Sango Bay

A(i)Site contains one or more globally threatened species, B(iii)Site contains an exceptional number of socially, economically or culturally valuable species

Sango Bay qualifies as an IPA under criterion A(i) with a total five trigger taxa, one Critically Endangered, one Endangered and four Vulnerable taxa meeting A(i) thresholds. Additional threatened species are known from Minziro Forest Reserve, which adjoins this IPA across the Tanzanian border, and it is highly likely that some of these species occur within this IPA and might also trigger sub-criterion A(i).
207 B(iii) species = 19% of the national list.

Sango Bay is a grouping of five separate Central Forest Reserves (CFR) in Rakai District of Uganda’s Central Region. These forest reserves include Malabigambo and Kaiso Forest Reserves, which meet the Uganda-Tanzania border at their southern extent, Namalala, nearest to Sango Bay town, and Tero East and Tero West Forest Reserves situated at the northernmost extent of this grouping.
Falling within the Kagera River floodplain, this site is dominated by swamp forests and inundated grasslands (Luke et al., in prep.). The swamp forests of Malabigambo and Kaiso from a continuous habitat corridor with Minziro Forest Reserve in Tanzania.
While the entirety of Sango Bay IPA falls within protected areas, much of the forest at these sites is secondary as it has been heavily logged in the past and continues to face threats from small-scale wood harvesting (Howard 1991; NELSAP-CU 2021). However, these forests are of significant conservation importance as together they encompass all of Uganda’s Baikiaea-Podocarpus Seasonal Swamp Forest and together represent the most extensive swamp forest known nationally (Langdale-Brown et al. 1964).

Sango Bay is of great botanical significance as one of the few, and most extensive, examples of swamp forest in Uganda. The site is highly biodiverse, possibly because the forests were Pleistocene refugia while forests elsewhere receded due to arid climatic conditions (Bakamwesiga et al. 2000). A checklist of the plants of the Sango Bay CFRs, and neighbouring Minziro Forest Reserve, compiled by Luke et al. (In prep), includes 576 different taxa recorded from Sango Bay (including taxa that have not been identified or described).
Several taxa recorded from this site are known to be globally threatened with extinction, for instance, Sango Bay is the only site globally from which the Critically Endangered variety Vangueria volkensii var. fyffei is known. This variety is known only from its type collection, made in Malabigambo CFR in 1913, and is threatened by habitat loss and disturbance within this forest (Gereau et al. 2017). Further research is therefore needed to confirm the continued presence of V. volkensii var. fyffei at this site.
One Endangered species, Rytigynia acuminatissima is known from this site. Although this species is also known from D.R. Congo, Rwanda, Burundi, Tanzania and Kenya, a number of sites throughout this species’ range are threatened by habitat loss with some local extirpations recorded (Ntore et al. in prep.). In addition, four Vulnerable species are known from this site: Psilotrichium majus, Grewia rugosifolia, *Dicranolepis pyramidalis* and Dasylepis eggelingii. The lattermost is near-endemic to Uganda, with the majority of this species’ range falling within Uganda’s borders and only three localities known from D. R. Congo (Kalema et al. 2021).
Two additional Vulnerable species, Khaya anthotheca and Prunus africana, are known from the Sango Bay Forest Reserves. Both of these species are socio-economically important: both species are harvested for their timber while P. africana is also used for its medicinal properties. Although both have been assessed as Vulnerable, they do not trigger sub-criterion A(i) at this site as they are widespread across Tropical Africa and nationally.
Although not an IPA trigger species, Afrocarpus dawei is of note as it is globally assessed as Near Threatened and is known only northern Tanzania, eastern D. R. Congo and Uganda (Farjon 2013). This species was previously co-dominant within this IPA, but only immature individuals remain due to extensive harvesting in the past (Luke et al., in prep.).
Some additional range-restricted and threatened plant species are known from neighbouring Minziro forest, which is contiguous with Malabigambo and Kaiso CFRs of Sango Bay, but have not yet been recorded from this IPA. Close to double the total number of plant taxa known from Sango Bay have been recorded in neighbouring Minziro including some species of conservation importance (Luke et al., in prep.). For instance, the range restricted species Oldenlandia lancifolia var. seseensis, which is only known from Minziro and Bugala and Bussi Islands in Lake Victoria, is also likely to occur within Sango Bay (Gereau et al. 2019). In addition, there are eight threatened species known from Minziro that have not yet been recorded from Sango Bay including the Endangered species Albertisia exelliana, Blotiella trichosora and Psychotria bagshawei (Luke et al., in prep.). Further survey work in the forests of Sango Bay would likely reveal the presence of some of these species currently only known from the Tanzanian side of this forest.

