The Nimba mountains, which extend for some 40 km along a south-west–north-east alignment in the north-east of the country, are shared jointly with Côte d’Ivoire and Guinea. The highest peak, 1,752 m, is shared between Guinea and Côte d’Ivoire. Rather less than half, the south-western part, of the mountain chain is Liberian territory. The isolated situation of the Nimba mountains gives them the character of an enormous inselberg. The site is contiguous with both IBAs GN017 and CI003, in Guinea and Côte d’Ivoire respectively. The slopes of the ridge are steep and extensively forested. The lower slopes are covered with mixed forest which grades, at 800–900 m, into Parinari cloud-forest, characterized by Parinari excelsa and many epiphytes. Above 1,200 m, on the peaks and ridges, the character of the forest changes again to montane forest dominated by Parinari excelsa and Garcinia polyantha with gnarled and stunted trees, seldom exceeding 9–10 m in height. In moist places, at about 1,000 m, there are several small areas with almost pure stands of the tree-fern Cyathea cylindrica. This, at least, is how Liberian Nimba used to be; much of the forest has now been destroyed through mining operations—see below. There are some isolated patches of grassland savanna, particularly at the foot of the western side of central Nimba. These grasslands extend into and are more extensive in Guinea. Hyparrhenia diplandra is the dominant grass, with Andropogon macrophyllus colonizing termite mounds. On the eastern slopes the vegetation merges into lowland forest. Dense cloud covers the Nimba mountains above 850 m for much of the year, and the average annual rainfall on Liberian Nimba is 3,000 mm. The wettest months are during May–October.
See Box and Tables 2 and 3 for key species. The forest avifauna of the Nimba mountains is extremely rich, although the current status of many of these species in the Liberian part is, as a result of the effects of mining, unclear. It is probable that Agelastes meleagrides at least no longer occurs. This is the only site in the country from which Prinia leontica is known.
Non-bird biodiversity: The floristic and faunistic importance of the Nimba mountains is considerable. Endemic flora include the fern Asplenium schnelli and the flowering plants Blaeria nimbana, Osbeckia porteresii and Dolichos nimbaensis. More than 500 species of fauna new to science have been described from specimens collected in the Nimba mountains, mostly however from the Guinean and Ivoirian territory. Endemics include the amphibian Schoutedenella nimbaensis, known only from the type-locality in Guinea, the viviparous toad Nimbaphrynoides occidentalis (EN) and the small mammal Micropotamogale lamottei (EN). Other, non-endemic, mammals of conservation concern include Colobus polykomos (LR/nt), Procolobus badius (LR/nt), Cercopithecus diana (VU), Pan troglodytes (EN), Syncerus caffer (LR/cd), Hexaprotodon liberiensis (VU), Genetta johnstoni (DD) and Cephalophus jentincki (VU). The current status of these on the Liberian side of the border in unknown.
Pressure/threats to key biodiversity
Part of the site was proposed as a Nature Reserve in 1983. The area includes two small National Forests, Nimba East and Nimba West. Over the last 30 years, mining of the extremely rich iron-ore deposits has destroyed much of the forest on the ridges and slopes of Mount Nimba in Liberia. The run-off from mining operations has caused pollution and siltation in the Yah river, the only important river in Liberian Nimba. In addition, the mining operations have led to a much increased human population in the area and consequent burning, farming and hunting activities. Although operations ceased during the civil war, the lasting effects of mining have had a disastrous effect on the conservation potential of the area. A large number of refugees displaced by the war settled in camps in the Nimba area. Surveys are needed to establish the current situation and to refine, if appropriate, site boundaries.
BirdLife International (2021) Important Bird Areas factsheet: Nimba mountains. Downloaded from
http://www.birdlife.org on 22/10/2021.