Bali Ngemba Forest Reserve

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

Bali Ngemba Forest Reserve qualifies as an IPA under Criterion A(i) through occurrence of around 50 threatened taxa. Several of these taxa have been collected in Cameroon only in the Bamenda highlands, and Bali Ngemba is often the only site, or one of very few, where they may survive—especially for those occurring below 2,000m. Many of these taxa have also been collected in the past in Nigeria, often from the Mambilla Plateau, although there are few recent records and those populations have likely suffered extensive habitat loss also. Because of the small size of the Bali Ngemba site compared to some much larger sites it is sometimes difficult to say that a taxon represents >= 1% of the global population or >=5% of the national population. However, for those taxa, it is often possible to be confident that Bali Ngemba is one the five best sites nationally because there are typically less than five sites nationwide. In addition, several taxa are strictly endemic or endemic to one or two other nearby sites as well as Bali Ngemba, for example: Allophylus ujori (EN), Vepris bali (CR), Polystachya anthoceros (EN), Clutia kamerunica (EN), Leptonychia kamerunensis (VU) and Magnistipula butayei subsp. balingembaensis (provisionally CR, Onana & Cheek, 2010). Several other endemic or range-restricted taxa included by Harvey et al. (2004) have not been included here as they are still to be described.
Because of the uniqueness of Bali Ngemba as a surviving remnant of submontane forest in the sub-1,900 (2,000) m zone (a vegetation type included in Letouzey's (1985) vegetation map as mapping unit 117) it could likely qualify also under IPA criterion B(i) if this habitat type were included on a national list of defined habits/vegetation types. The small area of the site means it is otherwise unlikely to qualifiy under criterion B although it is botanically very rich for its size.
Given the >95% loss of forest over 1,500 m in the Bamenda Highlands reported by Harvey et al., (2004) it seems very likely that Bali Ngemba Forest Reserve site would qualify under criterion C(iii) as an instance of regional submontane forest when a suitable national list of habitats is compiled.

Bali Ngemba Forest is a small but important patch of remaining forest in the Bamenda Highlands of Northwest Region, Cameroon. The Bamenda Highlands, part of the Cameroon Highlands which extend north from Bioko and Mount Cameroon following a geological fault line, are an upland area of high rainfall that was previously heavily forested but has been extensively converted to grassland and savannah. It is estimated that over 95% of original forest area above 1,500 m has been lost (Cheek et al., 2000). Much of this deforestation has occurred recently.
The site is located in a valley around 15 km southwest of the city of Bamenda (3rd largest in Cameroon) and 10 km southeast from the town of Bali. It is more directly accessed from the villages of Mantum, probably the main base for small-scale logging (Harvey et al., 2004), Baba II to the northeast and Pinyin to the south, the latter likely being the base for cocoyam farming and other agriculture within the reserve. The Baba II community forest and connecting territory are included here in addition to the Bali Ngemba Forest Reserve itself. Covering an altitudinal range from 1,300–2,200m, the site contains submontane closed canopy forest (with degraded understory vegetation), heavily degraded montane forest, montane scrub and grassland, grassy inselberg areas, a Eucalyptus plantation and derived savanna and farm-fallow.

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The significance of this small, imperfectly preserved fragment of forest is mainly in relation to the deforestation that has occurred in the rest of the Bamenda highlands, formerly one of the richest plant areas in Tropical Africa. In particular, Bali Ngemba is unique in preserving primary (albeit degraded) vegetation over a continuous altitudinal range from c. 1,300 m to over 2,000 m. While larger protected areas exist in the Bamenda Highlands for montane forest above 2,000 m, Bali Ngemba represents the largest and only officially protected block of submontane forest remaining (Harvey et al., 2004).
Prior to surveys from 2000 onwards by teams associated with RBG Kew and Herbier National du Cameroun, culminating in the 2004 Conservation Checklist (Harvey et al., 2004), Bali Ngemba was almost unknown to botanical science, having been neglected by the main collectors in the region. The bulk of pre-twenty-first century collecting, c. 50 specimens, was performed by the Nigerian Ujor in 1951 including three specimens which 50 years later have been published as new species: Allophylus ujori (EN), Vepris bali (CR) and Deinbollia oreophila. Two of these are globally threatened, with Vepris Bali presumed likely extinct having not been seen since it was collected. Deinbollia oreophila was provisionally assessed as Vulnerable by Cheek & Etuge (2009) but new records suggest it may no longer qualify as threatened. Another feared lost species, Newtonia cameroonensis (CR), has been successfully rediscovered at Bali Ngemba and used for native reforestation projects (Cheek et al., 2010).
The surveys carried out between 2000 and 2004 over four expeditions led to Harvey et al., (2004) listing 12 taxa as strictly endemic to Bali Ngemba, plus another 11 near-endemic taxa and 39 threatened Red Data species. Several of these taxa were unpublished at the time and some remain so. However, c. 50 taxa threatened taxa are listed here from the site with seven of these endemic or near endemic.

