Kalinzu Central Forest Reserve

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

Kalinzu CFR meets sub-criterion A(i) of the IPA criteria, with seven Endangered and seven Vulnerable taxa known from this site (see botanical significance). This site also triggers sub-criterion B(iii) for exceptional botanical richness in useful species. This IPA has 13% of the national list for useful plant species, far exceeding the 3% threshold needed to trigger B(iii). Finally, this site also triggers criterion C(iii) as one of the five best sites nationally for threatened habitat medium altitude evergreen forest.

Kalinzu Central Forest Reserve (CFR) is located across Bushenyi, Rubirizi and Mitooma Districts of Western Region along the Albertine Rift escarpment, 20 km east of Lake Edward. This IPA occupies a landscape of undulating hills dominated by mid-elevation, deciduous forest and is an important conservation corridor, connecting the Queen Elizabeth protected areas (Queen Elizabeth National Park, Kyambura and Kigezi Wildlife Reserves, North and South Maramagambo CFRs) to the west with Kasyoha-Kitomi CFR in the east. This site was visited in 2023 as part of Uganda TIPAs fieldwork.

Kalinzu CFR is a hugely important site for plant conservation and is one of the richest nationally for species threatened with extinction. In total, there are seven species assessed as Endangered and seven as Vulnerable on the IUCN Red List. One of these Endangered species, the liana Tiliacora latifolia, is endemic to Uganda, known from only five localities. This species has not been collected at Kalinzu since 1938, however, there have been no extensive surveys looking for this species and good habitat remains at this site. We can conclude that the species is very likely to be extant at Kalinzu, although further surveys are highly recommended.
For two other Endangered species, the epiphtic orchid Kylicanthe bueae and the understorey tree Pavetta ankolensis, Kalinzu is the only site known nationally. For the former species this is the only site known in the entire East Africa floral region. K. bueae has a disjunct distribution and is otherwise native to west Africa where several localities are known to be threatened by habitat loss (Cheek & Cable 2000). P. ankolensis, contrastingly, is a range-restricted species known from only the Lake Edward to Lake Kivu section of the Albertine Rift but is also threatened elsewhere in its range with localities in neighbouring D.R. Congo subject to forest fragmentation and encroachment (De Block, Simo-Droissart & Tack 2021). For both of these species, Kalinzu represents an important site, both on a national and global scale, to conserve them.
In addition to K. bueae, four other threatened epiphytic orchids are known from this site, all of the same genus: Polystachya hastata (VU), P. laurentii (VU), P. nyanzensis (VU) and P. meyeri (EN). P. laurentii is known from across western and central Africa with Kalinzu representing the easternmost locality globally and the only record in Uganda and the East Africa floral region (Gereau et al. 2019). All but one of the extinction risk assessments for these species noted that these epiphytic orchids may be threatened at Kalinzu by illegal tree felling (Fischer et al. 2019a; Fischer et al. 2019b; Gereau et al. 2019).
Two timber species that are globally threatened with extinction are also known from this site. Mimusops bagshawei and Prunus africana are both categorised as Vulnerable. Notably, P. africana is widespread in sub-Saharan Africa but Kalinzu is known to host one of the largest populations of this species nationally (BGCI 2023). P. africana was observed during Uganda TIPAs fieldwork to be frequent in forest margins in the south-east along the tea estates. Mimusops bagshawei has a more restricted distribution, native to Kenya, Rwanda, South Sudan, Tanzania and Uganda, and is threatened at several sites by habitat degradation (Amani et al. 2022).

Kalinzu is one of the richest sites nationally for useful species, with 13% (142 species) of the national checklist of useful plants present within this IPA exceeding the 3% threshold to trigger criterion B(iii). In total, 96 species from this IPA have uses as materials (32%), while this site has a significant proportion of species used for fuel nationally (41% – 78 species). One particularly notable species within this IPA, Warburgia ugandensis, is valued for both its timber and medicinal properties (Orwa 2009). W. ugandensis has been assessed as nationally Vulnerable due to unsustainable harvesting (Orwa 2009; WCS 2016). In Uganda this species is recorded in at least five forests, and only 53 adult trees were found in Kalinzu CFR (Ipulet et al 2011). There are two useful species not found elsewhere in the IPA network, namely Lasiosiphon glaucus and Rytigynia neglecta.

In addition to species of conservation importance, the site is one of the five best for nationally Vulnerable medium altitude evergreen moist forest. Kalinzu hosts an estimated 124 km2 of this habitat, 8.7% of the national resource, the third largest area for this forest nationally. Protection of this habitat also supports populations of the forest-dependent, threatened species known from this site.

