Mount Vokré

Hoséré Vokré, Monts de Poli

CMNTIPA046
Mount Vokré

Country: Cameroon

Administrative region: North (Region)

Central co-ordinates: 8.34000 N, 13.25000 E

Area: 962km²

Qualifying IPA Criteria

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

IPA assessment rationale

Mount Vokré qualifies as an IPA under criterion A(i) through its important populations of several globally threatened species, most notably Antherotoma clandestina (EN), Crotalaria ledermannii (VU) and Ledermanniella raynaliorum (EN).

Site description

Mount Vokré in North Region, Cameroon, is a horseshoe shaped mountain ridge reaching nearly 2000 m. It lies 100 km south of Garoua and a few km south of the town of Poli, and between Faro and Benoué National Parks which are of predominantly low altitude. As well as the summit, several additional peaks in the range are named, including Hosere Kogo and Hosere Mango. To the Northwest, narrowly separated by a 300-400 m valley a related peak, Hosere Gode rises to 1600 m and is included here. A smaller separated peak, Hosere Poli, also rises to nearly 1000 m on the eastern edge of Poli itself but is excluded. To the east the range forms a plateau which slopes away gradually. The proposed boundary is a tentative suggestion and surveying is required to indicate what parts retain conservation value.

Botanical significance

These mountains have seen a fairly high number of collections compared to elsewhere in the North, Far North and Adamawa regions but there are no recent records of the more notable taxa. G. Fotius, J & A Raynal, H Jaques-Felix, C. Geerling and A.P.M Van der Zon are responsible for most of the collecting and important records which date from the 1960s-1980s. A large number of non-vouchered observations by Le Bourgeois in 1990 and OUSTALET in 2003 do not appear to have returned rare or threatened taxa.
Antherotoma clandestina (EN) is endemic to Adamaoua region and only recorded at one other nearby site, Mt Nganha, while Ledermanniella raynaliorum (EN) is only otherwise recorded from a single site in Nigeria (Cheek, 2015; Cheek & Lovell, 2021). Rhynchosia ambacensis subsp. cameroonensis (provisionally EN, Onana & Cheek, 2011) is also very rare. Other species such as Wahlenbergia ramosissima subsp. ramosissima and Panicum acrotrichum are somewhat more widely recorded but still assessed as Vulnerable. Mount Vokré is also notable for hosting outlier populations of taxa otherwise limited to Northwest and Southwest regions of Cameroon, such as Crotalaria ledermannii (VU) a national endemic, and Podocarpus milanjianus. The remarkable orchid Ansellia africana (VU), although widespread in Africa, has rarely been scientifically recorded in Cameroon but twice collected at this site. It is threatened by horticultural and ethnobotanical collecting (Crook, 2013). Echinops mildbraedii is provisionally assessed as NT by Onana & Cheek (2011). Thesium equisetoides (NE) also has a large range across Africa but is very sparsely recorded and is only known in Cameroon from this site.
In addition, several other taxa are recorded from nearby Hosere Godé, including narrow endemic Eugenia poliensis, Cyphostemma leucotrichum (provisionally EN), Globimetula oreophila (VU in Onana & Cheek, 2011 but now more widely recorded), Dombeya ledermannii (CR), Vernonia chapmannii (provisionally VU) and Vitex bogalensis (Not Evaluated).

