Otzi-Atiya

A(i)Site contains one or more globally threatened species, C(iii)Site contains nationally threatened or restricted habitat or vegetation types, AND/OR habitats that have severely declined in extent nationally

Otzi-Atiya qualifies as an IPA under criterion A(i) triggered by the presence of seven Vulnerable plant taxa, namely Afzelia africana, Aloe macleayi, Ansellia africana, Cordyla richardii, Khaya grandifoliola, K. senegalensis and Vitellaria paradoxa. It also qualifies under criterion C(iii) as it is one of the five best sites in Uganda for the nationally threatened (Endangered) habitat of Vitellaria (Butyrospermum ) wooded grassland.

The Otzi-Atiya IPA covers Otzi (East and West), Atiya and Ayipe Central Forest Reserves and Otze Forest Wildlife Sanctuary, as well as some currently unprotected and threatened habitat of Vitellaria woodland in the landscape where the natural vegetation is still partially intact. The IPA is situated in Metu sub-county of Moyo District, east of Moyo town. It is located on an escarpment (or high ridge) overlooking the confluence of the Achwa River with the White Nile as it flows into South Sudan. It is bounded to the north by the international border with South Sudan (Davenport & Howard 1996). About half of the area can broadly be classified as Vitellaria (Butyrospermum) wooded grassland, whilst the rest is Combretum wooded grassland with undifferentiated semi-deciduous thicket. Due to the sparse population densities around the reserves as well as steep slopes and rugged terrain which limit cultivation, the protected areas are mainly intact except for light encroached enclaves, mainly at the lower altitudes.

This IPA is important for holding extensive areas of intact savanna vegetation types, and id one of the best sites in Uganda for the nationally Endangered habitat of Vitellaria (Butyrospermum) wooded grassland (Richards et al. 2024), representing 3.9% of the national resource for this habitat. The botanical richness of Otzi-Atiya IPA includes 261 species of trees and shrubs (Davenport & Howard 1996). This richness is likely to increase significantly once all the other plant life forms are fully surveyed. The site holds populations of seven Vulnerable plant taxa, namely Afzelia africana, Aloe macleayi, Ansellia africana, Cordyla richardii, Khaya grandifoliola, K. senegalensis and Vitellaria paradoxa.

Afzelia africana is a widely distributed tree species in Africa, from Senegal eastwards to South Sudan and Uganda, and south to Democratic Republic of the Congo (Hills 2020). However, its population has declined significantly, primarily as a result of over-exploitation for timber with an estimated global population reduction of at least 30% over three generations (Hills 2020).

Aloe macleayi has only recently been found from this site, where it occurs in grassy areas on rock outcrops, and the known locations within this IPA all lie outside of protected areas at present. It is otherwise known only from the Agoro-Agu CFR, also an IPA, and from the Imatong Mountains of South Sudan (Weber & Carter 2013) where it is considered to be threatened (Cole & Forrest 2017). It has been assessed as globally Vulnerable (H. Wheatcroft, in press). The Otzi-Atiya IPA therefore represents an opportunity to protect this species in Uganda.

Ansellia africana is a globally Vulnerable orchid species found throughout tropical and southern Africa (Crook 2013). It occurs in savannas and riverine vegetation, growing on trees and shrubs. Although no documented information is available on the utilisation of this species in Uganda, there is excessive collection of it for commercial purposes in neighbouring Kenya (Crook 2013).

Cordyla richardii is a range-restricted tree species known only from northern Uganda and South Sudan. It has been assessed as globally Vulnerable (Makerere University Institute of Environment and Natural Resources 1998). There is scanty information on the uses of this species within its native range. This IPA is considered to be one of the critical sites in Uganda for this species.

Khaya grandifoliola has been assessed as Vulnerable globally (Hawthorne 1998). It is a localised tree species in Uganda which occurs more frequently in dry semi-deciduous forest and forest outliers. The major threat facing its population in this IPA is the exploitation of mature individuals for timber which eventually retards regeneration.

Khaya senegalensis has been categorised as Vulnerable in the IUCN Red List of Threatened Species (World Conservation Monitoring Centre 1998). It is a very important and valuable timber tree species that is widely exploited throughout its range. In fact, logging and local exploitation are the major threats to this taxon.

Vitellaria paradoxa is globally Vulnerable (Makerere University Institute of Environment and Natural Resources 1998). The largest populations of this species in Uganda are in the eastern and northern regions. Felling this species for charcoal burning is by far the biggest threat to this species in this IPA and other parts of Uganda (Kalema and Beentje 2012). This species is a major component of the threatened habitat of Vitellaria wooded grassland.