The following is taken from Cheek's summary in Harvey et al., (2004):
"Bali Ngemba Forest Reserve is positioned facing west in a concave part of the steep scarp slope that connects the High Lava Plateau (1,500–2,100 m alt.) of the Bamenda Highlands with the Low Lava surface (900–1,200 m alt.) on which the former appears to rest; see Fig. 1 (Hawkins & Brunt 1965). These basalts and trachytes are of ancient volcanic origin (Courade 1974). The Bamenda Highlands themselves are the most extensive of the mountainous areas, usually known as the Cameroon Highlands, that begin with the Atlantic Ocean islands of São Tomé, Príncipe, Annobon and Bioko and proceed NE, in a band 50–100 km wide. These mountains have their origin in a geological fault and are formed largely of igneous material. Three main periods of volcanic activity and one of plutonic uplift have been reviewed by Courade (1974). The Bamenda Highlands were largely formed in the Tertiary, in the second of the three main periods of volcanic activity ‘the middle white series’. Courade (1974) classifies the soils in the area of Bali as being ancient, ferralitic, and of volcanic origin, being of medium fertility (3rd class out of 4 possible classes). Tye (1986) refers to soils in the Bamenda Highlands area as being ‘clayey’, resulting in more permanent streams than some of the mountain areas of more recent origin in the Cameroon Highlands, such as Mt Kupe and Mwanenguba.
Courade’s (1974) rainfall map shows the area in which Bali Ngemba falls being somewhere between the 1 m and 2 m isohyets. However, rainfall data for a meteorological station at Bali, only 5 km W and at the same altitude as the lower part of Bali Ngemba (1,300 m alt.) gives an annual total of c. 2.25 m (Hawkins & Brunt, 1965). Most of this falls in the single long wet season in March–October inclusive, when 20 cm or more falls in each month, only 3–9 cm falling in each of the months from Nov. to Feb. when average max. monthly temperatures are 26.7°–27 °C, the coolest months being 21.8 °C and 22.6 °C. Average minimum monthly temperatures range from 11.1 °C to 14.4 °C. Temperatures at Bali, and at Bali Ngemba are partly depressed by temperature inversion, cold air draining off the high lava plateau (Hawkins & Brunt, 1965)."
As mentioned, Bali Ngemba contains a transition from submontane forest from 1,300 m asl to montane forest, scrub and grassland up to 2,200 m (Harvey et al., 2004; Hawkins & Brunt, 1965; Letouzey 1968, 1985). The submontane forest from 1,300–1,700 m is characterised by a notable abundance of the large, deciduous canopy trees, Pterygota mildbraedii. Montane forest (1,900 m upwards) is rare and poorly surveyed, with forest cover lost to farming but apparently little evidence of Sporobolus grassland which typically succeeds degraded montane forest (Letouzey, 1985). Podocarpus milanjianus was collected in 1951 but has not recently been recorded since (Harvey et al., 2004). Scrub and grassland with is considered partly natural and a non-forest, "saxicole" grassland vegetation also occurs at lower altitude on inselberg areas (Letouzey 1985, Harvey et al., 2004). There are also areas of derived scrubland, farm fallow and Eucalyptus plantation.

Although the origins of the Bali Ngemba Forest Reserve are unclear and no official maps have been seen, it is thought to be a Production Reserve, gazetted for the commercial exploitation of timber probably some time during the British mandate period (Harvey et al., 2004). Therefore, it has only limited protection and the survival of the forest in any form is probably largely due to the steep slopes, the use of the canopy trees for growing shade crops such as cocoyams, and other value to the local community. As a forest reserve, there appears to be little tribal tradition protecting the forest as occurs elsewhere such as at Mt Kupe or Oku, nor the same community concern to protect water resources as at Dom (Harvey et al., 2004; Cheek et al., 2010). The forest is isolated and surrounded by farmland (largely Coffea arabica) which encroaches on all sides except the steepest sloping parts (Birdlife International, 2001). There is a large Eucalyptus plantation within the reserve and small-scale logging continues; the vegetation understorey has been largely cleared for cultivation and the canopy forest has been mostly replaced by grass and shrubland above 2,000 m (Harvey et al, 2004). The site also lies within an area approved for quarrying exploration (MINFOF & WRI, 2021).
According to Birdlife International (2001), the government forest agency (ONADEF) had recently become actively involved in the management of the reserve at that time, including creation of conservation areas and reforestation along watercourses. However, it is not known what became of these initiatives and Harvey et al. (2004) report alarming levels of forest degradation over the period of their surveys between 2000–2004. The charity ANCO have been active in the area and are currently investigating the possibility of reforesting a corridor connecting the Baba 2 forest with the nearby Santa Mbei community forest. There is reportedly good community support for such reforestation (M. Njoya, 2021, pers. comm. 23 September).
Despite repeated surveys of the small area, some species such as Vepris bali and Podocarpus milanjianus have not yet been rediscovered at the site after initially being collected and described in the early 1950s. Similarly, while Birdlife International (2001) mentioned reports of Preuss’s monkey (Cercopithecus preussi, EN) surviving at the site, it is not known if they still occur.

Plants within the reserve serve a variety of uses to the local community, including as timber, fuel, medicines and food.
The forest is also an Important Bird Area (Birdlife International, 2001) and supports a variety of threatened bird species including Tauraco bannermani (EN), Platysteira laticincta (EN), Malaconotus gladiator (VU) and Phylloscopus herberti as well as still possibly providing habitat for Preuss's Monkey (EN). There is potential for ecotourism and educational activities (Birdlife International, 2001), especially given the deforestation that has occurred to the rest of the Bamenda Highlands and the uniqueness of the forest altitudinal range preserved here.
Land within the reserve presumably drains into the Alatening river which serves the city of Bamenda, while the forest also helps prevent erosion of soils on the steep scarp slope as well as landslides, which are a serious concern along the Cameroon Volcanic Line (Mukenga et al., 2016).

Bruce Murphy, Royal Botanic Gardens, Kew

Kenneth Tah, COMAID (formerly ANCO)

Martin Cheek, Royal Botanic Gardens Kew

Moses Njoya, ANCO