Habitat and geology

Mount Vokré is in the Central African Fold Belt region, a zone between the Congo Craton, the West African Craton and the Chad basin. The mountains are formed of Neoproterozoic granitoids, uplifted as a horst like structure and surrounded by metabasalts and micaschists (Kouske et al., 2012; Essi et al., 2017; Thiéblemont et al., 2021). Many large granite boulders, forming deep crevices, are exposed at the summit area and found in gallery forest at slightly lower altitudes (Bauer et al., 2006). One of only two known Cameroon uranium deposits (the Kitongo occurrence) is known from the northwestern margin and occupies an area of ~ 1.8 km by ~ 1.3 km (Kouske et al., 2012). The higher altitude areas are characterised by leptosols, with gleyic luvisols and planosols in the lower areas to the west, and ferric luvisols and regosols to the east (Yerrima & Van Ranst 2005; Letouzey, 1982).
Average annual precipitation at Poli (478 m) is 1352 mm. There is a single wet season (Koppen type: Aw) running from mid March to the end of October and peaking in August (275 mm, humidity 80%). Very little rain (<=5mm) falls from November to February. Average annual temperature is 24 °C, with January being the coolest month (average 21.4 °C) and temperatures peaking in April (average 27.6 °C) as the rains build (WeatherBase, 2022).
Letouzey (1982) maps the main ridge as vegetation type 119, a strongly degraded submontane forest of Guineo-Congolian type, sometimes colonised by thorny trees. The highest region is mapped as type 113, mountain pastures with Sporolobus africanus and forest galleries, and at this altitude Letouzey (1982) comments on similarity with the rest of the Cameroon Line mountains. Lower slopes consist of mainly type 66, "Mid-Sudanian wooded savannas with Isoberlinia doka, sometimes degraded, on rocky soils; sometimes stands of Isoberlinia doka as open dry forests", although a considerable area at lower altitude is uncategorised, perhaps indicating anthropic degradation. Groves of Borassus aethiopum are cultivated around Poli and Hosére Godé. The Main forest trees are Syzigium guineensis and Phoenix reclinata (Larison et al., 1996; Bauer et al., 2006).

Conservation issues

The area has a high population density and impacts on the natural habitat have been described as "extremely high" (Larrison et al. 2000). Forest is largely limited to narrow gallery forests in valleys and gorges with dry wooded savanna in between. The summit area appears largely bare. It is assumed that forest cover was formerly much more complete although perhaps not reaching the highest regions. Grazing is likely to be the main cause of degradation (Cheek, 2015). Pastoral villages and cattle grazing are reported on the plateau itself, with streams used for watering livestock. There is also cultivation of the lower slopes and even on the plateau. Fire is not mentioned but is likely to be used to rejuvenate grazing land, and fuelwood gathering is likely a further impact. Numerous fire alerts are indicated over the latest month (prior to 18/03/2022) by infrared satellite imaging using a 375 m pixel size (NASA FIRMS, 2022). Gallery forests are targeted for both grazing, particularly in the dry season, and for cultivation because of the moister soils (Bauer et al., 2006). One of the globally threatened and narrowly endemic species, Ledermannia raynaliorum is a rheophytic species from waterfalls and rapids and likely to be susceptible to impacts on these streams (Cheek & Lovell, 2021).
Hidden crevices between the large granite boulders may shelter surviving populations of important species.
The Kitongo uranium deposit is thought to contain up to 13,000 tonnes of ore material but is of low value (IAEA, 2009). Drilling in 2010 by Mega Uranium Ltd revealed nothing of economic significance. Further drillling in 2011 was defered and does not appear to have resumed (KPMG, 2014). A large area, extending through Benoué National Park remains under various mining permits (MINFOF & WRI, 2020).

Ecosystem services

The site is one of only three locations for Vepris oubanguiensis, which is widely used as a remedy for asthma and cough. Phytochemical research has isolated novel chemical compounds from samples of this species collected on Mount Vokré (Ayafor et al.,1982, 1986). Other medicinal and edible species are recorded and are likely to be highly utilised by local people.
The remaining gallery forest protects the streams and rivers that provide fresh water to local communities including Poli. Denser forest may have previously intercepted and condensed atmospheric moisture at high elevations, increasing total precipitation, suggesting restoration may have benefits for water supply.
A species of Gecko, Cnemaspis alantika (EN) is narrowly endemic to Mount Vokré and the nearby Atlantika mountains (Bauer et al., 2006; LeBreton et al., 2021). Ninety-one bird species have been recorded, three of which were at their most northern recorded site (Larison et al., 2000), although none were rare and few forest species were found. The spider Malinella vokrensis appears to be narrowly endemic to the site (Bosmans & Van Hove, 1986; World Spider Catalog,2022).

