Kibale

A(i)Site contains one or more globally threatened species, B(ii)Site contains an exceptional number of species of high conservation importance, B(iii)Site contains an exceptional number of socially, economically or culturally valuable species, C(iii)Site contains nationally threatened or restricted habitat or vegetation types, AND/OR habitats that have severely declined in extent nationally

Kibale National Park qualifies as an IPA under all three criteria. Twenty-four species known from Kibale are threatened with extinction, triggering criterion A(i). The site supports globally important populations of 18 taxa (1 Critically Endangered, 8 Endangered and 9 Vulnerable), including four unique to Kibale within the Ugandan IPA network: Rotheca violacea subsp. kigeziensis (CR), Aerangis jacksonii (EN), Albertisia exelliana (EN) and Dicliptera alternans (VU). In addition, it supports nationally important populations of several species, including Entandrophragma cylindricum (VU) and Turraeanthus africanus (VU). Further, A(i) trigger species are also present at this site, as Kibale contains populations of five further globally Vulnerable timber species, including Prunus africana, but it is currently uncertain whether the populations in this IPA meet the thresholds under this sub-criterion. Under criterion B, Kibale qualifies under B(ii) as it is among the top 13 richest sites for endemic taxa, whilst under criterion B(iii) it contains 200 (19%) species on the national checklist of useful species, and so greatly exceeds the 3% threshold. Alongside species of conservation importance, Kibale triggers criterion C(iii) as it contains extensive areas of Medium Altitude Evergreen Moist Forest (VU) for which this IPA is the best site nationally, encompassing 17% of the national resource.

Kibale National Park (KNP) is situated in Kabarole, Kamwenge, Kasese and Kyenjojo Districts of Western Uganda. It covers an area of 794 km2, extending over 50 km from north to south, and between 8 and 25 km from east to west, with an elevation range of 920 to 1590 m a.s.l. It lies primarily on the western Ugandan plateau to the southeast of Fort Portal and northeast of Kasese towns, but with its southwestern portion extending down the escarpment onto the Rift floor. The park is crossed in its northern sector by the main Kampala to Fort Portal road, and in its central sector by the Fort Portal to Kamwenge road, with the park headquarters and main ecotourist centre lying along the latter road at Kanyanchu. The southern boundary of the park is contiguous with the northern extension of Queen Elizabeth National Park and encompasses the northern part of the Lake George Ramsar site. KNP supports extensive areas of intact rainforest across an undulating terrain which is drained by a number of rivers. These include the Mpanga and Dura that flow southwards to Lake George, passing through more open bushland, savanna and swampy habitats in the southwest portion of the National Park.

The northern portion of this IPA contains extensive areas of the nationally Vulnerable habitat Medium Altitude Evergreen Moist Forest, a sub-type of Lake Victoria drier peripheral semi-evergreen Guineo-Congolian rainforest. Kibale is the best site nationally for this sub-type, representing 17% of the national resource. This habitat is now largely restricted to protected areas, although it is thought to have been previously more widespread (Richards et al. 2024a, 2024b). The extensive forests of this IPA contain several plant species of conservation concern, with important populations of 18 globally threatened taxa. These include two Ugandan endemics, the shrubby liana Rotheca violacea subsp. kigeziensis (CR), Kibale being its only protected site, and the epiphytic orchid Aerangis jacksonii (EN - pending), which is otherwise known historically only from Mpanga Central Forest Reserve (CFR), Fort Portal and the nearby Amabeere Caves where the subpopulations are likely to be threatened or extinct. For both these taxa, therefore, Kibale is the prime site for their future survival. Other threatened species of note are Albertisia exelliana (EN), a widespread but scarce liana known from only two areas in Uganda, with the second being Entebbe, where it may no longer be extant, and the forest herb Dicliptera alternans (VU), for which Kibale is the only known Ugandan site. It is also a key site for Dasylepis eggelingii (VU), which is frequent and widespread in the forest here (I. Darbyshire, pers. obs. 2017).

Although not an IPA trigger species, the presence of Acanthopale macropcarpa (LC) at Kibale is notable as this species is otherwise known only from Kakamega Forest in Kenya and from a recently discovered population at Cyamudongo in Rwanda (E. Fischer, pers. comm., 2017). This species is assessed as LC because of effective conservation measures at Kibale and Kakamega. At Kibale, it was recorded as “common on lower slopes and ridge tops” at Kanyawara (T. Struhsaker #377, 1982). This IPA is the only known Ugandan site and the easternmost locality globally for another scarce liana, Syrrheonema fasciculatum (Eilu 1999), which is not yet evaluated on the IUCN Red List. The Kibale subpopulation is notable for having irregularly lobed/toothed leaves and may warrant subspecific status (I. Darbyshire, unpubl. data). Kibale is also the only known Ugandan site for other more widespread taxa, including Embelia nilotica, Engloerophytum natalense (LC) and Euclinia longiflora (LC) (Lwanga 1996a).

