Nimini Hills North

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

The Nimini Hills North IPA hosts two globally threatened species and is recognized as the best site nationally for Cola boxiana EN, therefore meeting criterion A(i). Approximately 50% of intact forest within this IPA remains intact, suggesting there maybe additional threatened species yet to be recorded in this area. Extensive research is necessary to confirm species presence. A well-structured management plan could potentially trigger criterion C(iii) for this IPA, which is currently accounts for 5% of moist evergreen forest in the country. However, the IPA is under immense threats of mining and logging activities.

The Nimini Hills Important Plant Area encompasses the Nimini Hills forest reserve, which is approximately 129 km², along with surrounding areas located in the southwest of Kono District. The Nimini Hills North forest shares boundaries with three chiefdoms: Nimiyama, Nimikoro, and Gorama. The nearest city, Koidu, is located about 40 kilometers away. The site is situated on distant mountains that are characterized by gaps and rolling hills, and it contains some good stands of undisturbed forests, totalling around 12,000 ha, However, mining and logging activities have significantly affected the portion of land shared with Nimikoro Chiefdom, resulting in existence of several substantial forest fragments within the IPA.

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The Nimini North IPA is biologically significant, it help protect an intact forest significant within the upper Guinean biodiversity hotspot and it contains two globally threatened plant species Cola boxiana EN and Combretum fulvum. The near threatened is also commonly found within this IPA Trichoscypha longifolia. Large tree species may include Parkia bicolor, Uapacca guniensis, Cola chlamydantha, Pyncnanthus angolensis, Canarium schweinfurthii Albizia zygia, Xylopia aethiopica, Piptadeniastrum africanum, Terminalia ivoriensis, Terminalia superba, Terminalia superba, and Chlorophora regia with a diverse understory of small trees, shrubs, and herbs. The higher slopes support forest with smaller-stature trees, and abundant epiphytes (Vines).

The vegetation of Nimini Hills North is characterised by moist evergreen and semi-deciduous forests on hill slopes with disturbances largely occurring mostly in the southeast of the reserve and beyond (Terry, 2012). Intact moist evergreen and semi-deciduous forests constitute about 45 % of the area, while the remaining vegetation includes vine forest formations (24.3), likely influenced by soil type or slope, as well as disturbed vegetation such as farm bush and secondary forest mostly located outside the reserve (Terry, 2012).
The IPA is situated in a wet microclimate, where the rolling hills act as topographic impediment against wet-season inclement weather systems from the Atlantic, resulting in an average annual rainfall of 2,659 mm. The site's elevation ranges between 232 to 750 m above sea level, with the topography varying from flat bottomlands to steep hillsides, and rounded ridge-tops (Terry, 2012). Geologically, the site is part of an Archean greenstone belt, measuring 2 to 8 km wide, lying within the West African Craton of the African Shield. It is surrounded by granitoid rocks to the east and west, interbanded with sedimentary formations,
including banded ironstones. The topsoil is deep and well drained with some laterite present, underlain by metamorphic rocks (Lebbie et al., 2023).

The main threats within this IPA includes extensive mining of gold and diamonds, despite Nimini Hill North being designated as a forest reserve in 1921. In 2008, the Trans-Atlantic Logging Mompany conducted a forest inventory (results unpublished) in Nimini Hills North Extension 1, which led to a temporary logging ban and shut down of commercial logging in the district in 2009 (Terry, 2012). Currently, a mining company, Wongor Mining Company, has been allocated 2/3 of the land for gold mining, while another company, Treesdales Company, has been granted logging rights within sections of the forest reserve. The mining company occupies approximately 15% of the available land in the region; however, the boundary is unclear to community members as they currently have a 25-years lease agreement with the government (Terry, 2012; Lebbie et al., 2023). Additionally, small-scale logging using power saws is rampant, with only a few saw owners obtaining timber licenses. The Nimini Hills Forest Reserve is already a significantly depleted and threatened forest, showing very few signs of wildlife and human footprints evident throughout the reserve, except in the far south. To preserve much of its forest cover in the future, a comprehensive inventory of all plant species, threats, and their status is required, alongside stringent management of the forest resources to maintain this vital resource. Control of small-scale logging with power saws are essential to prevent further depletion of standing timber in the reserve.
The road network to the site is in dilapidated and challenging condition.

The area provides raw materials and food for local communities. Portions of the land are cleared for farm bush and slash-and-burn agriculture, primarily for cacao and other vegetables, which supports the livelihood of local residents (Lebbie et al., 2023; Terry, 2012). In addition, the area is home to a several animal species such as Maxwell's duiker, black duiker, bushbuck, red river hog, bay duiker, yellow-backed duiker, porcupine, civet, and Colobus monkey. These species are under immense threat of poaching activities throughout the region (Terry, 2012).

Fanny Massally, Royal Botanic Gardens, Kew

Date of first assessment: 10th Apr 2026

Aiah Lebbie, The University of Sierra Leone