Mungo and Bakossi Forest Reserves

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

The Mungo River and Bakossi Forest Reserves qualify as a potential IPA under criterion A(i) through their important populations of globally threatened species such as Piptostigma goslineanum (VU), Chlamydocardia subrhomboidea (EN), Belonophora ongensis (CR), Cola metallica (CR) and local endmics Vitex yaundensis (CR) and Coffea charrieriana (CR).

This proposed IPA site is constituted by two adjacent forest reserves in Meme and Kupe-Muanenguba divisions of Southwest Region, Cameroon. Located between the towns of Kumba and Tombei and separated by the Mungo river which runs north-south between them, the Bakossi and Mungo River Forest Reserves were created, along with Loum and Manehas Forest Reserves, by the colonial government of the Sourthern Cameroons during the League of Nations Mandate period, apparently in reaction to rapid development of cash crop farming in the area from 1920 (Wild, 2004).

Although less diverse and well preserved than nearby sites such as Mt Kupe, the Mungo River and Bakossi Forest Reserves are a valuable site of lowland forest, supplementing the limited remaining resources of this habitat in the area. They also harbour several taxa not otherwise known from nearby sites, such as Belonophora ongensis, Salacia lehmbachii var. pes ranualae and two globally unique taxa, Vitex yaundensis which is assumed extinct at its only ever recorded location, and Coffea charrieriana, a low caffeine coffee species which may have potential for crop breeding or as a gene donor. Cola metallica, Cola praecuta and Chlamydocardia subrhomboidea are other notably rare species found here. Additionally of note is the rare and enigmatic Eugenia buchholzii, recorded in 1874 from "Mungo", Cameroon and never subsequently collected. The exact locality of the collection is unknown (Onana & Cheek, 2011).

The site slopes down from around 700 m in the north extreme of the Bakossi reserve to c. 80 m in the south along the river Mungo. The Bakossi Reserve, in two separated parts east of the Mungo river, has more undulating terrain, perhaps cinder cones of minor eruptions, similar to those described by Wild (2004) as occurring between Tombel and Loum. The narrow far end of the northern section extends up the southwestern foothills of Mount Kupe to Mahole and towards Nyasoso. The Mungo River Forest Reserve, west of the river is flatter, sloping gradually south and west down to the river.
The geology of this area is complicated but the site appears to be mainly basaltic, with lava flows filling a trough formed in association with the uplifted horst of Mt Kupe, and a layer of windblown ash and scoria deposited over this (Yerima & Van Rast, 2005). Volcanic soils in the area are often highly fertile (Wild, 2004) although Cheek et al. (2004) suggests those at the site are less so than in the Jide valley further north. Low resolution soil maps indicate eutrophic, humic brown soils on basic rocks in the northern section of Bakossi Forest Reserve and brown ferrallitic soils on acid rocks in the other areas of the site (Vallerie, 1970).
This is one of the wettest areas of tropical Africa and the western flanks of Mt Kupe are subject to particularly high rainfall as they induce orographic precipitation. Mean rainfall at Tombel and Nyasoso just east of the Mungo-Bakossi site was 3,657 mm and 4,045 mm respectively, with the single drier season falling between November and February (Ejedepang-Koge, 1986 cited by Wild et al., 2004). Temperature fluctuates little seasonally around a mean of 25 °C and humidity is consistently high.
Letouzey & Fotius's (1985) vegetation maps assign the intact areas of the site to the Atlantic-Biafran sector of the dense humid evergreen Guineo-Congolian forest, particularly to subcategories 228 (Foret Atlantiques biafreenes à Caesalpinaceae) and 231 (Foret Atlantiques biafreenes à Caesalpinaceae encore abondantes, avec Sarcoglottis gabonensis et autres indices littoraux), both with additional semi-deciduous elements.

The site was established as a production forest and has been selectively logged (Cheek et al., 2004). Under its current status of Forest Reserve it is not listed as a production forest on the Cameroon Forest Atlas (2020) and it is unclear if official logging continues. However, encroachment for unofficial logging and fire wood extraction has been reported and likely continues (Cheek et al., 2004). Some areas have been replanted with timber trees such as Meliaceae according to collector notes to specimen Cheek 10152 (http://specimens.kew.org/herbarium/K000008854). Conversion to farmland has also taken place, particularly following logging incursions (Cheek et al. 2004) and around the Kumbe–Mamfe road. The great majority of people in and around Tombel and Kumba are employed in agriculture (PNDP, 2011) and agro-industry draws in migrant workers creating additional demand for subsistence farming. Extensive banana and palm oil plantations surround Kumba and appear to have infringed on marked boundaries in the southwest of the site, with informal cultivation and degradation also apparent in this area from satellite imagery.
Anthropogenic activity further north threatens the water quality of the river and therefore the habitats of some species at the site such as Brillantaisia lancifolia (Cheek, 2014). A banana plantation also abuts the eastern boundary of the site. A huge mining reconaissance permit also overlaps the southeastern corner.
The northeastern part of the site is close to theproposed Mount Kupe IPA and every effort should be made to ensure habitat continuity between these sites in the area between Nyasoso and Ngusi.

The site is the only recorded location of the Coffee wild relative, Coffea charrieriana, a species of potential commercial interest due to its low caffeine levels.
Located between the Bakossi area to the north, and Mt Cameroon and the remains of Southern Bakundu to the south, the Mungo-Bakossi reserves are an important link in a forest corridor allowing potential genetic exchange and migration, particularly in response to climate change.
The forest limits soil erosion on the sloping land and protects the Mungo river from the downstream pollution and silting which would be caused by further expansion of settlements or agricultural plantations onto this land. The forested banks will also help regulate flow and limit downstream flooding.
The site could be an important recreation and educational resource for residents of Kumba.

Bruce Murphy, Royal Botanic Gardens, Kew