Important timber species of conservation concern at this site include Entandrophragma cylindricum (VU), Milicia excelsa (NT) and Lovoa swynnertonii (NT). Overall, Kibale is the third most species-rich IPA in the network for useful plants, containing 200 (19%) species on the national checklist of useful species. Amongst these, it holds the second-highest proportion of food (83 spp., 16% of total food species) and medicinal (163 spp., 22%) species. The site also contains high numbers of species used for fuel (84 spp., 44%) and materials (107 spp., 36%) (O’Sullivan et al 2025).

It should be noted that most of the records of conservation priority species at Kibale are from the northern, wetter section of the park and that the southern drier and more open sections are less significant botanically. However, the Near-Threatened succulent tree Euphorbia dawei has been recorded from Kisangi CFR within the southwest of the park (Lwanga 1996).

Based on survey data for birds, mammals, lepidoptera and trees, Kibale ranks as the fifth most species-rich site, the fourteenth for rarity value and seventh for overall biodiversity importance within the Ugandan forest reserve network (Howard et al. 2000). A total of 351 tree and shrub species have been recorded from the site, excluding the recently incorporated southwestern portion, whilst only 98 tree and shrub species were recorded in the Kisangi CFR (Lwanga 1996a, 1996b). Several subsequent botanical surveys have been conducted (e.g., Eilu et al. 2004; Poulsen et al. 2005; Hafashimana 2010). In particular, surveys of the epiphytic plant communities of Kibale (Mucunguzi 2007, 2008; Hafashimana 2010) have also revealed significant richness, with 57 epiphytic orchid species noted, including frequent Eggelingia ligulifolia (EN), and many species scarce in Uganda, such as Angraecum minus. Botanical survey of this large site, however, remains incomplete, particularly for non-woody terrestrial taxa, and further species of conservation concern are likely to be uncovered here.

The forest at Kibale transitions from medium altitude moist evergreen forest in the north to medium altitude moist semi-deciduous forest in the south. In the north at elevations over 1,500 m, Parinari excelsa dominates with Aningeria (Pouteria) altissima, Carapa grandiflora, Newtonia buchananii, Olea welwitschii and Strombosia scheffleri as typical associates. At 1200 – 1500 m elevation, where the large majority of the forest lies, dominant species include Celtis africana, Diospyros abyssinica, Gambeya (Chrysophyllum) albida, G. gorungosana, Markhamia lutea, Newtonia buchananii and Piptadeniastrum africanum, with P. excelsa occurring in low numbers. In the south at 1100 – 1200 m elevation, it is dominated by Pterygota mildbraedii and Olea welwitschii with Diospyros abyssinica, Lovoa swynnertonii and Markhamia lutea. Pure stands of Cynometra alexandri (ironwood) occur along the southern river valleys. Trema orientalis is a common pioneer of secondary forest habitats. The flat terrain in the southwest, which is often flooded, holds stands of palms of Phoenix reclinata and Raphia (presumably R. farinifera), together with Pandanus chiliocarpus (Howard 1991; UWA 2015). These areas also support extensive grassland and swamp communities. Dominant species in the drier grasslands are Cenchrus purpureus, Imperata cylindrica and Cymbopogon nardus, indicators of past disturbance and periodic burning (UWA 2015). Acanthus polystachius scrub typically dominates the transition from forest to grassland (Zanne & Chapman 2005).

The underlying rocks are pre-Cambrian in age and are sedimentary, strongly folded and sometimes metamorphosed. Prominent ridges of quartzite, schists and phyllites, intruded by amphibolites, gneiss and granites overlie these formations, whilst some hills have exposed layers of hard laterite. Most of the site has red ferralitic sandy clay loams and clay loams of low to moderate fertility except for a small area in the west around Mpokya and Isunga where fertile eutrophic soils occur over volcanic ash. The climate is tropical with two rainfall peaks, from March to May and September to November. Annual mean temperature range, minimum: 14–15C, maximum: 26–27C, the temperatures being highest on the Rift Valley floor in the southwest. Annual rainfall ranges from 1,100–1,700 mm, mostly during March – May and September – November (Howard 1991; Howard et al. 1996; UWA 2015).

Kibale was first gazetted as a Crown Forest in 1932 and was managed as a Forest Reserve of 560 km2 until 1993 when it was designated as a National Park. By incorporating the Kibale Forest Corridor Game Reserve and most of the 54 km2 Kisangi CFR in the southwest, the newly created National Park was expanded to 794 km2 and became contiguous with Queen Elizabeth National Park to the south. Kibale is recognised as a Key Biodiversity Area based on the important populations of chimpanzee (Pan troglodytes, EN) and Uganda mangabey (Lophocebus [albigena] ugandae, VU) as well as the endemic tree Balsamocitrus dawei (EN) (Plumptre et al. 2019). The site is also an Important Bird Area, with high richness in restricted-range and biome-restricted species as well as supporting three globally threatened bird species (BirdLife International 2024).