Site assessor(s)

Bruce Murphy, Royal Botanic Gardens, Kew

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
Pterocarpus erinaceus Poir. A(i) False True True False True
Ledermanniella raynaliorum C.Cusset A(i) True True True False False
Vitellaria paradoxa C.F.Gaertn. A(i) False False False False True
Crassocephalum bauchiense (Hutch.) Milne-Redh. A(i) False False False False False
Panicum acrotrichum Hook.f. A(i) True True False False False
Crotalaria ledermannii Bak.f. A(i) True True True False False
Afzelia africana Sm. ex Pers. A(i) False True False False True
Ansellia africana Lindl. A(i) False False True False False
Wahlenbergia ramosissima (Hemsl.) Thulin subsp. ramosissima A(i) True False False False False
Antherotoma clandestina Jacq.-Fél. A(i) True True True True False
Dombeya ledermannii Engl. A(i) False False False False False
Globimetula oreophila (Oliv.) Tiegh. A(i) False False False False False
Vepris oubanguensis (Aubrév. & Pellegr.) Onana A(i) True True True True False
Garcinia afzelii Engl. A(i) False False False False False
Indigofera dasycephala Baker f. A(i) True True True False False
Cyphostemma leucotrichum (Gilg & M.Brandt) Desc. A(i) True True True False False
Eugenia poliensis Aubrév. & Pellegr. A(iii) True True True True False

Pterocarpus erinaceus Poir.

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

Ledermanniella raynaliorum C.Cusset

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:

Vitellaria paradoxa C.F.Gaertn.

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

Crassocephalum bauchiense (Hutch.) Milne-Redh.

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

Panicum acrotrichum Hook.f.

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

Crotalaria ledermannii Bak.f.

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:

Afzelia africana Sm. ex Pers.

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

Ansellia africana Lindl.

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

Wahlenbergia ramosissima (Hemsl.) Thulin subsp. ramosissima

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:

Antherotoma clandestina Jacq.-Fél.

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:

Dombeya ledermannii Engl.

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

Globimetula oreophila (Oliv.) Tiegh.

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

Vepris oubanguensis (Aubrév. & Pellegr.) Onana

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:

Garcinia afzelii Engl.

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

Indigofera dasycephala Baker f.

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:

Cyphostemma leucotrichum (Gilg & M.Brandt) Desc.

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:

Eugenia poliensis Aubrév. & Pellegr.

Qualifying sub-criterion:
A(iii)
≥ 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
Savanna - Moist Savanna No value
Grassland - Subtropical/Tropical High Altitude Grassland No value
Forest - Subtropical/Tropical Moist Montane Forest No value

Savanna - Moist Savanna

Percent coverage:
No value
Importance:

Grassland - Subtropical/Tropical High Altitude Grassland

Percent coverage:
No value
Importance:

Forest - Subtropical/Tropical Moist Montane Forest

Percent coverage:
No value
Importance:

Land use types

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

Harvesting of wild resources

Percent coverage:
No value
Importance:

Agriculture (pastoral)

Percent coverage:
No value
Importance:

Agriculture (arable)

Percent coverage:
No value
Importance:

Threats

Threat Severity Timing
Agriculture & aquaculture - Annual & perennial non-timber crops - Small-holder farming High Ongoing - trend unknown
Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming High Ongoing - trend unknown
Natural system modifications - Fire & fire suppression - Increase in fire frequency/intensity High Ongoing - trend unknown
Biological resource use - Gathering terrestrial plants - Intentional use (species being assessed is the target) Medium Ongoing - trend unknown
Energy production & mining - Mining & quarrying Medium Ongoing - trend unknown
Biological resource use - Logging & wood harvesting High Ongoing - trend unknown

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

Severity:
High
Timing:
Ongoing - trend unknown

Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming

Severity:
High
Timing:
Ongoing - trend unknown

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

Severity:
High
Timing:
Ongoing - trend unknown

Biological resource use - Gathering terrestrial plants - Intentional use (species being assessed is the target)

Severity:
Medium
Timing:
Ongoing - trend unknown

Energy production & mining - Mining & quarrying

Severity:
Medium
Timing:
Ongoing - trend unknown

Biological resource use - Logging & wood harvesting

Severity:
High
Timing:
Ongoing - trend unknown

Bibliography

Letouzey, R., 1985

Notice de la carte phytogéographique du Cameroun au 1: 500,000.

