Mpanga Gorge

UGATIPA2
Mpanga Gorge

Country: Uganda

Administrative region: Western (Region)

Central co-ordinates: 0.06650 N, 30.32150 E

Area: 0.88km²

Qualifying IPA Criteria

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

IPA assessment rationale

Mpanga Gorge qualifies as an IPA under criterion A(i), hosting the entire global population of the Critically Endangered cycad, Encephalartos whitelockii.

Site description

Mpanga Gorge is situated in Kamwenge District of western Uganda and covers an area of 0.88 km2. The IPA encompasses the gorge around Mpanga Falls, with the Mpanga River flowing towards Lake George, situated 3 km southwest of the site. The gorge itself has steep slopes, with an incline around 35° in places, while altitudes range from 920 m in the valley floor toward Lake George up to 1175 m at the upper edge of the gorge.
Part of the site falls within Queen Elizabeth National Park, although the majority of the IPA falls outside this protected area. The site has been subjected to serious degradation through the construction of a hydroelectric dam on the waterfall. However, as the host of the only population of Encephalartos whitelockii known globally, Mpanga Gorge is of great botanical significance. The site is also thought to support one of the highest concentrations of arborescent cycads globally, with much of the population focused within a 70ha area (Roberts 2008).

Botanical significance

Mpanga Gorge is of great botanical importance as it contains the entire population, estimated to consist of around 8,000 individuals, of the Critically Endangered cycad Encephalartos whitelockii or Muhure cycad (Kalema 2010). This rare arborescent cycad is under threat due to the previous construction of a hydroelectric dam within the gorge, alongside agriculture, particularly the use of fire to refresh pasture.
E. whitelockii occurs mostly on the gorge slopes, and surveys suggest that juveniles (seedlings and saplings) are significantly more abundant than mature individuals (Ogwal 2017). While loss of individuals is expected between life stages, the degree of drop off between saplings and mature trees is such that the population has likely been subject to considerable disturbance (Ogwal 2017). As cycads are long-lived species that take time to reach maturity, the loss of individuals before maturity will have significant impacts on seed production in the future.

Habitat and geology

The slopes of Mpanga Gorge are largely covered by moist forest dominated by Cynometra alexandri (ironwood). Vepris trichocarpa is also very common in the lower storey of this forest while shrubs, including Whitfieldia elongata, are common in the understorey (Darbyshire #1066, #1072). On the upper slopes of the valley, forest transitions to woodland with common species in this woodland including Cordia monoica, Dodonaea viscosa, Grewia bicolor and Strycnos xx (Darbyshire, pers. comm.). The substrate underlying this IPA is a mixture of black granitic soil and areas of sandy loam within the forest (Musis, Harrop & Luzinda 1960).
Encephalartos whitelockii grows on rocky granitic slopes in areas of open grassland and at forest edges (Kalema & Beentje 2012). Species that grow in association with E. whitelockii include Combretum molle and Grewia mollis (Ogwal 2017). On very steep slopes, vegetation is very open and cycads are most abundant in these areas. Alongside E. whitelockii, there are numerous succulent Euphorbia xxx.
Further research is needed to fully categorise the habitats of this site.