As a Crown Forest, the main objective at Kibale was exploitation for timber and charcoal, hence, the site was subject to selective logging particularly in the northern sector where a sawmill was established in 1950. Harvesting of wild robusta coffee (Coffea canephora) also occurred, with peak yields of 40 tons p.a. (UWA 2015). Elsewhere, particularly in the south, the forest was severely encroached by local farmers (Face the Future 2011). Some areas of forest are, therefore in the process of regeneration and restoration. The natural regeneration process has been slower than anticipated in areas where logging resulted in a high level of canopy openings, potentially due to a combination of the lack of rapid colonising tree species, elephant activity being concentrated in logged areas and an aggressive herbaceous community (Chapman & Chapman 1997). All human activity, except research and tourism, was initially excluded when Kibale was first designated as a National Park, and the enforcement of the boundary resulted in effective protection of habitats within the park. Indeed, analysis of satellite imagery from 1984 to 2003 revealed that the forest and other natural habitat cover in Kibale was stable throughout that period (Southworth et al. 2010). However, much of the park is adjacent to areas of high and growing human populations and intensive cultivation. This resulted in significant transformation of habitats outside the park in the same 1984 – 2003 time period, including expanding commercial tea plantations and continuing forest fragmentation and wetland loss (Southworth et al. 2010). Further, human-wildlife conflicts around the park margins increased due to crop raiding and damage by animals from the park and the laying of snares by local farmers, and there is also continued encroachment and setting of fires and illegal harvesting of wild resources from within the park. The current management strategy (UWA 2015), therefore gives more emphasis to balancing biodiversity conservation with support for local community needs. This is achieved in part through zonation of the park, each zone with permitted and restricted activities; these include (a) a narrow Resource Use Zone as a 1 km band along the boundary of selected areas of the park, where sustainable harvesting of wild resources is permitted, (b) three Tourism Zones where ecotourist activities and infrastructure are focused, (c) a large Wilderness Zone where resource use is prohibited and disturbance is minimised, and (d) a ca. 100 km2 Restoration Zone. This latter zone is the site of an ongoing reforestation scheme led by Face the Future (Netherlands) and UWA in the previously encroached southern plateau area of the park, which has been in place since the 1990s, with 6,500 ha restored to date (Face the Future 2011, 2024). The tree species planted include Bridellia micrantha, Cordia africana, C. millenii, Croton macrostachyus, C. megalocarpus, Spathodea campanulata and Warbugia ugandensis. Past plantations of exotic conifers and other non-native timber trees are in the process of being removed, along with the eradication of other invasive species of concern, including Lantana camara and Senna spectabilis (UWA 2015). Furthermore, a community conservation programme is fully integrated into the new management plan to reduce the human-wildlife conflicts around the park boundary and to generate local income streams (UWA 2015).

From an ecological and conservation perspective, Kibale is one of the most comprehensively studied forest sites in Africa, with over 40 years of continuous research by a range of participants, resulting in over 500 scientific publications (Southworth et al. 2010). The Makerere University Biological Field Station has been operating at Kanyawara since 1985 and provides both research and training functions (UWA 2015). However, much of the research carried out has been directed at the fauna and/or the more general ecology of the site, with research into the floristic diversity remaining limited and much further research needed on the understorey diversity in particular.

Kibale National Park provides critical habitat for a rich biodiversity within an area otherwise surrounded by intensive agricultural activity and high population densities. This diversity includes the greatest range and concentrations of primates in East Africa, (Face the Future 2011), with 13 species present, including the largest population of chimpanzees, some of which are habituated (UWA 2015). The park also holds 372 bird species. As a result, Kibale is an important site for ecotourism. Between 2005 and 2012, visitor numbers increased modestly from ca. 6,500 to ca. 10,000. Tourism provides an important source of income and employment and so forms an important part of the current business plan for the park (UWA 2015). The forest also provides some provisioning services for local communities within the Resource Use zone of the new management plan and provides important regulatory services, including carbon sequestration and the provision of fresh water resources as part of the important water catchment area feeding Lake George and the Albertine Rift (UWA 2015). The forest also protects the plateau and escarpment soils from erosion.

Iain Darbyshire, Royal Botanic Gardens, Kew

Sophie Richards, Royal Botanic Gardens, Kew

James Kalema, Makerere University Herbarium

Samuel Ojelel, Makerere University Herbarium

Florence O'Sullivan, Royal Botanic Gardens, Kew

Date of first assessment: 19th Nov 2024

Patrick Mucunguzi, Makerere University