Yerima, B. & Van Ranst, E., 2005

Major Soil Classification Systems Used in the Tropics: Soils of Cameroon

MINFOF (Ministry of Forestry and Wildlife) & WRI (World Resources Instiute), 2021

Forest Atlas of Cameroon

Available online

Thiéblemont D. (edit.) et al., 2021

Geological Map of Africa at 1:10 M scale, CGMW-BRGM 2016

Larison, B., Smith, T.B., Fotso, R. & McNiven, D., 2000

Comparative avian biodiversity of five mountains in northern Cameroon and Bioko

Ostrich, Vol 71(1 & 2), page(s) 269-276

Bosmans, R. and van Hove, M., 1986

New species and new records of spiders of the genus Langbiana (Araneae: Zodariidae) scientific report of the Belgian Cameroon expeditions 1981 and 1983 XVI.

Revue suisse de zoologie, Vol 93, page(s) 373-392

Bauer, A.M., Chirio, L., Ineich, I. & Lebreton, M., 2006

New species of Cnemaspis (Squamata: Gekkonidae) from Northern Cameroon, a neglected biodiversity hotspot

Journal of Herpetology, Vol 40(4), page(s) 510-519

IAEA (International Atomic Energy Agency), 2009

World Distribution of Uranium Deposits (UDEPO). Kitongo, Cameroon

Available online

KPMG, 2014

KPMG Global Mining Institute. Cameroon: Country mining Guide.

Available online

Abate Essi, J.M., Marcel, J., Yene Atangana, J.Q., Ahmad, A.D., Fita Dassou, E., Mbossi, E.F., Ondoa, J.M. & Penaye, J., 2017

Interpretation of gravity data derived from the Earth Gravitational Model EGM2008 in the Center-North Cameroon: structural and mining implications

Arabian Journal of Geosciences, Vol 10, 130

Kouske, A.P., Suh, C.E, Ghogomu, R.T. & Ngako, V., 2012

Na-Metasomatism and Uranium Mineralization during a Two-Stage Albitization at Kitongo, Northern Cameroon: Structural and Geochemical Evidence

International Journal of Geosciences, Vol 3(1), page(s) 258-279

Weatherbase, 2022

Climate summary: Poli, Cameroon

Available online

Ayafor, J.F, Sondengam, B.L, Bilon, A.N., Tsamo, E. & Kimbu, S.F., 1982

Furoquinoline alkaloids of Teclea ouabanguiensis

Journal of Natural Products, Vol 45(6), page(s) 714-717

Ayafor, J.F., Sondengam, B.L, Bilon, A.N., Connolly, J.D., 1986

Limonoids of Teclea Ouabanguiensis

Journal of N, Vol 49(4), page(s) 583-7

LeBreton, M., Chirio, L. & Gonwouo, N.L., 2021

Cnemaspis alantika. The IUCN Red List of Threatened Species 2021: e.T104681745A104681747

Available online

World Spider Catalog, 2022

World Spider Catalog. Version 23.0. Natural History Museum Bern

Available online

Bosmans, R. & Van Hove, M., 1986

New species and new records of spiders of the genus Langbiana (Araneae: Zodariidae). Scientific report of the Belgian Cameroon Expeditions 1981 and 1983 XVI.

Revue Suisse de Zoologie, Vol 93(2), page(s) 373-392

Cheek, M., 2015

Antherotoma clandestina. The IUCN Red List of Threatened Species 2015: e.T202774A2752585

Available online

Crook, V., 2013

Ansellia africana. The IUCN Red List of Threatened Species 2013: e.T44392142A44437667

Available online

NASA FIRMS, 2022

“VIIRS Active Fires.” Accessed through Global Forest.

Available online

Recommended citation

Bruce Murphy (2024) Tropical Important Plant Areas Explorer: Mount Vokré (Cameroon). https://tipas.kew.org/site/mount-vokre/ (Accessed on 21/05/2024)