - Plantations

Percent coverage:
No value
Importance:

Land use types

Land use type Percent coverage Importance
Agriculture (arable) No value
Harvesting of wild resources No value

Agriculture (arable)

Percent coverage:
No value
Importance:

Harvesting of wild resources

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 - Small-holder farming High Ongoing - increasing
Energy production & mining - Mining & quarrying High Future - inferred threat
Geological events - Avalanches/landslides Medium Future - inferred threat
Natural system modifications - Fire & fire suppression - Increase in fire frequency/intensity High Ongoing - trend unknown
Biological resource use - Logging & wood harvesting High Ongoing - trend unknown

Residential & commercial development - Housing & urban areas

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:
High
Timing:
Future - inferred threat

Geological events - Avalanches/landslides

Severity:
Medium
Timing:
Future - inferred threat

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

Severity:
High
Timing:
Ongoing - trend unknown

Biological resource use - Logging & wood harvesting

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

Achoundong, G., 1996

Les forêts sommitales du Cameroun: Végétation et flore des Collines de Yaoundé.

Bois et forêt des tropiques, Vol 247, page(s) 37-52

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

Noumi, E., 2015

Floristic structure and diversity of a tropical sub-montane evergreen forest, in the Mbam minkom massif (Western Yaoundé).

Journal of Biology and Life Science, Vol 6(1), page(s) 149-193

Simo, M., Droissart, V., Sonké, B. & Stévart, T., 2009

The Orchid Flora of the Mbam Minkom Hills (Yaoundé, Cameroon)

Belgian Journal of Botany, Vol 142(2), page(s) 111-123

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

Madiapevo, S.N., Makemteu, J. & Noumi, E., 2017

Plant Woody Diversity of the Highest Summit Forest (1156 m), in the Kala Massif, Western Yaoundé

International Journal of Current Research in Biosciences and Plant Biology, Vol 4(10), page(s) 1-30

Recommended citation

Bruce Murphy, Martin Cheek, Olivier Lachenaud (2024) Tropical Important Plant Areas Explorer: Akokndoué hill (Cameroon). https://tipas.kew.org/site/akokndoue-hill-nkolbisson-yaounde/ (Accessed on 27/05/2024)