Kalinzu CFR lies on the edge of the Albertine Escarpment and, with neighboring Maramagambo, occupies a continuous forest gradient across over 900 m in altitude. This is of great significance for conservation of the forest species as the ecosystem likely has some resilience against climatic changes. Kasunju Hill represents the highest point in the reserve (1836 m) and a collection of the Endangered species Pavetta ankolensis was made on this hill. Overall, the forest is underlain by gneisses and schists, with some prominent quartzite ridges, with deep red loamy soils (Howard 1991; Howard, Davenport & Baltzer 1996).
Kalinzu CFR is categorised as median altitude moist evergreen forest. Parts of this IPA are dominated by Parinari excelsa while areas of mixed forest consist of species such as Drypetes spp., Strombosia scheffleri and Funtumia africana (Hashimoto & Tashiro 1999). The Vulnerable tree species Musanga leo-errerae is a common pioneer at this site (Kalema & Hamilton 2020) and its presence defines a distinct type of secondary forest at the site, described by Hashimoto & Tashiro (1999) as “Musanga-dominated secondary forest”, although such areas are mixed in nature with other species such as F. africana similarly abundant.

Kalinzu CFR was established in 1932. Part of the reserve was cleared to establish Kyamuhunga and Igara tea plantations in 1954. Though forest encroachment is largely controlled, some private planters permitted within the CFR, usually growing Eucalyptus and food crops, are known to have exceeded their land allocation and have annexed over 75 acres of additional land (WWF 2015). The site has previously been targeted by pitsawing, for instance, the area designated as a Nature Reserve within Kalinzu, west of Kasunju Hill, has previously been heavily exploited for timber (Howard 1991; Lwanga 1996). Some illegal logging continues today while unsustainable harvesting of bark of highly commercial, medicinal tree species, particularly Warburgia ugandensis, threatens the forest and the activity continues unabated to date (Ipulet et al 2011; CUPTD Workshop 2023).
To improve sustainable resource use in the CFR, collaborative forest management (CFM) group, the Ndangara and Nyakiyanja Parishes Tutungukye Group, was established following an initiative led by the National Forest Authority and the World Wide Fund for Nature (WWF 2016). The group has been designated a 350 ha area of land within the north of the forest reserve for planting trees, beekeeping and plots for food cultivation. Alongside this, they are also able to collect non-timber forest products from part of the forest (WWF 2014). In turn, the CFM group has agreed not to extract timber or poach wild animals elsewhere in the forest and report others coming to the reserve to undertake illegal activities. Further support for tree planting in communities surrounding Kalinzu CFR, in the parishes of Rubirizi and Mitooma, has been delivered through the Trees for Global Benefits initative, led by Ecotrust and Plan Vivo. The initiative is a carbon offsetting scheme which links carbon markets to rural livelihoods through planting of native tree species, including threatened species, and small-scale use of planted trees for provision of fuel and timber to reduce pressure on protected areas such as Kalinzu (ECOTRUST 2020).
Kalinzu also benefits from a significant chimpanzee population and has been recognised as a Key Biodiversity Area due to the presence of this species (Plumptre et al. 2019). The conservation of chimpanzee within the CFR helps support the protection of the entire forest ecosystem. The Kalinzu Forest Research Project, launched in 1992 and run in collaboration between The Primate Research institute, University of Kyoto and the NFA. This NGO is focused on the research and conservation of primates, particularly chimpanzee, at Kalinzu (Primate Research Institute, 2024). In addition to running the Kalinzu Conservation Education Centre, the NGO has conducted long standing research on primates in the forest, maintains a trail system, a field station, and ecotourism services that include local communities. The project has contributed immensely to conservation of the forest.
Kalinzu Eco Lodge was under construction during the Uganda TIPAs visit to the site in 2023. The site was made accessible by constructing a new road of around 0.5 km. We observed the growth of invasive species such as Lantana camara and Solanum mauritianum on the newly created forest margins. While the presence of an Eco Lodge may well provide sustainable livelihoods and offer greater security from threats such as logging and encroachment, care is needed to ensure that further disturbance to the ecosystem is minimised.

Kalinzu supports a strong ecotourism sector, in part, due to the presence of chimpanzees although the site is also important for other faunal taxa, including two butterfly species endemic to the site (WWF 2014). A new eco-lodge was under construction during our 2023 visit and elsewhere the site hosts a visitors’ centre, that helps to educate visitors on the conservation work undertaken at the reserve.
Modelling suggests that this site has high carbon stocks (Kasangaki et al. 2012), while given the position and size of this site on the edge of the Albertine escarpment, Kalinzu has an important role in stabilising soils and in water catchment.
This IPA is one of the richest nationally for useful plant species (see Botanical Significance). The forest provides resources to local communities through the CFM plots, where smallholder crops and timber trees are grown as well as hosting apiaries, while parts of the forest are accessible for collection of firewood, medicinal plants (WWF 2014, 2016). Edible mushrooms are also harvested from the site, although they may be at risk of over-harvesting (P. Ipulet, pers. comm. 2024). Bark of Warburgia ugandensis is harvested, at an unsustainable rate, within this IPA (Ipulet et al 2011) while Zanthoxylum mildbraedii and Prunus africana bark is harvested to a lesser extent.

Sophie Richards, Royal Botanic Gardens, Kew

Iain Darbyshire, Royal Botanic Gardens, Kew

Florence O'Sullivan, Royal Botanic Gardens, Kew

Samuel Ojelel, Makerere University Herbarium

James Kalema, Makerere University Herbarium