Conservation issues

Only a small part of Mpanga Gorge is within Queen Elizabeth National Park (QENP), with around 90% of the global population of Encephalartos whitelockii falling outside the National Park (Ogwal 2017). There have been previous discussions surrounding the expansion of QENP into Mpanga Gorge (Nampindo & Plumptre 2005); however, this has not come to fruition to date. Due to the presence of this Critically Endangered cycad, the site has been proposed as a Key Biodiversity Area, with the additional recommendation that this site should be a priority for conservation financing (Plumptre et al. 2017).
The site suffered extensive disturbance with the construction of a small hydroelectric dam on Mpanga Falls in 2011. This dam diverts water away from the falls through a channel used to generate energy. While the Ugandan Wildlife Authority did raise objections to this development, mostly due to the large and unique population of E. whitelockii at this site, the National Environment Management Authority granted permission for it to proceed (Roberts 2008).
The impact of the changing hydrology on the E. whitelockiii is not fully understood as yet. However, the change in waterflow and mist precipitation may be detrimentally impacting this cycad (Kalema 2010). The construction of the dam itself resulted in the mortality of many E. whitelockii individuals, when access roads were built along contour lines where cycads are most concentrated (Roberts 2008; Kalema & Beentje 2012).
The other major risk to habitats is agricultural activity. Cycads have been seen at the borders of crop gardens at the forest edge and, as such, it has been inferred that farming may have restricted the distribution of E. whitelockii to more inaccessible areas (Ogwal 2017). While the steep gorge sides are largely unsuitable for farming, the use of fire to refresh pasture on the hills above and within the gorge itself has led to destruction of cycads. In addition, farmers would previously bring their cattle down the steep gorge sides to access water, causing habitat disturbance at the site (Bradley 2019). People have also been injured, and on rare occasions killed, traversing the steep gorge slopes to access clean drinking water from the Mpanga River (SOSpecies et al. 2017).
However, a partnership between the NGOs JESE and PROTOS alongside the IUCN Save Our Species Programme has helped to support conservation of E. whitelockii among local communities. New hydraulic pumps were installed to bring water up and outside the gorge, with pumps for both people and livestock. This benefits local communities by providing easier and safer access to clean drinking water and making water more accessible for cattle, which in turn reduces the disturbance on E. whitelockii caused by accessing the river gorge (Moorthamers 2016). In addition, the pumps have been used to support crop irrigation which has reduced reliance of local people on maize and has allowed the growth of a wider range of fruit and vegetable crops, thereby improving nutritional variety and increasing income through agricultural sales (Lawrence & Christopher 2020).
As part of the same conservation programme, the area in which E. whitelockii grows has been demarcated by white poles and awareness has been raised among local people. PROTOS also undertook a 15-month project focussing on propagation of Encephalartos whitelockii seedlings which included the construction of 8 large propagators that can house up to 6,400 seeds, alongside training of youth group leaders in caring for seeds in the propagators (Bradley 2019). While it was previously thought that this cycad was dependent on baboons for germination, seeds were successfully germinated in propagators in community nurseries. Seedlings have subsequently been planted out in the gorge in areas where fire has previously destroyed cycads and also along the access roads where cycads were previously cleared (JESE 2017). A subsequent Darwin Initiative project focussed on Ugandan cycads raised 6,700 E. whitelockii seedlings between 2014 and 2017, with over 6,000 of these planted at two sites within the gorge (Pritchard & Seal 2017). Further research is required to understand how well these seedlings have persisted in the area. As part of this Darwin Initiative project, engagement work was also undertaken, including the production of educational materials and the inclusion of two additional local communities in nursery work (Pritchard & Seal 2017).
There have been reports of some collecting of the cycad for ornamental purposes, which would have a detrimental impact on an already threatened population (Kalema 2010). However, with the success of the local propagation programmes, local people are now able to sell E. whitelockii seedlings sustainably, providing an income source while also increasing cycad numbers (IUCN Save Our Species et al. 2017).

Ecosystem services

Encephalartos whitelockii provides a number of ecosystem services. Seedlings of this species are sold to collectors and sustainable propagation has been established amongst local communities to meet this demand (Bradley 2019). While thousands of seedlings were produced as part of the Darwin Initiative project, the vast majority were replanted as only ca. 100 seedlings were sold per three to six month period (Pritchard and Seal 2017). In addition to its use as an ornamental, E. whitelockii is used for building materials while the cones are edible (Kalema & Beentje 2012).
Tourist trails have been established within the gorge, with the presence of E. whitelockii the main draw. However, due to the steep gorge sides these tours are limited in terms of accessibility (Kabiza Wilderness Safaris 2022). The Uganda Tourist Board is also looking to capitalise on interest in E. whitelockii further and develop tourism opportunities similar to other initiatives in South Africa, such as the Modjadji Cycad Nature Reserve. Scoping is being undertaken for other tourist activities that could be hosted in the gorge including water rafting, zip lining, rock climbing and cable cars (Amia 2019). While tourism in the area could help support and secure the population of E. whitelockii, further developments would need to consider the sensitivity of the ecosystem and not exacerbate the threats already faced by this unique cycad species. The infrastructure and increased footfall that would be associated with establishing the aforementioned tourist activities would likely cause significant damage to the integrity of the site.
The river itself is important for fishing, with fish forming a significant part of the diets of local communities, and is also used to generate power through the hydroelectric dam around Mpanga Falls (Nampindo & Plumptre 2005; Moorthamers 2016). The habitats of this site are also likely important in maintaining ecosystem integrity, particularly for the wetlands downstream of this site in QENP.

Site assessor(s)

IPA criterion A species

Species Qualifying sub-criterion ≥ 1% of global population ≥ 5% of national population 1 of 5 best sites nationally Entire global population Socio-economically important Abundance at site
Encephalartos whitelockii P.J.H.Hurter A(i) True True True True True Abundant

Encephalartos whitelockii P.J.H.Hurter

Qualifying sub-criterion:
A(i)
≥ 1% of global population:
True
≥ 5% of national population:
True
1 of 5 best sites nationally:
True
Entire global population:
True
Socio-economically important:
True
Abundance at site:
Abundant

General site habitats

General site habitat Percent coverage Importance
Forest - Subtropical/Tropical Moist Lowland Forest No value Major
Wetlands (inland) - Permanent Rivers, Streams, Creeks [includes waterfalls] No value Minor
Savanna - Moist Savanna No value Minor
Rocky Areas - Rocky Areas [e.g. inland cliffs, mountain peaks] No value Minor
Artificial - Terrestrial - Pastureland No value Minor
Artificial - Aquatic - Canals and Drainage Channels, Ditches No value Minor