The habitat in Otzi-Atiya comprises of Vitellaria (Butyrospermum)-Hyparrhenia and dry Combretum savanna with undifferentiated semi-deciduous thicket (Langdale-Brown et al. 1964, Davenport & Howard 1996), as well as riverine fringing forest, bamboo thickets and Protea communities (Howard et al. 1997). The relief includes rocky ridges, steep hillsides, plateaux, ravines, and broader river valleys. The Western arm of the Mount Otzi forest reserve has steep gorges with a highly rugged terrain while the eastern area has rolling hills rising in a series of hills and peaks. Thus, the western arm is not easily accessible, limiting human disturbance, while the eastern is relatively accessible by both livestock and humans (Acanakwo 2010).

The geology of the area is composed of schist, quartzite and marble which occur in the mountains surrounding Metu County (SOER, 1994 in Acanakwo 2010). Generally, the West Nile region is underlain by rocks of the basement complex of Precambrian age which are composed largely of granite fascia-grade rocks (BIMCO, 2017 cited in UNRA 2021). The area is largely composed of sandy alluvial sediments with vertisol-arenosol complexes (FAO, 2018 cited in UNRA 2021) towards the Nile.

The area receives a tropical wet and dry (savanna) climate with a mean annual temperature at 27.7o C and ca. 1,250 mm of annual rainfall. There is a distinct dry period that begins from December to February while November and March have moderate rainfall. Rainfall is divided into two peaks of April and August-October (UPPA, 2000). The rain is associated with the northern and southern movements of the intertropical front.

Otze Forest Wildlife Sanctuary was established in 1946 and is under the management of Uganda Wildlife Authority (UNEP-WCMC & IUCN 2024). Otzi (East and West) and Atiya Central Forest Reserves were established in 1948 while Ayipe was established in 1965, and all are under the jurisdiction of National Forestry Authority (NFA). This IPA, together with Lobajo and Era CFRs in the west, are some of the nature conservation sites in the Sudanian Regional Centre of Endemism (White 1983) in Uganda.

Otzi-Atiya IPA is mostly intact except for some light encroachment especially in the lower elevations, due to the sparse population density around the reserve as well as the rugged terrain that greatly limit human settlement and cultivation. However, around Metu sub-county, farmland has increased by at least 10% between 1986 and 2004 because of the relatively flat plains with deep well drained soils and the available transport infrastructure (Acanakwo 2010). The reserve also experiences annual disturbances caused by wild fires ignited by inhabitants of the area in search of pasture for livestock. There is also a threat of exploitation of species such as Khaya grandifoliola whose mature individuals are felled for timber, and this retards its regeneration. According to Plumptre et al. (2019), Mt. Otzi is a priority site for conservation in Uganda but is among the 11 poorly funded and protected forest reserves. The site qualifies as a Key Biodiversity Area due to the presence of a range-restricted mammal, the Moon shrew (Crocidura selina).

In the Northern and West Nile regions of Uganda where this IPA is located, Afzelia africana has declined dramatically in recent years due to harvesting for charcoal and carvings for the tourist market (Kirunda et al. 2016). The rampant illegal harvesting of the species has also been driven by timber export to Asia and charcoal production. As a response, the government banned its harvest and trade in 2017, though this did not stop illegal harvesting. Additionally, the species is also categorized as a reserved taxon by the National Forestry Authority (NFA).

The local communities consider the Otzi and Atiya CFRs as a natural store of forest products from which they obtained both woody and non-woody forest products (Acanakwo 2010). It is a significant site for harvesting of poles, building materials and other non-timber forest products by the adjacent communities. Other products include firewood for domestic use, wood for small scale industry such as brick baking, iron works; fibre, thatch, herbal medicine, wild edible fruits, and vegetables; and game meat (Acanakwo 2010). The forest reserve is also important as a water catchment area (BirdLife International 2024). Additionally, it provides habitat to over 168 bird species including 14 of the 22 species native to the Sudan-Guinea Savannah Biome found in Uganda, thus providing an opportunity for bird watching. However, due to its remote location, very little ecotourism takes place here at present.

Assessed by:

Samuel Ojelel, Makerere University Herbarium

James Kalema, Makerere University Herbarium

Iain Darbyshire, Royal Botanic Gardens, Kew

Haley Gladitsch, Royal Botanic Gardens, Kew

Date of first assessment: 12th Nov 2024

Reviewed by:

William Olupot, Nature and Livelihoods