Sango Bay IPA is a wetland landscape, dominated by swamp forests alongside some permanently flooded papyrus swamp and seasonally inundated grasslands (NELSAP-CU 2020). The area is underlain by granite and gneiss basement rocks, overlain by sandstones, with clay-peat soils throughout most of the IPA (Langdale-Brown et al. 1964; Elshehawi et al. 2019; NELSAP-CU 2020). The site experiences a bi-modal rainy season, from September to November and March to May with average precipitation ranging from 800 to 2,000 mm and daily temperatures averaging around 28°C (NELSAP-CU 2020).
Much of the IPA is covered by swamp forest, which Howard (1991) found to be an outlier of the Guineo-Congolian forests in terms of species composition. Langdale-Brown et al. (1964) categorise these forests as Baikiaea-Podocarpus seasonally flooded swamp dominated by Baikiaea insignis, a species typical of Guineo-Congolian forest, and Podocarpus latifolius (LC). Both of these species are valued for their timber (IUCN 2022) and, as a result of previously widespread logging at this site, the majority of stands at this site are now secondary forest (Luke et al., in prep). Due to the high moisture levels at this site, Usnea lichens are common (Langdale-Brown 1964). Afrocarpus dawei (formerly Podocarpus usambarensis var. dawei) was previously co-dominant at this site, however, logging for its timber has greatly decreased the population size at this site (NELSAP-CU 2020) and this species is now assessed as Near Threatened on the IUCN Red List (Farjon 2013). The swamp forests within this IPA are important for several threatened taxa including Vangueria volkensii var. fyffei (CR) and Rytigynia acuminatissima (EN).
There is some papyrus swamp within this IPA, dominated by Cyperus papyrus, which is mostly confined to parts of Tero West and Namalala (Langdale-Brown et al. 1964). Areas of seasonally inundated grassland include co-dominant species such as Hyparrhenia diplandra, H. rufa, Imperata cylindrica, Setaria sphacelata and Sorghastrum stipoides (Luke et al., In prep.).

Sango Bay IPA consists of five different Central Forest Reserves, Malabigambo, Kaiso, Namalala, Tero East and Tero West, each established in 1932 (World Resources Institute 2022). The Malabigambo and Kaiso CFRs are of particular importance as they form a continuous forest patch with Minziro across the border in Tanzania. This large area of forest is of great importance for supporting viable and resilient populations of species that would otherwise not survive in more fragmented habitat (Howards 1991). However, there has been a long history of logging within this IPA, particularly of dominant Podocarpus and Afrocarpus species which were harvested for timber, such that much of these forest stands are now secondary regeneration.
The Sango Bay forests are still used by local communities today, particularly as a source of fuelwood but also for harvesting materials, medicines, food and for grazing livestock (Bakamwesiga et al. 2000). The impact of most of these activities on the habitats of this IPA is yet to be quantified. There is some encroachment into wetland habitats by farmers when land becomes degraded elsewhere, while there is also a potential future threat from the establishment of commercial sugarcane or rice cultivation in the area (NELSAP-CU 2020). Sango Bay Estates Limited, one of the largest sugar manufacturers in Uganda, has plantations covering around 65,000 hectares northwest of this site (Luke et al., in prep). There is a potential future threat of encroachment into this IPA, or indirect habitat disturbance through disruption or degradation of water supply to this IPA.

However, the Nile Equatorial Lakes Subsidiary Action Program (NELSAP) has been working in the area to better understand the threats and conservation needs of both Sango Bay and Minziro, compiling a Conservation Investment Plan to help promote and direct conservation funding for the area. In addition, as part of the the 2003 National Forestry and Tree Planting Act, several Collaborative Forest Management (CFM) groups have been established around CFRs within Sango Bay. The aim of these groups is to “improve forest conservation and livelihoods of forest adjacent communities” and they have attracted support from both NGOs and research initiatives (Kazoora et al. 2019). However, a number of CFM agreements have not been formalised and large areas of land allocated to tree planting are being used for food crops. Despite some limitations, there have also been successes, for example, the Kigazi CFM was able to raise their concerns of illegal encroachment in Malabigambo CFR with the President of Uganda (Kazoora et al. 2019).

The wider Sango Bay area, was assessed in 2012 as an Important Bird Area, based on the presence of significant populations of biome-restricted bird species, as well as some threatened bird species such as Grey Parrot (Psittacus erithacus, EN) and Blue Swallow (Hirundo atrocaerulea, VU) (Birdlife International 2022). The presence of Blue Swallow also triggers a Key Biodiversity Area (Plumptre 2019). The Sango Bay-Musambwa Island-Kagera Wetland System (SAMUKA) RAMSAR site has been designated due to the unique wetland habitats. SAMUKA meets several RAMSAR criteria including unique wetland habitat that represents a regional transition between central and eastern Africa, the presence of large waterbird colonies and records of numerous threatened taxa (Byaruhanga & Kigoolo 2005). All three of these conservation designations cover a larger area than the proposed IPA, including the wetland habitats between the CFRs of this IPA.

The Sango Bay forests are of great importance to local communities. The site is a source of timber and fuelwood, while several tree species from this area are noted to have medicinal properties (NELSAP-CU 2021). Numerous different plants are valued for their fibres, including Ficus natalensis which has traditionally been used in the area to produce bark cloth, which itself has great cultural significance in some local communities and is still produced in nearby Kyotera (NELSAP-CU 2020).
The wetland environments, some of which retain water year-round, attract pastoralists from drier districts including Lyantonde and Lwengo as a reliable source of water for their cattle (NELSAP-CU 2021). The site also has great value in carbon sequestration. The Kagera basin, including much of this IPA, is underlain by peat soils which are known to store large amounts of carbon dioxide (Elshehawi 2019).
There may be some tourism potential as the site is reasonably accessible due to its proximity to Masaka and the Masaka-Kakuto road and the wide variety of plant and faunal taxa may attract ecotourists to the site. Although the seasonal flooding of the area may limit accessibility at times.
A paleolithic archaeological site of global importance at Sango Bay, after which the Sangoan tool manufacturing style is named, covers wetland and forested areas dating from around 200,000 years ago (NELSAP-CU 2020).
The wetland habitats promote soil stability which, in turn, prevents silting in the Kagera River and Lake Victoria (NELSAP-CU 2020).