Forest - Subtropical/Tropical Moist Lowland Forest

Percent coverage:
No value
Importance:
Major

Wetlands (inland) - Permanent Rivers, Streams, Creeks [includes waterfalls]

Percent coverage:
No value
Importance:
Minor

Savanna - Moist Savanna

Percent coverage:
No value
Importance:
Minor

Rocky Areas - Rocky Areas [e.g. inland cliffs, mountain peaks]

Percent coverage:
No value
Importance:
Minor

Artificial - Terrestrial - Pastureland

Percent coverage:
No value
Importance:
Minor

Artificial - Aquatic - Canals and Drainage Channels, Ditches

Percent coverage:
No value
Importance:
Minor

Land use types

Land use type Percent coverage Importance
Industrial development No value Major
Agriculture (pastoral) No value Minor
Tourism / Recreation No value Minor

Industrial development

Percent coverage:
No value
Importance:
Major

Agriculture (pastoral)

Percent coverage:
No value
Importance:
Minor

Tourism / Recreation

Percent coverage:
No value
Importance:
Minor

Threats

Threat Severity Timing
Energy production & mining - Renewable energy High Ongoing - stable
Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming Low Ongoing - declining
Natural system modifications - Fire & fire suppression - Increase in fire frequency/intensity Medium Ongoing - declining
Residential & commercial development - Tourism & recreation areas Medium Future - planned activity

Energy production & mining - Renewable energy

Severity:
High
Timing:
Ongoing - stable

Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming

Severity:
Low
Timing:
Ongoing - declining

Natural system modifications - Fire & fire suppression - Increase in fire frequency/intensity

Severity:
Medium
Timing:
Ongoing - declining

Residential & commercial development - Tourism & recreation areas

Severity:
Medium
Timing:
Future - planned activity

Protected areas

Protected area name Protected area type Relationship with IPA Areal overlap
Queen Elizabeth National Park National Park protected/conservation area overlaps with IPA No value

Queen Elizabeth National Park

Protected area type:
National Park
Relationship with IPA:
protected/conservation area overlaps with IPA
Areal overlap:
No value

Conservation designation

Designation name Protected area Relationship with IPA Areal overlap
Mpanga Falls Key Biodiversity Area protected/conservation area overlaps with IPA No value

Mpanga Falls

Protected area:
Key Biodiversity Area
Relationship with IPA:
protected/conservation area overlaps with IPA
Areal overlap:
No value

Bibliography

Kalema, J., & Beentje, H., 2012

Conservation Checklist of the Trees of Uganda

Amia, P., 2019

Uganda Tourism Board Targets 300 Million Year Old Cycad Plants

Available online

Bradley, S., 2019

6,400 Seeds of Critically Endangered Cycads Planted

Available online

IUCN Save Our Species, Protos, Tooro Botanic Gardens & Joint Effort to Save the Environment, 2017

Save Our Cycad!

Kabiza Wilderness Safaris, 2022

The Cycad Trail in the Mpanga River Gorge-Best Cycad Location in Africa

Available online

Kalema, J., 2012

Encephalartos whitelockii. The IUCN Red List of Threatened Species 2010: e.T41928A10601803.

Available online

Lawrence, T. & Busiinge C., 2020

IWRM Program - Positively Impacting Communities in Mpanga River Catchment

Available online

Moorthamers, D., 2016

Exchange Uganda 2016: Action Research & Integrated Water Resources Management

Harrap, J.F.,

The Soils of the Western Province of Uganda

Nampindo, S. & Plumptre, A., 2005

A socio-economic assessment of community livelihoods in areas adjacent to corridors linking Queen Elizabeth National Park to other protected areas in Western Uganda

Ogwal, J. J., 2017

Population structure of the Cycad along River Mpanga, Western Uganda

African Journal of Rural Development, Vol 2, page(s) 95–103

Plumptre, A. J., Ayebare, S., Pomeroy, D., Tushabe, H., Nangendo, G., Mugabe, H., Kirunda, B. & Nampindo, S., 2017

Conserving Uganda’s Biodiversity: Identifying critical sites for threatened species. Unpublished Report to USAID and Ministry of Tourism, Wildlife and Antiquities

Pritchard, H., & Seal, C., 2017

Darwin Initiative Final Report: Protecting Ugandan endemic cycads from biodiversity loss and trafficking

Roberts, A., 2008

New threat to Ugandan cycads

Oryx, Vol 42, page(s) 325–328 Available online

Recommended citation

(2024) Tropical Important Plant Areas Explorer: Mpanga Gorge (Uganda). https://tipas.kew.org/site/mpanga-gorge/ (Accessed on 21/05/2024)